A new high-resolution model of non-tidal atmosphere and ocean mass variability for de-aliasing of satellite gravity observations: AOD1B RL06

Abstract

S U M M A R YThe release 06 (RL06) of the Gravity Recovery and Climate Experiment (GRACE) Atmosphere and Ocean De-Aliasing Level-1B (AOD1B) product has been prepared for use as a timevariable background model in global gravity research. Available since the year 1976 with a temporal resolution of 3 hr, the product is provided in Stokes coefficients up to degree and order 180. RL06 separates tidal and non-tidal signals, and has an improved long-term consistency due to the introduction of a time-invariant reference orography in continental regions. Variance reduction tests performed with globally distributed in situ ocean bottom pressure recordings and sea-surface height anomalies from Jason-2 over a range of different frequency bands indicate a generally improved performance of RL06 compared to its predecessor. Orbit tests for two altimetry satellites remain inconclusive, but GRACE K-band residuals are reduced by 0.031 nm s −2 in a global average, and by more than 0.5 nm s −2 at numerous places along the Siberian shelf when applying the latest AOD1B release. We therefore recommend AOD1B RL06 for any upcoming satellite gravimetry reprocessing effort.

Sea Level Budgets Should Account for Ocean Bottom Deformation

“…We use the JPL Release 06 GRACE mascon data because they have been shown to match the in situ ocean bottom pressure (Watkins et al, 2015;Wiese et al, 2018). One of the differences between Releases 05 and 06 is the improved Atmosphere Ocean Dealiasing model (AOD1B), which improves product quality over oceans (Dobslaw et al, 2017;Göttl et al, 2018;Wiese et al, 2018). Since the native resolution of GRACE products is around 3 • (Tapley et al, 2004;Vishwakarma et al, 2018;Watkins et al, 2015), the coastal ocean is affected by land-ocean signal leakage (Chambers et al, 2004).…”

Using GRACE to Explain Variations in the Earth's Oblateness

“…First, we define two types of mass distribution over land areas: ice-related and hydrology-related ones. We do not estimate the atmosphere and dynamic ocean effects (AO), since they are largely removed from GRACE level 2 data product by means of the Atmosphere and Ocean Dealiasing (AOD) product (RL05 or RL06; Dobslaw et al, 2017;Flechtner & Dobslaw, 2013). They are obtained by splitting land areas into geographical regions, assuming that a unit mass is distributed uniformly over each of those regions.…”

“…In addition, we define GIA-related mass distributions to account for the solid Earth contribution. We do not estimate the atmosphere and dynamic ocean effects (AO), since they are largely removed from GRACE level 2 data product by means of the Atmosphere and Ocean Dealiasing (AOD) product (RL05 or RL06; Dobslaw et al, 2017;Flechtner & Dobslaw, 2013).…”

“…The AOD RL05 is based on the atmosphere model by the European Center for Medium-Range Weather Forecast (Dee et al, 2011) and the ocean model for circulation and tides (Thomas, 2002). The AOD RL06 (Dobslaw et al, 2017) makes use of the same atmosphere model but is based on a different ocean model, that is, the Max-Planck-Institute for Meteorology Ocean model (Jungclaus et al, 2013). In this study, we use both the CSR RL05 (Bettadpur, 2012) and CSR RL06 (Save, 2018) models completed to degree and order 60.…”

Resolving Geophysical Signals by Terrestrial Gravimetry: A Time Domain Assessment of the Correction‐Induced Uncertainty

“…The nontidal ocean loading effects were acquired from EOST Loading Service ) utilizing ECCO-JPL (Fukumori, 2002), ECCO2 (Menemenlis et al, 2008), and TUGOm (Loren & Florent, 2003) models (download at loading.u-strasbg.fr, access date 28 February 2018). In addition, nontidal ocean mass variations of the OMCTv06 model (Dobslaw et al, 2017) were converted to their gravity effect using mGlobe. Identical minimal integration radius of 0.1 • from the study site and maximal available model temporal resolution was used in all cases.…”