Longwave Radiation Processes on the Antarctic Plateau

南极高原上空的大气在全球气候系统中发挥着独特的作用。它是地球上最冷、最干燥的大气层，辐射过程主导着地表和大气层顶层的能量收支。在夏季，四个辐射分量(向下和向上、短波和长波)分别在每平方米100到400瓦的范围内，一般比感热和潜热通量高至少一个数量级。冬季没有短波辐射，向下和向上的长波通量是地表能量收支的主要贡献者。在光谱分辨的情况下，长波辐射也可用于大气和地表属性的遥感。因此，人们希望开发利用极地轨道卫星进行遥感的方法，以便能够确定整个大陆的特征。地面观测对于验证卫星观测以及获取关于气候过程的信息来说是非常宝贵的，这些信息最好在现场进行研究。五个独立的项目将基于对南极大气辐射和云激光雷达实验(SPARCLE)数据的分析，SPARCLE是一项关于云、水蒸气、大气冰晶和地表积雪对地表测量的长波辐射光谱的影响的全年实验。项目1将利用长波光谱气候学数据库来确定不同气体对地面下行长波通量和地面云辐射强迫的贡献。项目2涉及南极云的长波辐射特性及其对地面和大气能量收支的影响。项目3涉及南极洲湿度剖面的测量和边界层温度和湿度剖面反演算法的开发。项目4涉及同时恢复雪的表面温度和光谱发射率。项目5是对近地表大气温度分布的研究。这些实验数据和随后的分析产品预计将在其他领域产生研究，包括遥感、气候建模和南极洲天气预报，以用于潜在的全年后勤行动。这里提出的数据分析项目还将提供南极高原的数据，有助于约束和测试大气环流模型。*

The atmosphere over the Antarctic Plateau plays a unique role in the global climate system. It is the coldest and driest atmosphere on earth, and radiation processes dominate both the surface and the top-of-atmosphere energy budgets. In summer, the four radiation components (downward and upward, shortwave and longwave) are each in the range of 100 to 400 watts per square meter, generally exceeding the sensible and latent heat fluxes by at least an order of magnitude. In winter, there is no shortwave radiation, so the downward and upward longwave fluxes are the dominant contributors to the surface energy budget. When spectrally resolved, longwave radiation is also useful for remote sensing of atmospheric and surface properties. Thus it is desirable to develop methods for remote sensing by polar-orbiting satellites so that the entire continent can be characterized. Surface-based observations are invaluable for validating satellite observations, as well as for obtaining information about climatic processes that are best studied in situ. Five separate projects will be based upon analysis of data from South Pole Atmospheric Radiation and Cloud Lidar Experiment (SPARCLE), a full-year experiment of the effects of clouds, water vapor, atmospheric ice crystals, and surface snow, on the longwave radiation spectrum measured at the surface. Project 1 will use the climatological database of longwave spectra to determine the contributions of different gases to the downward longwave flux at the surface and the surface cloud radiative forcing. Project 2 involves longwave radiative properties of Antarctic clouds and their effects on the surface and atmospheric energy budgets. Project 3 involves the measurement of humidity profiles and development of retrieval algorithms of boundary-layer temperature and humidity profiles for Antarctica. Project 4 involves the simultaneous retrieval of the surface temperature and the spectral emissivity of snow. Project 5 is a study of near-surface atmospheric temperature profiles. The experimental data and the subsequent analysis products are expected to generate research in other areas, including remote sensing, climate modeling, and weather forecasting in Antarctica for potential year-round logistical operations. The data analysis projects proposed here will also provide data from the Antarctic Plateau useful in constraining and testing general circulation models.***