A regionally refined and mass-consistent atmospheric and hydrological
de-aliasing product for GRACE, GRACE-FO and future gravity missions
Abstract
De-aliasing products are used in the estimation process of
satellite-based gravity field computation to reduce errors from
high-frequency mass variations that alias into monthly gravity fields.
The latest official product is AOD1B RL07 and describes non-tidal
atmosphere and oceanic mass variations at 3-hourly resolution. However,
the model-based de-aliasing products are inevitably incomplete and prone
to temporally and spatially correlated errors that substantially
contribute to errors in the estimated gravity fields.
Here, we investigate possible enhancement of current de-aliasing
products by nesting a regional high-resolution atmospheric reanalysis
over Europe into a global reanalysis. As further novelty we include
almost mass consistent terrestrial water storage variability from a
regional hydrological model nested into a global model as additional
component of the de-aliasing product.
While we find in agreement with earlier studies only minor contributions
from increasing the temporal resolution beyond 3-hourly data, our
investigations suggest that contributions from continental hydrology and
from regional non-hydrostatic atmospheric modeling to sub-monthly mass
variations could be relevant already for gravity fields estimated from
current gravity missions. Moreover, in the context of extreme events, we
find regionally contributions from additional moisture fields, such as
cloud liquid water, in the order of few mm over Europe. We suggest this
needs to be taken into account when preparing data analysis schemes for
future space gravimetric missions.