[G02-3] Regional gravity and geoid

[G02-3-05] Combining airborne and terrestrial gravity data to improve the geoid model in Brazil

^○Gabriel do Nascimento Guimaraes¹, Ana Cristina Oliveira Cancoro de Matos², Denizar Blitzkow² (1.Federal University of Uberlandia, Monte Carmelo, Brazil, 2.University of Sao Paulo, Sao Paulo, Brazil)

Brazil is a country of continental proportions and with different geographic characteristics. From its coast of nearly 7,400 km, where it houses 25% of the population, up to the 5,500,000 km² that form the Amazon region, this country has great challenges for Geodesy. One of these challenges is linked to the improvement of the geoid model quality to meet the needs related to the areas of knowledge, besides having homogeneous geoid undulation precision in most of the Brazilian territory. The country has about 450,000 ground gravimetric stations. While the South and Southeast regions have a regular distribution, the North (Amazon) and Northeast regions lack terrestrial gravimetric data. In this sense, this work aims to combine terrestrial and airborne gravity data to improve the Brazilian geoidal model. Two areas were selected. The first is bounded by 20S and 24S in latitude and 48W and 54W in longitude and has terrestrial and airborne gravity data. The second area is located in the Amazon region and is limited by 05N and 05S in latitude and 50W and 75W in longitude and does not have regular distribution of terrestrial data, only airborne data. The computation are being conducted using the GRAVSOFT package. The geoid models computed were based on EIGEN-6C4 up to degree and order 200 as a reference field. The oceanic region was completed with the mean free-air gravity anomalies derived from a satellite altimetry model from the Danish National Space Center, called DTU10. The short wavelength component was estimated via FFT. It is expected that the result will be aggregated to the calculation of the new Brazilian geoid model predicted for 2018.