Data

HIGH RESOLUTION PRECIPITATION CLIMATOLOGY FROM THE TROPICAL RAINFALL MEASURING MISSION (TRMM) PRECIPITATION RADAR (PR)

Data Access

An updated version (v2) of the data described in Nesbitt and Anders (2009, Geophysical Research Letters) may be found in the following netCDF files:

trmm_pr_0.05_ANN_1998-2008_v2.nc.gz: Annually averaged

trmm_pr_0.05_DJF_1998-2008_v2.nc.gz: December – February

trmm_pr_0.05_MAM_1998-2008_v2.nc.gz: March – May

trmm_pr_0.05_JJA_1998-2008_v2.nc.gz: June – August

trmm_pr_0.05_SON_1998-2008_v2.nc.gz: September – November

Updates in version 2 (17 March 2010): Self describing netCDF files, doubling of spatial resolution (0.1° to 0.05°), addition of 2008 data, addition of variables (number of samples, ETOPO 2 topography).

These files contains the following variables:

RRATE - mean precipitation rate (mm/day) (near surface rain in algorithm 2A25 version 6) from the TRMM PR for January 1998 – December 2008 at 0.05° resolution, grid center latitude and longitudes given in variables LAT and LON

FREQ - precipitation frequency (near surface rain > 0 in algorithm 2A25 version 6) from the TRMM PR for January 1998 – December 2008 at 0.05° resolution, grid center latitude and longitudes given in variables LAT and LON

SAMP - number of raining and non-raining samples in algorithm 2A25 version 6) from the TRMM PR for January 1998 – December 2008 at 0.05° resolution, grid center latitude and longitudes given in variables LAT and LON – useful for calculation of sampling errors as in Nesbitt and Anders (2009)

TOPO - USGS ETOPO2 digital elevation model linearally interpolated to 0.05° resolution, grid center latitude and longitudes given in variables LAT and LON

Important notes on use of this dataset

Please cite the following article when using this dataset: Nesbitt, S. W., and A. M. Anders, 2009: Very high resolution precipitation climatologies from the Tropical Rainfall Measuring Mission precipitation radar. Geophys. Res. Lett., 36, L15815, doi:10.1029/2009GL038026. (pdf)

Note that this product contains significant measurement errors (which are undergoing ongoing validation) as well as sampling errors that can easily exceed 100% in pixel by pixel comparisons. Measurement errors are likely highest in snow and mixed precipitation, so use caution in areas where these precipitation types are expected. Also, limited ground clutter is present in some areas of steep topography, and ongoing work is idenifying these areas. Large sampling errors are due to the fact that the PR has a narrow (~250 km) swath in a low earth orbit. The error model presented in Nesbitt and Anders (2009) may be used to estimate these sampling errors.

For more information about the Tropical Rainfall Measuring Mission, visit the TRMM web site, and for more information about the 2A25 algorithm used to create this product, see Iguchi et al. (2000, Journal of Applied Meteorology) and theTRMM 2A25 README.

Questions or comments?

If you have questions, please contact Profs. Steve Nesbitt (snesbitt@illinois.edu) or Alison Anders (amanders@illinois.edu).

Funding Acknowledgement

This work was supported by the NASA New Investigator Program in Earth System Science.