INSTITUTE OF ATMOSPHERIC SCIENCE, SCHOOL OF EARTH AND ENVIRONMENT (ENVIRONMENT), UNIVERSITY OF LEEDS, LEEDS LS2 9JT UK ------------------- T-REX AWS DATA SETS ------------------- Version 1.1: 26th April 2007. Changelog --------- Changes from 1.0 to 1.1 (1) The "Middle" site has now been processed and calibrated in the same manner as the previous AWS, and the data have now been released. (2) The document now contains the elevations of the AWS as determined by DGPS. See Section 2 "AWS Locations". Previous versions: ------------------ Version 1.0: 12th October 2006. 1. General Description ---------------------- These data represent the AWS data collected during the field phase of the T-REX experiment, 1st March - 30th April 2006. The data were collected at the sites specified below. With the exception of the "Notch" site (see below for list of site names) all AWS consisted of a 10m instrumented mast; the "Notch" site being 2m high (to minimise visual impact at this exposed site). The mast system, instrumentation amd logger boxes used to store the data were designed, constructed and maintained by the T-REX team at Leeds University. Users are advised to inspect the headers of each AWS file before using any of the data. 2. AWS Locations ----------------- The following list gives the locations of the Leeds AWS, determined by DGPS. Note that the "names" of the sites are for descriptive purposes only and need not have any relation to a specific physical landmark (although they often do.) All latitudes and longitudes are given relative to the WGS84 datum. North1 Lat = 36.890469 Lon = -118.181652 Elev = 1135.4 North2 Lat = 36.858714 Lon = -118.171024 Elev = 1133.0 Middle Lat = 36.823254 Lon = -118.152543 Elev = 1125.4 Railroad Lat = 36.827198 Lon = -118.128576 Elev = 1128.1 Low Inyo Lat = 36.879301 Lon = -118.100626 Elev = 1761.9 Santa Rita Lat = 36.920047 Lon = -118.121993 Elev = 2176.5 Mazourka Lat = 36.974447 Lon = -118.119365 Elev = 2843.9 Windy Hill Lat = 36.794350 Lon = -118.302564 Elev = 2115.9 Trailhead Lat = 36.774322 Lon = -118.337822 Elev = 2766.3 Airport Lat = 36.824762 Lon = -118.190643 Elev = 1142.7 Notch Lat = 36.775229 Lon = -118.312870 Elev = 2557.3 NOTCH: IMPORTANT NOTE: SEE BELOW. DRI 1 Lat = 36.768455 Lon = -118.276087 Elev = 1708.0 Fish Hatchery Lat = 36.830148 Lon = -118.246418 Elev = 1294.2 DRI 4 Lat = 36.794682 Lon = -118.166195 Elev = 1142.1 BLM Lat = 36.804068 Lon = -118.227635 Elev = 1274.7 Notes: i). The mast at the Notch site blew down at some point in its operation. The exact time at which this happened has not been determined yet. The instruments all seemed to function correctly after the mast was blown down, and so all the Notch data is given here, but the data must be used WITH APPROPRIATE CAUTION. ii). DRI1 and DRI4 were, as the names imply, co-located with the DRI AWS stations 1 and 4 (based on the numbering system shown at http://www.wrcc.dri.edu/trex/ accessed 12th October 2006). iii). These data were post-processed using Gringo-P4, http://www.nottingham.ac.uk/iessg/gringo/READMEP4.HTM with IGS Precise Ephemeris data. The reference station used was Musick Mountain, http://archive.unavco.org/network/logs/musblog.txt For accuracy of DGPS see "What is the accuracy of DGPS?" by Monteiro et al., Journal of Navigation 58: 207-225 3. Naming Conventions --------------------- Files are named according to the location of the AWS, following the names given above in Section 2. For example, Railroad.nc contains the AWS data (in netCDF format- see below) for all of the T-REX field phase at the Railroad site. Notes: i). Where the name consists of two parts, e.g. Low Inyo, a single word is constructed via an underscore to form the filename, e.g. Low_Inyo.nc. 4. Data Description ------------------- Each AWS data file contains the following fields: A) Time in Julian days since 1st January 2006, GMT; So that 1.500000 is the 1st January at 12Z. B) GPS flag; included for University of Leeds diagnostic purposes but should be IGNORED by end users. This field will be removed in future versions of these data sets. C) Wind speed; nominally at 10m. D) Wind direction; nominally at 10m. E) Surface pressure; nomially at the surface. F) Digital temperature; included for University of Leeds diagnostic purposes but should be IGNORED by end users. This field will be removed in future versions of these data sets. G) Relative humidity at a (nominal) height of 2m. H) Air Temperature at a (nominal) height of 2m. I) Air Temperature at a (nominal) height of 10m. Notes: i). The true heights of the 10m temperature sensor, etc. can be found in the header file for each AWS data set. ii). Data was recorded at 3s intervals and is presented as such. No averaging has been applied to the data. iii). Further information on sensor type, etc. can be found in the header of the relevant AWS data file. iv). Data HAS BEEN CALIBRATED and can be used as-is. v). The Notch site did not have a 10m temp. sensor (see above, Section 1) and so this field is uniformly error-flagged. 5. Data Set Description ----------------------- The files are in netCDF format and can be read and manipulated by a variety of means, see: http://www.unidata.ucar.edu/software/netcdf/ (accessed 12 Oct. 2006). The data contains the fields mentioned above, stored in the order described above. The following table gives the type of each field (with the associated Fortran field descriptor in brackets) and associated error flag: Field Type Error Time Real (f12.7) N/A GPS Integer (i3) N/A Wind Speed Real (f8.2) -999.00 Wind Direction Integer (i5) -999 Pressure Real (f8.2) -999.00 Dig. temp. Real (f7.1) -999.0 Rel. humidity Real (f7.1) -999.0 2m temperature Real (f7.1) -999.0 10m temperature Real (f7.1) -999.0 Notes: i). The error flags represent the "missing_value" in netCDF terminology. ii). There are no "errors" in the time since this is the independent variable. 6. Contact Information ---------------------- The Leeds T-REX P.I. is Stephen Mobbs who can be contacted at the address at the head of this document, or at stephen@env.leeds.ac.uk The author of this document and person responsible for processing the T-REX data sets is Ralph Burton, same address as above, or at ralph@env.leeds.ac.uk 7. Use of the Data ------------------ Please use the following citation as an acknowledgement, if using this data in any scientific report/ paper/presentation: "This AWS 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.