GCOS Atmospheric Surface ECV: Pressure
Contributing Networks & Status

Status:

Surface air pressure is monitored adequately over most of the Earth's land surface. The analysis products are enhanced by the incorporation of wind fields through dynamical relationships in models. There has been and increase in the deployment of drifting buoys. However, the data coverage over some regions of the ocean, particularly in the southern hemisphere and over Antarctica remains too sparse.

Finding: Drifting buoys deployed in the southern oceans have ameliorated uncertainties in surface pressure fields, and should be continued in conjunction with sea-surface temperature measurements.

(Source: The Second Report on the Adequacy of The Global Observing Systems for Climate in Support of the UNFCCC (April 2003) GCOS-82 (WMO/TD No. 1143))

Contributing Networks:

• GCOS Surface Network (GSN) (subset of full WWW/GOS surface synoptic network). At least 95% of stations are active, but only about 80% transmit CLIMAT reports. The GSN comprises about 1000 stations that have been selected from the full available network based on past performance and their contribution towards a global representation of the climate system. The operators of GSN stations, in particular are encouraged to fully meeting the GCMOs for observation and for data exchange, where possible for all surface ECVs. The GSN data can be analysed to yield basic indicators of the global climate system, and also provide benchmark locations for higher-density regional and national networks. Important contributions to such regional networks are the WOM WWW Regional Basic Climatological Networks (RBCN, total ~3000 station subset of the WWW/GOS surface synoptic network), established in all regions of the world including Antartica to support regional representations of the climate system. The GSN is implemented through cooperation among NMSs and the international community; through the AOPC working with the WMO Commission for Basic Systems (CBS) and WMO Regional Associations (RA); and through capacity-building initiatives such as those of the WMO Voluntary Cooperation Programme and the GCOS Cooperation Mechanism. The AOPC, in cooperation with the WMO CBS, carries out detailed analysis of the problems in the receipt of GSN observations and works with national services to resolve them.

• Full WWW/GOS surface synoptice Network. Some inconsistencies in pressure reduction methods to mean sea level.

• Additional national networks. Some national networks inadequate for climate studies.

• Buoys and ships. In addition to the land-based observations of pressure, pressure data over the ocean are required from sensors mounted on drifting buoys (also in the sea-ice areas of the Arctic and Antarctic), on VOS including the higher-quality VOSClim subset, on parts of the Tropical Mooring Network, and on the Reference Buoy Network.  Many of these measurements have been operational over the last 30 years; the data are exchanged and inserted into the operational meteorological WWW system and are subject to quality-control procedures at the time of data acquisition and again at the analysis centres. Of particular concern is that surface pressure sensors are not included on all drifting buoys. Although there has been a significant improvement in recent years, particularly in the extra-Tropics where surface pressure measurements are most useful, the OOPC, working through the Joint Technical Commission for Oceanography and Marine Meteorology (JCOMM), and the national agencies that deploy drifting buoys, should endeavour to ensure that surface pressure sensors are included as a component of the suite of instruments on all buoys deployed.

(Source: WMO/IOC Implementation Plan for the Global Observing System for Climate in Support of the UNFCCC (2010 Update) GCOS-138/GOOS-184/GTOS-76/WMO-TD/No. 1523)

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