GLOBAL CLIMATE OBSERVING SYSTEM
ESSENTIAL CLIMATE VARIABLE - Water Vapour |
| Domain | Atmospheric | Description | Temperature is one of the fundamental state variables for which observation is essential for understanding and predicting the behaviour of the atmosphere. It is basic to the energy budget of the climate system as a whole through the temperature-dependence of the longwave radiation of energy from the atmosphere to space. Upper-air observations are of key importance for detecting and attributing climate change in the troposphere and stratosphere. They are needed for the development and evaluation of climate models, and for the initialization of forecasts. They are also needed for characterising the extratropical atmospheric circulation, which is often done using analyses of geopotential height rather than wind. Variations in temperature influence the formation of clouds and precipitation and the rates of chemical reactions, thereby influencing the hydrological and constituent cycles. Data on temperature are also crucial for understanding radiatively important changes in water vapour and cloud in the upper troposphere and lower stratosphere. Temperature affects in particular the formation of polar stratospheric clouds and consequential ozone loss. [GCOS-195 4.5.3] |
| Sub-domain | Upper-air |
| Full Name | Water Vapour |
| Satellite Signficant Contribution | Yes  |
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| GCOS Actions |
Action
Status* | Description | Who | Time Frame | Performance Indicator | Cost Implications |
A8
Cat-B | Ensure continuity of satellite precipitation products. | Space agencies. | Continuous | Long-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). |
A22
Cat-B | Finalise standard and implement exchange of data globally from the networks of ground-based GPS receivers. | WMO CIMO and WMO CBS, in cooperation with national agencies. | WMO CIMO and WMO CBS, in cooperation with national agencies. | Number of sites providing data. | <1M US$ (20% in non-Annex-I Parties). |
A26
Cat-D | Establish long-term limb-scanning satellite measurement of profiles of water vapour, ozone and other important species from the UT/LS up to 50 km. | Space agencies, in conjunction with WMO GAW. | Ongoing, with urgency in initial planning to minimize data gap. | Continuity of UT/LS and upper stratospheric data records. | 100-300M US$ (including mission costs) (Mainly by 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.
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| GCOS Products | |
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| 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.
[A26 (A.9.3, A.5.2, A.8.1)]
2015 Update: The Canadian Space Agency approved the continuation of the SCISAT mission through the end of 2015. The atmospheric chemistry experiment (ACE) Fourier transform infrared spectrometer is unique in its ability to make measurements of upper atmosphere chemistry in the trace gases responsible for ozone depletion. A complete review of this experiment can be found at the following website http://www.ace.uwaterloo.ca/index.html
Limb Sounding Mission Gap
Participants in the CEOS Atmospheric Chemistry Virtual Constellation meeting of 2014 recognize the significance of the looming gap in limb sounding data. Following the demise of the currently operating but aging instruments:- MLS on Aura (microwave emission),
- SMR (microwave emission) on Odin,
- OSIRIS (limb scatter UV-Vis-NIR) on Odin,
- ACE-FTS (solar occultation IR) on SCISAT, and
- ACE-MAESTRO (solar occultation UV-Vis-NIR) on SCISAT,
the only limb sounding instruments will be:- OMPS Limb Profiler on Suomi-NPP (limb scatter UV-Vis-NIR),
- SAGE-III/ISS (solar occultation & limb scatter UV-Vis-NIR, planned for 2016),
- OMPS Limb Profiler on JPSS-2 (limb scatter UV-Vis-NIR, planned for ~2021).
Specific Deliverable #2
Maximize use of existing sensors and develop a collaborative framework to advocate and facilitate near-term calibration/validation activities and other coordinated science team planning for near-term space-based missions with limb sounding capability (e.g., to include, but not limited to, Stratospheric Aerosol and Gas Experiment (SAGE) III-ISS and Sentinel 5-Precursor) to maximize scientific output.
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