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Garrity, C, Lubin D, Kern S, Pedersen LT.  2002.  Linescan camera evaluation of SSM/I 85.5 GHz sea ice retrieval. Remote Sensing of Environment. 83:472-487.   10.1016/s0034-4257(02)00063-9   AbstractWebsite

Retrievals of total sea ice concentration from four algorithms using the 85.5 GHz vertically and horizontally polarized channels of the Special Sensor Microwave Imager (SSM/I) over the marginal ice zone in the Barents and Greenland Seas are compared with retrievals of total sea ice concentration from helicopter-borne linescan camera observations made during a cruise of the R/V Polarstern during May-June 1997. The goals are to evaluate (1) SSM/I 85.5 GHz retrievals of total sea ice concentration for climatological purposes, and (2) the ability of 85.5 GHz data to show the sea ice edge through cloud cover, for operational purposes. The SSM/I 85.5 GHz channels offer a spatial resolution of 12.5 km, which is sufficient to resolve ice edge features and small polynyas; however, there is generally more atmospheric contamination of the sea ice signal at 85.5 GHz than at the lower frequencies (19 and 37 GHz) traditionally used for sea ice remote sensing. A self-adjusting algorithm that performs a nonlinear correction for atmospheric moisture, without explicit atmospheric input data, yields the best accuracy over total sea ice concentrations greater than 30%. However, this algorithm can misclassify clouds over open water as sea ice, and is therefore unreliable for locating the sea ice edge. The best algorithm for locating the sea ice edge is found to be the SEA LION algorithm, which explicitly uses meteorological reanalysis data to correct for atmospheric contamination. For total sea ice concentrations in the range 20-70%, empirical 85.5 GHz hybrids of lower-frequency algorithms developed at the NASA Goddard Space Flight Center can improve the accuracy of these algorithms. (C) 2002 Elsevier Science Inc. All rights reserved.

Garrity, C, Lubin D, Kern S, Pedersen LT.  2003.  Linescan camera evaluation of SSM/I 85.5 GHz sea ice retrieval (vol 83, pg 472, 2002). Remote Sensing of Environment. 84:321-321.   10.1016/s0034-4257(02)00180-3   AbstractWebsite
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Lubin, D, Simpson AS.  1994.  The Longwave Emission Signature of Urban Pollution - Radiometric Ftir Measurement. Geophysical Research Letters. 21:37-40.   10.1029/93gl03374   AbstractWebsite

Air pollutants trapped beneath frequent temperature inversions in the Los Angeles basin bring about surface radiance enhancements of up to fifty percent in the middle-infrared window (8-12 microns). This constitutes an anthropogenic modification to the downwelling longwave flux which can be as large as 9 W/m2. A Fourier Transform Infrared (FTIR) spectroradiometer has been used to measure middle-infrared atmospheric emission spectra under Los Angeles smog, and these 1 cm-1 resolution spectra demonstrate that both anthropogenic aerosols and increased tropospheric ozone abundance contribute to enhancements in surface longwave radiation.

Lubin, D, Satheesh SK, McFarquar G, Heymsfield AJ.  2002.  Longwave radiative forcing of Indian Ocean tropospheric aerosol. Journal of Geophysical Research-Atmospheres. 107   10.1029/2001jd001183   AbstractWebsite

A spectrally resolved discrete-ordinates radiative transfer model is used to calculate the change in downwelling surface and top-of-the-atmosphere (TOA) outgoing longwave (3.9-500 mum) radiative fluxes induced by tropospheric aerosols of the type observed over the Indian Ocean during the Indian Ocean Experiment (INDOEX). Both external and internal aerosol mixtures were considered. Throughout the longwave, the aerosol volume extinction depends more strongly on relative humidity than in most of the shortwave (0.28-3.9 mum), implying that particle growth factors and realistic relative humidity profiles must be taken into account when modeling the longwave radiative effects of aerosols. A typical boundary layer aerosol loading, with a 500-nm optical depth of 0.3, will increase the downwelling longwave flux at the surface by 7.7 W m(-2) over the clean air case while decreasing the outgoing longwave radiation by 1.3 W m(-2). A more vertically extended aerosol loading, exhibiting a high opacity plume between 2 and 3 km above the surface and having a typical 500-nm optical depth of 0.7, will increase the downwelling longwave flux at the surface by 11.2 W m(-2) over the clean air case while decreasing the outgoing longwave radiation by 2.7 W m(-2). For a vertically extended aerosol profile, approximately 30% of the TOA radiative forcing comes from sea salt and approximately 60% of the forcing comes from the combination of sea salt and dust. The remaining forcing is from anthropogenic constituents. These results are for the external mixture. For an internal mixture, TOA longwave forcings can be up to a factor of two larger. Therefore, to complete our understanding of this region's longwave aerosol radiative properties, more detailed information is needed about aerosol mixing states. These longwave radiative effects partially offset the large shortwave aerosol radiative forcing and should be included in regional and global climate modeling simulations.