[G03-4] Mass transport and redistrubution

[G03-4-05] Detection and interpretation of multi-annual mass variation in GRACE monthly gravity solutions

^○Lorant Foldvary^{1, 2}, Annamaria Kiss³ (1.Institute of Geoinformatics, Obuda University, Szekesfehervar, Hungary, 2.Geodetic and Geophysical Institute, Research Centre of Astronomy and Earth Sciences, Hungarian Academy of Science, Sopron, Hungary, 3.Budapest University of Technology and Economics, Budapest, Hungary)

The GRACE mission provides monthly gravity field solutions for nearly 15 years with very few gaps in the consecutive series of gravity field models. The time series of gravity field models provides primarily a tool for annual and sem-annual mass variations. The length of the data already enables investigations of variations on multi-annual periods. The non-unique sampling of the epochs calls for an appropriate method for determining the multi-annual signal; for the purpose Burg spectrum, modified periodogram, Thompson's multitaper method and Lomb–Scargle periodogram has been adapted. Regions of statistically convincing variations in the 2-10 year periods has been identified. In most cases at these regions the mass variation was found to be related to the El Nino/La Nina events.