BOREAS AFM-04 Twin Otter Aircraft Sounding Data Summary The BOREAS AFM-04 team used the NRC Twin Otter aircraft to make sounding measurements through the boundary layer. These measurements included concentrations of carbon dioxide and ozone, atmospheric pressure, dry bulb temperature, potential temperature, dewpoint temperature, calculated mixing ratio, and wind speed and direction. Aircraft position, heading, and altitude were also recorded. Data were collected at both the NSA and the SSA in 1994 and 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 Aircraft Sounding 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 to make sounding measurements through the boundary layer. These measurements included concentrations of carbon dioxide and ozone, atmospheric pressure, dry bulb temperature, potential temperature, dewpoint temperature, calculated mixing ratio, and wind speed and direction. Aircraft position, heading, and altitude were also recorded. Data were collected at both the Northern Study Area (NSA) and Southern Study Area (SSA) in 1994 and 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 sounding flights was to make measurements through the boundary layer to document the vertical structure of the atmosphere over the test area (MacPherson, 1996; MacPherson and Bastian, 1997). The mixed layer was of particular interest in this research. 1.4 Summary of Parameters Atmospheric Pressure, Orthogonal Components of the Wind Velocity, Wind Speed and Direction, Dry Bulb Temperature, Potential Temperature, Dewpoint Temperature, Calculated Mixing Ratio, Carbon Dioxide Concentration, Ozone Concentration, Aircraft Position, Heading, Altitude (Radar and Pressure). 1.5 Discussion The Twin Otter operated in all three Intensive Field Campaigns (IFCs) in 1994 and in July and August 1996. The archived data were collected on sounding runs over the BOREAS site from near the surface to between 6,000 and 8,000 ft (2 and 2.5 km). The Twin Otter flew 51 sounding flights in 1994 and 26 flights in 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-02 Wyoming King Air 1994 Aircraft Sounding Data BOREAS AFM-03 NCAR Electra 1994 Aircraft Flux Data BOREAS AFM-03 NCAR Electra 1994 Aircraft Moving Window Data BOREAS AFM-03 NCAR Electra 1994 Aircraft Sounding Data BOREAS AFM-04 NRC Twin Otter Aircraft Flux 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 (1988, 1990a, 1990b, 1992, 1996), MacPherson and Morgan (1981), 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 (1988, 1990a, 1990b, 1996), MacPherson and Morgan (1981), 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) Dewpoint E, G, and G Model 137-S10 Cambridge dewpoint sensor Ozone TECO Ozone Analyzer Model 49 (these O3 data reported to the BOREAS Information System (BORIS)) GFAS (unit borrowed from German Aerospace Research Establishment) Scintrex LOZ-3 ozone detector Momentum Wind Components Inertial Velocity Litton LTN-90-100 IRS 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 from near the surface to between 6,000 and 8,000 ft (2 and 2.5 km). 4.1.2 Source/Platform Twin Otter DHC-6-200 twin turboprop utility transport. The maximum gross takeoff weight is 11,579 lb. The service ceiling is 20,000 ft. The endurance is 3 to 4 hours, depending on instrumentation and weather. 4.1.3 Source/Platform Mission Objectives The primary objective was to make measurements through the boundary layer to document the vertical structure of the atmosphere over the test area (MacPherson, 1996; MacPherson and Bastian, 1997). The mixed layer was of particular interest in this research. 4.1.4 Key Variables Atmospheric Pressure, Orthogonal Components of the Wind Velocity, Wind Speed and Direction, Dry Bulb Temperature, Potential Temperature, Dewpoint Temperature, Calculated Mixing Ratio, Carbon Dioxide Concentration, Ozone Concentration, Aircraft Position, Heading, Altitude (Radar and Pressure). 4.1.5 Principles of Operation The principles of operation of the aircraft and its instrumentation and software are given in detail in MacPherson (1988, 1990a, 1990b, 1996), MacPherson and Morgan (1981), 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, MacPherson (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 at this revision. 4.2.1.1 Tolerance Not available at this revision. 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 The data were collected from the aircraft, flying from near the surface to between 6,000 and 8,000 ft (2 and 2.5 km) in a spiral pattern. 6. Observations 6.1 Data Notes The following is a table that describes how the data were recorded. Note: 128 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. 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 (TAS), wind velocity, and fluxes. **Note:*** This is basically the recorder buffer to be used in the BOREAS site visit in May 1993. Additional parameters were recorded in BOREAS (e.g., satellite simulator). A Trimble 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 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 Litton 90/100 IRS should fail: calculation of wind components is described in reports referenced in Section 17.1. The air velocity relative to the aircraft is measured by the 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, roll, attitude, and 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 three Earth axes. The IRS is similar to an Inertial Navigation System (INS), 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 Dobosy et al., 1997. 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). 6.2 Field Notes None. 7. Data Description 7.1 Spatial Characteristics 7.1.1 Spatial Coverage The sounding flights were made centered over a specific point, flying in a spiral pattern, ascending in altitude. The start and end points for each sounding flight were as follows: START END Latitude Longitude Latitude Longitude IFC-1: 25-May-1994 53.51883N 105.48317W 53.59817N 105.25850W 53.58183N 106.27834W 53.49650N 106.10700W 26-May-1994 53.51467N 105.48350W 53.62700N 105.10416W 53.78517N 104.82267W 53.67783N 105.06850W 29-May-1994 53.51900N 105.48317W 53.65617N 105.38084W 01-Jun-1994 53.60417N 106.29400W 53.51883N 106.13850W 04-Jun-1994 53.62283N 105.20500W 53.76150N 104.87217W 53.63650N 106.20467W 53.52950N 106.06033W 07-Jun-1994 55.80250N 98.38917W 55.84517N 98.47000W 08-Jun-1994 55.79000N 98.41100W 55.88383N 98.82283W 55.94933N 98.39883W 55.89467N 98.14183W 09-Jun-1994 55.84883N 98.41950W 55.80550N 98.03200W 10-Jun-1994 55.79583N 98.41783W 55.77517N 98.56100W 11-Jun-1994 55.79817N 97.87016W 55.83650N 98.09634W 55.87500N 98.37517W 55.84083N 98.32350W 13-Jun-1994 55.95250N 98.39600W 55.93683N 98.24050W 55.82833N 98.32750W 55.83117N 98.45900W IFC-2: 20-Jul-1994 53.52433N 105.48083W 53.59583N 105.28967W 21-Jul-1994 53.53117N 105.47667W 53.62850N 105.22800W 53.52850N 105.47933W 53.71933N 105.32267W 22-Jul-1994 53.63283N 106.18916W 53.54867N 105.91483W 24-Jul-1994 53.52850N 105.47816W 53.62033N 105.23367W 53.52417N 105.48217W 53.69150N 105.42416W 25-Jul-1994 53.52567N 105.48100W 53.61467N 105.17733W 53.39400N 105.99416W 53.53667N 106.30717W 26-Jul-1994 53.52800N 105.48083W 53.63300N 105.19083W 27-Jul-1994 53.52400N 105.48383W 53.54600N 105.75816W 28-Jul-1994 55.93433N 98.43684W 55.86283N 98.08283W 29-Jul-1994 55.80000N 97.86333W 55.85450N 98.20634W 01-Aug-1994 55.78867N 98.41367W 55.94533N 98.94550W 02-Aug-1994 55.91933N 98.67316W 55.79033N 98.27766W 04-Aug-1994 55.79433N 98.39983W 55.81483N 98.34267W 08-Aug-1994 55.90267N 98.31233W 55.92767N 98.24866W IFC-3: 31-Aug-1994 55.81317N 98.37100W 55.77517N 98.50450W 02-Sep-1994 55.79716N 97.87117W 55.86967N 98.35633W 08-Sep-1994 55.92333N 98.66634W 55.92883N 98.41517W 53.64500N 106.15800W 53.64333N 105.81067W 11-Sep-1994 53.51900N 105.48233W 53.70433N 105.34650W 53.49117N 106.00517W 53.53767N 106.28000W 13-Sep-1994 53.51733N 105.48183W 53.66017N 105.24450W 14-Sep-1994 53.52167N 105.48050W 53.74967N 105.38450W 53.93367N 105.35000W 53.90200N 105.37634W 15-Sep-1994 53.33067N 105.81433W 53.44700N 105.97350W 53.49133N 105.45050W 53.71200N 105.31883W 16-Sep-1994 53.52000N 105.48067W 53.65750N 105.01950W 17-Sep-1994 53.36100N 105.93784W 53.59817N 106.34866W 18-Sep-1994 53.41450N 106.07133W 53.56283N 106.41734W 54.95267N 101.96133W 55.88883N 97.99500W 55.88883N 97.99500W 55.92300N 97.92367W 19-Sep-1994 55.79833N 98.08283W 55.80353N 98.32050W 55.89717N 98.27634W 55.87133N 98.02666W 1996: 09-Jul-1996 53.68847N 105.48505W 53.77241N 105.10998W 53.78666N 104.81798W 53.75954N 105.10448W 53.42411N 105.93343W 53.62444N 106.19762W 10-Jul-1996 53.68332N 105.48402W 53.94030N 105.21469W 11-Jul-1996 53.96244N 104.92509W 53.83380N 105.21297W 12-Jul-1996 53.68967N 105.48196W 53.83541N 105.29588W 14-Jul-1996 53.68813N 105.47733W 53.77911N 105.26052W 53.78923N 105.28061W 53.84983N 105.32730W 19-Jul-1996 53.45467N 105.96296W 53.54633N 106.19831W 20-Jul-1996 53.93017N 105.14603W 53.99265N 105.14139W 53.89687N 105.28954W 53.85172N 105.36043W 53.85841N 105.40403W 53.77928N 105.37331W 53.64933N 105.16645W 53.76005N 104.90450W 26-Jul-1996 53.58015N 106.29976W 53.54736N 106.18561W 27-Jul-1996 53.91438N 104.97076W 53.89841N 104.92166W 29-Jul-1996 53.52213N 105.48334W 53.62976N 105.22104W 53.78666N 104.82622W 53.72709N 104.98947W 53.48213N 105.91318W 53.65328N 106.13737W 30-Jul-1996 53.46806N 106.13874W 53.56144N 106.39194W 54.95413N 101.96686W 54.87190N 101.89870W 55.87458N 98.37261W 55.88642N 98.19408W 31-Jul-1996 55.80608N 98.11426W 55.78463N 98.33227W 55.87921N 98.62667W 55.87870N 98.26447W 55.77793N 98.41999W 55.80059N 98.19494W 02-Aug-1996 55.79424N 97.88835W 55.80025N 98.15804W 55.90101N 98.30532W 55.88951N 98.23975W 03-Aug-1996 55.87440N 98.24009W 55.79716N 98.45861W 05-Aug-1996 55.79630N 97.87411W 55.89071N 98.19528W 55.99354N 98.50307W 55.94582N 98.59818W 55.91887N 98.63697W 55.85175N 98.41106W 07-Aug-1996 55.79613N 97.87239W 55.81535N 98.11391W 55.82874N 98.32780W 55.85604N 98.20215W 08-Aug-1996 55.87492N 98.37106W 55.92693N 98.20438W 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), 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 These data were collected at point locations. 7.1.5 Grid Description None. 7.2 Temporal Characteristics 7.2.1 Temporal Coverage Sounding data were collected from 25-May-1994 to 19-Sep-1994 and 09-Jul-1996 to 08-Aug-1996. 7.2.2 Temporal Coverage Map IFC-1: 25-May-1994 to 26-May-1994 29-May-1994 01-Jun-1994 04-Jun-1994 07-Jun-1994 to 11-Jun-1994 13-Jun-1994 IFC-2: 20-Jul-1994 to 22-Jul-1994 24-Jul-1994 to 29-Jul-1994 01-Aug-1994 to 02-Aug-1994 04-Aug-1994 08-Aug-1994 IFC-3: 31-Aug-1994 02-Sep-1994 08-Sep-1994 11-Sep-1994 to 19-Sep-1994 1996: 09-Jul-1996 to 12-Jul-1996 14-Jul-1996 19-Jul-1996 to 20-Jul-1996 26-Jul-1996 to 27-Jul-1996 29-Jul-1996 to 31-Jul-1996 02-Aug-1996 to 03-Aug-1996 05-Aug-1996 07-Aug-1996 to 08-Aug-1996 7.2.3 Temporal Resolution The aircraft data were recorded at a basic rate of 16 Hz in 1994 and 32 Hz in 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 (afm4toas.def). 7.4 Sample Data Record Sample data format shown in the companion data definition file (afm4toas.def). 8. Data Organization 8.1 Data Granularity All of the AFM-04 Twin Otter Aircraft Sounding 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 (afm4toas.def). 9. Data Manipulations 9.1 Formulae See MacPherson (1990b). 9.1.1 Derivation Techniques and Algorithms See MacPherson (1990b). 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 database. 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 the data before submitting them 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 if there should be a problem with the Litton 90/100 IRS. 9.3 Calculations 9.3.1 Special Corrections/Adjustments Calculation of wind components is described in MacPherson (1990b) and MacPherson and Morgan (1981). The air velocity relative to the aircraft is measured by the true airspeed (TAS) and noseboom angles of attack and sideslip. The TAS vector is then resolved into Earth axes (north, east, and vertical components). From these are subtracted 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 the 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 heading. 9.3.2 Calculated Variables None given. 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 high-pass 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). 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 None given. 11.3 Usage Guidance None. 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 None given. 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 NRC: 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. 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. 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. 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 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 GMT - Greenwich Mean Time GPS - Global Positioning System 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 NAD83 - North American Datum of 1983 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: 06-Aug-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 CONCENTRATION OZONE CONCENTRATION TEMPERATURE BOUNDARY LAYER AFM04_Soundings.doc 08/21/99