从空间测量陆面温度的可行性

THE FEASIBILITY STUDY OF LAND SURFACE TEMPER-ATURE MEASUREMENTS FROM SPACE

为了将用于从卫星热红外数据测量海面温度的多波段方法应用到陆面温度的测量,我们通过大气辐射输运模型的模拟计算进行了可行性研究。所模拟的大气条件和表面温度的变化范围宽得足于覆盖晴天大气性质和表面温度的实际变化,这些变化对陆地来说比对海洋的大。地面高程也作为最重要的地形影响包括在模拟计算中。用频谱发射率的测量值或计算值表征的地面覆盖,包括雪、粘土、沙地和树叶的样品。从统计分析得到的经验反演模型在无云条件下可由卫星三个红外波段测量,较精确地估算陆面温度,在0—40°观察角范围内,其标准偏差小于0.3 K,最大误差小于1K。热红外波段可以是气象卫星甚高分辨率辐射计(AVHRR),也可以是正被EOSAT和NASA考虑用于将来遥感测量的传遥器,即陆地卫星上增加的热红外多波段或为陆面/海面测量设计的宽视野传遥器(Sea WiFS)。

This feasibility study was conducted for extention of the multiple-wavelength method used for satellite measurement of sea surface temperature from thermal infrared data to land surface tempera tures through atmospheric radiative transfer simulations. The range of atmospheric conditions and surface temperatures simulated is wide enough to cover variations in clear atmospheric properties and surface temperatures, both of which are larger over land than over sea. Surface elevation is also included in the simulation as the most important topographic effect. Land covers characterized by measured Or modeled spectral emissivities include snow, clay, sands, and tree leaf sampks. The statistical inverse model Can estimate the surface temperature with a standard deviation less than 0.3 K and a maximum error less than1 K, for viewing angles up to 40° from nadir under cloud-free conditions, given satellite measurements in three infrared channels. Bands from the NOAA AVHRR (Advanced Very High Resolution Radiometer) may be used, as can selected bands from one of two sensors under consideration by EOSAT and NASA for a future remote sensing instruments, either the addition of multispectral thermal infrared channels to Landsat or a sensor with a wide field-of-view designed for measurements over land or sea (SeaWiFS).