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Creating Climate Forcing Files

This page describes methods for developing your own climate forcing dataset, and information on finding existing climate datasets.

Note

This page needs to be updated.

Developing a New Climate Forcing Dataset

Existing Climate Data Forcing Datasets

  • Tools for standard processing of climate data into gridded fields

    Note

    When gridding raw observational files, if the entire domain cannot be gridded at once due to space limitations, smaller subsets can be gridded to fit together correctly if grid cells are nested within the observational network used.  For example, to grid climate data for the state of Indiana include stations in Michigan, Illinois, Ohio and Kentucky at a minimum.  If you use only stations from Indiana, then the program must extrapolate what occurs between the available stations and the state border, which can result in discontinuities between gridded data sets for Indiana and its surrounding states.  Using stations outside of the region you are gridding will result in a smoother, more stable transition between gridded subsections - even if you don\'t currently plan to grid those other regions.

    • Original gridding programs can be downloaded here, if updates have not been posted to the VIC model web site under Gridding Meteorological Data from the National Climatic Data Center. These tools will result in gridded fields that preserve daily observations at individual stations to a high degree - all data is interpolated to grid cell centers, so stations closest to the grid cell center will experience the least change.  Application of the PRISM national mean fields will cause a change in bias for some stations, which can correct some localized problems in the spatial data set at the expense of preserving actual observations.

    • As of August 9, 2012 the full set of global daily meteorological observations can be downloaded from the NCDC ftp site: ftp://ftp.ncdc.noaa.gov/pub/data/ghcn/daily/.  See the readme.txt file for details related to the current files in the directory.  This file appears to be updated regularly, mostly by appending the latest climate data (perhaps every Monday).

    • The file is also available from our ftp-site as downloaded on August 9, 2012. File should include data through August 3, 2012.

  • An updated version of the gridding program that includes support for a list of lat-long cell centers can also be downloaded for use when generating gridded meteorology files for equal area grids, irregular grids, or other situations not easy to complete using an ArcInfo ASCII grid mask file.  Some instructions on the use of this program can be found here.

    Note

    Make sure and check the grd.f file to determine the proper format for your infofile (e.g., lon,lat,elev) and maskfile (e.g., lat,lon,elev). The regrid program will still run, without any warnings, even if the latitude and longitude are switched!

    In the future, it would be useful to modify this code to print calculated distances or to plot the regions for the station data and the output locations to make sure they match up.

  • Alan Hamlet (Hamlet and Lettenmaier, 2005) updated the gridding methodology to produce a more temporally  consistent long term dataset by relying on a subset of long-term, high-quality climate observation stations to reduce statistical anomalies caused by stations coming on-line, going off-line, moving locations, and changing instrumentation.  This results in a smoother long-term record that does not preserve data from individual stations (outside the long-term network), but is also very good for long term analysis. (VIMAL MISHRA)

  • Tools for developing bias-corrected daily future climate forcing for the VIC model. These tools will rescale gridded meteorological observations (e.g., those generated by above methods) to produce continuous daily time series based on GCM projections.

Tools for disaggregating precipitation from daily to sub-daily

  • Original method documented on the VIC model web site under Disaggregation of Daily Precipitation into Sub-Daily Amounts

  • Method developed by Mao et al. (2009)  making use of the CLIGEN climate generator from NSERL and WEPP development teams.  Documentation and tools... (LILI WANG, link to VIC-WEPP pages?).