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Water is fundamental to life on Earth, affecting the behavior of the weather, climate, energy and ecological systems as water moves through the Earth’s water cycle as vapor, liquid and ice. Precipitation, a key component of the water cycle, is difficult to measure since rain and snow vary greatly in both space and time.

Obtaining reliable ground-based measurements of rain and snow often presents a formidable challenge due to large gaps between reliable instruments over land and, particularly, over the oceans. From the vantage point of space, satellites provide more frequent and accurate observations and measurements of rain and snow around the globe. This allows key insights into when, where and how much it rains or snows globally, supplying vital information to unravel the complex roles water plays in Earth systems.

In order to gain further insights into the relationships between the components of the Earth’s water cycle, we need to know not only how much rain falls at the surface but also the distribution of rain, snow, and other forms of precipitation within the atmosphere above the surface. This allows us to characterize precipitation processes that are vital to understanding the links and the transfer of energy (heat) between the Earth’s surface and atmosphere.

NASA’s Global Precipitation Measurement Mission (GPM) provide advanced information on rain and snow characteristics and detailed three-dimensional knowledge of precipitation structure within the atmosphere, which help scientists study and understand Earth's water cycle, weather and climate.

Related Articles
IMERG Sees a Dry September
Rainfall was scarce across much of the country in the month of September, pushing the eastern and southern thirds of the country into drought conditions. IMERG, the Integrated Multi-satellitE Retrievals for GPM, is a unified satellite precipitation product produced by NASA to estimate surface precipitation over most of the globe.
Observing the Intertropical Convergence Zone with IMERG
The intertropical convergence zone or “ITCZ” roughly forms a band that circumnavigates the Earth near the Equator where the northeast trade winds in the Northern Hemisphere converge with the southeast trade winds in the Southern Hemisphere. Sailors have often referred to it as the “doldrums” due to its generally light winds. Yet, the ITCZ is an important part of the global circulation as it forms the ascending branch of the Hadley circulation. This is ultimately driven by incoming solar radiation, which peaks near the Equator. This warms the air and the ocean, causing warm buoyant air to rise...
How TRMM and GPM Study Latent Heating
Latent heating (LH) arises predominantly from the release of heat associated with the condensation of water vapor into cloud droplets in clouds with active updrafts. Other sources of LH include ice deposition and freezing, while evaporation, melting and sublimation induce cooling, but condensation is the dominant heating term. Like a hot-air balloon, LH can keep air parcels warmer than their surrounding environment and therefore rising. On a large scale, LH is responsible for driving the ascending branch of the Hadley Circulation. LH is also an important component in the dynamics of a regional...
Finding Strong Storms with TRMM & GPM
Spring is severe storms season here in the US, but not everyone has NEXRAD radar coverage; however, NASA’s TRMM and GPM satellites with their onboard radars have made it possible to search the entire global Tropics and midlatitudes and systematically identify areas where there are strong to intense thunderstorms. Researchers now headed by Dr. Chuntao Liu at Texas A&M University have built a comprehensive database of “precipitation features” based on regions of contiguous radar echoes from first the TRMM and now the GPM satellite. These precipitation features can then be mined to locate areas...
TMPA Shows El Niño Conditions in the Pacific
An El Niño that began to form last fall has matured and is now fully entrenched across the Pacific. Changes in sea surface temperatures, or SSTs, brought about by an El Niño affect the atmosphere, resulting in distinctive changes in the rainfall pattern across the Pacific Basin. These changes show up as anomalies or deviations in NASA’s analysis of climatological rainfall. This map shows sea surface temperature (SST) anomalies for the Pacific Basin, shown as degrees Celsius above or below average. Credit: NOAA Climate Prediction Center. In a typical El Niño, warmer than average SSTs off of the...

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