Global Daily Measured Surface Air Temperature, Air Water Vapor Pressure, Precipitation and Snow Depth From 2000 to 2007 (Up To 7000 Worldwide Stations Per Year) 03/31/2009 *********************************************************************** DESCRIPTIONS: These data were derived from NCDC Global Summary of the Day Version 8 data set by Ke Zhang at NTSG,The University of Montana. The origianl data were provided by the ground observation stations and compiled by NCDC. The information about the original data can be found through http://www.ncdc.noaa.gov/cgi-bin/res40.pl?page=gsod.html. Due to the movements and changes of ground stations, the number of stations with sufficient measurements are different every year. ************************************************************************ DETAILS/FORMAT The derived data include six variables: Tmax -- Daily maximum surface air temperature (Celsius degrees) Tmin -- Daily minimum surface air temperature (Celsius degrees) Tavg -- Daily average surface air temperature (Celsius degrees) AVP -- Daily average air water vapor pressue (Pa) Prcp -- Daily precipitation (both snowfall and rainfall) (mm) Snow -- Snow depth (mm) These stations without enough records in temperature and relative humidity (less than 20 records in one month) were discarded. A simple linear interpolation was appled to fill in the missing values of Tmax, Tmin, Tavg and AVP using the two nearest records. However, the missing values of precipitation and snow depth are marked as -9999.0. The missing values can mean either no precipitation/no snowcover or missing reports. There are seven files for each year in the derived data set, including "Datalist_????.txt","NCDC_Tavg_????.dat", "NCDC_Tmax_????.dat", "NCDC_Tmin_????.dat", "NCDC_Prcp_????.dat", "NCDC_Snow_????.dat" and "NCDC_AVP_????.dat" where "????" denotes the year. The "Datalist_????.txt" file is an ASCII file, has four columns, and lists the information of available stations in this year. The 1st column is the WMO/DATSAV3 numbers, the 2nd column is the WBAN (Weather Bureau Air Force Navy) numbers, the 3rd column is the latitudes and the 4th column is the longitudes of these stations. The "NCDC_Tavg_????.dat", "NCDC_Tmax_????.dat", "NCDC_Tmin_????.dat", "NCDC_Prcp_????.dat","NCDC_Snow_????.dat" and "NCDC_AVP_????.dat" are saved as singly-precision floating-point (4 bytes) binary data flows and have the same size in the same year. The size of each of these files is equal to (number of stations in this year) * (number of days in this year) * 4 (size of singly-precision "float" type). Take the year of 2000 as an example. There are 5727 stations with data and 366 days in this year. Therefore, the "NCDC_Tmax_2000.dat",..., and "NCDC_AVP_2000.dat" files have size of 5727*366*4=8384328 bytes. The first 366 singly-precision floating-point data are daily values for this first station in 2000. The 5727th 366 singly-precision floating-point data are daily values for the 5727th station. ************************************************************************ CONTACT: John S. Kimball (johnk@ntsg.umt.edu) Ke Zhang (zhang@ntsg.umt.edu)