CHIRPS-GEFS

CHIRPS-GEFS is a bias-corrected and downscaled version of NCEP Global Ensemble Forecast System (GEFS) version 12 precipitation forecasts made to be spatially compatible with Climate Hazards Center InfraRed Precipitation with Stations (CHIRPS) data. The CHIRPS-GEFS data set provides next 5-day to 15-day precipitation forecasts, updated daily, at a spatial resolution of ~5 km across the globe.

CHIRPS-compatible GEFS precipitation forecasts for anticipating flood and drought hazards

CHIRPS-GEFS unites key precipitation observation and forecast resources to support more streamlined situation assessments and hazards early warning. CHIRPS-GEFS forecasts are provided with compatible spatial characteristics and statistical distributions that facilitate their “inter-operation” with CHIRPS. This supports users producing timely impact assessments of forecast rainfall amounts and anomalies, as well as potential changes to agro-climatological or hydrological situations that are being monitored with CHIRPS data. Please find a more detailed overview below. 
 
For comments or inquiries, please contact Marty Landsfeld at marty.landsfeld@ucsb.edu

CHIRPS-GEFS Forecasts

Daily 5-day, 10-day, 15-day Forecasts

5-day

10-day 

15-day

Dekadal Forecasts

First (5-8 day lead)

  • Total & Anomaly         Data

Last (0-day lead) 

  • Total & Anomaly         Data

Daily Forecasts

Daily

  • Total                           Data

 

In blending CHIRPS and real-time GEFS forecasts, a quantile-matching procedure modifies the GEFS forecast precipitation amount to be consistent with the local historical CHIRPS record. The procedure identifies how the forecast amount ranks historically, compared to historical GEFS forecasts from 2000 to present. Using that rank-based percentile, an amount corresponding to the same percentile of the CHIRPS data distribution is identified. The new forecast thus retains important information from the GEFS, including the advanced weather forecasting ability of the GEFS version 12 system and the historical extremity of the current forecast, while also now aligning with the CHIRPS’s high-quality 5-km resolution climatology and CHIRPS historical variance.
 
Operational CHIRPS-GEFS data are a bias-corrected 0.05-degree version of the 0.25-degree resolution Day 1 to 10 and 0.5-degree resolution Day 11 to Day 16 GEFS real-time 00 UTC ensemble mean forecasts for total precipitation. The data used in the quantile-matching procedure are 16-day GEFS version 12 ensemble mean “reforecasts” for 2000 to 2019, real-time ensemble mean forecasts from October 2020, and CHIRPS version 2.0 historical precipitation. The GEFSv12 FV3 Phase II “reforecast” data are produced by NCEP/EMC and are described in Guan et al., 2019 (link to pdf here). More information on the GEFS is available here.

Accessing CHIRPS-GEFS

CHIRPS-GEFS data and images are available through several online interfaces.
 
Data Update Schedule: 5-day, 10-day, and 15-day CHIRPS-GEFS are updated daily. Dekads and pentads periods are updated on the first day of each period (every ~5 to 10 days). 

CHIRPS-GEFS Data Repository

Forecast data are provided for several time periods to support users. The table above provides links to the latest forecasts and to the historical data archive for most time periods, in GeoTIFF format (0.05-degree, 50N to 50S, 180W to 180E). All data is available here.

5-day, 10-day, 15-day CHIRPS-GEFS: January 2000 to December 2019 and October 2020 to present. In addition to precipitation totals (mm), anomalies (mm) and standardized precipitation index (Z scores) are available for download. These are computed using all available data.

Dekads CHIRPS-GEFS: October 2020 to present. Dekads correspond to the calendar dates 1-10, 11-20, and 21-end of each month. The “First” dekad forecast is produced 16 days before the last day of the dekad, corresponding to the first opportunity to do so using the GEFS 16-day forecast. The “Last” dekad forecast is produced on the 1st, 11th, and 21st day of each month. The “Last” forecast is preferred, due to the GEFS being initialized with closer-to-actual conditions. 

Pentads CHIRPS-GEFS: October 2020 to present. Pentads correspond to the calendar dates 1-5, 6-10, 11-15, 16-20, 21-25, and 26-end of each month. All are updated on the 1st, 6th, 11th, 16th, 21st, 26th of each month. Similar to the dekad forecasts, the “First,” “Second,” and “Last” names correspond to the first, second, and last time that a forecast is produced for the pentad of interest.

Early Warning Explorer (EWX)

In the CHC EWX and USGS EWX viewers, users can view the CHIRPS-GEFS and other data, including precipitation from several products, MODIS land surface temperature, eMODIS NDVI, modeled evapotranspiration and soil moisture, and more. 

As explained here, these EWX viewers provide historical time-series for a variety of regions, such as administrative zones, crop zones, and hydrologic catchment basins. In the USGS EWX viewer, CHIRPS-GEFS pentad forecasts are appended to CHIRPS time-series.

How to cite this data

This page is the registered CHIRPS-GEFS data repository. The assigned DataCite DOI is doi:10.15780/G2PH2M. Code used in producing CHIRPS-GEFS is available here.

Please cite CHIRPS-GEFS data as: CHIRPS-GEFS Precipitation Forecasts https://doi.org/10.15780/G2PH2M (2021)
 
A journal article describing CHIRPS-GEFS and an evaluation of forecast skill, for regions across the globe, is under review. 

CHIRPS-GEFS in Action

  • CHIRPS-GEFS is used in CHC Early Estimates, a data and map resource for monitoring seasonal precipitation and agro-climatological hotspots. The CHC Early Estimates Recent Rainfall Monitor and Seasonal Rainfall Monitor show rainfall accumulations for recent time periods based on the CHIRPS final and preliminary data. The  “+ Forecast” version includes the CHIRPS-GEFS 15-day forecast.
 
  • Monthly GEOGLAM Crop Monitor for Early Warning bulletins. CHIRPS-GEFS are used for evaluating rainfall conditions and for highlighting areas of concern in Regional Outlooks. 
 
 
 
 
  • A video presentation of Dr. Chris Funk showcasing a number of products for southern Africa is available on the CHC YouTube channel here.
 
 
 
  • SERVIR’s ClimateSERV portal has featured CHIRPS-GEFS data. ClimateSERV tools include user-defined boundaries for spatial data extraction and historical time series.