气候变化领域集成服务门户(CCPortal): The impact of melt ponds on summertime microwave brightness temperatures and sea-ice concentrations

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DOI	10.5194/tc-10-2217-2016
	The impact of melt ponds on summertime microwave brightness temperatures and sea-ice concentrations
	Kern S.; Rösel A.; Toudal Pedersen L.; Ivanova N.; Saldo R.; Tage Tonboe R.
发表日期	2016
ISSN	19940416
卷号	10 期号:5
英文摘要	Sea-ice concentrations derived from satellite microwave brightness temperatures are less accurate during summer. In the Arctic Ocean the lack of accuracy is primarily caused by melt ponds, but also by changes in the properties of snow and the sea-ice surface itself. We investigate the sensitivity of eight sea-ice concentration retrieval algorithms to melt ponds by comparing sea-ice concentration with the melt-pond fraction. We derive gridded daily sea-ice concentrations from microwave brightness temperatures of summer 2009. We derive the daily fraction of melt ponds, open water between ice floes, and the ice-surface fraction from contemporary Moderate Resolution Spectroradiometer (MODIS) reflectance data. We only use grid cells where the MODIS sea-ice concentration, which is the melt-pond fraction plus the ice-surface fraction, exceeds 90%. For one group of algorithms, e.g., Bristol and Comiso bootstrap frequency mode (Bootstrap-f), sea-ice concentrations are linearly related to the MODIS melt-pond fraction quite clearly after June. For other algorithms, e.g., Near90GHz and Comiso bootstrap polarization mode (Bootstrap-p), this relationship is weaker and develops later in summer. We attribute the variation of the sensitivity to the melt-pond fraction across the algorithms to a different sensitivity of the brightness temperatures to snow-property variations. We find an underestimation of the sea-ice concentration by between 14% (Bootstrap-f) and 26% (Bootstrap-p) for 100% sea ice with a melt-pond fraction of 40%. The underestimation reduces to 0% for a melt-pond fraction of 20%. In presence of real open water between ice floes, the sea-ice concentration is overestimated by between 26% (Bootstrap-f) and 14% (Bootstrap-p) at 60% sea-ice concentration and by 20% across all algorithms at 80% sea-ice concentration. None of the algorithms investigated performs best based on our investigation of data from summer 2009. We suggest that those algorithms which are more sensitive to melt ponds could be optimized more easily because the influence of unknown snow and sea-ice surface property variations is less pronounced. © Author(s) 2016.
学科领域	algorithm; brightness temperature; pond; reflectance; satellite data; sea ice; summer; Arctic Ocean
语种	英语
scopus关键词	algorithm; brightness temperature; pond; reflectance; satellite data; sea ice; summer; Arctic Ocean
来源期刊	Cryosphere
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/119575
作者单位	Center for Climate System Analysis and Prediction CliSAP, Hamburg, Germany; Norsk Polar Institute, Tromsø, Norway; Danish Meteorological Institute, Copenhagen, Denmark; Nansen Environmental and Remote Sensing Center NERSC, Bergen, Norway; Danish Technical University-Space, Copenhagen, Denmark
推荐引用方式 GB/T 7714	Kern S.,Rösel A.,Toudal Pedersen L.,et al. The impact of melt ponds on summertime microwave brightness temperatures and sea-ice concentrations[J],2016,10(5).
APA	Kern S.,Rösel A.,Toudal Pedersen L.,Ivanova N.,Saldo R.,&Tage Tonboe R..(2016).The impact of melt ponds on summertime microwave brightness temperatures and sea-ice concentrations.Cryosphere,10(5).
MLA	Kern S.,et al."The impact of melt ponds on summertime microwave brightness temperatures and sea-ice concentrations".Cryosphere 10.5(2016).