Arctic waters and marginal ice zones: 2. An investigation of arctic atmospheric infrared absorption for advanced very high resolution radiometer sea surface temperature estimates

Abstract

[1] The derivation of sea surface temperatures (SST) from satellite radiometric data is well established in temperate latitudes. Water vapor is typically the greatest clear sky absorber of infrared (IR) energy between the emitting surface and spaceborne sensor, necessitating a corrective term for SST calculation. Algorithms developed for advanced very high resolution radiometers (AVHRR) use the difference in brightness temperatures between Channel 4 (10.3 to 11.3 mm) and Channel 5 (11.5 to 12.5 mm), or T45, to estimate the amount of IR absorption in the atmosphere. While relatively accurate in temperate latitudes, this approach is not applicable to Arctic waters, typically overestimating the SST by 2 to 3 K as a result of high T45 values that are not indicative of IR absorption by water vapor. The high T45 values in the Arctic may be attributable to atmospheric ice crystals. The attenuation of IR energy increases sharply across Channel 4 and 5 for ice crystals, the amount of which is a function of crystal size, shape and orientation. In the development of the Composite Arctic Sea Surface Temperature Algorithm in the North Water polynya (NOW), it was demonstrated that when T45 exceeded a threshold of 2 K the surface temperature could not be estimated owing to the presence of a clear sky absorptive feature. Observations from the NOW study led to the assessment that areas where T45 > 2K were covered by ice fog. This is a significant finding since these regions must be identified to achieve an accurate mapping of the surface temperature.Citation: Vincent, R. F., R. F. Marsden, P. J. Minnett, and J. R. Buckley (2008), Arctic waters and marginal ice zones: 2. An investigation of arctic atmospheric infrared absorption for advanced very high resolution radiometer sea surface temperature estimates,

Subarctic and Arctic sea surface temperature and its relation to ocean heat content 1982–2010

“…This study exploits the efforts of the Global Ocean Data Assimilation Experiment (GODAE) High Resolution SST Pilot Project to recalibrate and match observations from a succession of seven NOAA polar orbiting satellites. Our brief comparison of this product to in situ surface temperature observations shows the presence of a À0.35 C cool bias in water with temperatures above 4 C, consistent with previous studies by Vincent et al [2008aVincent et al [ , 2008b. Unexpectedly we also find enhanced scatter and a warm bias of up to 1 C in regions of cooler temperatures that are also close to the edges of the sea ice.…”

A Satellite-Derived Climate-Quality Data Record of the Clear-Sky Surface Temperature of the Greenland Ice Sheet

“…This technique has also been employed by Vincent et al (2008) for the retrieval of surface temperatures in the polar regions. The atmospheric humidity is much lower in polar regions and use of the window channels (e.g., channel 4 and channel 5 of AVHRR) may not work well because of the lack of correlation of the difference of these channels with water vapor and humidity in these regions.…”

Pan-Arctic Land Surface Temperature from MODIS and AATSR: Product Development and Intercomparison

“…In addition, studies on SST retrieval have shown that split window algorithms, sometimes, perform poorly in high latitudes. During winter, ice fog and ice clouds, which are difficult to detect, interfere with IR absorption and emission [60]. Therefore, we speculate that misestimating Arctic atmosphere properties (by using atmospheric profiles from lower latitudes with relatively higher temperature and water vapor concentration) could result in the high negative bias observed during the winter.…”