DOI: 10.5194/tc-10-2217-2016
Scopus记录号: 2-s2.0-84966351859
论文题名: The impact of melt ponds on summertime microwave brightness temperatures and sea-ice concentrations
作者: Kern S ; , Rösel A ; , Toudal Pedersen L ; , Ivanova N ; , Saldo R ; , Tage Tonboe R
刊名: Cryosphere
ISSN: 19940416
出版年: 2016
卷: 10, 期: 5 起始页码: 2217
结束页码: 2239
语种: 英语
英文关键词: algorithm
; brightness temperature
; pond
; reflectance
; satellite data
; sea ice
; summer
; Arctic Ocean
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. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/75071
Appears in Collections: 影响、适应和脆弱性 气候变化与战略
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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
Recommended Citation:
Kern S,, Rösel A,, Toudal Pedersen L,et al. The impact of melt ponds on summertime microwave brightness temperatures and sea-ice concentrations[J]. Cryosphere,2016-01-01,10(5)