INSTITUTE OF ATMOSPHERIC SCIENCE, SCHOOL OF EARTH AND ENVIRONMENT (ENVIRONMENT), UNIVERSITY OF LEEDS, LEEDS LS2 9JT UK http://www.see.leeds.ac.uk/ -------------------------------------- T-REX FLUX TOWER DATA SETS: ASCII DATA -------------------------------------- 0. Document Version ------------------- Version 1.0: 10th January 2007. 1. General Description ---------------------- These data were collected at the flux towers specified below, during during the field phase of the T-REX experiment, 1st March - 30th April 2006. Anyone interested in obtaining the raw, high-rate data should contact Dr Ian Brooks (see below). 2. Data processing ------------------ The data were processed by Ian Brooks (P.I.) and Cathryn Birch. See below for contact information. 3. Flux Tower Locations and ancillary data ------------------------------------------- BLM: lon = -118.2276 lat = 36.8040 elevation = 1300m height of sonic #1 above surface = 5.15m height of sonic #2 above surface = 8.00m Airport: lon = -118.1906 lat = 36.8248 elevation = 1166m height of sonic above surface = 6.20m Railroad: lon = -118.1283 lat = 36.8274 elevation = 1151m height of sonic above surface = 6.20m Notes (i). Each of these sites had a University of Leeds AWS (with the same name); see the catalogue for AWS data. 4. Naming Conventions --------------------- Files are named according to the date on which the data were collected, the type of data contained, and the location, and are in the format: YYYYMMDD_var-string_loc-string.dat where: YYYY = year MM = month DD = day of month var_string = either "uvw_variances" or "ustar_H" (i.e. the type of data in the file, see below) loc-string = either "BLMs1" (sonic#1 at the BLM site), "BLMs2" (sonic#2 at the BLM site), "railroad" or "airport". (See above for the locations of the flux towers) See below for descriptions of the two different types of file, determined by the var_string. 5. Data Description ------------------- Flux data plots fall into two types: A). var_string = uvw_variances - These files contain the 15-minute averaged variances of: , and . Data files have 10 columns: YYYY MM DD hh mm ss UU VV WW flag YYYY = year MM = month DD = day HH = hour mm = minute ss = second UU, VV, WW = turbulent intensities (m^2 s^-2) flag = 0 (clear flow) or 1 (obstructed flow) - see Note (i) below B). var_string = ustar_H - These files contain the 15-minute averaged heat fluxes rho*c_p* and the friction velocity u_*. Data files have 9 columns: YYYY MM DD hh mm ss ustar H flag YYYY = year MM = month DD = day HH = hour mm = minute ss = second ustar = friction velocity (m s^-1) H = heat flux (W m^-2) flag = 0 (clear flow) or 1 (obstructed flow) - see Note (i) below Notes i). "Obstructed flow" periods represent events where the wind direction has passed through (or very close to) the mast or other instruments behind the sonic anemometer. ii). Flux data were not calculated if there was less than 12 min of usable data during a 15-min period - all dependent variables take the value 'NaN' if this occurs. iii). There were no inclinometers on the Airport, Railroad and BLM#2 sonics, so no corrections of wind components to true vertical have been applied. Each 15min run was rotated into a streamline coordinate system. iv). For the BLM#1 sonic, inclinometer data was available and so data have first been corrected to true vertical, then corrected using a planar fit to rotate fluxes into the plane of the mean flow for the entire data record. 6. Contact Information ---------------------- The Leeds T-REX Flux Tower P.I. is Ian Brooks who can be contacted at the address at the head of this document, or at ibrooks@env.leeds.ac.uk Cathryn Birch processed much of the data and can be contacted at the address at the head of this document, or at lec2ceb@env.leeds.ac.uk The author of this document is Ralph Burton (with help from Cathryn Birch), same address as above, or at ralph@env.leeds.ac.uk 7. Use of the Data - IMPORTANT ------------------------------ Please use the following citation as an acknowledgement, if using this data in any scientific report/ paper/presentation: "This flux data was gathered as part of the Terrain-induced Rotor Experiment (T-REX). The primary sponsor of T-REX was the US National Science Foundation. The acquisition of this data was carried out by workers at the Institute for Atmospheric Science, University of Leeds, UK and was funded by the Natural Environment Research Council (NERC), UK." If the contribution of this data product is significant to the publication/ presentation, the Leeds P.I.s should be offered the right to joint authorship. Any redistribution of this data must include this data acknowledgement statement.