Remote Sens. 2012, 4(10), 3022-3054; doi:10.3390/rs4103022
Article

Simulations of Infrared Radiances over a Deep Convective Cloud System Observed during TC4: Potential for Enhancing Nocturnal Ice Cloud Retrievals

1 NASA Langley Research Center, Hampton, VA 23681, USA 2 Science Systems and Applications, Inc., Hampton, VA 23666, USA 3 Earth System Laboratory, National Center for Atmospheric Research, Boulder, CO 80301, USA 4 NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA 5 Science Systems and Applications, Inc., Lanham, MD 20706, USA 6 LASP, University of Colorado, Boulder, CO, USA 7 Universities Space Research Association, Columbia, MD 21044, USA 8 Department of Meteorology, Pennsylvania State University, State College, PA 16802, USA 9 GESTAR, Morgan State University, Baltimore, MD 21251, USA 10 Department of Atmospheric Sciences, Texas A&M University, College Station, TX 77843, USA
* Author to whom correspondence should be addressed.
Received: 20 August 2012; in revised form: 29 September 2012 / Accepted: 6 October 2012 / Published: 11 October 2012
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Abstract: Retrievals of ice cloud properties using infrared measurements at 3.7, 6.7, 7.3, 8.5, 10.8, and 12.0 mm can provide consistent results regardless of solar illumination, but are limited to cloud optical thicknesses t < ~6. This paper investigates the variations in radiances at these wavelengths over a deep convective cloud system for their potential to extend retrievals of t and ice particle size De to optically thick clouds. Measurements from an imager, an interferometer, the Cloud Physics Lidar (CPL), and the Cloud Radar System (CRS) aboard the NASA ER-2 aircraft during the NASA TC4 (Tropical Composition, Cloud and Climate Coupling) experiment flight during 5 August 2007, are used to examine the retrieval potential of infrared radiances over optically thick ice clouds. Simulations based on coincident in situ measurements and combined cloud t from CRS and CPL measurements are comparable to the observations. They reveal that brightness temperatures at these bands and their differences (BTD) are sensitive to t up to ~20 and that for ice clouds having t > 20, the 3.7–10.8 µm and 3.7–6.7 µm BTDs are the most sensitive to De. Satellite imagery appears to be consistent with these results suggesting that t and De could be retrieved for greater optical thicknesses than previously assumed. But, because of sensitivity of the BTDs to uncertainties in the atmospheric profiles of temperature, humidity, and ice water content, and sensor noise, exploiting the small BTD signals in retrieval algorithms will be very challenging.
Keywords: clouds; optical depth; particle size; satellite; TC4; multispectral thermal infrared

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MDPI and ACS Style

Minnis, P.; Hong, G.; Ayers, J.K.; Smith, W.L., Jr.; Yost, C.R.; Heymsfield, A.J.; Heymsfield, G.M.; Hlavka, D.L.; King, M.D.; Korn, E.; McGill, M.J.; Selkirk, H.B.; Thompson, A.M.; Tian, L.; Yang, P. Simulations of Infrared Radiances over a Deep Convective Cloud System Observed during TC4: Potential for Enhancing Nocturnal Ice Cloud Retrievals. Remote Sens. 2012, 4, 3022-3054.

AMA Style

Minnis P, Hong G, Ayers JK, Smith WL, Jr, Yost CR, Heymsfield AJ, Heymsfield GM, Hlavka DL, King MD, Korn E, McGill MJ, Selkirk HB, Thompson AM, Tian L, Yang P. Simulations of Infrared Radiances over a Deep Convective Cloud System Observed during TC4: Potential for Enhancing Nocturnal Ice Cloud Retrievals. Remote Sensing. 2012; 4(10):3022-3054.

Chicago/Turabian Style

Minnis, Patrick; Hong, Gang; Ayers, J. Kirk; Smith, William L., Jr.; Yost, Christopher R.; Heymsfield, Andrew J.; Heymsfield, Gerald M.; Hlavka, Dennis L.; King, Michael D.; Korn, Errol; McGill, Matthew J.; Selkirk, Henry B.; Thompson, Anne M.; Tian, Lin; Yang, Ping. 2012. "Simulations of Infrared Radiances over a Deep Convective Cloud System Observed during TC4: Potential for Enhancing Nocturnal Ice Cloud Retrievals." Remote Sens. 4, no. 10: 3022-3054.

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