BOREAS AFM-06 Mean Wind Profile Data Summary: The BOREAS AFM-06 team from the National Oceanic and Atmospheric Administration Environment Technology Laboratory (NOAA/ETL) operated a 915 MHz wind/Radio Acoustic Sounding System (RASS) profiler system in the Southern Study Area (SSA) near the Old Jack Pine (OJP) tower from 21-May-1994 to 20-Sep-1994. The data set provides wind profiles at 38 heights, containing the variables of wind speed, wind direction and the u-, v-, and w-components of the total wind. 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-06 Mean Wind Profile Data 1.2 Data Set Introduction The data were collected by Boreas Ecosystem Atmospheric Study (BOREAS) Aircraft Flux and Meteorology Team #6 (AFM-06) team during 5 months covering late spring and summer in 1994. The Wind profiler data were measured by the NOAA/ETL 915 MHz wind/RASS profiler. The data were collected near the SSA-OJP tower. 1.3 Objective/Purpose The BOREAS field work objectives were to measure continuous hourly profiles of wind velocity and temperature in the atmospheric boundary layer and lower troposphere, to measure the depth of the daytime convective boundary layer, and to measure the occurrence of precipitation, all using a 915 MHz radar wind/RASS profiler. The data were then to be used to document average boundary layer structure, and especially changes in boundary layer structure during the course of the boreal summer growing season. 1.4 Summary of the parameters. The AFM-06 wind profile data includes vertical profiles of wind velocity and u-, v-, w-components of the wind. 1.5 Discussion. NOAA/ETL operated a 915 MHz wind profiling radar and surface meteorological station near the Old Jack Pine site in the BOREAS Southern Study Area. These instruments ran continuously from 21-May-1994 through 20-Sep-1994. The data provided by the wind profiler are vertical profiles of wind speed and direction and virtual temperature, as well as boundary layer depth (Zi) and the presence of precipitation. These measurements were made with 100 m vertical resolution with the lowest measurement height at 150 m above ground level. The maximum height sampled was 3850 m agl, although on many days the maximum height of the wind measurements was in the range of 2-3 km due to weak signal strength in the region of the lower troposphere above the atmospheric boundary layer (ABL). 1.6 Related Data Sets. BOREAS AFM-06 Mean Temperature Profile Data BOREAS AFM-06 Boundary Layer Height Data BOREAS AFM-06 Surface Meteorological Data 2. Investigator(s) 2.1 Investigator(s) Name and Title Robert Banta, Brooks Martner, James Wilczak NOAA Environmental Laboratory 2.2 Title of Investigation Outer Boundary Layer Effects on Surface Fluxes of Momentum, Heat, Moisture, and Greenhouse Gases from the Boreal Forest 2.3 Contact Information Contact 1 ------------- James Wilczak NOAA/ETL Boulder, CO Phone: (303) 497-6245 E-mail: jwilczak@etl.noaa.gov Contact 2 ------------ Jeffrey A. Newcomer Raytheon ITSS NASA GSFC Greenbelt, MD (301) 286-7858 (301) 286-0239 (fax) Jeffrey.Newcomer@gsfc.nasa.gov 3. Theory of Measurements The above measurements were obtained by measuring the zeroth, first, and second moments of the radar Doppler spectrum. The zeroth moment is the signal power. The range corrected signal power can alternatively be expressed in terms of the turbulence structure parameter Cn2. It is well-known that the vertical profile of Cn2 exhibits a sharp peak at the midpoint of the inversion transition region, due to local mixing of relatively cool, moist boundary layer air with warmer and dryer air aloft. Our measurements of Zi were obtained from the peak value in the vertical profile of Cn2 from a vertically pointing radar beam. The first moment of the Doppler spectrum is the Doppler velocity. The vertical profile of wind velocity was measured by combining the Doppler velocities measured along three radar beams: one vertical, and two oblique beams pointing at elevations of 75 degrees, oriented 90 degrees apart. The vertical profile of virtual temperature was measured using RASS (Radio Acoustic Sounding System), in which an array of acoustic speakers surround the radar and generate a sound pulse. The radar signal reflects off of this acoustic wave front, and the measured Doppler shift indicates the velocity of the sound pulse, which is proportional to the virtual temperature of the air. The second moment of the Doppler spectrum, or spectral width, can provide a measure of the strength of the turbulence within the boundary layer. The second moment has not been directly used in the present analysis. Finally, the presence of precipitation is determined by using both signal power and the vertical velocity. Rain and snow have much greater signal power than does clear air, and nearly uniform downward velocities. Rain can be distinguished from snow by its greater reflectivity, and by its greater fall velocity. Because of the high sensitivity of the profiler, it is capable of detecting small amounts of rain that might not be measured by a traditional surface rain gauge. The profiler detects only the presence of precipitation, however, and at present cannot give a quantitative measure of rainfall amount. 4. Equipment: 4.1 Sensor/Instrument Description 915 MHz wind profiling radar with RASS. 4.1.1 Collection Environment The 915 MHz profiler was used during various ambient weather conditions that occurred at the BOREAS SSA-OJP site. 4.1.2 Source/Platform Ground based. 4.1.3 Source/Platform Mission Objectives The ground supported the needed instrumentation. 4.1.4 Key Variables Included in this data set are wind profiles at 38 heights, containing the variables of wind speed, wind direction and the u-, v-, and w-components of the total wind. 4.1.5 Principles of Operation Standard Doppler radar techniques. 4.1.6 Sensor/Instrument Measurement Geometry One vertical beam, two oblique beams 15 degrees from vertical at an elevation of 75 degrees. 4.1.7 Manufacturer of Sensor/Instrument Wind Profiler: NOAA/ETL (Contact: James Wilczak at the address found in Section 2) 4.2 Calibration 4.2.1 Specifications None given. 4.2.1.1 Tolerance None given. 4.2.2 Frequency of Calibration None given. 4.2.3 Other Calibration Information None given. 5. Data Acquisition Methods During the course of one hour the radar makes 18 cycles through each of the three radial beams, averaging for 60 seconds on each beam. These measurements require a total of 54 minutes. Prior to this the RASS temperature profile is measured on the vertical beam during the first 5 minutes of the hour. During BOREAS, the RASS temperature observations consisted of 15 measurements, each 15 seconds in length. Each of these individual radial measurements of both wind and temperature are then quality controlled through an automated pattern recognition scheme, and then combined into a single value of wind and temperature reported for each hour. 6. Observations 6.1 Data Notes The wind profiler operated unattended for most of the 4 month observation period. 6.2 Field Notes The wind profiling radar and surface meteorological stations were located at a site 1.0 km south and 1.6 km east of the SSA-OJP tower flux site. The radar site was in a clearing in the Jack Pine forest, with fetches (clear distances) of 200 m to the north, 500 m to the south, 150 m to the east, and 1.0 km to the west. Ground cover within the clearing consisted of grass, brush, and young Jack Pine trees, approximately 1-2 m tall. 7. Data Description 7.1 Spatial Characteristics 7.1.1 Spatial Coverage The North American Datum 1983 (NAD83) coordinates of the site are: Lat. = 53.91 degrees, North Long. = 104.40 degrees, West Alt. = 511 m meters above sea level This is located 1.0 km south, and 1.6 km east of the SSA-OJP flux tower. 7.1.2 Spatial Coverage Map Not applicable. 7.1.3 Spatial Resolution Beamwidth = 9.9 degrees (One-way, 3 dB) Range resolution = 101 m Range limits = 0.112 - 3.889 km above ground level (38 range gates) 7.1.4 Projection Not applicable. 7.1.5 Grid Description Not applicable. 7.2 Temporal Characteristics 7.2.1 Temporal Coverage Measurements were made from 21-May-1994 through 20-Sep-1994. 7.2.2 Temporal Coverage Map Not available 7.2.3 Temporal Resolution Measurements were made 15 times per hour during the period. 7.3 Data Characteristics Data characteristics are defined in the companion data definition file (afm06pwd.def). 7.4 Sample Data Record Sample data format shown in the companion data definition file (afm06pwd.def). 8. Data Organization 8.1 Data Granularity All of the mean wind profile data are in one file. 8.2 Data Format(s) The data files contain ASCII 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 (afm06pwd.def). 9. Data Manipulations 9.1 Formulae 9.1.1 Derivation Techniques and Algorithms None given. 9.2 Data Processing Sequence 9.2.1 Processing Steps During the course of one hour the radar makes 18 cycles through each of the three radial beams, averaging for 60 seconds on each beam. These measurements require a total of 54 minutes. Prior to this the RASS temperature profile is measured on the vertical beam during the first 5 minutes of the hour. During BOREAS, the RASS temperature observations consisted of 15 measurements, each 15 seconds in length. Each of these individual radial measurements of both wind and temperature are then quality controlled through an automated pattern recognition scheme, and then combined into a single value of wind and temperature reported for each hour. 9.2.2 Processing Changes None given. 9.3 Calculations 9.3.1 Special Corrections/Adjustments None given. 9.3.2 Calculated Variables None given. 9.4 Graphs and Plots None given. 10. Errors 10.1 Sources of Error During spring and autumn seasons it is possible that the profiler winds can be contaminated by the presence of migrating birds. These errors are now well- understood, and can be recognized from large values of signal power, spectral width, and sudden changes in wind speed occurring near sunset and sunrise. Periods of contaminated winds have been hand edited from the data set. Birds do not directly effect RASS temperatures, although they could have a secondary effect by contaminating vertical velocity, which is used to correct RASS temperatures. No corrections for contaminated vertical velocities on RASS have been made. 10.2 Quality Assessment 10.2.1 Data Validation by Source See 10.2.3 10.2.2 Confidence Level/Accuracy Judgement See 10.2.3 10.2.3 Measurement Error for Parameters During the first 3 days and last three days of operation, ETL personnel were at the site taking balloon intercomparisons. These assessments have shown typical values of agreement of the balloons with profiler, typically 1-2 m/s and 1 deg C. Winds velocity differences between 915 MHz wind profilers and precision research aircraft have been found to be on the order of 0.9 m/s. 10.2.4 Additional Quality Assessments None given. 10.2.5 Data Verification by Data Center BORIS personnel verified that the delivered data agreed with the information provided by the AFM-06 team. 11. Notes 11.1 Limitations of the Data None given. 11.2 Known Problems with the Data None given. 11.3 Usage Guidance None given. 11.4 Other Relevant Information None given. 12. Application of the Data Set These data would be used to study and model wind motion at various levels of the atmosphere above the site. 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 Information Ms. Beth Nelson BOREAS Data Manager NASA GSFC Greenbelt, MD (301) 286-4005 (301) 286-0239 (fax) Elizabeth.Nelson@gsfc.nasa.gov 15.2 Data Center Identification See section 15.1 15.3 Procedures for Obtaining Data Users may place requests on line or by telephone, electronic mail, or FAX. 15.4 Data Center Status/Plans The AFM-06 wind profiler data are available from the EOSDIS ORNL DAAC (Earth Observing System Data and Information System) (Oak Ridge National Laboratory) (Distributed Active Archive Center). The BOREAS contact at ORNL is: ORNL DAAC User Services Oak Ridge National Laboratory (865) 241-3952 ornldaac@ornl.gov ornl@eos.nasa.gov 16. Output Products and Availability 16.1 Tape Products None. 16.2 Film Products None. 16.3 Other Products Tabular ASCII files. 17. References 17.1 Platform/Sensor/Instrument/Data Processing Documentation Angevine, W. M., and Ecklund, W. L.: 1994, Errors in Radio Acoustic Sounding of Temperature, J. Atmos. Ocean. Technol. 11, 42 49. Angevine, W. M., and MacPherson, J. I.: 1995, Comparison of Wind Profiler and Aircraft Wind Measurements at Chebogue Point, Nova Scotia, J. Atmos. Ocean. Technol. 12(2), 421 426. Gage, K. S., Williams, C. R., and Ecklund, W. L.: 1994, UHF Wind Profilers: A New Tool for Diagnosing Tropical Convective Cloud Systems. Bull. Amer. Meteor. Soc. 75, 2289 2294. Gossard, E. E., and Strauch, R. G.: 1983, Radar Observations of Clear Air and Clouds, Elsevier, Amsterdam, 280 pp. May, P. T., Moran, K. P., and Strauch, R. G.: 1989, The Accuracy of RASS Temperature Measurements, J. Appl. Meteor. 28, 1329 1335. Moran, K. P., and Strauch, R. G.: 1994, The Accuracy of RASS Temperature Measurements Corrected for Vertical Air Motion, J. Atmos. Ocean. Technol. 11, 995 1001. Peters, G.: 1994, Correction of Turbulence Induced Errors of RASS Temperature Profiles, Proc., 3rd Intl Symp. on Tropospheric Profiling: Needs and Technologies, Hamburg, Max Planck-Gesellschaft zur F"rderung der Wissenschaften, pp. 266 268. 17.2 Journal Articles and Study Reports Angevine, W. M., White, A. B., and Avery, S. K.: 1994b, Boundary-Layer Depth and Entrainment Zone Characterization with a Boundary-Layer Profiler, Boundary- Layer Meteorol. 68, 375 385. May, P. T., and Wilczak, J. M.: 1993, Diurnal and Seasonal Variations of Boundary Layer Structure Observed with a Radar Wind Profiler and RASS, Mon. Wea. Rev. 121, 673 682. Merritt, D. A.: 1995, A Statistical Averaging Method for Wind Profiler Doppler Spectra, J. Atmos. Ocean. Technol. (accepted for publication). Ralph, F. M.: 1995, Using Radar-Measured Radial Vertical Velocities to Distinguish Precipitation Scattering from Clear-Air Scattering, J. Atmos. Ocean. Technol. 12, 257 267. Rogers, R. R., Ecklund, W. L., Carter, D. A., Gage, K. S., and Ethier, S. A.: 1993, Research Applications of a Boundary-Layer Wind Profiler, Bull. Amer. Meteor. Soc. 74, 567 580. Sellers, P. and F. Hall. 1994. Boreal Ecosystem-Atmosphere Study: Experiment Plan. Version 1994-3.0, NASA BOREAS REPORT (EXPLAN 94). 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., F. Hall, K.F. Huemmrich. 1996. Boreal Ecosystem-Atmosphere Study: 1994 Operations. NASA BOREAS Report (OPS DOC 94). Sellers, P., F. Hall. 1996. Boreal Ecosystem-Atmosphere Study: Experiment Plan. Version 1996-2.0, NASA BOREAS Report (EXPLAN 96). Sellers, P., F. Hall, K.F. Huemmrich. 1997. Boreal Ecosystem-Atmosphere Study: 1996 Operations. NASA BOREAS Report (OPS DOC 96). 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 (JGR), BOREAS Special Issue, 102(D24), Dec. 1997, pp. 28731-28770. Whiteman, C. D., and Bian, X.: 1994, Semidurnal Solar Tides in the Mountain Atmosphere, Proc., 23rd Conf. on Alpine Meteorology (Lindau, Germany), Deutsche Wetterdienst, Offenbach, Germany. Wilczak, J. M., Strauch, R. G., Ralph, F. M., Weber, B. L., Merritt, D. A., Jordan, J. R., Wolfe, D. E., Lewis, L. K., Wuertz, D. B., Gaynor, J. E., McLaughlin, S. A., Rogers, R. R., Riddle, A. C., and Dye, T. S.: 1995, Contamination of Wind Profiler Data by Migrating Birds: Characteristics of Corrupted Data and Potential Solutions, J. Atmos. Ocean. Technol. 12, 449 467. 17.3 Archive/DBMS Usage Documentation None. 18. Glossary of Terms None given. 19. List of Acronyms ABL - Atmospheric Boundary Layer BOREAS - BOReal Ecosystem-Atmosphere Study BORIS - BOREAS Information System DAAC - Distributed Active Archive Center EOS - Earth Observing System ETL - Environment Technology Laboratory EOSDIS - EOS Data and Information System GMT - Greenwich Mean Time GSFC - Goddard Space Flight Center NASA - National Aeronautics and Space Administration NOAA - National Oceanic and Atmospheric Administration OJP - Old Jack Pine ORNL - Oak Ridge National Laboratory RASS - Radio Acoustic Sounding System SSA - Southern Study Area URL - Uniform Resource Locator 20. Document Information 20.1 Document Revision Dates Written: 07-Jun-1996 Last Updated: 05-Feb-1999 20.2 Document Review Dates BORIS Review: 29-Jan-1999 Science Review: 20.3 Document ID 20.4 Citation Wind profiler (and/or surface meteorological) data provided by Dr. James Wilczak, NOAA Environmental Technology Laboratory 20.5 Document Curator 20.6 Document URL Keywords -------- Atmospheric wind profiles Wind Speed Wind Direction AFM06_WindProf.doc 03/03/99