Diurnal variation in the latent heat flux

Short-term variability exists in the surface moisture flux over the oceans impacting latent heat flux values. These fluxes demonstrate a diurnal signal. The magnitude of this signal is not well quantified. Errors in the latent heat flux on the order of 10 Wm^-2 have significance for the tropics on an annual scale. Additionally, errors of this magnitude are significant on a seasonal scale for the mid-latitudes where the mixed layer is relatively thin. For these time scales, substantial errors may exist in the sea-surface temperatures (SSTs) for non-assimilative models, and erroneous fluxes in the assimilative models may not be representative of the true diurnal cycle. Establishing an accurate, representative value for the diurnal variation in the surface moisture flux is key to improving latent heat flux products, a consideration that could be important for coupled climate models.

A preliminary project will use Modern Era Retrospective-Analysis for Research and Applications (MERRA) data to calculate the hourly latent heat flux for at least 2001 through 2004. Daily averages will be computed and removed from the hourly latent heat flux. This process will quantify diurnal variation in the surface moisture flux enabling a reduction in short-term variability from current latent heat flux products.