GHRSST interest in upgraded drifters - Summary from the GHRSST Joint Workshop Melbourne Andrea Kaiser-Weiss, Gary Corlett, Chris Merchant, Piere LeBorgne, Matt Martin and Peter Minnett

Uncertainties in the buoy temperature measurements is a significant, if not dominant factor in the value of difference between drifter and satellite SST, and thus lead to a false estimate of SST accuracies. Higher quality buoys (resolution, uncertainty, stability): would lower uncertainty in GHRSST products (relevant for the ST-VAL: SSES improvements) would help to verify algorithm improvement (relevant for the EARWiG) over final space scales are important for climate applications (relevant for CDR-TAG) Motivation within Andrea Kaiser-Weiss, GHRSST Joint Workshop Melbourne, 9 th March 2012

Activities within Peter Minnett (RSMAS) matchup with MODIS and VIIRS and AVHRR: sufficient number of matchups will take time, initial results planned for GHRSST XIII Tokyo, 4-8 June Matt Martin (UK MetOffice) : initial comparisons against FOAM/OSTIA inconclusive, needs larger statistical sample Gary Corlett (University of Leicester): matchups with AATSR too sparse Pierre LeBorgne (MeteoFrance-CMS) and Jean-Francois Piolle (Ifremer) using the GHRSST MDB related to the upgraded drifters Andrea Kaiser-Weiss, GHRSST Joint Workshop Melbourne, 9 th March 2012

Where would be the most important deployment areas? 1) Canary Island : area of the Aquarius surface salinity validation campaigns (SPURS); effects of Saharan Air Layer and aerosols on infrared SSTs 2) SE-Asia: high water vapor and periodic smoke aerosols from forest fires 3) Upwelling areas: anomalous air-sea temperature differences; surface flow divergence tends to reduce buoys drifting into upwelling areas 4) High Latitudes: very low water vapor content; anomalous air- sea temperature differences) The effect of the higher quality might be best seen in the connection with the SPURS campaign Andrea Kaiser-Weiss, GHRSST Joint Workshop Melbourne, 9 th March 2012

© Crown copyright Met Office Data used in the comparison: Comparing the operational FOAM model output 1-day SST forecast (before assimilation) with the surface drifters. For a 10 day period (8 th – 17 th Feb 2012). Selected a region where most of the new type of drifters are: 70W -> 10W, 40N -> 70N. Caveats to bear in mind when looking at the results: Despite reasonable numbers of obs (~9300 of the old type, ~6400 of the new type), the number of independent obs is fairly small (only a limited number of actual drifters, each of which reports many times). Difficult to distinguish model errors from observation errors. Overall summary: old drifter obs types have a much smaller mean error than the new types (0.02 vs 0.26). new drifter obs types have a slightly smaller standard deviation than the old type (0.42 vs 0.44). Preliminary comparison of SST from the new and old type of surface drifters with operational FOAM output (Matthew Martin, MetOffice) Andrea Kaiser-Weiss, GHRSST Joint Workshop Melbourne, 9 th March 2012

© Crown copyright Met Office Old buoys New buoys Preliminary results provided by Matthew Martin: Andrea Kaiser-Weiss, GHRSST Joint Workshop Melbourne, 9 th March 2012

© Crown copyright Met Office Preliminary results provided by Matthew Martin: Andrea Kaiser-Weiss, GHRSST Joint Workshop Melbourne, 9 th March 2012

Summary of GHRSST interest in the upgraded drifters 1)The effect of the higher resolution (HRSST-1) will be discernable only in a statistically significant sample. The current sample is not sufficient. 1)The effect of the drifters drougue retention remains to be investigated 2)Higher resolution (HRSST-1) and especially the better calibrated, higher stability drifters (HRSST-2) will: - be of benefit for determining and reducing the uncertainties of the satellite products, - allow to demonstrate the improvements of algorithms, and - help in building climate data sets Andrea Kaiser-Weiss, GHRSST Joint Workshop Melbourne, 9 th March 2012