Notebook
Home page > Data Assimilation > NEMOVAR at ECMWF > Reynolds SST products

Reynolds SST products

Monday 9 August 2010, by Tital

The sea surface temperature (SST) is based on Optimum Interpolation Sea Surface Temperature Analyses received daily from NCEP. It is based on ship, buoy and satellite observations. In shallow waters where rapid changes due to upwelling can take place close to land the observed SST can sometimes differ as much as 5 deg from the NCEP analysis. The SST is kept constant over the integration [1]

Satellite observation come from AVHRR remote instruments first launched in 1981. It is is a radiation-detection imager that can be used for remotely determining cloud cover and the surface temperature : http://noaasis.noaa.gov/NOAASIS/ml/... [2]. SST retrieval algorithm is designed to minimize the effects of atmospheric water vapor. Algorithms are tuned by regression against quality controlled buoy data using the multichannel SST technique of McClain et al. (1985) [3]. This procedure converts the retrieval of the temperature of the "skin" (roughtly a micron in depth) to a bulk (roughly 0.5 m in depth) SST. The tuning is redone when a new satellite becomes operational or when comparison with the buoy data shows increasing errors.

The optimum interpolation (OI) sea surface temperature (SST) analysis is produced weekly on a one-degree grid. The analysis uses in situ and satellite SSTs plus SSTs simulated by sea ice cover. Before the analysis is computed, the satellite data is adjusted for biases using the method of Reynolds (1988) and Reynolds and Marsico (1993). A description of the OI analysis can be found in Reynolds and Smith (1994). The bias correction improves the large scale accuracy of the OI. In November 2001, the OI fields were recomputed for late 1981 onward. The new version will be referred to as OI.v2. [4]

The most significant change for the OI.v2 is the improved simulation of SST obs from sea ice data following a technique developed at the UK Met Office. This change has reduced biases in the OI SST at higher latitudes. Also, the update and extension of COADS has provided us with improved ship data coverage through 1997, reducing the residual satellite biases in otherwise data sparse regions. For more details, see Reynolds, et al (2002).

Other links:
- NOAA 1/4 degree Daily OI SST Analysis
- NCDC’s Extended Reconstructed Sea Surface Temperature (ERSST) Analysis Data
- The ENACT project: http://www.ecmwf.int/research/EU_pr...


On ecfs: ec:/ocx/NEMO/FORCING/V2/ORCA1_Z42_v2/oiv2

Footnotes

[1] source: http://www.ecmwf.int/products/forec...

[2] also in french: http://www.wmo.int/pages/prog/sat/C...

[3] McClain, E. P., W. G. Pichel, and C. C. Walton (1985), COMPARATIVE PERFORMANCE OF AVHRR-BASED MULTICHANNEL SEA SURFACE TEMPERATURES, J. Geophys. Res., 90(C6), 11,587–11,601, doi:10.1029/JC090iC06p11587.

[4] source: http://www.emc.ncep.noaa.gov/resear...)

SPIP | template | | Site Map | Follow-up of the site's activity RSS 2.0