Data portal

In this section I provide several global climate raster data entirely or partialy derived from remote sensing data. Please do not hesitate to contact me in case you experince any issue with these data.

Precipitation and temperature

BIO12

Mean annual precipitation from CHIRPS v. 2.0 1981-2013

The 19 climatic variables described in the ANUCLIM scheme were derived from MOD11C3 (MODIS sensor, 2001-2013) land surface temperature and CHIRPS (1981-2013) precipitation dataset. Data range from 50°S to 50°N. It is available at 3 arc-minutes (i.e. 0.05 degree or 5.5 km on the equator) and 6 arc-minutes (i.e. 0.1 degree or 11 km on the equator) ground resolution. The archives linked below contain sets of GeoTIFFs. The maps use a geographic coordinate system (WGS1984) which is embedded in the files. -9999 corresponds to missing values. To explore the maps, you will need a GIS program such as QGIS or the R raster package.

This dataset should be cited as:

Deblauwe V., Droissart V., Bose R., Sonké B., Blach-Overgaard A., Svenning J-C, Wieringa J. J., Ramesh B. R., Stévart T. & Couvreur T. L. P. 2016. Remotely sensed temperature and precipitation data improve species distribution modeling in the tropics. Global Ecology and Biogeography. 25(4): 443-454

Water availability

WD

Mean annual Climatic Water Deficit (2000-2014)

I derived several global indexes of water balance from the monthly precipitation values provided by CHIRPS v. 2.0 and the monthly Potential EvapoTranspiration (PET) provided by the MODIS project MOD16. MOD16 uses ground-based meteorological observations and MODIS data to calculate evapotranspiration (ET) and PET with a revised Penman–Monteith equation that considers both the surface energy partitioning process and the  environmental constraints. ET is the sum of water lost to the atmosphere (usually expressed in milimeters) from the soil surface through evaporation and from plant tissues via transpiration. The period considered is 2000-2014.

  1. Aridity index. For each year, the yearly sum of precipitation is divided by the annual PET expressed in the same units (e.g. mm). The resulting dimentionless ratio is then averaged for the period. The smaller the index value the higher the aridity. This index has been adopted by the UNEP to establish a Generalized climate classification scheme with threshold values that define various degrees of aridity (UNEP, 1992, World Atlas of Desertification).
  2. Climatic Water Deficit. Because the humidity index does not account for the seasonality of precipitation and temperature, we propose here a layer of climatic water deficit. It is measured in mm/yr of the difference between rainfall and PET during dry months only (defined as months where PET exceeds rainfall) and is, by definition, negative. For each month a water deficit is obtained by substracting the PET to the precipitations. Positive values (excess water) are set to zero. Then the monthly water deficit are summed over the year and these yearly deficit are averaged over the period.
  3. Number of dry months. Dry months are counted for each year and averaged over the period.

 

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