A Note on Reviving the Goddard Satellite-Based Surface Turbulent Fluxes （GSSTF） Dataset

Accurate sea surface flux measurements are crucial forunderstanding the global water and energy cycles. The oceanicevaporation, which is a major component of the global oceanic freshwater flux, is useful for predicting oceanic circulation andtransport. The global Goddard Satellite-based Surface TurbulentFluxes Version-2 (GSSTF2; July 1987--December 2000) dateset that wasofficially released in 2001 has been widely used by scientificcommunity for global energy and water cycle research, and regionaland short period data analyses. We have recently been funded by NASAto resume processing the GSSTF dataset with an objective ofcontinually producing a uniform dataset of sea surface turbulentfluxes, derived from remote sensing data. The dataset is to bereprocessed and brought up-to-date (GSSTF2b) using improved inputdatasets such as a recently upgraded NCEP/DOE sea surfacetemperature reanalysis, and an upgraded surface wind and microwavebrightness temperature V6 dataset (Version 6) from the SpecialSensor Microwave Imager (SSM/I) produced by Remote Sensing Systems(RSS). A second new product (GSSTF3) is further proposed with afiner temporal (12-h) and spatial (0.25^ox0.25^o)resolution. GSSTF2b (July 1987--December 2008) and GSSTF3 (July1999--December 2009) will be released for the research community touse by late 2009 and early 2011, respectively.     

Stable sulfur isotopes in the water column of the Cariaco Basin

Previous geochemical and microbiological studies in the Cariaco Basin indicate intense elemental cycling and a dynamic microbial loop near the oxic-anoxic interface. We obtained detailed distributions of sulfur isotopes of total dissolved sulfide and sulfate as part of the on-going CARIACO time series project to explore the critical pathways at the level of individual sulfur species. Isotopic patterns of sulfate (δ³⁴S_SO4) and sulfide (δ³⁴S_H2S) were similar to trends observed in the Black Sea water column: δ³⁴S_H2S and δ³⁴S_SO4 were constant in the deep anoxic water (varying within 0.6‰ for sulfide and 0.3‰ for sulfate), with sulfide roughly 54‰ depleted in ³⁴S relative to sulfate. Near the oxic-anoxic interface, however, the δ³⁴S_H2S value was ∼3‰ heavier than that in the deep water, which may reflect sulfide oxidation and/or a change in fractionation during in situ sulfide production through sulfate reduction (SR). δ³⁴S_H2S and Δ³³S_H2S data near the oxic-anoxic interface did not provide unequivocal evidence to support the important role of sulfur-intermediate disproportionation suggested by previous studies. Repeated observation of minimum δ³⁴S_SO4 values near the interface suggests ‘readdition’ of ³⁴S-depleted sulfate during sulfide oxidation. A slight increase in δ³⁴S_SO4 values with depth extended over the water column may indicate a reservoir effect associated with removal of ³⁴S-depleted sulfur during sulfide production through SR. Our δ³⁴S_H2S and Δ³³S_H2S data also do not show a clear role for sulfur-intermediate disproportionation in the deep anoxic water column. We interpret the large difference in δ³⁴S between sulfate and sulfide as reflecting fractionations during SR in the Cariaco deep waters that are larger than those generally observed in culturing studies.