海洋表面大气下行辐射遥感估算

Estimation of atmospheric downward longwave radiation with remotely sensed data

在海-气相互作用研究中,大气下行辐射的准确估算具有重要意义。在气象站点分布密集的地区,大气下行辐射可通过常规的仪器测量获取。但海洋表面布点成本高,维护比较困难,严重影响我们对海区辐射特征的认识和了解。遥感可提供良好的时空连续性和多层次数据,是研究大气下行辐射的有效手段。本文模拟了不同大气条件下海表的长波下行辐射,考虑到大气下行辐射不仅与所在层的大气有关,还受临近大气层的影响,我们通过增加大气水汽含量重新参数化大气比辐射率,改进Brutsaert模型,建立基于MODIS数据遥感估算海洋表面大气下行辐射的模型,并利用"中国近海海洋综合调查与评价"项目中黄海区观测的海-气通量观测资料对所提出的模型进行检验。结果表明,本文所改进的参数化模型在模拟数据中的均方误差(RMSE)为11.2 W/m^2;在实际数据验证中,RMSE为20.9 W/m^2;模型的精度基本达到了海-气作用研究中对瞬时大气下行辐射的精度要求。

Accurate estimation of atmospheric downward radiation is very significant in the researches about air-sea interaction.It can be obtained by conventional instrument measurement which is suitable for the area of dense meteorological stations.However,it is costly and has high-maintenance to put those instruments on the sea surface,which is seriously affecting our understanding of the radiation characteristics of the ocean.Satellite can provide time-space continuity and multi-level of information about the sea and it is an effective means to study atmospheric downward radiation.In this study,we have simulated the atmospheric downward long-wave radiation under all kinds of atmospheric conditions.Considering of that the atmospheric downward long-wave radiation is not only the contribution of bottom atmosphere but also the adjacent atmosphere levels,the atmosphere emissivity is parameterized by adding the atmosphere water vapor content and a new model is developed based on the‘Brutsaert’model.And the model is tested by the site flux data acquired from the Yellow Sea area in the project of"Integrated survey and evaluation of the resources of Chinese coastal zone".Results show that the root mean square error(RMSE)of the improved model is 11.2 W/m2 in the simulation data and is 20.9 W/m2 in the site measurements,and the accuracy of the model is conformed to the precision of instantaneous atmospheric downward radiation in the study of air-sea interaction.