TITLE:(Updated) ETL Doppler Lidar Wind Velocity andDirection Profiles from EPIC 2001 1.AUTHORS and CONTACT INFORMATION: Instrument: NOAA/ETL?s Mini-MOPA Doppler Lidar Instrument and Technical Contacts: Alan.Brewer@noaa.gov Scott.P.Sandberg@noaa.gov Raul.Alvarez@noaa.gov Data Products: High-resolution vertical profiles of Doppler Wind Velocity and Direction. Data Processing and Product Contacts: Janet.Intrieri@noaa.gov Brandi.McCarty@noaa.gov Website: http://www.etl.noaa.gov/et2/ Mailing Address: NOAA/Environmental Technology Laboratory Optical Remote Sensing Division, R/E/ET2 325 Broadway Boulder, CO 80305 2.DATA SET OVERVIEW: http://www.etl.noaa.gov/programs/2001/epic/ Vertical profiles of wind velocity and direction are produced from Doppler lidar measurementstaken aboard the Ron Brown from September 12th through October 22nd, 2001. The VADtechnique (Browning and Wexler, 1968) was employed to process wind information taken inscanning mode to produce the high-resolution vertical profiles. All velocities are in m/s andheights in meter. 3.INSTRUMENT DESCRIPTION: http://www.etl.noaa.gov/et2/instruments/mini-mopa/ The mini-MOPA Doppler lidar was originally developed at ETL to provide wind velocity anddirection in clear-air (non-cloud) regions. It was modified for the EPIC project with an additionallaser line to provide water vapor profiles using a Differential Absorption (DIAL) technique. 4.DATA COLLECTION AND PROCESSING: http://www.etl.noaa.gov/et2/data/data_pages/epic_winds.html The lidar operated every day with some exceptions due to rain. The data were obtained byscanning in VAD mode (i.e. sweeping in a full circle around the compass (0 to 360 degrees) andthen stepping up in discrete steps between 0 and 65 degrees in elevation angle). A velocity profileis then built from these successive set of scans to produce the vertically resolved ?profiler? likedata displayed in the images. Scans used to build the velocity profiles were taken no longer than30 minutes apart. 5.DATA FORMAT: Data file structure and file naming conventions: Two gif images are available, one representing the region from 0 to 1200 meters, and the other a closer view of the region from 0 to 200 meters. Also available are ASCII data files which include height, wind speed, direction and standarddeviation. The naming convention for the data files is the following: dd-mm-yyyy [X]. Where d represents the day of the month, m represents the month of the year, and y is the year. If the file has a letter in square brackets, this corresponds in the following manner: [A] is the early part of the day, [B] is the later part of the day. Data format and layout : The ASCII file header looks like the following: 36 0 29 4 9 7 2001 55.75 1.00 2 d:\EPIC\Data\010906\^numrows hr min sec mon dy yr el std_thr filenum/ v hght spd ang std The second line describes the first line of the file as well as the data from the 3rd row and after. FIRST ROW DESCRIPTION: 1. Data location, in the above example: d:\EPIC\Data\010906\ [string] 2. numrows, the number of rows of data to follow the header, in the above example: 36 [integer] 3. hr, the hour of the day corresponding to the profile, in the above example: 0 [integer] 4. min, the minute of the hour corresponding to the profile, in the above example: 29 [integer] 5. sec, the second of the minute corresponding to the profile, in the above example: 4 [integer] 6. mon, the month of the year corresponding to the profile, in the above example: 9 [integer] 7. dy, the day of the month corresponding to the profile, in the above example: 7 [integer] 8. yr, the year corresponding to the profile, in the above example: 2001 [integer] 9. el, the elevation angle corresponding to the elevation level of the scan of which the profiles were taken, in the above example: 55.75 This number is fairly arbitrary as multiple scans were used to calculate this high resolution profile. [float] 10. std_thresh, the threshold in which the data standard deviation must not exceed to be included in the profile, in the above example: 1.0 [float] 11. filenum, the original file number that the profile was calculated from, in the above example: 2 This number is arbitrary as multiple files were concatonated in order to calculate thevelocity profile [integer] . THIRD AND SUBSEQUENT ROWS DESCRIPTION:1. v hght corresponds to the first column of data. These values are the vertical height in meters corresponding to the location of the measured velocity. [float] 2. spd is the second column of data. These values are the wind velocity in meters/second. 3. ang corresponds to the third column of data. These values range from 0 to 359 degrees. Where a value of 90 represents easterly flow, and 0 (or 360) represents northerly winds. List of parameters with units, sampling intervals, frequency, range: The parameters representedin this file are height [meters], velocity [meters/sec], wind direction [degrees], and standard deviation. The values were calculated by averaging scans (in the elevation plane) in which the time between them is no longer than 30 minutes. Data version number and date: Data version number 1, December 5, 2002 Description of flags, codes used in the data, and definitions (i.e., good, questionable, missing,estimated, etc.): The missing or bad data flag in this data set is -999.0 6.DATA REMARKS: The Doppler lidar profiles provided herein have been updated (as of August 2003) from ourpreliminary version. Note however that only minimal QC has been applied to the data andtherefore occasional outliers may still exist in the data. 7.REFERENCES: VAD reference: Browning, K.A., and R. Wexler, 1968: The determination of kinematic properties of a wind fieldusing a Doppler radar. J. Appl. Meteor., 7, 105-113.