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2.1.1.Surface-land observations Anchor Section2.1.1 Section2.1.1
This module displays stations with the following criteria in OSCAR/Surface:
- Stations of Facility Type seaFixed, lakeRiverFixed, lakeRiverMobile, landFixed, landMobile, landOnIce or airFixed;
- One or more observations out of surface pressure, temperature, humidity or wind;
- The declared status of a program affiliated with the variable displayed is either operational or partly operational;
- The “international exchange” field set to “yes” on the variable;
- The reporting schedule indicates that the variable is reported during the period for which data is displayed.
ECMWF, DWD, NCEP and JMA are providing quality monitoring reports of land surface observations based on feedback from their data assimilation (DA) systems on a daily basis. These reports include qualitative and quantitative (Observation-minus-Background, O-B, departures) information covering the following observed physical quantities: surface pressure (or geopotential height for some high-altitude stations), 2-metre temperature, 2-metre relative humidity and 10-metre wind (meridional and zonal components). The qualitative information includes a description on the usage (Status, i.e., used or not used on the assimilation) and the type of report (i.e., the Traditional Alphanumeric Code -TAC-, or the Binary Universal Format for the Representation of Meteorological Data -BUFR) of each of the above mentioned physical quantities. It is worth noting that surface pressure is the most important in situ observed quantity for global NWP forecasting, and in some cases the only observed surface quantity over land used in the global atmospheric data assimilation, e.g. in the JMA global atmospheric data assimilation system (JMA, 2019). ECMWF’s atmopsheric 4D-Var also assimilates relative humidity over land at nighttime (Owens and Hewson, 2018). Based on these reports (four daily, centred at the main synoptic hours, 00, 06, 12 and 18UTC), it is possible to infer the performance of the land surface network both in terms of availability and quality.
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