Sea-ice concentration retrieval in the Antarctic based on the SSM/ I 85.5 GHz polarization
Sea-ice concentration retrieval in the Antarctic based on the SSM/ I 85.5 GHz polarization
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DOI：
10.3189/172756401781818905
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发表时间：
2001
影响因子：
2.9
通讯作者：
S. Kern;G. Heygster
中科院分区：
文献类型：
--
作者：
S. Kern;G. Heygster
摘要：与其他通道相比，使用来自特殊传感器微波/成像仪 (SSM/I) 85 GHz 通道的数据可以将分辨率提高至少四倍。因此可以获得更高分辨率的海冰浓度数据，进而可用于改进数值天气预报（NWP）和全球环流模型的结果。提出的新海冰浓度反演算法（SEA LION 算法）使用 85 GHz (p) 的极化。大气水的排放和风使海面粗糙的散射（天气效应）会降低 p 并导致对海冰浓度的高估。我们使用辐射传输模型以及从 NWP 模型和其他 SSM/I 通道获得的大气数据来量化天气影响，并校正该影响的 p。每个月的开放水域和海冰联络点分别根据每日网格 85 GHz SSM/I 亮度温度确定。使用新算法计算 1992−98 年期间每一天整个南大洋的海冰浓度，空间分辨率为 12.5 × 12.5 km2。将这些冰浓度与业务线扫描系统可见图像进行比较，揭示了有关监测沿海冰间湖和春季浮冰破裂的令人信服的结果。 SEA LION 海冰范围和面积，以及 SEA LION 海冰浓度和船舶观测值之间的比较，与 NASA 团队和 Bootstrap 算法获得的结果一致：
Abstract Using data from the 85 GHz channels of the Special Sensor Microwave/ Imager (SSM/I) allows a resolution improvement by at least a factor of four compared to the other channels. Consequently higher-resolution sea-ice concentration data can be obtained which in turn can be used to improve the results of numerical weather-prediction (NWP) and global circulation models. The proposed new sea-ice concentration retrieval algorithm (SEA LION algorithm) uses the polarization at 85 GHz (p). Emission from atmospheric water and scattering at the wind-roughened sea surface (weather effect) decrease p and cause an overestimate of the sea-ice concentration. We quantify the weather effect with a radiative transfer model and atmospheric data obtained from NWP models and the other SSM/I channels, and correct p for this effect. Tie points of open water and sea ice are determined for each month separately from daily gridded 85 GHz SSM/I brightness temperatures. Sea-ice concentrations are calculated with the new algorithm for the entire Southern Ocean for each day of the period 1992−98 with a spatial resolution of 12.5 × 12.5 km2. Comparisons of these ice concentrations with Operational Linescan System visible images reveal convincing results concerning the monitoring of coastal polynyas and the break-up of the pack ice in spring. SEA LION sea-ice extents and areas, and comparisons between SEA LION sea-ice concentrations and ship observations, agree with those obtained by the NASA Team and the Bootstrap algorithms: