基于Ku、C和Ka波段卫星测高数据的海冰厚度和冰上积雪厚度反演方法研究

Sea ice thickness and snow depth over the sea ice cover are important parameters of the water cycle in the polar cryosphere, and they have important applications in climate change research and data assimilation in operational forecasts. Satellite altimetry is the only effective method for continuous acquisition of hemispheric sea ice thickness information among numerous sea ice thickness measurement methods. The accuracy of the sea ice thickness derived from satellite altimetry is limited by the estimation of snow depth. The snow depth observation data widely used are climatological snow depth data or as derived from reanalyses. These snow depth data cannot describe the true state of snow, which result in large uncertainty in the derived sea ice thickness. The penetration depth of the radar signal into the snowpack is closely related to the frequency. The retrieval method of snow depth using Ku and Ka-band altimetry data has been validated, but the retrieval of snow depth for thick snow is still difficult. The penetration depth of the radar signal into the snowpack at C-band frequency is larger than those at Ku and Ka-band frequencies. This project proposes a method for retrieval of sea ice thickness and snow depth based on Ku, C and Ka-band satellite altimetry data. The sea thickness and snow depth can be simultaneously retrieved by combining the Ku and C-band altimetry data from HY-2 satellite and the Ka-band altimetry data from SARAL/Altika satellite. The retrieval method can reduce the retrieval error effectively, and has broad application prospects in many aspects such as sea ice volume estimation, polar air-sea interaction, and seasonal prediction.

海冰厚度和冰上积雪厚度是极地冰冻圈水循环的重要参数，在气候变化研究和业务化预报数据同化中具有重要的应用。卫星测高是众多海冰厚度探测方法中唯一可连续获得半球尺度海冰厚度的方法，其精度受限于积雪厚度的估计，而目前广泛使用的积雪厚度是基于气候态观测或者再分析资料的积雪厚度数据，这些数据不能很好刻画冰上积雪的真实状态，使得海冰厚度估计有很大的不确定性。基于Ku和Ka波段卫星测高数据反演冰上积雪厚度的方法已得到了验证，但厚雪的积雪厚度反演还比较困难。C波段雷达信号在积雪中的穿透深度大于Ku和Ka波段，本项目提出一种基于Ku、C和Ka波段卫星测高数据的海冰厚度和冰上积雪厚度反演方法，将海洋二号卫星Ku和C波段以及SARAL/Altika卫星Ka波段测高数据进行结合，同时反演海冰厚度和冰上积雪厚度这两个参数，并可有效降低反演误差，在海冰体积估计、极地海气相互作用、季节预估等方面具有广泛的应用前景。

海冰厚度和冰上积雪厚度是极地冰冻圈水循环的重要参数，在气候变化研究和业务化预报数据同化中具有重要的应用。卫星测高是众多海冰厚度探测方法中唯一可连续获得半球尺度海冰厚度的方法，其精度受限于积雪厚度的估计，而目前广泛使用的积雪厚度是基于气候态观测或者再分析资料的积雪厚度数据，这些数据不能很好刻画冰上积雪的真实状态，使得海冰厚度估计有很大的不确定性。基于Ku和Ka波段卫星测高数据反演冰上积雪厚度的方法已得到了验证，但厚雪的积雪厚度反演还比较困难。本项目分析了C、Ku和Ka波段雷达信号在积雪中的穿透深度，提出一种基于Ku、C和Ka波段卫星测高数据的海冰厚度和冰上积雪厚度反演方法，并利用海洋二号B卫星雷达高度计Ku和C波段以及SARAL/Altika卫星雷达高度计Ka波段数据进行验证，联合反演得到海冰厚度和冰上积雪厚度。本项目提出的方法在海冰体积估计、极地海气相互作用、季节预估等方面具有广泛的应用前景。