Real Time Precipitation Estimates
|HyDIS Website||HyDIS GWADI Map Server||PERSIANN 0.25° Product Access Tools|
Other satellite precipitation products:
In the last decade, different satellite precipitation products have become widely available. These products, some of which are global and available in near-real time, integrate different estimates of precipitation from different sensors and satellites into a homogeneous format product, with a specific grid cell resolution and temporal aggregation. The use of these products in hydrologic applications has opened new venues to support water management globally. Especially in poorly gauged basins and large basins with larger concentration times, satellite precipitation products may be the only input data timely enough to allow flow predictions downstream with enough lead time to implement management and response actions based on such predictions.
Many satellite-based precipitation products have recently been developed. The differences between these products lie in what data from what combination of satellites is used and how it is processed by a data assimilation algorithm to produce a precipitation estimate. Satellite product algorithms can use one type of measurement or can assimilate data from various types of sensors, merging data from frequent, extensive but less accurate estimates (from infrared sensors), with data from other sensors that may be less frequent and cover less area, but provide more accurate rainfall estimates (passive microwave sensors). Present in a lot of satellites, infrared (IR) sensors provide very frequent estimates with a large spatial coverage but with less accuracy. They measure cloud-top temperatures from which rain rates at the earth surface are calculated using a relationship that is often weak and contains a lot of scatter when comparing satellite estimates and ground observations. If the relationship is calibrated regionally, the error in IR measurements can be reduced. On the other hand microwave sensors offer a more direct measurement of rainfall, but their usefulness is restricted to low-Earth orbiting satellites, having less spatial and temporal coverage. Except for snow covered areas where microwave sensors do not work well, their measurements are significantly more accurate than infrared estimates.
In addition to PERSIANN (0.25°, 3 hours) and PERSIANN-Cloud Classification System (0.04°, 3hours) shown above through the HyDIS system, other available real-time satellite precipitation products are:
CMORPH (NOAA, from 8km, 30 min to 0.25°, 3 hours)
TMPA-TRMM (NASA & JAXA, 0.25°, 3 hours): ftp://trmmopen.nascom.nasa.gov/pub/merged/mergeIRMicro/
RFE-2 (NOAA-CPC, 10km, daily):
For an exhaustive list of precipitation products (including products from satellite data, gauge data and combined sources) please visit the International Precipitation Working Group site at http://www.isac.cnr.it/~ipwg/data/datasets.html.