The Brazilian gravimetric geoid: MAPGEO2010

The Brazilian geoid model MAPGEO2010 is limited by 6°N and 35°S in latitude and 30°W and 75°W in longitude with a 5' resolution. The terrestrial gravity data for the continent have been updated by surveys in Brazil and in the neighbour countries until 2010. The complete Bouguer and Helmert gravity anomalies have been derived through the Canadian package SHGEO. The short wavelength component was estimated via FFT. The geopotential model EGM2008 was used as a reference field restricted to degree and order 150. The geoid height was corrected from the zero-order term, -0.41 meter, for compatibility with the GRS80 ellipsoid, used by SIRGAS2000. The RMS difference associated with the MAPGEO2010 model was ±0.28 meter, determined from the comparison of IBGE GPS/levelling points. The geoid model is provided in ISG format 2.0 (ISG Format Specifications), while the file in its original data format is available at the model ISG webpage.

巴西大地水准面模型MAPGEO2010的纬度覆盖范围为6°N至35°S，经度覆盖范围为30°W至75°W，空间分辨率为5角分。本次建模所用的南美大陆陆地重力数据，已基于截至2010年巴西及其邻国的实地勘测成果完成更新。完整布格（Bouguer）重力异常与赫尔默特（Helmert）重力异常通过加拿大SHGEO软件包解算得到。短波分量通过FFT（快速傅里叶变换）进行估算。建模过程以EGM2008地球重力场模型作为参考场，截断至阶数与次数150。为兼容SIRGAS2000所采用的GRS80椭球，对大地水准面高施加了零阶项（-0.41米）的校正。通过与巴西地理与统计研究所（IBGE, Instituto Brasileiro de Geografia e Estatística）的GPS/水准测点对比测算，得到MAPGEO2010模型的均方根误差为±0.28米。该大地水准面模型以ISG格式2.0（ISG格式规范）对外提供，原始数据格式的文件可在该模型对应的ISG官方网页获取。