Efforts have been taken at the Woods Hole Oceanographic Institution (WHOI) to develop high-quality, gridded, time-dependent surface turbulent and radiative fluxes to support studies of climate variability and predictability under the auspices of the NOAA CLIVAR Atlantic program. The emphasis of this presentation will be on the newly constructed latent and sensible fluxes product and its comparison with in situ flux buoy measurements and the SOC climatology. The product has daily, 1° by 1° resolution and covers the period from 1988 to 1999. It is developed by using a weighted objective analysis approach to improve the estimates of flux-related basic surface meteorological variables (e.g., wind speed, air humidity, air temperature, and sea surface temperature) through synthesizing data from satellite retrievals and outputs from NCEP and ECMWF global analysis/forecast models. The state-of-the-art COARE bulk flux algorithm 2.6a is then applied to compute the flux fields.
Two types of errors can affect the representativeness of a flux product, i.e., the systematic error that influences the mean and the random error that influences the variance. Therefore, the two aspects at the heart of the comparison study are the mean and variability of flux fields. The primary reference data used in the comparison are high accuracy in situ buoy measurements. Comparisons are also made with the analysis of the Southampton Oceanography Centre (SOC) flux climatology. The latter provides high-quality depiction of global air-sea heat exchanges on climatological mean basis, while the former, though available for only limited locations and short spanning periods, provide the benchmark time series to identify regional biases. Good agreement is found between the new WHOI flux product and the independent research buoy measurements. The analysis also shows that the mean field structure and year-to-year variations of the WHOI latent and sensible fluxes are very similar to those obtained from the SOC fluxes, despite the different methods used to produce the two datasets. The buoy and SOC comparisons show that the WHOI synthesis is a considerable improvement over those of the ECMWF and NCEP2 outputs and the improvement comes not only from the use of a better flux algorithm but more importantly from the use of improved estimates of bulk variables. |
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