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