Joint ECMWF/OceanPredict workshop on Advances in Ocean Data Assimilation
Session
This work presents the implementation of the Ensemble Kalman Filter (EnKF) on the REMO Ocean Data Assimilation System (RODAS) with the Hybrid Coordinate Ocean Model (HYCOM) with 1/12° on the western tropical and South Atlantic. The new version of RODAS employs a joint and multivariate assimilation of hydrographic profiles, UK MetOffice OSTIA Sea Surface Temperature (SST) and AVISO Absolute...
We present recent developments in (pre-)operational CMEMS system on the North-West European Shelf (NWES). In the presented work, the system has been expanded to assimilate physical and biogeochemical observations from multiple platforms (satellite, gliders). The multi-platform assimilative system has been tested in series of experiments and it has been demonstrated that it has the capability...
Propagating sea surface temperature (SST) information to depth is a non-trivial problem in data assimilation since the vertical correlations of temperature are complex and varying, and information about mixed layer salinity is sparse. At the Met Office a parameterised function is used to specify the vertical length scales over which SST information is spread. At the surface the vertical...
Argo temperature and salinity (T & S) profiles form an integral part of ocean data assimilation (DA) systems. Similar is the case with Hyperspectral infrared (IR) satellite measurements for any atmospheric DA system. However, these two “essential” measurement platforms are not necessarily collocated in space and/or time. In this presentation we explore a few possibilities of collocating them,...
Land & Ocean processes in the ECMWF coupled system are represented by a variety of dedicated surface 1D 2D and 3D models (ECLand, ECWAM, NEMO3.4) that are coupled to the atmosphere with plans to connect also directly the land water cycle to the ocean fresh-water inflow via river-discharges (with the 2D CAMA-Flood scheme, already integrated in ECLand).
Presenting the poster I will illustrate...
A novel approach of data assimilation based on Neural Networks (NN's) is presented and applied to a wave model WAM. A case study demonstrated here is the German Bight. The method takes advantage of the ability of NN's to emulate models and to invert them. Combining forward and inverse model NN with the Levenberg–Marquardt algorithm provides boundary values or wind fields in agreement with...
Graphical Processing Units (GPUs) are increasingly being used in compute intensive non-graphical applications due to their large performance potential in tasks that can be made highly parallel and are bound by memory bandwidth; and potentially improved power efficiency for appropriate workloads.
During a series of hackathons we are porting key sections of the ocean data assimilation code...
The ocean is a fundamentally turbulent system characterizes by the presence of several processes occurring at different scales, particularly mesoscale (ranging from 5km up to several hundreds of kilometers) which is the most energetic scale in the ocean.The latter dominates the ocean's circulation by a variety of physical structures comprising eddies, meandering currents, filaments, and jets....
Arctic sea ice is one of the most rapidly and visibly changing components of the global climate system. Although global analysis and forecasting systems have been used successfully for mid-latitude ocean prediction for some time, their application to Arctic sea ice is less mature, since observations are much less abundant and data assimilation techniques less advanced in the polar regions than...
Designing effective ocean observing networks warrants deliberate, quantitative strategies, given the heavy cost and logistical challenges of ocean observing. We leverage Hessian uncertainty quantification (UQ) within the ECCO (Estimating the Circulation and Climate of the Ocean) data assimilation framework to explore a quantitative approach for ocean climate observing systems. Here, an...
The meridional overturning circulation (MOC) transports heat and mass within the ocean. MOC variations are driven by changes in wind stress and density. A recent study (Tandon et al., J. Phys. Oceanogr., 2020) has shown that interannual variability of the global MOC is dominated by variability in the Pacific MOC, and this variability is characterized by a prominent cross-equatorial cell (CEC)...
Ocean biogeochemical models are increasingly used in the Earth system modelling efforts for climate simulations, and also for the development of marine environmental applications and services. Like any other geoscientific models, the processes within biogeochemical models include simplified schemes called parameterizations. However, the parameter values can be poorly constrained and involve...
An 11-yr reanalysis (2008-2018) was produced with the HYCOM+REMO ocean data assimilation system (RODAS) in the South Atlantic. RODAS is based on the ensemble optimal interpolation method. It assimilated data from OSTIA sea surface temperature (SST), AVISO gridded sea surface height (SSH) and 61,031 vertical profiles of temperature and salinity (T/S) from Argo and XBTs, in addition to data from...
The Met Office’s operational Forecasting Ocean Assimilation Model (FOAM) global system has recently been upgraded from an eddy permitting 1/4 degree resolution (FOAM-ORCA025) to an eddy resolving 1/12th of a degree resolution (FOAM-ORCA12). The increase in resolution allows mesoscale processes to be resolved at a much larger range of latitudes, representation of finer resolution bathymetric...