# Satellite Remote Sensing of Precipitation and the Terrestrial Water Cycle in a Changing Climate
## 4 Applications Related to the Water Cycle
### Analysis of Precipitation Climatological Patterns  
The discussion on the water cycle closure on the regional and global scales requires knowledge of sources and sinks of atmospheric moisture, both oceanic and terrestrial. This is particularly important, since changes in the intensity and location of sources can affect the distribution of continental precipitation in a changing climate [265]. The availability of satellite precipitation products contributes to shedding light on climatological precipitation patterns in climate hot spots, such as the Amazon forest. Molina et al. [266] have found that precipitation exponentially increases with distance from the ocean along wind streamlines flowing over forests, while it exponentially decreases downwind of the forests. Drier regions of the world, such as East Africa, are frequently affected by severe droughs that are strongly linked to the seasonal cycles, intraseasonal and interannual variability, and local geography [267]. Satellite precipitation products can significantly help in understanding trends and variability of rainfall in the area [268] and their links with SST and soil moisture [269]. Moreover, they are starting to contribute significantly to devising strategies for managing the increased demand of groundwater connected with drought episodes [270; 271], and to identifying trends in Africa's freshwater resources. [272] Changes in precipitation patterns under different future scenarios in the Hindu-Kush Karakoram Himalaya region are linked to the monsoon system. Palazzi et al. [273] have used satellite precipitation data, together with reanalyses and in situ gauge data, finding an increasing trend over the Himalaya during summer, associated with an increase in wet extremes and daily intensity and a decrease in the number of rainy days. The precipitation and moisture patterns over the Tibetan Plateau (previously identified as the \"Third Pole\") have so far been poorly documented due to a scarcity of in situ observations over such an enormous area. Once again, satellite data help in investigating the seasonality and variability of precipitation together with reanalyses [274; 275; 276]. The continuous development of reanalysis datasets is encouraging this synergy of analysis and observation data and their intercomparison for a better quantification of the closure terms. The reanalysis datasets  
Figure 9: 24 hr eTRaP quantitative precipitation forecast (QPF) from 15 independent ensemble members on 24 September 2019 for Tropical Storm Jerry over the Atlantic Ocean. Courtesy of NOAA-NESDIS ([[https://www.ssd.noaa.gov/PS/TROP/etrap.html?storm=JERRY](https://www.ssd.noaa.gov/PS/TROP/etrap.html?storm=JERRY)]([https://www.ssd.noaa.gov/PS/TROP/etrap.html?storm=JERRY](https://www.ssd.noaa.gov/PS/TROP/etrap.html?storm=JERRY)), last accessed 24 September 2019).  
most used for global and regional water cycle research are those from the National Centers for Environmental Prediction (NCEP, [277]), the Japan Meteorological Agency (JMA, [278]), NASA, [279], and ECMWF [280]. The Twentieth Century Reanalysis (20 CR, [281]) makes available a comprehensive global atmospheric circulation dataset with quantified uncertainties for validations of climate model simulations of the twentieth century on all time-scales.