BOREAS AFM-04 Twin Otter Aircraft Flux Data Summary The BOREAS AFM-04 team used the NRC Twin Otter aircraft in 1994 and 1996 to make measurements in the boundary layer of the fluxes of sensible and latent heat, momentum, ozone, methane, and carbon dioxide, plus supporting meteorological parameters such as temperature, humidity, and wind speed and direction. Aircraft position, heading, and altitude were also recorded, as were several radiometric observations for use in interpretation of the data (greenness index, surface temperature, incoming and reflected radiation). Data were collected at both the NSA and SSA during the three 1994 IFCs and in July and August of 1996. These data are stored in tabular ASCII files. Table of Contents * 1 Data Set Overview * 2 Investigator(s) * 3 Theory of Measurements * 4 Equipment * 5 Data Acquisition Methods * 6 Observations * 7 Data Description * 8 Data Organization * 9 Data Manipulations * 10 Errors * 11 Notes * 12 Application of the Data Set * 13 Future Modifications and Plans * 14 Software * 15 Data Access * 16 Output Products and Availability * 17 References * 18 Glossary of Terms * 19 List of Acronyms * 20 Document Information 1. Data Set Overview 1.1 Data Set Identification BOREAS AFM-04 Twin Otter 1994 Aircraft Flux Data 1.2 Data Set Introduction The BOReal Ecosystem-Atmosphere Study (BOREAS) Airborne Fluxes and Meteorology (AFM)-04 team used the National Research Council (NRC) Twin Otter aircraft in 1994 and 1996 to make measurements in the boundary layer of the fluxes of sensible and latent heat, momentum, ozone, methane, and carbon dioxide, plus supporting meteorological parameters such as temperature, humidity, and wind speed and direction. Aircraft position, heading, and altitude were also recorded, as were several radiometric observations for use in interpretation of the data (greenness index, surface temperature, incoming and reflected radiation). Data were collected at both the Northern Study Area (NSA) and Southern Study Area (SSA) during the three 1994 IFCs and in July and August of 1996. These data are stored in tabular American Standard Code for Information Interchange (ASCII) files. 1.3 Objective/Purpose The Twin Otter was one of four flux aircraft operated in BOREAS. The purpose of its flights was to make measurements in the boundary layer of the fluxes of sensible and latent heat, momentum, ozone, methane, and carbon dioxide, plus supporting meteorological parameters such as temperature, humidity, and wind speed and direction. Aircraft position, heading, and altitude were also recorded, as were several radiometric observations for use in interpretation of the data (greenness index, surface temperature, incoming and reflected radiation). These data will be used to attempt to relate boundary layer processes (atmosphere/vegetation exchanges) to radiometric data available from satellites, i.e., ground truthing of satellite data. Through this research, it is hoped that techniques can be developed to utilize satellite data for global monitoring of climate change. 1.4 Summary of Parameters Temperature, Dewpoint Temperature, Pressure, Downwelling Radiation, Upwelling Radiation, Greenness Index, Three Orthogonal Components of the Wind Velocity, Along-Wind Component, Across Wind Component, H2O Mixing Ratio, CO2 Mixing Ratio, Ozone Concentration, Methane, Sensible Heat Flux, Latent Heat Flux, Momentum Flux, Carbon Dioxide Flux, Ozone Flux, Methane Flux, Aircraft Position, Heading, Altitude (Radar and Pressure), Surface Temperature, Satellite Simulator 1.5 Discussion The Twin Otter operated in all three Intensive Field Campaign (IFCs) in 1994. In 1994 the aircraft made 57 flights, including 1100 flux runs. In 1996, a total of 27 project flights were made. The recorded data rate was increased from 16 Hz (as in 1994) to 32 Hz (for 1996), improving the resolution of the data contributing to the flux estimates. The archived data were collected on straight and level flux runs over the BOREAS site and on regional runs between Prince Albert and Thompson and in each project area. A variety of flight profiles are possible (grids, L- patterns, profiling stacks, soundings), which are described in Section 7.3. The archive data include run-averaged data, focusing on the fluxes and the supporting meteorological, radiometric, and aircraft positional data. No attempt was made to archive the high-rate (16-Hz or 32-Hz) data, which can be acquired from NRC directly, if required. There was a significant difference in the instrumentation configuration on the Twin Otter for 1996 when compared with the 1994 campaign. It carried additional cloud physics and aerosol instruments belonging to the Atmospheric Environment Service (AES). These additional data are not included in this data set. Please consult MacPherson (1996) and MacPherson and Bastian (1997) for detailed information about the instrument configurations in 1994 and 1996. 1.6 Related Data Sets BOREAS AFM-01 NOAA/ATDD Long-EZ 1994 Aircraft Flux Data over the SSA BOREAS AFM-02 Wyoming King Air 1994 Aircraft Flux and Moving Window Data BOREAS AFM-03 NCAR Electra 1994 Aircraft Flux Data BOREAS AFM-03 NCAR Electra 1994 Aircraft Moving Window Data BOREAS AFM-04 NRC Twin Otter Aircraft Sounding Data BOREAS AFM-05 Level-1 Upper Air Network Data BOREAS AFM-05 Level-2 Upper Air Network Standard Pressure Level Data 2. Investigator(s) 2.1 Investigator(s) Name and Title J. Ian MacPherson Flight Research Laboratory Institute for Aerospace Research National Research Council of Canada Ottawa, Ontario Canada Raymond L. Desjardins Centre for Land and Biological Resources Research Agriculture Canada Central Experimental Farm Ottawa, Ontario Canada 2.2 Title of Investigation Atmospheric Boundary Layer Analyses from Canadian Twin Otter Aircraft 2.3 Contact Information Contact 1 ---------- J. Ian MacPherson National Research Council Ottawa, Ontario Canada (613) 998-3014 (613) 952-1704 (fax) jim@u614ji.iar.nrc.ca Contact 2 ---------- David Knapp Raytheon ITSS NASA GSFC Greenbelt, MD (301) 286-1424 (301) 286-0239 (fax) David.Knapp@gsfc.nasa.gov 3. Theory of Measurements A series of reports addressing the theory and practice of measuring atmospheric variables from a moving, aircraft platform may be found in MacPherson (1981, 1988, 1990a, 1990b, 1992, 1996) and MacPherson and Bastian (1997). A basic requirement for measuring gas fluxes from a moving aircraft is to account for the motion of the air relative to the motion of the aircraft. The true air motion is derived from the vector difference between the air velocity relative to the aircraft velocity relative to the ground. Air motion relative to the aircraft is measured by a nose-mounted gust boom incorporating a Rosemount 858AJ28 5-hole probe. This device and the associated pressure transducers measure static pressure (altitude), dynamic pressure (airspeed) and the angles of attack and sideslip. These instruments in combination with a global positioning system (GPS) and an inertial reference system (IRS) are used to derive the flux measurements. 4. Equipment 4.1 Sensor/Instrument Description The Twin Otter atmospheric research aircraft is a highly instrumented platform for research on the atmospheric boundary layer, air pollution, etc. Descriptions of the aircraft and its instrumentation and software are given in detail in MacPherson (1981, 1988, 1990a, 1990b, 1996) and MacPherson and Bastian (1997). The instruments used to make these measurements included: Parameter Instrument Sensible Heat Rosemount fast response 102DJ1CG Incident Solar Rad. Kipp and Zonen CM-11 pyranometer (305-2800 nm range) Reflected Solar Rad. Eppley pyranometer Greenness Index Skye Industries Vegetation Greenness Indicator Surface Temperature Barnes PRT-5 infrared radiometer Satellite Simulation Exotech 100BX Satellite Simulator CO2, H2O LI-COR LI-6262 CO2/H2O analyzer (these CO2 data reported to BORIS) ESRI (developed by Agriculture Canada) Dew Point E, G, and G Model 137-S10 Cambridge dew point sensor Ozone TECO Ozone Analyzer Model 49 (these O3 data reported to BORIS) GFAS (unit borrowed from German Aerospace Research Establishment) Scintrex LOZ-3 ozone detector Momentum Wind Components Inertial Velocity Litton LTN-90-100 Inertial Reference System Position Trimble Model TNL-7880SR GPS/VLF/Omega Altitude (AGL) Sperry AA-200 Radio Altimeter (1994 and 1996) Riegl LD-90-3 Laser Altimeter (1996 only) 4.1.1 Collection Environment The data were collected from the aircraft, flying at various altitudes. 4.1.2 Source/Platform Twin Otter DHC-6-200 twin turboprop utility transport. Maximum gross takeoff weight 11,579 lb. Service ceiling 20,000 ft. Endurance 3 to 4 hours, depending on instrumentation and weather. 4.1.3 Source/Platform Mission Objectives The primary objective was to measure the vertical flux of sensible and latent heat, CO2, ozone, methane, and momentum for scaling up surface-based measurements to regional scales. The ultimate objective is to develop algorithms to relate boundary layer processes to satellite-derived data. 4.1.4 Key Variables Temperature, Dewpoint Temperature, Pressure, Downwelling Radiation, Upwelling Radiation, Greenness Index, Three Orthogonal Components of the Wind Velocity, Along-Wind Component, Across Wind Component, H2O Mixing Ratio, CO2 Mixing Ratio, Ozone Concentration, Methane, Sensible Heat Flux, Latent Heat Flux, Momentum Flux, Carbon Dioxide Flux, Ozone Flux, Methane Flux, Aircraft Position, Heading, Altitude (Radar and Pressure), Surface Temperature, Satellite Simulator 4.1.5 Principles of Operation A basic requirement for measuring gas fluxes from a moving aircraft is to account for the motion of the air relative to the motion of the aircraft. The true air motion is derived from the vector difference between the air velocity relative to the aircraft velocity relative to the ground. Air motion relative to the aircraft is measured by a nose-mounted gust boom incorporating a Rosemount 858AJ28 5-hole probe. This device and the associated pressure transducers measure static pressure (altitude), dynamic pressure (airspeed) and the angles of attack and sideslip. These instruments in combination with a global positioning system (GPS) and an inertial reference system (IRS) are used to derive the flux measurements. The principles of operation of the aircraft and its other instrumentation and software are given in detail in MacPherson (1981, 1988, 1990a, 1990b, 1996) and MacPherson and Bastian (1997). 4.1.6 Sensor/Instrument Measurement Geometry See MacPherson (1988, 1990a, 1990b, 1996) and MacPherson and Bastian (1997). 4.1.7 Manufacturer of Sensor/Instrument See Sections 4.1 and 6, and MacPherson (1988, 1990a, 1996) and MacPherson and Bastian (1997). 4.2 Calibration Instruments on the aircraft were calibrated prior to each IFC. Key instruments (such as temperature probes) were calibrated two or three times during each IFC. 4.2.1 Specifications Not available. 4.2.1.1 Tolerance Not available. 4.2.2 Frequency of Calibration All instruments were calibrated at least once per IFC. 4.2.3 Other Calibration Information See MacPherson (1988, 1990a, 1990b, 1996) and MacPherson and Bastian (1997). 5. Data Acquisition Methods There were several types of flight profiles. These are described in MacPherson (1988, 1990a, 1996) and MacPherson and Bastian (1997). Plotted flight tracks are shown for every flight. One hundred and twenty-eight channels of data are recorded digitally in 16-bit words at 16 samples per second (1994) or 32 samples per second (1996) on a Digital Archive Tape (DAT) Drive. Most signals are low- pass filtered with a breakpoint of 5 Hz to prevent aliasing. Fluxes are calculated using the procedures detailed in MacPherson (1990b, 1996, 1997). It should be noted that in the final submission to the BOREAS Information System (BORIS), three sets of flux and root mean square (RMS) data were submitted. The first used untreated time histories in the derivation of fluxes using the eddy correlation technique, the second used linearly detrended data, and the third used time histories that were high-pass filtered with a third-order algorithm with a break point set at 0.012 Hz (5 km wavelength). It is felt that most scientists working with these data would prefer to use the linearly detrended data. Data from the National Center for Atmospheric Research (NCAR) and University of Wyoming King Air aircraft were archived with the identical formats. 6. Observations 6.1 Data Notes None. 6.2 Field Notes Note: 128 channels of data are recorded digitally in 16-bit words at 16 samples per second on a DAT drive. Signals are low-pass filtered with a breakpoint of 5 Hz to prevent aliasing. The following table lists the 128 recorded signals. Not all of these are archived to BORIS (see Section 8), but many contribute to calculated quantities such as true airspeed, wind velocity, fluxes, etc. **Note:*** This is basically the recorder buffer to be used in the site visit in May 1993. Additional parameters were recorded in BOREAS (e.g., satellite simulator). A Trimble global positioning system (GPS) replaced or augmented the Loran-C in 1994. Channel Number Variable Name Units Recorded Instrument Description Resolution (per bit) __________________________________________________________________________ 1 FILEHR HRS 1 NAE CLOCK COMBINED WORD, TAPE FILE AND GMT HOURS. 2 MINSEC MIN/SEC 1 NAE CLOCK COMBINED WORD, GMT MINUTES/ SECONDS. 3 EVENT - 1 EVENT MARKER MULTI LEVEL EVENT MARKER 4 LTD DEG 1 ARNAV LORAN-C | LATITUDE DEGREES 5 LTM MIN 0.01 MODEL 40-AVA-100 | LATITUDE MINUTES 6 LGD DEG 1 "" | LONGITUDE DEGREES 7 LGM MIN 0.01 "" | LONGITUDE MINUTES 8 LTML MIN 0.01 LITTON INERTIAL REF | LATITUDE MINUTES 9 LGML MIN 0.01 SYSTEM, LTN-90-100 | LONGITUDE MINUTES 10 HDGT DEG 0.1 SPERRY C-12 GYRO TRUE HEADING (MAGNETIC HEADING CORRECTED TO TRUE HEADING USING MAG VARIATION OUTPUT FROM LORAN-C) 11 HDGTL DEC 0.1 LITTON 90 IRS TRUE HEADING, LITTON 12 WDTI DEG 0.1 * DERIVED* WIND DIRECTION FROM DOPPLER/ INERTIAL SYSTEM, DEGREES TRUE ( NOTE 1) 13 WDTL DEG 0.1 * DERIVED* FROM LITTON SYSTEM (SEE NOTE 2) 14 WSMI M/S 0.01 * DERIVED* WIND SPEED FROM DOPPLER INERTIAL SYSTEM ( NOTE 1) 15 WSML M/S 0.01 * DERIVED* FROM LITTON SYSTEM (SEE NOTE 2) 16 UGE M/S 0.01 * DERIVED* NORTH/SOUTH WIND COMPONENT FROM DOPPLER/INERTIAL SYSTEM, + FROM N 17 VGE M/S 0.0 * DERIVED* EAST/WEST, + FROM EAST 18 WGE M/S 0.0 * DERIVED* VERTICAL WIND, + UP 19 LWN M/S 0.0 * DERIVED* NORTH/SOUTH WIND COMPONENT FROM LITTON SYSTEM, (NOTE 2), + FROM N 20 LWE M/S 0.01 * DERIVED* EAST/WEST WIND COMPONENT, + FROM E 21 WEP M/S 0.01 * DERIVED* VERTICAL WIND COMPONENT 22 TSNBC DEG C 0.01 * DERIVED* STATIC TEMPERATURE, DERIVED FROM TAS & TOTAL TEMP (SEE CH 48) NOSE STARBOARD TEMPERATURE PROBE 23 DEWPTC DEG C 0.01 EGG MODEL 137 DEW POINT 24 SDCTC DEG C 0.01 * DERIVED* STATIC TEMPERATURE IN C02 ANALYZER DUCT, DERIVED FROM DUCT TAS & DUCT TOTAL TEMP; ROSEMOUNT 102 PROBE 25 PRT5C DEG C 0.01 BARNES PRT-5 SURFACE TEMPERATURE 26 RADUP W/M2 0.1 KIPP & ZONEN CM-11 UPWARD FACING RADIOMETER, MEASURES INCIDENT RADIATION (SEE ALSO NOTE 3) 27 RADOWN W/M2 0.1 EPPLEY PYRANOMETER-2 DOWNWARD FACING RADIOMETER, MEASURES REFLECTED RADIATION. 28 C02N02 MG/M3 0.1 AGRICULTURE CANADA CARBON DIOXIDE CONC ESRI C02/H20 ANALYZER 20 HZ RESPONSE, LOW PASS FILTERED AT 5.5 HZ FOR ANTI-ALIASING 29 H20 G/M3 0.01 C02/H20 ANALYZER WATER VAPOR CONC, ESRI 30 RALT M 0.1 SPERRY AA-200 RADIO HEIGHT ABOVE GROUND ALTIMETER 31 TASFK KTS 0.1 * DERIVED* TRUE AIRSPEED, FUSELAGE PROBES. 32 TASNBK KTS 0.1 * DERIVED* TRUE AIRSPEED, NOSEBOOM PROBES. 33 TASDCT KTS 0.1 * DERIVED* TRUE AIRSPEED IN C02/H20 ANALYZER DUCT. 34 PSDUCT MB 0.1 A.I.R. AIR-DB-2C STATIC PRESSURE IN DUCT. 35 PSNBC MB 0.1 PAROSCIENTIFIC STATIC PRESSURE 215L-AW-012 NOSEBOOM, CORRECTED FOR POSITION ERROR 36 TSFC DEG C 0.01 * DERIVED* STATIC TEMPERATURE, DERIVED FROM TAS AND TOTAL TEMP MEASURED BY FUSELAGE PORT ROSEMOUNT PROBE (SEE CHANNEL 47) 37 GRNRAT - 0.001 SKYE INDUSTRIES GREENNESS RATIO, 730 SKR-100 NM SIGNAL/660 NM SIGNAL. 38 VDTM M/S 0.1 DECCA DOPPLER GROUND SPEED, TOTAL RADAR-72 VECTOR FROM DOPPLER RADAR. 39 GSL KTS 0.1 LITTON 90 IRS GROUND SPEED, TOTAL VECTOR FROM LITTON 40 LCC02 MV 1.0 LICOR 6262 C02 CONCENTRATION, RECORDED AS MILLIVOLTS, CONVERTED TO PPM 41 LCTSC DEG C 0.01 LICOR 6262 TEMPERATURE IN LICOR ANALYZER TEST CELL 42 UGEIL M/S 0.01 * DERIVED* NORTH/SOUTH WIND COMPONENT FROM DOPPLER/LITTON SYSTEM, + FROM N. 43 VGEIL M/S 0.01 * DERIVED* EAST/WEST, + FROM E. 44 WGEIL M/S 0.01 * DERIVED* VERTICAL WIND, + UP 45 LCH20 MV 1.0 LICOR 6262 H20 CONCENTRATION RECORED AS MILLIVOLTS, CONVERTED TO PPT 46 WFIL M/S 0.01 *DERIVED* HIGH-PASS FILTERED VERTICAL WIND FOR EDDY ACCUMULATION SYSTEM 47 TTF DEG K 0.01 ROSEMOUNT 102DJ1CG TOTAL TEMPERATURE, FAST RESPONSE, PORT FUSELAGE PROBE 48 TTNB DEG K 0.01 ROSEMOUNT 102DJ1CG TOTAL TEMPERATURE, FAST RESPONSE, STAR'B FUSELAGE PROBE 49 PSFC MB 0.1 ROSEMOUNT 1201F1B4A1B STATIC PRESSURE, FUSELAGE PORTS, CORRECTED FOR POSITION ERROR. 50 METHAN PPB 1.0 UNISEARCH TDL METHANE CONCENTRATION METHANE ANALYZER 51 -- --- NOT USED 52 TECO PPB 0.1 TECO-49 OZONE OZONE CONCENTRATION ANALYZER SLOW RESPONSE FOR MEAN CONCENTRATIONS 53 OZD PPB 0.1 GERMAN OZONE ANALYZER OZONE CONCENTRATION GFAS OS-G-2 FAST RESPONSE (>10 HZ) 54 DOZD PPB 0.01 "" HI-SENSITIVITY OZONE FLUCTUATIONS FROM START OF FLUX RUN 55 UCO2N2 MG/M3 0.1 AGRICULTURE CANADA RAW C02 UNFILTERED SIGNAL C02/H20 ANALYZER 56 UH20N2 G/M3 0.01 AGRICULTURE CANADA RAW H20 UNFILTERED SIGNAL C02/H20 ANALYZER 57 THETAL DEG 0.01 LITTON-90 IRS PITCH ATTITUDE + NOSE UP 58 PHIL DEG 0.01 LITTON-90 IRS ROLL ATTITUDE + RIGHT WING DOWN 59 VXMLTN M/S 1/128 DECCA DOPPLER RADAR-72 ALONG-HEADING COMPONENT OF GROUND SPEED, POSITIVE FORWARD. 60 VYMLTN M/S 1/256 DECCA DOPPLER RADAR-72 ACROSS-HEADING COMPONENT OF GROUND SPEED, POSITIVE STARBOARD 61 VZMLTN M/S 1/512 DECCA DOPPLER RADAR-72 VERTICAL COMPONENT OF AIRCRAFT VELOCITY REL TO GROUND, + DOWN. (ABOVE 3 CORRECTED TO POSITION OF LITTON-90 IRS). 62 ULN M/S 0.01 LITTON-90 IRS NORTH/SOUTH INERTIAL VELOCITY, + TO NORTH. 63 VLE M/S 0.0 LITTON-90 IRS EAST/WEST, + TO EAST 64 WZL M/S 0.0 LITTON-90 IRS VERTICAL, + DOWN 65 PDF MB 0.01 ROSEMOUNT TRANSDUCER DYNAMIC PRESSURE 1221F-2VL7A1A FUSELAGE PITOT UNCORRECTED FOR P.E. 66 PDNB MB 0.01 ROSEMOUNT TRANSDUCER DYNAMIC PRESSURE 1221F-1V7A1B NOSEBOOM PITOT UNCORRECTED FOR P.E. 67 PSF MB 0.10 ROSEMOUNT TRANSDUCER STATIC PRESSURE, 1201F-1B4A1B FUSELAGE PORTS, UNCORRECTED FOR P.E. 68 PSNBLR MB 0.10 PAROSCIENTIFIC STATIC PRESSURE 215L-AW-012 NOSEBOOM, CORRECTED TO LAB STANDARD, UNCORRECTED FOR P.E. 69 PD MB 0.01 *DERIVED* DYNAMIC PRESSURE USED (PDNB OR PDF) IN REAL TIME SOFTWARE SELECTED BY FUNCTION SWITCH 70 PDFNB MB 0.01 *DERIVED* DYNAMIC PRESSURE FROM FUSELAGE PORT CORRECTED TO NOSEBOOM POSITION, USED AS PDNB BACKUP 71 EACONT BITS 1.0 *DERIVED* SIGNAL THAT CONTROLS EDDY ACCUMULATION SYSTEM,1000 WHEN WFIL IS UP -1000 WHEN WFIL IS DOWN ZERO IN DEAD ZONE 72 TS DEGC 0.01 *DERIVED* STATIC TEMP USED IN REAL (TSFC OR TSNBC) TIME SOFTWARE, SELECTED BY FUNCTION SWITCH 73 GRN660 - 0.01 SKYE INDUSTRIES 660 NM SIGNAL FROM SKR-100 GREENNESS DEVICE 74 GRN730 - 0.01 SKYE INDUSTRIES 730 NM SIGNAL FROM SKR-100 GREENNESS DEVICE 75 TSPARO DEGF 0.01 PAROSCIENTIFIC TRANSDUCER TEMPERATURE 215L-AW-012 USED TO CORRECT STATIC PRESSURE SIGNAL 76 WGAI M/S 0.01 *DERIVED* VERTICAL WIND, DOPPLER SYSTEM, A/C AXES 77 LALT FT 1.0 LITTON 90/100 IRS ABSOLUTE HEIGHT 78 PALT FT 1.0 *DERIVED* PRESSURE HEIGHT, USES PSNBC 79 LTDL DEG 1.0 LITTON 90/100 IRS LITTON LATITUDE, DEG ONLY 80 LTDL DEG 1.0 "" LITTON LONGITUDE, DEG ONLY 81 PDFC MB 0.01 ROSEMOUNT TRANSDUCER DYNAMIC PRESSURE 1221F-2VL7A1A FUSELAGE PITOT CORRECTED FOR P.E. 82 PDNBC MB 0.01 ROSEMOUNT TRANSDUCER DYNAMIC PRESSURE 1221F-1V7A1B NOSEBOOM PITOT CORRECTED FOR P.E. 83 VX KNOTS 0.10 DECCA DOPPLER RADAR-72 GROUND SPEED, X COMPONENT A/C AXES, + FORWARD 84 VY KNOTS 0.10 "" GROUND SPEED, Y COMPONENT A/C AXES, + TO STARBOARD 85 VX KNOTS 0.10 "" GROUND SPEED, Z COMPONENT A/C AXES, + DOWN 86 THETA DEG 0.01 KEARFOTT ATTITUDE PITCH ATTITUDE GYRO, T2109 + NOSE UP 87 PHI DEG 0.01 KEARFOTT ATTITUDE ROLL ATTITUDE GYRO, T2109 + RIGHT WIND DOWN 88 AZL M/S2 0.01 LITTON 90/100 IRS VERTICAL ACCELERATION, A/C AXES,+ A/C DOWN 89 EAZL M/S2 0.01 "" VERTICAL ACCELERATION EARTH AXES, +A/C DOWN 90 UAIRN M/S 1/128 *DERIVED* NORTH COMPONENT OF TRUE AIRSPEED (TAS) VECTOR 91 VAIRE M/S 1/128 *DERIVED* EAST COMPONENT OF TRUE AIRSPEED VECTOR 92 WAIRZ M/S 1/128 *DERIVED* VERTICAL COMPONENT OF TRUE AIRSPEED VECTOR,+ A/C DOWN 93 UAIR M/S 1/128 *DERIVED* X-AXIS TAS COMPONENT 94 VAIR M/S 1/128 *DERIVED* Y-AXIS TAS COMPONENT 95 WAIR M/S 1/128 *DERIVED* Z-AXIS TAS COMPONENT 96 UANAE M/S 1/128 *DERIVED* X-AXIS TAS COMPONENT, CORRECTED TO NAE ACCELEROMETER LOCATION 97 VANAE M/S 1/128 *DERIVED* Y-AXIS TAS COMPONENT, CORRECTED TO NAE ACCELEROMETER LOCATION 98 WANAE M/S 1/128 *DERIVED* Z-AXIS TAS COMPONENT, CORRECTED TO NAE ACCELEROMETER LOCATION 99 UALTN M/S 1/128 *DERIVED* X-AXIS TAS COMPONENT, CORRECTED TO LITTON IRS LOCATION 100 VALTN M/S 1/128 *DERIVED* Y-AXIS TAS COMPONENT, CORRECTED TO LITTON IRS LOCATION 101 WALTN M/S 1/128 *DERIVED* Z-AXIS TAS COMPONENT, CORRECTED TO LITTON IRS LOCATION 102 UMIX7 M/S 1/128 *DERIVED* X INERTIAL VELOCITY COMPONENT FROM NAE/DOP SYSTEM 103 VMIX7 M/S 1/128 *DERIVED* Y INERTIAL VELOCITY COMPONENT FROM NAE/DOP SYSTEM 104 WMIX7 M/S 1/128 *DERIVED* Z INERTIAL VELOCITY COMPONENT FROM NAE/DOP SYSTEM 105 PDDUCT MB 0.01 ROSEMOUNT TRANSDUCER DYNAMIC PRESSURE IN C02 1221F-2VL7A1A MEASUREMENT DUCT 106 ALPHA DEG 0.01 ROSEMOUNT 858AJ28 ANGLE OF ATTACK PROBE & 12211F1VL5A1 MEASURED BY 5 TRANSDUCER HOLE PROBE ON NOSEBOOM 107 BETA DEG 0.01 ROSEMOUNT 858AJ28 ANGLE OF SIDE-PROBE & 12211F1VL5A1 SLIP MEASURED TRANSDUCER BY 5 HOLE PROBE ON NOSEBOOM. 108 UDOTN M/S2 1/128 *DERIVED* DERIVATIVE OF X INERTIAL VELOCITY FROM NAE/DOP SYSTEM 109 VDOTN M/S2 1/128 *DERIVED* DERIVATIVE OF Y INERTIAL VELOCITY FROM NAE/DOP SYSTEM 110 WDOTN M/S2 1/128 *DERIVED* DERIVATIVE OF Z INERTIAL VELOCITY FROM NAE/DOP SYSTEM 111 UGAI M/S 0.01 *DERIVED* LONGITUDINAL WIND, DOPPLER SYSTEM, A/C AXES 112 VGAI M/S 0.01 *DERIVED* LATERAL WIND, DOPPLER SYSTEM, A/C AXES 113 PALFNB MB 0.01 ROSEMOUNT TRANSDUCER DIFFERENTIAL PRESSURE 1221-1F1VL5A1 R-858 ANGLE OF ATTACK PORTS 114 UGAIL M/S 0.01 *DERIVED* LONGITUDINAL WIND, LIT/DOP SYSTEM, A/C AXES 115 VGAIL M/S 0.01 *DERIVED* LATERAL WIND, LIT/DOP SYSTEM, A/C AXES 116 WGAIL M/S 0.01 *DERIVED* VERTICAL WIND, LIT/DOP SYSTEM, A/C AXES 117 AXL M/S2 0.01 LITTON 90/100 IRS LONGITUDINAL ACCELERATION, A/C AXES, + A/C FWD 118 AYL M/S2 0.01 LITTON 90/100 IRS LATERAL ACCELERATION, A/C AXES, + A/C STARB 119 PBETNB MB 0.01 ROSEMOUNT TRANSDUCER DIFFERENTIAL PRESSURE 1221-1F1VL5A1 R-858 ANGLE OF SIDESLIP PORTS 120 AX M/S2 0.01 SYSTRON DONNER 4211 LONGITUDINAL ACCELERATION, A/C AXES, BACKUP SYSTEM 121 AY M/S2 0.01 SYSTRON DONNER 4211 LATERAL ACCELERATION, A/C AXES 122 AX M/S2 0.01 SYSTRON DONNER 4211 VERTICAL ACCELERATION, A/C AXES 123 PRATEL DEG/S 0.01 LITTON 90/100 IRS ROLL RATE, + RIGHT WING D 124 QRATEL DEG/S 0.01 "" PITCH RATE, + NOSE UP 125 RRATEL DEG/S 0.01 "" YAW RATE, + NOSE RIGHT 126 PRATE DEG/S 0.01 SMITHS GYROS 402-RGA ROLL RATE, + RIGHT WING D 127 QRATE DEG/S 0.01 "" PITCH RATE, + NOSE UP 128 RRATE DEG/S 0.01 "" YAW RATE, + NOSE RIGHT --------------------------------------------------------------------------- NOTE 1: This is the backup, or alternative, wind measuring system in case the Litton 90/100 inertial reference system (IRS) should fail. Calculation of wind components is described in reports by MacPherson (1988, 1990a, 1990b, 1996) and MacPherson and Bastian (1997). The air velocity relative to the aircraft is measured by the true air speed (TAS) and noseboom angles of attack and sideslip. The aircraft inertial velocity relative to Earth is measured in aircraft axes by a system incorporating complementary filtering in real time on the aircraft microprocessor. A system of accelerometers and rate gyros provides the high- frequency components to this filter; the Decca 3-axis Doppler radar provides the low-frequency components. The resulting calculated velocity components in a/c axes are subtracted from the TAS components to get the three components of winds in a/c axes. These are then resolved into Earth axes using the pitch and roll attitude and the aircraft heading to get uge, vge, and wge (channels 16-18). NOTE 2: The primary wind system uses a Litton 90/100 IRS to measure the aircraft inertial velocity components in 3 Earth axes. The IRS is similar to an INS (Inertial Navigation System), but measures the velocities, accelerations and rates in aircraft axes as well as Earth axes. This is also used to derive wind given in channels 11, 13, 15, 19, 20, 21, 42, 43, and 44 above. Numerous tests have been done to compare flux data derived with these two different wind measuring systems on the Twin Otter. Some of this appears in MacPherson (1990a, 1996). These studies reveal that fluxes derived with the older Doppler-based system appear to be underestimated by 10-15 percent. The Litton based wind should be used whenever possible (channels 19, 20, 21, 13, and 15). Note 3: MacPherson (1988, 1990b, 1996) gives a description of a routine used to correct the radup reading for aircraft attitude changes. In 1996, AFM-04 submitted the following table describing the instrumentation status. 1996 Flights There may be some steps in some of the analog channels; Most obvious in high- altitude inputs and tests; Required further investigation. It appears that the ESRI and LICOR are slightly motion dependent, producing small additional downward C02 flux for ESRI, upward for LICOR. There is a sawtooth on the WAIRZ that originates from the basic resolution of the digiquartz transducers, PALPHA, PBETA and PDNB. The PDNB is quite steppy when compared with the Rosemount for PDF. The range of the PDNB is too high (0- 12 psi, which good for about 700 knots!). It should be replaced with one that does no more than 0-1 psi, or at least that of the PALPHA and PBETA transducers. Satellite simulator _ in MSS mode, 1 deg field of view for Flights 58-62, in SPOT 15-deg field of view for Flights 63-69 in MSS mode, 15 deg field of view, Flights 70-83 NOTE: In flux re-analysis with Kalman filtering and ground-calculated winds, the TASNB used in most flights was low by about 0.3 mps. When TASF was used for Flight 65, it was low by 1.3 mps; For Flights 66- when TASF used, then correction factor of 1.3 was applied in airborne program, so no additional adjustment would be required except when working right from pressure data (recalculated in TASFUSE) Bias required to beta of +0.35 for all flights except Flt 75, in which it should be 0.54 TASF will be low by 1.3 mps until Flight 66, for which a bias was added to the airborne program TASNB will be low by 0.3 mps until Flight 67, for which a bias was added to the airborne program TASNB low by 1.10 mps on Flight 67, possibly due to loose connection on transducer For Flight 68 - TAS bias removed from airborne program, but biases added to PDNB of 0.4 mb, and to PDF of 1.2 mb: PDNB bias changed to +0.2 for Flight 69 and subsequent flights Temperatures start to diverge about Flight 72, with TSPort greater than starboard, increasing to 1.0 deg by Flight 78. NOTE: BOREAS airborne program was inadvertently using old noseboom PE values, not new ones derived on May 16 test flights: In recalculation, run PLOTPOK96_new with correct PE's, then re-run the reciprocal wind checks to get new biases for TAS and Beta. Data suggests that old PE's may be the more accurate. Need to do verification of May 16 PE's on another flight. NOTE: Also have noticed that the PDFNB is using the new PE's (0.904*PDFC); To match the old PE's used in the other calculations, 0.936 should be used. Airborne program changed to 0.936 on August 1 before Flight 78 RADUP reads -6 while in hangar; add bias in REDEF programs GPS has lag of several seconds; must adjust in ARCPOK96_new TECO possibly reads 3 ppb high; Must check all zeros for each individual flight prior to final archive round of flux calculations. NOTE: Greenness index is not necessarily associated with healthy plants and good C02 uptake on Ag run, for Canola indicates a greenness index of 1.9, when it is at least as developed as wheat fields giving 3.2-3.5 LICOR spikes caused by spikes in PSLICOR; affects C02 more than H20. The following table indicates instrument status during the flights in 1996. Date Flight # Instrument Status Jul 09 58 - GPS quit twice, first enroute from YPA to W to start Ag run, second in last run of first grid (approx 1755 GMT). Returned to normal at 1808. - LOZ3 ozone analyzer u/s most of flight, turned off for part of flight - NO/N02 analyzer reads high throughout flight, although recorded reading is perhaps only a tenth of what was shown on face of unit. - ESRI C02/H20 analyzer intermittent, but H20 OK after Run 14; C02 signal looks OK except for Runs 13 and 14 when unit turned off - Reciprocal runs suggest TAS low by 0.5 mps; apply this bias in re-calc - DLR ozone analyzer has spikes and poor correlation with TECO; Not useable - Laser altimeter drops to below zero in several spikes, perhaps an indication of a signal or error level. Jul 09 59 - NO/N02 analyzer possibly u/s throughout flight - LOZ3 recycled off/on in sounding (Run 01), but then OK rest of flight; use 1.0 slope when doing fluxes from regression against TECO - Reciprocal runs suggest TASNB low by 0.45 mps Jul 10 60 - GPS quit at 1754 Z for about 4 minutes. Caused abort of Run 13 at OJP - TASNB appears to be low by 0.4 mps - ESRI H20 signal unusable for Run 09; spikes - NO/N02 analyzer not correct, drifting downwards through flight from 20 ppb - Time lost 20 sec at start-up, so IAR time behind AES and cameras by about 20 seconds Jul 11 61 - GPS quit at 1751 for a few minutes - NO/N02 analyzer u/s - Time 20 seconds behind cameras, but synchronized with AES DAS - TASNB appears low by about 0.3 mps - Note: C02 and H20 analyzers calibrated prior to this flight - LICOR C02 has some spikes and seems noisy and poorly correlated with the ESRI during the OBS runs late in the flight. Jul 12 62 - GPS problem, recycled Off/On at 1745 GMT; Problem identified as poor satellite configuration - DLR ozone analyzer turned off at 1743 due to rain on Run 04 - LOZ3 power supply failed, so unit operated on battery but failed at 1853 Z in Run 11 - ESRI C02 should be distrusted on several runs when rain encountered. - NO/NO2 analyzer removed from aircraft Jul 14 63 - Satellite Simulator changed to SPOT Mode, Gains set at B=5, C=25, and D=5: D is limiting at about 42 W/m2 only over Ag Run - Flew into rain on Run 10; DLR selected OFF at 1740 - DLR signal alive for first 9 runs, but biased off to near zero concentration for unknown reason - AES DAS quit at 1649 GMT - GPS outage again most of time between 1725 and 1740 GMT - New routine to hold Laser_alt constant when signal drops below zero. Unit does not work over water - Note: Runs 5-11 across Candle Lake include 2 n miles of forest before and after the lake surface, thus the flux calculated over the whole event will not be accurate; Runs must be subdivided to get fluxes for water only. Date Flight Instrument Status July 14 (cont) - Good agreement between the ESRI and LICOR C02 fluxes, but the LICOR H20 fluxes quite a bit smaller than the ESRI. - NO/NO2 analyzer removed from aircraft - Reciprocal Ag runs suggest TASNB too low, as in previous flights. Jul 15 64 - ABORT Flight due to failure of P_Alpha pressure transducer, therefore no vertical gust capability - NO/NO2 analyzer removed from aircraft Jul 15 65 - TEST Flight; Temporary pressure transducer configuration: _ P_beta transducer (0-3 PSID) moved to P_alpha position _ Noseboom PD transducer (0-12 PSID) moved to P-beta position _ NO PDNB or TASNB recorded _ Winds and static temperature use TAS_F (i.e., F/S 2 ON) _ Alpha and Beta use PDFNB (i.e., F/S 3 ON) - TAS_F reads 1.3 mps low - Beta bias of -0.4 deg: Add 0.4 deg to beta (which already has an additional 0.35 deg) - Greenness Index sensors not turned on - NO/NO2 analyzer removed from aircraft - DLR ozone analyzer reads near zero throughout flight - Magnetic heading mis-set until 1910. - PSNBC incorrect; not corrected for Position Error Jul 19 66 - Pressure transducers back in usual configuration - Beta bias again to add 0.35, and TASNB add 0.3 mps - DLR instrument not flown - NO/NO2 analyzer removed from aircraft - GPS out at 1715 at end of Run 06 and through Run 07 - First flight with bias of 1.3 mps added to TASF - First flight with Laser altimeter updating at 50 Hz Jul 20 67 - First flight with bias of 0.3 mps added to TASNB - TASNB was low by 1.1 mps, possibly due to loose connection on transducer - Also discovered that airborne program was using old noseboom PE's, rather than new ones derived on May 16 test flight. Will leave that way until end of program - PSduct appears to be 3 mb high. - NO/N02 analyzer on aircraft, but N02 signal seems highly correlated with altitude. Jul 20 68 - For this flight (and subsequent ones), the TAS bias was removed and instead, a bias was added to PDNB (0.4 mb) and PDF (1.2 mb) to bring them to zero while at zero airspeed in the hangar. - Reciprocal data from each grid gives the same TAS error; 0.37 mps should be subtracted from TASNB. Beta bias less than 0.1 deg. - Run 12 was wrong line (FR-FP instead of FR-FQ); Was repeated - GPS locked up on last run of first grid (Run 11); run may have been extended a bit too far east. - GPS out between grids; Poor satellite configuration - PDNBC has little steps that are not identical to PDNB, even on ramp. - Care with fluxes: There are trends and discontinuities in some of the runs for C02 and H20, perhaps due to large clouds just west of grid. Date Flight Instrument Status Jul 23 69 - ABORT flight; generator out, then brake fire - PDNB bias set to +0.2 this and subsequent flights; PDF bias remains at +1.2 Jul 25 T-11 - GPS not turned on, and heater circuit breakers pulled - Generator failure on takeoff; abort rest of flight - No DAT tape Jul 25 T-12 - Generator test: GPS not used; no DAT tape Jul 26 70 - GPS from Convair 580 installed after Flight 69; first project use this flight - GPS intentionally left OFF until after takeoff in case there was a generator problem; selected ON at about 1942Z, a minute after takeoff - Satellite Simulator in MSS Mode, 15 deg, gains 5,5,5,1 - DLR ozone analyzer not installed this flight - PSDUCT checked and found 3 mb high on landing. - Event marker off too short time between Runs 01 and 02: Flux program groups them together, so need to re-run by event time - LICOR H20 plotted vs ESRI had slope of about 0.85, and resulted in low fluxes compared to ESRI. Prior to this flight, a major calibration was performed on LICOR with many test gases to answer 480 vs 422 problem. No problem was found, but now slope seems low compared to ESRI. Jul 27 71 - GPS intentionally left OFF until after takeoff in case there was a generator problem; selected ON at about 1655Z, a minute after takeoff - DLR ozone analyzer not flown - Runs 20 and 21 through rain shower, may affect ESRI C02/H20 fluxes - Time 20 seconds behind cameras, but aligned with AES DAS - GPS into Standby for about a minute after Ag Run 01 - NB: LICOR H20 fluxes seemed low compared to ESRI, and even compared to those from DewPt: LICOR H20 cospectrum has funny shape, with peak at wavelength different from either LICOR C02 or ESRI H20. - Spikes and/or dropouts in ESRI H20 signal on at least one run; Must check all runs for H20 spikes, especially since there is concern about its comparison with the LICOR H20 Jul 29 72 - GPS intentionally left OFF until after takeoff in case there was a generator problem; selected ON at about 1513Z, a minute after takeoff - First flight with difference in static pressures; PSNBC greater than PSFC by 1.8 mb; PSFC later proven to be the errant one- Time 20 seconds behind cameras, but synchronized with AES DAS - LICOR H20 could be low on first 3 or 4 runs - Cospectra indicate that LICOR calibration too low, or ESRI too high - GPS went into Standby at 1720Z at end of Run 18; selected OFF then ON - Spikes in ESRI H20 signal Jul 29 73 - Time 20 seconds behind the cameras, but synchronized with AES DAS - Static pressure difference; PSFC about 2.5 mb too low Jul 30 74 - Time 20 seconds behind the cameras, but synchronized with AES DAS - There is a 2.5 mb difference in PSFC and PSNBC (PSFC probably too low) - GPS went into Standby enroute to 'A' Date Flight Instrument Status Jul 30 75 - Time 20 seconds behind the cameras, but synchronized with AES DAS - There is a 2.5 mb difference in PSFC and PSNBC (PSFC probably too low) - NO/N02 device off scale high Jul 31 76 - Time 20 seconds behind the cameras, but synchronized with AES DAS - There is a 2.5 mb difference in PSFC and PSNBC. Ground check August 01 indicate PSFC is errant transducer - NO/N02 device off scale high - Standard deviation of ESRI C02 signal was high relative to LICOR on several runs, (eg., Run 22); Large spikes in ESRI occasionally, H20 and C02 (Run 5 - LICOR C02 signal suspect. seems to lack high frequency, like the H20 signal of Flight 71. Also, see notes on Flight 77 re: the LICOR C02 lag LICOR span also found low on August 01 calibration - For some reason, the TAS bias has dropped to zero Jul 31 77 - Time 20 seconds behind the cameras, but synchronized with AES DAS - There is a 2.5 mb difference in PSFC and PSNBC - NO/N02 device off scale high - The difference between the LICOR and ESRI C02 fluxes seems larger than usual; check cospectra; LICOR C02 has many spikes. Also, Run 02 has positive LICOR C02 flux when ESRI negative. Data compared with Harry McCaughey at YJP, LE's agreed, but his C02 fluxes agreed well with ESRI (his -0.23, ours ESRI -0.215), and NOT the LICOR (-0.04) - Cospectra show that LICOR C02 very suspect (see Run 6); Also, the LICOR C02 signal seems to require a different lag than the H20, which is very unusual. The C02 signal looks like it should have only been lagged 8 time slices, rather than 19 like the H20: Found out August 4 that this is due to pressure used in conversion from ppm to concentration. Mixing ratio lags OK - Data archived using ESRI for C02 flux, but LICOR for H20 - When calibrated Aug. 1, the span was low on the LICOR C02 by approximately 10 percent. - LICOR Ser. 649 removed from aircraft after this flight and replaced by LICOR Ser. 703 - For some reason, the TAS bias has dropped to zero Aug 01 78 - First flight with LICOR Ser. 703 - LICOR C02 fluxes larger, but still well below ESRI - Also, LICOR H20 fluxes low, particularly on 100' runs; Low at all frequencies, suggesting calibration has low span - Data archived using ESRI for H20 flux, but LICOR for C02 - GPS total failure at 1847Z prior to first run - No AES data recorded this flight - There is a 2.5 mb difference in PSFC and PSNBC - PDFNB factor changed to old values of 0.936 PSFC - PSFC less than PDNBC - Port temperature greater than Starboard Date Flight Instrument Status Aug 02 79 - LICOR fluxes very low compared to ESRI: regression of 32-Hz data suggest calibration sensitivity too low when compared with ESRI On some runs at YJP, LICOR C02 trace very different than ESRI LICOR C02 trace trails ESRI by about 1/2 second, while H20 is OK. - PSFC less than PDNBC - Port temperature greater than Starboard by about 2 deg C. - Time 20 seconds behind the cameras, but synchronized with AES DAS - Turned ESRI instrument OFF at 1751 after sounding since nitrogen was getting low - DLR ozone analyzer has some large excursions that are not duplicated by LOZ3 or TECO Aug 03 80 - First Flight with LICOR Ser. # 176 (same unit flown in 1994, still using Dec. 1993 calibration constants) - LICOR C02 fluxes still well below those of ESRI, and became near zero at end of flight, as in Flight 79 - LICOR H20 span adjusted in flight right after takeoff; set to approximate data from aircraft dew point sensor. Was reading about 5 gm/Kg high until then (approx. 1610 Z) - PSFC still about 2 mb less than PSNBC - Temperature probes cleaned and recalibrated prior to this flight. - Time 20 seconds behind the cameras, but synchronized with AES DAS - Evidence of steps in most analog channels, most clearly seen in high altitude runs where signals are clean (see pitches) Aug 05 81 - LICOR calibrated before flight; also filter and filter line replaced; old unit had possible small leak at connector - PSFC less than PSNBC by about 2 mb - DLR ozone device matched LOZ3 in flight for first time in quite some time; CWT cleaned unit after last flight - Airborne LICOR subroutine changed before this flight: The C02 and H20 concentrations in mg/m3 and gm/m3 respectively are now calculated using the PS_LICOR and LC_TEMP instead of the noseboom pressure and temperature. - Evidence of steps in most analog channels, most clearly seen in high altitude runs where signals are clean (see pitches) Aug 06 T-13 - TEST FLIGHT with ESRI dust closed and 'bagged'; LICOR still plumbed to duct - PSFC lower than PSNBC by about 2 mb - DLR ozone analyzer not installed Aug 07 82 - PSFC lower than PSNBC by about 2 mb - DLR ozone analyzer turned OFF at 1545 Z due to rain - Time about 20 seconds behind camera, but synchronized with AES DAS Aug 08 83 - PSFC lower than PSNBC by about 2 mb - DLR ozone analyzer not flown this flight Time about 20 seconds behind camera, but synchronized with AES DAS Summary of 1996 Fluxes SSA Date DoY/Flt Site GMT Runs1 Wind d/mps Temp degC H W/m2 LE3 W/m2 BR C024 mg/m2/s Oz ug/m2/ s NetR W/m2 Jul 09 191 58 Grid Grid 1730 1845 9 9 197/5.0 198/5.0 19.4 20.0 190 222 208 212 0.91 1.05 -0.39 -0.30 679 712 Jul 09 191 59 OA 2130 6 182/5.5 20.3 104 270 0.39 -0.73 -0.32 506 Jul 10 192 60 OBS OJP 1715 1800 8 7 133/6.0 119/5.2 21.3 22.3 183 224 193 214 0.95 1.05 -0.24 -0.28 -0.31 -0.37 616 644 Jul 11 193 61 OA OBS 1715 1845 9 6 012/2.4 036/3.9 20.7 22.3 74 168 313 180 0.23 0.93 -0.81 -0.19 -0.44 -0.10 573 583 Jul 14 196 63 Ag Lake 1815 1730 7 7 256/3.8 231/2.5 21.4 20.6 42 1 339 25 0.12 0.06 -0.88 0.00 -0.25 0.00 616 - Jul 19 201 66 OA 1700 6 202/5.6 17.4 120 268 0.45 -0.79 -0.59 615 Jul 20 202 67 Lake 1145 6 124/2.0 13.7 7 59 0.12 +0.14 -0.04 - Jul 20 202 68 Grid Grid 1630 1745 9 9 158/3.2 187/2.6 17.5 19.3 152 199 153 247 0.99 0.81 -0.38 -0.39 -0.17 -0.17 557 693 Jul 26 208 70 OA 2045 6 165/2.1 18.0 84 215 0.39 -0.82 -0.35 381 Jul 27 209 71 Grid Grid OBS 1745 1845 1915 9 9 2 131/3.9 155/4.5 166/4.9 16.9 17.2 17.1 47 42 33 121 5 125 50 0.39 0.34 0.65 -0.49 6 -0.43 -0.21 -0.34 -0.34 -0.17 311 6 245 64 Jul 29 211 72 OBS Grid Grid 1600 1700 1745 8 9 9 174/1.8 148/1.5 152/1.8 18.6 19.4 20.5 130 134 149 160 187 227 0.82 0.71 0.66 -0.33 -0.37 -0.40 -0.26 -0.24 -0.26 500 578 621 Jul 29 211 73 OA 2015 7 177/2.5 22.3 23 173 0.13 -0.43 -0.17 212 7 1 - Only nominal 100' runs 3- From LICOR 4- From LICOR 5 - LICOR H20 suspiciously low this day 6- Overcast this day 7 - Clouds over; decreasing radiation study Note : Fluxes computed with linearly detrended data with Kalman-corrected winds, as archived NSA Date DoY/Flt Site GMT Runs Wind d/mps Temp H W/m2 LE W/m2 BR C02 mg/m2/ s Oz ug/m2/ s NetR W/m2 July 31 213 76 Grid Grid OBS OJP 1515 1615 1700 1730 9 9 5 8 203/3.6 219/4.3 222/3.9 218/4.3 23.3 24.3 25.0 25.3 92 132 196 237 150 190 135 96 0.61 0.70 1.45 2.46 -0.23 -0.22 -0.19 -0.09 -0.03 -0.09 0.01 0.00 450 527 586 609 July 31 213 77 Burn YJP Burn 1915 1945 2000 4 8 5 216/5.4 222/5.0 212/5.5 26.1 26.5 26.3 81 175 90 171 75 211 0.47 2.32 0.43 -0.27 8 -0.22 -0.34 -0.20 -0.03 -0.25 439 368 479 Aug 01 214 78 Burn 1900 4 200/6.4 24.3 64 185 9 0.35 -0.29 -0.16 317 Aug 02 215 79 Grid Grid OBS OJP YJP 1500 1600 1645 1715 1745 9 9 5 8 6 225/4.6 235/5.4 233/5.7 228/6.1 230/7.5 23.6 24.8 25.7 26.1 26.4 62 106 148 200 206 172 150 170 83 124 0.36 0.71 0.87 2.41 1.66 -0.22 -0.16 -0.19 -0.07 -0.09 -0.18 -0.16 -0.16 -0.12 -0.10 431 515 599 554 575 Aug 03 216 80 Grid Grid OBS YJP 1630 1730 1815 1845 9 9 6 5 100/3.5 115/3.2 127/3.5 104/3.4 25.1 25.9 26.7 27.0 135 162 205 174 167 145 159 67 0.81 1.12 1.28 2.60 -0.26 -0.17 -0.18 -0.02 -0.15 -0.16 -0.18 -0.05 509 554 591 418 Aug 05 218 81 OJP Grid Grid OJP 1600 1645 1745 1815 6 9 9 6 201/3.6 195/3.9 196/4.3 203/4.4 21.6 22.2 23.1 23.1 141 138 129 68 148 222 180 101 0.95 0.62 0.62 0.67 -0.13 -0.27 -0.31 -0.11 -0.21 -0.30 -0.17 -0.16 510 538 462 182 Aug 07 220 82 OBS2 OBS2 Burn 1500 1545 1645 4 4 6 295/4.6 280/4.6 295/6.5 12.9 13.5 13.6 48 87 61 143 190 135 0.33 0.46 0.45 -0.29 -0.36 -0.34 -0.31 -0.33 -0.17 283 296 20710 Aug 08 221 83 Grid Grid OBS 1515 1615 1700 9 9 6 004/4.1 009/4.0 014/3.7 9.2 10.1 11.1 88 144 183 88 116 136 1.00 1.24 1.35 -0.43 -0.51 -0.50 -0.17 -0.22 -0.19 272 400 482 2 - Flux divergence or advection study, only 30 m runs shown 8 - ESRI C02 fluxes used Flt 77 9 - ESRI LE fluxes used Flt 78 10 - Increasing cloud Note : Fluxes computed with linearly detrended data using Kalman-corrected winds: as archived 7. Data Description 7.1 Spatial Characteristics 7.1.1 Spatial Coverage Grid flight patterns consisted of twin sets (one in the NSA and one in the SSA) of nine parallel lines flown at 100 feet above ground level (AGL) at a 2-km spacing covering a 16- by 16-km area. For each of these grids, two flight plans were stored in the aircraft’s GPS system; one with the east/west lines, and one with the north/south lines. On a given day, the wind direction was measured and the flight pattern was chosen that was closest to cross wind. Since turbulent eddies are elongated in the direction of the wind, crosswind tracks encounter more eddies; thus, the determination of the flux is statistically more reliable. On each grid flight, the grid pattern was flown twice, with the repeated pass flown in the opposite direction to the first. In this way, each pair of runs on a given line can be examined for possible biases in wind measurement or other variables. The double grid pattern took nearly 2 hours to fly. Some regional runs were also flown, for example, from Prince Albert to Nipawin, Saskatchewan. Very long regional runs were flown (at approximately 500 feet) on the transit flights between Prince Albert (near the SSA) and Thompson (in the NSA). The two 16-km grids fall within the NSA and SSA. The North American Datum of 1983 (NAD83) corner points for these grid patterns are: SSA Latitude Longitude -------- --------- Northeast 53.930° N 104.565° W Northwest 53.930° N 104.810° W Southwest 53.787° N 104.810° W Southeast 53.787° N 104.565° W NSA Latitude Longitude -------- --------- Northeast 55.947° N 98.397° W Northwest 55.947° N 98.653° W Southwest 55.803° N 98.653° W Southeast 55.803° N 98.397° W In their 1996 report, AFM-04 reported the following waypoints for non-grid runs. Waypoint 1 Waypoint 2 Site Lat. Long. Lat. Long. Comments OA - SSA 53 34.9 -106 16.8 53 38.4 -106 09.6 About 11 km, homogeneous vegetation OBS - SSA 53 59.0 -105 08.2 53 57.8 -104 56.0 14.5 km, mostly spruce, tower near west end OJP - SSA 53 53.6 -104 44.2 53 56.0 -104 39.5 Only 6 km homog., so marginal for TS Agricultural Run 53 21.0 -105 28.8 53 31.0 -105 28.9 18.5 km, pasture, canola and wheat Extended Ag to forest 53 31.0 -105 28.9 53 41.0 -105 29.0 18.5 km interface from Ag to forest Full Candle Lake Run 53 34.7 -106 23.8 53 59.0 -104 47.2 115 km, Heterogeneous, 3 lakes Candle Lake Run for morning Flight 67 53 49.8 -105 27.9 53 51.6 -105 12.9 14 km run across Candle lake OBS - NSA 55 52.5 -98 22.5 55 52.4 -98 34.0 12 km good sfc. OJP - NSA 55 55.6 -98 37.7 55 56.6 -98 36.2 3 km homog. veg, marginal for TN Burn - NSA 55 49.7 -98 19.4 55 51.6 -98 30.0 11 km all burned; used for almost all runs in 1994 YJP - NSA 55 53.8 -98 16.4 55 54.2 -98 18.8 < 3km, marginal for flux Flux runs were also made over Candle Lake over a length of 115 km. These runs were made to cover a heterogeneous track across the study area in order to see how flux varies over different land cover types. En route from the Prince Albert Airport to the area of the flux towers in the boreal forest, an agricultural area was overflown consisting mostly of pasture, rapeseed, and wheat. To collect data to monitor fluxes over the whole growing season in an agricultural area, a 20-km north/south track was selected in this area. This was flown by the Twin Otter at a 30-m altitude on 40 occasions during the three IFCs in 1994. On 08-Sept-1994, a 500-km flux run was made along the transect between the NSA and SSA from 1640 to 2040 Greenwich Mean Time (GMT). 7.1.2 Spatial Coverage Map None. 7.1.3 Spatial Resolution The spatial resolution of the original data used in the flux computations is a function of the aircraft speed (approximately 55 m/s) and the digital recording rate (16 Hz in 1994, 32 Hz in 1996) and the anti-alias filtering applied to the data prior to recording (5.5 Hz). This translates to a basic sampling resolution of approximately 12 m (1994) and 6 m (1996) for the Twin Otter. 7.1.4 Projection None. These data were collected at point locations. 7.1.5 Grid Description The data were collected at point locations, primarily in a regular grid pattern. The grid spacing was approximately 2 km. 7.2 Temporal Characteristics 7.2.1 Temporal Coverage In 1994, data were collected on the following dates: IFC-1: 25-May-1994 to 27-May-1994 29-May-1994 31-May-1994 to 01-Jun-1994 04-Jun-1994 06-Jun-1994 to 11-Jun-1994 13-Jun-1994 IFC-2: 20-Jul-1994 to 29-Jul-1994 01-Aug-1994 to 02-Aug-1994 04-Aug-1994 08-Aug-1994 IFC-3: 31-Aug-1994 to 03-Sep-1994 06-Sep-1994 08-Sep-1994 11-Sep-1994 to 19-Sep-1994 In 1996, data were collected on the following dates: 06-Jul-1996 to 07-Jul-1996 09-Jul-1996 to 12-Jul-1996 14-Jul-1996 to 15-Jul-1996 19-Jul-1996 to 20-Jul-1996 23-Jul-1996 25-Jul-1996 to 27-Jul-1996 29-Jul-1996 to 31-Jul-1996 01-Aug-1996 to 03-Aug-1996 05-Aug-1996 to 10-Aug-1996 SSA * number of runs of each type Date Fl Ag Intf CL Grid SS Bud TRS Othe r Snd 1996 W-X X-Y OA BS J P Fen Jul 09 58 2 2 18 2 Jul 09 59 6 1 Jul 10 60 2 2 8 7 1 Jul 11 61 1 1 1 9 6 1 Jul 12 62 2 2 11 1 Jul 14 63 8 2 7 2 Jul 15 65 2 Jul 19 66 6 1 Jul 20 67 2 16 3 Jul 20 68 2 18 1 Jul 26 70 1 1 6 1 1 Jul 27 71 1 18 2 1 Jul 29 72 2 18 8 2 Jul 29 73 1 7 8 1 Jul 30 74 1 1 2 17 24 9 3 72 34 26 7 11 1 32 20 NSA Date Fl Grd SS M-O TRS Other Snd 1996 burn BS OJP YJP Jul 30 75 6 1 1 1 Jul 31 76 18 5 8 2 2 Jul 31 77 9 8 1 Aug 01 78 8* Aug 02 79 18 5 8 6 2 Aug 03 80 18 6 5 4 1 Aug 05 81 18 12 6 3 Aug 07 82 6 12 4 2 Aug 08 83 18 6 1 09 90 23 40 28 19 1 1 16 13 CL: 62 nm Candle Lake Snd: Sounding Bud: Flux Budget TRS - transect PA/Flin Flon (SSA) Flin Flon/Thompson (NSA) SS: Site-specific (towers) * 4 runs at 100', 4 at 500' 7.2.2 Temporal Coverage Map None. 7.2.3 Temporal Resolution The aircraft data were recorded at a basic rate of 16 Hz (1994) or 32 Hz (1996). Flight durations were typically 3 to 3.5 hours. On several occasions there were two flights per day. 7.3 Data Characteristics Data characteristics are defined in the companion data definition file (afm4tofx.def). 7.4 Sample Data Record Sample data format shown in the companion data definition file (afm4tofx.def). 8. Data Organization 8.1 Data Granularity All of the AFM-04 Twin Otter Aircraft Flux Data are contained in one data set. 8.2 Data Format(s) The data files contain numerical and character fields of varying length separated by commas. The character fields are enclosed with single apostrophe marks. There are no spaces between the fields. Sample data records are shown in the companion data definition file (afm4tofx.def). 9. Data Manipulations 9.1 Formulae The principal equations used to compute wind components and fluxes from the Twin Otter data are given in MacPherson (1990b, 1992, 1996). 9.1.1 Derivation Techniques and Algorithms See MacPherson (1990b, 1992, 1996) and MacPherson and Bastian (1997). 9.2 Data Processing Sequence 9.2.1 Processing Steps 1. AFM-04 processed the data and sent them to BORIS. 2. BORIS staff received the data, made necessary conversions to standard units, and loaded the data into the data base. 3. BORIS staff documented the data set and compiled basic statistics about the data. See MacPherson (1988, 1990a, 1990b, 1996) and MacPherson and Bastian (1997) for more detailed information about the processing that AFM-04 did to its data before submitting the data to BORIS. 9.2.2 Processing Changes There are quite a number of selectable options in the playback program for the Twin Otter data. These include the option to use the alternative (backup) wind computations in case of a problem with the Litton 90/100 IRS. 9.3 Calculations 9.3.1 Special Corrections/Adjustments 1. Calculation of wind components is described in MacPherson (1981, 1990b, 1996) and MacPherson and Bastian (1997). The air velocity relative to the aircraft is measured by the true air speed (TAS) and noseboom angles of attack and sideslip. The TAS vector is then resolved into Earth axes (north, east, and vertical components). Subtracted from these are the aircraft inertial velocity components measured by a Litton 90/100 IRS, to get the three components of the wind velocity in Earth-fixed axes. An alternative, or backup, wind system is employed on the Twin Otter in case the Litton 90 is unserviceable (rare). For this system, known as the NAE/DOP winds, the aircraft inertial velocity relative to Earth is measured in aircraft axes by a system incorporating complementary filtering in real time on the aircraft microprocessor. A system of accelerometers and rate gyros provides the high- frequency components to this filter; the Decca 3-axis Doppler radar provides the low-frequency components. The resulting calculated velocity components in A/C axes are subtracted from the TAS components to get the three components of wind in A/C axes. These are then resolved into Earth axes using the pitch, roll, attitude, and aircraft heading. 2. For each flight, the ground speed for all runs is averaged. The high-pass filtered breakpoint is then selected as the average ground speed divided by 5,000 m. This gives a breakpoint of about 0.012 Hz for high-pass filtered flux estimates. 3. Three sets of fluxes were derived, one using 'raw' data, one using linearly detrended time histories, and one using high-pass filtered data. All are included in the archive, as well as correlation coefficients and RMS values of parameters contributing to the flux estimates. 9.3.2 Calculated Variables There was no direct measurement of net radiation made on the Twin Otter in BOREAS. Rather, it was calculated at each interval using incident and reflected solar radiation (RADUP and RADOWN), with longwave contributions derived from PRT-5 surface temperature (Ts in deg K) and air temperature (Ta in deg K) in the following equation: NETRAD = RADUP - RADOWN + [1.20*?*Ta4 - 171.0] - [0.98*?*Ts4] where the last two terms represent the incident and reflected longwave components, using the Stephan-Boltzmann Constant ??= 5.6924*10-8 and a surface emissivity of 0.98. This computed value of net radiation has agreed quite well with tower measurements. 9.4 Graphs and Plots None. 10. Errors 10.1 Sources of Error Errors can result from a number of different sources. The flux measurements are subject to possible errors relating to the measurements from the IRS. A problem was detected with the ESRI CO2 analyzer. Possible reasons for this problem are listed in MacPherson (1996). As a result of this problem with the ESRI, data from the LI-COR were reported for the CO2 and H2O fluxes. 10.2 Quality Assessment 10.2.1 Data Validation by Source Great care has been taken in the collection and analysis of the Twin Otter data. The wind measuring system is continually monitored for accuracy using techniques such as wind boxes, control input cases, and intercomparisons with other aircraft (Dobosy et al., 1997). Cospectral plots have been used to check the flux contributions at all wavelengths to ensure that they were not contaminated by inadequate compensation for aircraft motion. Aircraft data were compared at various BOREAS workshops. This led to the decision to include all three sets of fluxes (i.e., from raw, detrended, and HP- filtered time histories) in the database. 10.2.2 Confidence Level/Accuracy Judgment See Section 10.2.1. 10.2.3 Measurement Error for Parameters Not available at this revision. 10.2.4 Additional Quality Assessments See Dobosy et al. (1997) for a comparison of fluxes from various aircraft. AFM-04 submitted the following comparison table based on 1996 data. COMPARISON BETWEEN TWIN OTTER AND FLUX TOWERS BOREAS 1996 a) Old Aspen - SSA Date 1996 Time1 GMT # runs Alt5 Temp H W m-2 LE3 W m-2 C024 Flux mg m-2 s-1 July 09 Flt 59 2130 2200 2120-2148 6 42 20.9 2 20.8 0 20.3 4 141 85 104 230 252 268 301 -0.61 -0.59 -0.71 -0.89 July 11 Flt 61 1730 1703-1730 6 36 21.6 0 20.5 9 100 75 338 306 350 -0.81 -0.78 -0.88 July 19 Flt 66 1730 1700-1720 4 46 17.8 6 17.4 0 204 138 285 266 280 -0.79 -0.80 -0.95 July 26 Flt 70 2100 2038-2103 6 32 18.9 5 17.9 5 157 84 171 214 260 -0.61 -0.81 -0.95 July 29 Flt 73 2030 2001-2025 6 34 23.2 3 22.1 9 7 10 93 154 186 -0.15 -0.36 -0.40 1 - Lines with single time are for tower; lines with time range are for aircraft For Aspen tower, time is for the end of the half hour period. b) Old Black Spruce - SSA Date 1996 Time1 GMT # runs Alt5 Net Rad W m-2 H W m-2 LE3 W m-2 C024 Flux mg m-2 s-1 U* m s-1 July 10 Flt 60 1722 1702-1730 5 43 545 613 349 183 134 173 179 -0.25 -0.22 -0.44 0.87 0.78 July 11 Flt 61 1900 1830-1902 6 38 727 583 475 168 336 180 179 -0.29 -0.19 -0.39 0.61 0.62 July 20 Flt 67 1100 1044-1047 1 35 -33 -69 -4 -6 3 2 2 +0.04 +0.06 +0.06 0.07 0.00 Jul 29 Flt 72 1630 1558-1626 5 35 483 515 227 134 120 174 199 -0.37 -0.34 -0.53 0.30 0.33 1 For tower, time is for end time of 1/2-hour period 3, 4 Left From LI-COR data, right - ESRI 5 From radar altimeter, generally above canopy 7 Only runs used within tower half-hour c) Old Jackpine - NSA Date 1996 Time1 GMT # runs Alt5 Temp8 Wind degT/m ps H W m-2 LE3 W m-2 C024 Flux mg m-2 s-1 U* m s-1 July 31 Flt 76 1700 1715- 1732 8 29 25.2 5 287/5. 4 210/4. 2 287 236 46 99 81 -0.19 -0.09 - 0.40 0.93 0.71 Aug 02 Flt 79 1707- 1727 8 32 26.0 3 287/7. 2 227/5. 6 364 197 95 90 109 -0.105 -0.07 - 0.31 1.49 0.89 Aug 05 Flt 81 1558- 1611 1811- 1823 6 6 32 31 21.6 2 23.1 1 201/4. 0 203/4. 2 141 67 144 145 99 99 -0.13 - 0.37 -0.11 - 0.21 0.53 0.67 1 For tower, time is for start of 1/2-hour period 3, 4 Left From LI-COR data, right - ESRI 5 From radar altimeter, generally above canopy 7 Only runs used within tower half-hour 8 Tower temperature at 30 m d) Old Black Spruce - NSA Date 1996 Time1 GMT # runs Alt5 Temp8 Wind degT/m ps H W m-2 LE3 W m-2 C024 Flux mg m-2 s-1 U* m s-1 July 30 Flt 75 2030 2017- 2048 6 33 27.0 6 27.2 5 214/2. 9 220/2. 4 370 176 113 167 173 -0.017 -0.12 - 0.31 0.29 0.42 Jul 31 Flt 76 1700 1650- 1713 5 34 24.8 9 24.9 7 216/4. 3 215/3. 8 501 194 206 137 143 -0.22 -0.18 - 0.40 0.80 0.63 Aug 02 Flt 79 1700 1642- 1704 5 33 25.4 9 25.6 3 227/6. 4 237/5. 6 294 145 176 184 232 -0.26 -0.19 - 0.35 0.91 0.83 Aug 03 Flt 80 1800 1830 1806- 1834 6 32 26.3 5 26.7 6 26.6 6 123/3. 7 135/2. 8 116/3. 2 420 335 203 82 195 158 171 -0.21 -0.23 -0.18 - 0.39 0.56 0.61 0.54 Aug 07 Flt 82 1500 1530 1456- 1514 1532- 1549 4 4 31 34 12.1 6 12.6 6 12.8 8 13.4 8 285/3. 7 283/4. 1 294/4. 9 289/4. 3 94 84 47 86 142 103 143 181 191 209 -0.27 -0.24 -0.29 - 0.50 -0.36 - 0.52 0.63 0.58 0.58 0.63 Aug 08 Flt 83 1700 1645- 1714 6 32 10.7 3 11.0 4 002/2. 9 018/4. 3 233 182 75 136 138 -0.30 -0.50 - 0.76 0.51 0.63 1 For tower, time is for mid time of 1/2-hour period 10.2.5 Data Verification by Data Center Data were examined for general consistency and clarity. 11. Notes 11.1 Limitations of the Data None given. 11.2 Known Problems with the Data Despite careful study by Agriculture Canada technicians and some modifications to the ESRI instrument, data from 1996 suggest that the problems with the ESRI analyzer persisted. 11.3 Usage Guidance Note that although there are fewer than 100 records in any data file, there are over 170 columns of data. Most spreadsheet software should be able to handle up to 256 columns of data. 11.4 Other Relevant Information None. 12. Application of the Data Set These data can be used to obtain study area and regional scale estimates of the various fluxes. 13. Future Modifications and Plans None given. 14. Software 14.1 Software Description The program used to generate the flux estimates for 1994 and output numerous summary files was called ARCPOK94, which was run on a Micro-VAX Alpha computer used in the field and in the lab. The program used to generate the flux estimates for 1996 and output numerous summary files for archive purposes was called ARCPOK96_NEW, which was run on the MicroVax-alpha computer used in the field and at the Flight Research Laboratory (FRL) in Ottawa. The principal equations used to compute wind components and fluxes from Twin Otter data are given in MacPherson (1996) and MacPherson and Bastian (1997). Contact Ian MacPherson for more information. 14.2 Software Access None given. 15. Data Access 15.1 Contact for Data Center/Data Access Information These BOREAS data are available from the Earth Observing System Data and Information System (EOS-DIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The BOREAS contact at ORNL is: ORNL DAAC User Services Oak Ridge National Laboratory (865) 241-3952 ornldaac@ornl.gov ornl@eos.nasa.gov 15.2 Procedures for Obtaining Data BOREAS data may be obtained through the ORNL DAAC World Wide Web site at http://www-eosdis.ornl.gov/ or users may place requests for data by telephone, electronic mail, or fax. 15.3 Output Products and Availability Requested data can be provided electronically on the ORNL DAAC's anonymous FTP site or on various media including, CD-ROMs, 8-MM tapes, or diskettes. The complete set of BOREAS data CD-ROMs, entitled "Collected Data of the Boreal Ecosystem-Atmosphere Study", edited by Newcomer, J., et al., NASA, 1999, are also available. 16. Output Products and Availability 16.1 Tape Products Not applicable. 16.2 Film Products Not applicable. 16.3 Other Products These data are available on the BOREAS CD-ROM series. 17. References 17.1 Platform/Sensor/Instrument/Data Processing Documentation The Twin Otter Atmospheric Research Aircraft and its instrumentation have been described in the following reports available from the National Research Council of Canada: MacPherson, J.I. 1988. NAE Twin Otter Operations in FIFE. National Research Council Canada Report LTR-FR-104. MacPherson, J.I. 1989. NAE Twin Otter Operations in the 1988 Eulerian Model Evaluation Field Study. National Research Council Canada Report LTR-FR-107. MacPherson, J.I. 1990a. NAE Twin Otter Operations in FIFE 1989. National Research Council Report LTR-FR-113. MacPherson, J.I. 1990b. Wind and Flux Calculations on the NAE Twin Otter. NAE Laboratory Technical Report LTR-FR-109. National Research Council. January 1990. MacPherson, J.I. 1992. NRC Twin Otter Operations in the 1991 California Ozone Deposition Experiment. National Research Council of Canada Report LTR-FR-118. May 1992. MacPherson, J.I. 1996. NRC Twin Otter Operations in BOREAS 1994. Laboratory Technical Report LTR-FR-129. National Research Council Canada. April 1996. MacPherson, J.I. and M. Bastian. 1997. NRC Twin Otter Operations in BOREAS 1996. Laboratory Technical Report LTR-FR-134. National Research Council of Canada. November 1997. MacPherson, J.I. and J.M. Morgan. 1981. The N.A.E. Twin Otter Atmospheric Research Aircraft. National Research Council Report LTR-FR-80. MacPherson, J.I. and S.W. Baillie. 1986. The N.A.E. Atmospheric Research Aircraft. National Research Council Report, NAE Misc 62. MacPherson, J.I., R.J. Grossman, and R.D. Kelly. 1992. Intercomparison Results for FIFE Flux Aircraft. Journal of Geophysical Research 97(D17):18,499-18,514. 17.2 Journal Articles and Study Reports Barr, A.G., A.K. Betts, R.L. Desjardins, and J.I. MacPherson. 1997. Comparison of regional surface fluxes from boundary-layer budgets and aircraft measurements above boreal forest. Journal of Geophysical Research 102(D24): 29,213-29,218. Desjardins, R.L., J.I. MacPherson, L. Mahrt, P. Schuepp, E. Pattey, H. Neumann, D. Baldocchi, S. Wofsy, D. Fitzjarrald, H. McCaughey, and D.W. Joiner. 1997. Scaling up flux measurements for the boreal forest using aircraft-tower combinations. Journal of Geophysical Research 102(D24): 29,125-29,133. Dobosy, R.J., T.L. Crawford, J.I. MacPherson, R.L. Desjardins, R.D. Kelly, S.P. Oncley, and D.H. Lenschow. 1997. Intercomparison among four flux aircraft at BOREAS in 1994. Journal of Geophysical Research 102(D24):29,101-29,111. Ogunjemiyo, S., P.H. Schuepp, J.I. MacPherson, and R.L. Desjardins. 1997. Analysis of flux maps versus surface characteristics from Twin Otter grid flights in BOREAS 1994. Journal of Geophysical Research 102(D24): 29,135- 29,145. MacPherson, J.I. and A.K. Betts. 1997. Aircraft encounters with strong coherent vortices over the boreal forest. Journal of Geophysical Research 102(D24): 29,231-29,234. MacPherson, J.I. and R.L. Desjardins. 1991. Airborne Tests of Flux Measurement by the Relaxed Eddy Accumulation Technique. Proceedings of the Seventh Symposium on Meteorological Observations and Instrumentation. American Meteorological Society. New Orleans. January, 1991. Sellers, P. and F. Hall. 1994. Boreal Ecosystem-Atmosphere Study: Experiment Plan. Version 1994-3.0, NASA BOREAS Report (EXPLAN 94). Sellers, P. and F. Hall. 1996. Boreal Ecosystem-Atmosphere Study: Experiment Plan. Version 1996-2.0, NASA BOREAS Report (EXPLAN 96). Sellers, P., F. Hall, and K.F. Huemmrich. 1996. Boreal Ecosystem-Atmosphere Study: 1994 Operations. NASA BOREAS Report (OPS DOC 94). Sellers, P., F. Hall, and K.F. Huemmrich. 1997. Boreal Ecosystem-Atmosphere Study: 1996 Operations. NASA BOREAS Report (OPS DOC 96). Sellers, P., F. Hall, H. Margolis, B. Kelly, D. Baldocchi, G. den Hartog, J. Cihlar, M.G. Ryan, B. Goodison, P. Crill, K.J. Ranson, D. Lettenmaier, and D.E. Wickland. 1995. The boreal ecosystem-atmosphere study (BOREAS): an overview and early results from the 1994 field year. Bulletin of the American Meteorological Society. 76(9):1549-1577. Sellers, P.J., F.G. Hall, R.D. Kelly, A. Black, D. Baldocchi, J. Berry, M. Ryan, K.J. Ranson, P.M. Crill, D.P. Lettenmaier, H. Margolis, J. Cihlar, J. Newcomer, D. Fitzjarrald, P.G. Jarvis, S.T. Gower, D. Halliwell, D. Williams, B. Goodison, D.E. Wickland, and F.E. Guertin. 1997. BOREAS in 1997: Experiment Overview, Scientific Results and Future Directions. Journal of Geophysical Research 102(D24): 28,731-28,770. 17.3 Archive/DBMS Usage Documentation None. 18. Glossary of Terms None. 19. List of Acronyms AES - Atmospheric Environment Service AFM - Airborne Fluxes and Meteorology AGL - Above Ground Level ASCII - American Standard Code for Information Interchange BOREAS - BOReal Ecosystem-Atmosphere Study BORIS - BOREAS Information System CD-ROM - Compact Disk-Read-Only Memory DAAC - Distributed Active Archive Center DAT - Digital Archive Tape EOS - Earth Observing System EOSDIS - EOS Data and Information System FIFE - First ISLSCP Field Experiment FIS - FIFE Information System FRL - Flight Research Laboratory GMT - Greenwich Mean Time GSFC - Goddard Space Flight Center HP - high pass HTML - HyperText Markup Language IAR - Institute for Aerospace Research IFC - Intensive Field Campaign INS - Inertial Navigation System IRS - Inertial Reference System ISLSCP - International Satellite Land Surface Climatology Project MSL - Mean Sea Level NAE - National Aeronautical Establishment NASA - National Aeronautics and Space Administration NCAR - National Center for Atmospheric Research NRC - National Research Council, Canada NSA - Northern Study Area ORNL - Oak Ridge National Laboratory PANP - Prince Albert National Park RMS - Root Mean Square SSA - Southern Study Area TAS - True Air Speed URL - Uniform Resource Locator 20. Document Information 20.1 Document Revision Date Written: 01-Jan-1993 Revision Date: 10-Aug-1999 20.2 Document Review Date(s) BORIS Review: 30-Jun-1999 Science Review: 20.3 Document ID 20.4 Citation These data were measured by the Twin Otter Atmospheric Research Aircraft operated by the National Research Council of Canada. J.I. MacPherson of NRC was the Principal Investigator responsible for the operation of the aircraft in BOREAS and the processing of the data. Other scientists on the Twin Otter project team were Ray Desjardins of Agriculture Canada and Peter Schuepp of McGill University. Funding for the Twin Otter participation in BOREAS was provided by Agriculture Canada, NSERC and the National Research Council of Canada. 20.5 Document Curator 20.6 Document URL KEYWORDS -------- CARBON DIOXIDE FLUX OZONE GREENNESS MIXING RATIO TEMPERATURE AFM04_AC_Flux.doc 08/21/99