THE CEOS DATABASE : Missions, Instruments and Measurements
DomainAtmosphericDescriptionPrecipitation, either liquid or solid, is perhaps the single most important climate variable directly affecting mankind. Through either its duration, intensity and frequency or its lack of occurrence, it influences the supply of water for personal consumption and use in agriculture, manufacturing industries and power generation, causes risks to life and the functioning of society when associated with floods, landslides and droughts, and affects infrastructure planning, leisure activities and more.

Precipitation is closely related to cloud properties, a number of terrestrial ECVs and to ocean surface salinity. It is indicative of the release of latent heat within the energy cycle as well as being at the heart of the hydrological cycle. Observations are needed for hydrological monitoring, to identify and understand climate variability and change, for understanding, interpreting and attributing particular climate events, for developing and evaluating climate models and for assimilation to constrain reanalyses. This is aside from the importance of these observations for weather prediction. Although classed as a surface ECV, information is needed on the vertical profile of falling hydrometeors, not only within clouds but also below clouds where melting and evaporation can occur. [GCOS-195 4.3.5]
Full NamePrecipitation
Satellite Signficant ContributionYes
GCOS Actions
DescriptionWhoTime FramePerformance IndicatorCost Implications
Submit all precipitation data, including hourly totals where possible and radar-derived precipitation products, from national networks to the International Data Centres.National Meteorological Services, with coordination through the WMO CCl.ContinuousPercentage of nations providing all precipitation data to the International Data Centres. Percentage of stations for which hourly data available.1-10M US$ (60% in non-Annex-I Parties).
Ensure continuity of satellite precipitation products.Space agencies.ContinuousLong-term homogeneous satellite-based global precipitation products.10-30M US$ (for generation of climate products, assuming missions funded for other operational purposes) (Mainly by Annex-I Parties).
Equip all buoys in the Ocean Reference Mooring Network with precipitation-measuring instruments. Who: Parties deploying moorings, in cooperation with JCOMM and OOPC.Parties deploying moorings, in cooperation with JCOMM and OOPC.Complete by 2014Number of instruments deployed and data submitted to International Data Centres.<1M US$ (Mainly by Annex-I Parties).
Develop and implement improved methods for observing precipitation and deriving global precipitation products that take into account advances in technology and fulfil GCOS requirements.Parties’ national research programmes through WCRP, in cooperation with GCOS.ContinuousImplemented methods; improved (in resolution, accuracy, time/space coverage) analyses of global precipitation.10-30M US$ (40% in non-Annex-I Parties).
*GCOS-195 Status Categories: Category A: Action completed, perhaps exceeding reasonable expectations. Very good progress on ongoing tasks. Category B: Action largely completed according to expectation. Good progress on ongoing tasks. Category C: Moderate progress overall, although progress may be good for some part of the action. Category D: Limited progress overall, although progress may be moderate or good for some part of the action. Category E: Very little or no progress, or deterioration rather than progress.
GCOS Products
Related Measurements/
from CEOS DB
A.2Estimates of liquid and solid precipitation, derived from specific instruments and provided by composite productsPrecipitation
Precipitation Profile (liquid or solid)
Precipitation intensity at the surface (liquid or solid)
Precipitation index (daily cumulative)
CEOS Response[A8 (A.2)]

2015 Update: Specific Deliverable #1
  • TRMM has continued to be operated; it is out of fuel and will be passivized in early 2015 when its orbit decays to a set altitude (325 km). The TMI is operating continuously, while the radar is only available when the altitude is in set ranges.
  • GPM was launched into a 65° orbit on 27 February 2014 (UTC), and Day-1 GMI and DPR products were released in stages through the summer.
  • The initial GPM-era constellation consists of microwave imagers (DMSP F15 SSMI [limited]; DMSP F16, F17, F18, and F19 SSMIS; TRMM TMI; GCOM-W1 AMSR2; GPM GMI) and microwave sounders (NOAA-18, NOAA-19, Metop-A, and Metop-B MHS; Megha-Tropiques SAPHIR; SNPP ATMS).
  • The pre-GPM PC calibrator was the TRMM observatory; it is planned that intercalibration of the TRMM and GPM observatories will allow the entire TRMM-GPM era to be treated as a continuous record, a long time series that is now viewed as critical for the long-term records demanded for societal applications, including climate studies.
  • Upon reflection, “completely characterize” seems unachievable for sensors “carefully” is a reasonable standard that agencies strive to achieve.
Specific Deliverable #2
The satellite operators work through GSICS to ensure calibration and geolocation at Level 1b.

Specific Deliverable #3
The GPM project’s XCal Team developed and maintains intercalibrations of all radiometers to the Core Observatory reference at Level 1c.

Specific Deliverable #4
GPM is developing a physically based Bayesian retrieval system that can be applied to both imagers and sounders, GPROF2014, which is designed to be useful over land, coast, ocean, and frozen surfaces. Independently, NOAA is pursuing a more assimilation-like approach that applies to both imagers and sounders, MiRS.

Specific Deliverable #5
The output of GPROF2014 applied to all the microwave sensors in the constellation is freely available as individual satellite orbits at Level 2 – IFOVs in the original scan/footprint coordinates.

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