David A Rutan — Science Systems and Applications. Inc./NASA - LRC
Fred G Rose — Science Systems and Applications. Inc./NASA - LRC
David Robert Doelling — Science Systems and Applications, Inc.
William L. Smith — NASA - Langley Research Center
Seiji Kato — NASA - Langley Research Center
Category
Radiation
Description
A lack of observational data in southern hemisphere oceans has long hindered validation of Global Climate Models, re-analyses and other data products (e.g. ISCCP FD, CERES SYN1Deg, etc..) that model radiative transfer components in these regions. Hence the need for the ARM/AMF “MARCUS” deployment. However, the ship upon which the ARM/AMF is deployed, Australian Antarctic supply vessel Aurora Australis, along with other Australian ships have made “simpler” observations (meteorology and broadband surface radiative flux) for a number of years and are available from the Australian Oceanic Data Network (https://portal.aodn.org.au/). To that end we obtained meteorology and surface flux observations from three ships, the Aurora Australis, R/V Southern Surveyor, and R/V Tangaroa across 9 years (2008 – 2016) for comparison to CERES data products.
NASA’s Clouds and the Earth’s Radiant Energy System (CERES) project produces the SYN1deg data product providing climate quality, hourly, globally gridded and temporally complete maps of top of atmosphere, in atmosphere, and surface fluxes using the Langley Fu and Liou radiative transfer model. Meteorological profiles are from GMAO’s GEOS-541 reanalysis product. Above 60 degrees latitude, cloud properties are derived solely from Terra and Aqua MODIS imagers while below 60 degrees, they are also derived from available geo-stationary satellite as well. In this poster we compare observed surface air temperatures and humidity from the ships (along with measurements from ARM and BSRN surface sites) with those from the GEOS-541 meteorological data used in CERES SYN1deg processing. We also compare observed downward radiative fluxes to those calculated in the SYN1deg calculated radiative fluxes. Ship tracks indicating comparison locations are shown in the figure below.
Comparisons indicate that SYN1deg LW down is on average approximately 5 Wm-2 too low relative to ship observations while SW down is approximate 3 Wm-2 too high. And though GEOS-541 near surface air temperature matches well with ship observations relative humidity is approximately 5-10% too high. Once differences are plotted as a function of latitude, larger differences in the downward longwave flux exist around 60 degrees south. A further analysis of difference as a function of local time indicates that the larger difference in both downward longwave and shortwave occurs in the afternoon. We will investigate the reason for the larger difference.
