Sobrino J A, Cuenca J
Global Change Unit, Department of Thermodynamics, University of Valencia, Calle Dr. Moliner, 50, 46100 Burjassot, Spain.
Appl Opt. 1999 Jun 20;38(18):3931-6. doi: 10.1364/ao.38.003931.
Multiangle algorithms for estimating sea and land surface temperature with Along-Track Scanning Radiometer data require a precise knowledge of the angular variation of surface emissivity in the thermal infrared. Currently, few measurements of this variation exist. Here an experimental investigation of the angular variation of the infrared emissivity in the thermal infrared (8-14-microm) band of some representative samples was made at angles of 0 degrees-65 degrees (at 5 degrees increments) to the surface normal. The results show a decrease of the emissivity with increasing viewing angle, with water showing the highest angular dependence (approximately 7% from 0 degrees to 65 degrees views). Clay, sand, slime, and gravel show variations of approximately 1-3% for the same range of views, whereas a homogeneous grass cover does not show angular dependence. Finally, we include an evaluation of the impact that these data can produce on the algorithms for determining land and sea surface temperature from double-angle views.
利用沿轨扫描辐射计数据估算海表面温度和陆表面温度的多角度算法需要精确了解热红外波段地表发射率的角度变化情况。目前，关于这种变化的测量数据很少。本文对一些代表性样本在热红外（8 - 14微米）波段的红外发射率随角度变化进行了实验研究，测量角度范围为相对于表面法线0度至65度（以5度为增量）。结果表明，发射率随观测角度的增加而降低，其中水的角度依赖性最高（从0度到65度观测，发射率降低约7%）。在相同的观测角度范围内，黏土、沙子、黏液和砾石的发射率变化约为1% - 3%，而均匀的草地覆盖则未表现出角度依赖性。最后，我们评估了这些数据对从双角度视图确定陆地和海洋表面温度的算法可能产生的影响。
