Inversion of marine gravity anomalies over southeastern China seas from multi-satellite altimeter vertical deflections

Citation:
Zhang, SJ, Sandwell DT, Jin TY, Li DW.  2017.  Inversion of marine gravity anomalies over southeastern China seas from multi-satellite altimeter vertical deflections. Journal of Applied Geophysics. 137:128-137.

Date Published:

2017/02

Keywords:

anomaly, CryoSat-2, ers-1, field recovery, geoid undulations, geosat, gravity, retracking, satellite altimetry, surface, Vertical deflection, wave-forms, Waveform retracldng

Abstract:

The accuracy and resolution of marine gravity field derived from satellite altimetry mainly depends on the range precision and dense spatial distribution. This paper aims at modeling a regional marine gravity field with improved accuracy and higher resolution (1' x V') over Southeastern China Seas using additional data from CryoSat-2 as well as new data from AltiKa. Three approaches are used to enhance the precision level of satellite-derived gravity anomalies. Firstly we evaluate a suite of published retracking algorithms and find the two-step retracker is optimal for open ocean waveforms. Secondly, we evaluate the filtering and resampling procedure used to reduce the full 20 or 40 Hz data to a lower rate having lower noise. We adopt a uniform low-pass filter for all altimeter missions and resample at 5 Hz and then perform a second editing based on sea surface slope estimates from previous models. Thirdly, we selected WHU12 model to update the corrections provided in geophysical data record. We finally calculated the 1' x 1' marine gravity field model by using EGM2008 model as reference field during the remove/restore procedure. The root mean squares of the discrepancies between the new result and DTU10, DTU13, V23.1, EGM2008 are within the range of 1.8-3.9 mGal, while the verification with respect to shipboard gravity data shows that the accuracy of the new result reached a comparable level with DTU13 and was slightly superior to V23.1, DTU10 and EGM2008 models. Moreover, the new result has a 2 mGal better accuracy over open seas than coastal areas with shallow water depth. (C) 2016 Elsevier B.V. All rights reserved.

Notes:

n/a

Website

DOI:

10.1016/j.jappgeo.2016.12.014