COS Faculty Works
Permanent URI for this collectionhttps://hdl.handle.net/1969.6/87602
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Browsing COS Faculty Works by Subject "air-sea"
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Item Improvement in air–sea flux estimates derived from satellite observations(Taylor & Francis Online, 2013-04-17) Bentamy, Abderrahim; Grodsky, Semyon; Katsaros, Kristina; Mestas-Nuñez, Alberto M.; Blanke, Bruno; Desbiolles, FabienA new method is developed to estimate daily turbulent air–sea fluxes over the global ocean on a 0.25° grid. The required surface wind speed (w 10) and specific air humidity (q 10) at 10 m height are both estimated from remotely sensed measurements. w 10 is obtained from the SeaWinds scatterometer on board the QuikSCAT satellite. A new empirical model relating brightness temperatures (T b) from the Special Sensor Microwave Imager (SSM/I) and q 10 is developed. It is an extension of the author's previous q 10 model. In addition to T b, the empirical model includes sea surface temperature (SST) and air–sea temperature difference data. The calibration of the new empirical q 10 model utilizes q 10 from the latest version of the National Oceanography Centre air–sea interaction gridded data set (NOCS2.0). Compared with mooring data, the new satellite q 10 exhibits better statistical results than previous estimates. For instance, the bias, the root mean square (RMS), and the correlation coefficient values estimated from comparisons between satellite and moorings in the northeast Atlantic and the Mediterranean Sea are –0.04 g kg−1, 0.87 g kg−1, and 0.95, respectively. The new satellite q 10 is used in combination with the newly reprocessed QuikSCAT V3, the latest version of SST analyses provided by the National Climatic Data Center (NCDC), and 10 m air temperature estimated from the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalyses (ERA-Interim), to determine three daily gridded turbulent quantities at 0.25° spatial resolution: surface wind stress, latent heat flux (LHF), and sensible heat flux (SHF). Validation of the resulting fields is performed through a comprehensive comparison with daily, in situ values of LHF and SHF from buoys. In the northeast Atlantic basin, the satellite-derived daily LHF has bias, RMS, and correlation of 5 W m−2, 27 W m−2, and 0.89, respectively. For SHF, the statistical parameters are –2 W m−2, 10 W m−2, and 0.94, respectively. At global scale, the new satellite LHF and SHF are compared to NOCS2.0 daily estimates. Both daily fluxes exhibit similar spatial and seasonal variability. The main departures are found at latitudes south of 40° S, where satellite latent and sensible heat fluxes are generally larger.Item Ocean variability and air-sea fluxes produced by atmospheric rivers(naure, 2019-02-15) Shinoda, Toshiaki; Zamudio, Luis; Guo, Yanjuan; Metzger, Joseph; Fairall, Chris W.Atmospheric rivers (ARs) cause heavy precipitation and flooding in the coastal areas of many mid-latitude continents, and thus the atmospheric processes associated with the AR have been intensively studied in recent years. However, AR-associated ocean variability and air-sea fluxes have received little attention because of the lack of high-resolution ocean data until recently. Here we demonstrate that typical ARs can generate strong upper ocean response and substantial air-sea fluxes using a high-resolution (1/12°) ocean reanalysis. AR events observed during the CalWater 2015 field campaign generate large-scale on-shore currents that hit the coast, generating strong narrow northward jets along the west coast of North America, in association with a substantial rise of sea level at the coast. In the open ocean, the AR generates prominent changes of mixed layer depth, especially south of 30°N due to the strong surface winds and air-sea heat fluxes. The prominent cooling of SST is observed only in the vicinity of AR upstream areas primarily due to the large latent heat flux. Using a long-term AR dataset, composite structure and variations of upper ocean and air-sea fluxes are presented, which are consistent with those found in the events during CalWater 2015.