摘要
在没有考虑高程数据的预处理方法得到的NOAA AVHRR资料中,每条扫描线数据中的51点经纬度定位信息常常有误差,尤其是在海拔较高、距卫星星下点较远的定位点,其定位信息与实际差别很大。针对这种情况,该文描述了一种引入高程数据并结合51点定位信息对2048个扫描点定位进行快速、简易的订正方法,可有效地修正AVHRR资料预处理未考虑高程信息引起的经纬度定位偏差,以便于对分辨率和定位精度要求不高的用户更好地使用AVHRR数据。
Errors can often be found in the 51 longitude and latitude location information of each scan line in the NOAA AVHRR data which are preprocessed without taking the Digital Elevation Model （DEM） into consideration, and are dramatically huge at the points with high altitude and far from the nadir. The simulation indicates that the horizontal location bias will be increased with the increasing of the zenith angle. This bias caused by the location error can reach the kilometer order level and is mainly displayed in the longitude direction, with small weight of the latitude direction. It is necessary to correct this deviation. Even to the users who project first and then re-correct with the surface control-point, orientation correction can reduce the difficulty in re-correction and improve the orientation precise.
A quick and simple method is developed by which localization information of 2048 satellite observation points in a scan line can be corrected with DEM and that of 51 original localization points in AVHRR LIB data. Firstly, latitudes and longitudes of 2048 satellite observation points are figured out using 51 original localization points＇ information by equidistance interpolation of one variable in an entire siding-to-siding block. Simultaneously the altitude of each point is looked up from DEM data. Secondly, one points is located exactly and the other is not revised. The horizontal location bias （i. e. , spherical surface radian deviation） of which the former is relative to the latter can be achieved with DEM and the uncorrected point latitude and longitude. Thirdly, new localization information of the inaccurate point is calculated by dint of original localization points information and spherical surface radian deviation, and then the correction is finished. Because DEM influence to the location of several points at nadir is minimal, they can be considered as original points located exactly and then those on both sides are set as ones to be revised. Thereupon corrections can be carried out from n
出处
《应用气象学报》
CSCD
北大核心
2007年第4期417-426,共10页
Journal of Applied Meteorological Science
基金
国家自然科学基金项目(40501048)
国家科技部基础条件平台工作(2005DKA31700)共同资助
