renfrew met obs SO nov06

Meteorological Observations in the Southern Ocean region: 

Meteorological Observations in the Southern Ocean region Ian Renfrew

Outline: 

Outline Operational observations Reanalysis validation for the Southern Ocean Climatologies from ships satellite

Routine observations assimilated by the ECMWF: 

Routine observations assimilated by the ECMWF Almost all images are snapshots for 00 UTC 20 September 2006 ECMWF use 4D VAR data assimilation ECMWF have a long observation window What is shown here is what is routinely available via the GTS There are other AWS, buoys, a/c data etc from special campaigns, which won’t go into these global reanalysis.

Met. Observing “gaps” : 

Met. Observing “gaps” T, q, U over SO & over sea-ice zone Solutions: Met buoys and/or met moorings? AWS on islands IMET on ships (summer only) a/c observations (summer case studies) AUVs (primarily summer)

Slide18: 

How good are the meteorological analyses and reanalyses over the open ocean? over the sea-ice zone? over ice shelves?

Slide26: 

Over SO, T and q are ok, p and U are not so good.

Slide28: 

See: Renfrew, I. A. , G. W. K. Moore, P. S. Guest, and K. Bumke, 2002: A comparison of surface-layer and surface turbulent-flux observations over the Labrador Sea with ECMWF analyses and NCEP reanalyses, J. Phys. Oceanogr., 32, 383-400.

Slide29: 

How good is this coverage: over the sea-ice zone?

Slide30: 

Validation of ECMWF Sea Level Pressure Analyses over the Bellingshausen Sea, Antarctica J. C. King “Despite the lack of in situ observations from this region, the analyses were found to be in very good agreement with the observed pressures and pressure gradients. Standard deviations of the differences between observed and analyzed pressures were typically around 1 hPa. When additional in situ surface pressure observations from this region became available for use in the analyses, the agreement between analyzed and observed pressures improved only slightly. This suggests that atmospheric analyses are constrained well by satellite temperature soundings and other remotely sensed data in this region.”

Other air-sea flux products: Ship-based in situ observations: 

Other air-sea flux products: Ship-based in situ observations UWN/COADS; SOC etc, i.e. ship observations-based (Fig. from Josey et al. 1999: Number of latent heat flux observations per 1x1 deg square)

Slide38: 

Fig. 5. Zonally averaged annual mean wind stress magnitude, units N m−2. Solid gray line: SOC; solid thick black line: HR; solid thin black line: UWM/COADS; dashed black line: ECMWF; dash–dot line: NCEP–NCAR From Josey et al. JPO, 2002

Slide39: 

Fig. 8. Zonally averaged annual mean net heat flux for the SOC climatology adjusted according to solution 3 (solid black line), UWM/COADS (adjusted; solid gray line), Trenberth residual (dashed black line), NCEP reanalysis (dashed gray line), and ECMWF reanalysis (black dot–dashed line) Grist and Josey, J. Climate, 2003

Other air-sea flux products:Satellite-based products: 

Other air-sea flux products: Satellite-based products http://www.gfdi.fsu.edu/SEAFLUX/ Great potential, so far little evaluation for SO? Singh et al. 2006: Surface heat fluxes over global oceans exclusively from satellite observations, Mon. Wea. Rev., 134, 965-980.

Conclusions: 

Conclusions There are gaps in the met. observations, but T, q, U, rather than p. Over open ocean: Little evaluation T, q, not so bad U poor during 1990s, but Quikscat now? Over sea-ice zone little evaluation over sea-ice zone Problems with T, q, U Numerous global air-sea flux products available Synthesis approach may yield progress

Met. Observing “gaps” : 

Met. Observing “gaps” T, q, U over SO & over sea-ice zone Solutions: Met buoys and/or met moorings? AWS on islands IMET on ships (summer only) a/c observations (summer case studies) AUVs (primarily summer)