Yang Yuekui, Marshak Alexander, Han Mei, Palm Stephen P, Harding David J
Universities Space Research Association, Columbia, MD.
NASA Goddard Space Flight Center, Greenbelt, MD.
J Quant Spectrosc Radiat Transf. 2017 Feb;188:159-164. doi: 10.1016/j.jqsrt.2016.03.033. Epub 2016 Apr 6.
Snow grain size is an important parameter for cryosphere studies. As a proof of concept, this paper presents an approach to retrieve this parameter over Greenland, East and West Antarctica ice sheets from surface reflectances observed with the Geoscience Laser Altimeter System (GLAS) onboard the Ice, Cloud, and land Elevation Satellite (ICESat) at 1064 nm. Spaceborne lidar observations overcome many of the disadvantages in passive remote sensing, including difficulties in cloud screening and low sun angle limitations; hence tend to provide more accurate and stable retrievals. Results from the GLAS L2A campaign, which began on 25 September and lasted until 19 November, 2003, show that the mode of the grain size distribution over Greenland is the largest (300 μm) among the three, West Antarctica is the second (220 μm) and East Antarctica is the smallest (~190 μm). Snow grain sizes are larger over the coastal regions compared to inland the ice sheets. These results are consistent with previous studies. Applying the broadband snow surface albedo parameterization scheme developed by Garder and Sharp (2010) to the retrieved snow grain size, ice sheet surface albedo is also derived. In the future, more accurate retrievals can be achieved with multiple wavelengths lidar observations.
雪粒大小是冰冻圈研究的一个重要参数。作为概念验证，本文提出了一种从冰、云和陆地高程卫星（ICESat）搭载的地球科学激光高度计系统（GLAS）在1064纳米处观测到的地表反射率中反演格陵兰、南极东部和西部冰盖这一参数的方法。星载激光雷达观测克服了被动遥感中的许多缺点，包括云筛选困难和低太阳角度限制；因此往往能提供更准确和稳定的反演结果。2003年9月25日开始并持续到11月19日的GLAS L2A活动结果表明，格陵兰的雪粒大小分布模式在三者中最大（约300微米），南极西部其次（约220微米），南极东部最小（约190微米）。与冰盖内陆地区相比，沿海地区的雪粒更大。这些结果与先前的研究一致。将Garder和Sharp（2010）开发的宽带雪面反照率参数化方案应用于反演得到的雪粒大小，还可以得到冰盖表面反照率。未来，利用多波长激光雷达观测可以实现更准确的反演。
