Assimilation of High-Density Low-Precision GNSS-R Altimetry Observations to Constrain Simulations of the Ocean Circulation - Impact on SSH and Subsurface Processes
Assimilation of High-Density Low-Precision GNSS-R Altimetry Observations to Constrain Simulations of the Ocean Circulation - Impact on SSH and Subsurface Processes
Abstract:
The Agulhas current system transports warm and salty water masses from
the Indian ocean into the Southern Ocean and into the Atlantic. The
transports impact present and future climate on local and global
scales. However, size and variability of the respective transports are still
much debated. In this study, prospective sea surface height (SSH)
anomalies obtained from Global Navigation Satellite System
Reflectometry (GNSS-R) are assimilated with a 4D-VAR method. A
space-borne GNSS-R detector on low Earth orbit is assumed and
simulated. The proposed GNSS-R measurements will surpass the
radar-based satellite altimetry missions in temporal and spatial
resolution but are less precise. The characteristics of the SSH
observations are estimated and respective observations are sampled
from a ocean model of the Agulhas region. With a twin-model data
assimilation approach the question is answered how the regional
internal water mass properties and transports in the Agulhas region
are determined by the high-density but low-accuracy GNSS-R based
SSH observations.
the Indian ocean into the Southern Ocean and into the Atlantic. The
transports impact present and future climate on local and global
scales. However, size and variability of the respective transports are still
much debated. In this study, prospective sea surface height (SSH)
anomalies obtained from Global Navigation Satellite System
Reflectometry (GNSS-R) are assimilated with a 4D-VAR method. A
space-borne GNSS-R detector on low Earth orbit is assumed and
simulated. The proposed GNSS-R measurements will surpass the
radar-based satellite altimetry missions in temporal and spatial
resolution but are less precise. The characteristics of the SSH
observations are estimated and respective observations are sampled
from a ocean model of the Agulhas region. With a twin-model data
assimilation approach the question is answered how the regional
internal water mass properties and transports in the Agulhas region
are determined by the high-density but low-accuracy GNSS-R based
SSH observations.