The OMCT configuration used for AOD1B RL05 has been gradually updated from the OMCT model version that has been in use for the generation of AOD1B RL04. The spatial resolution was increased to 1.0° on a regular latitude-longitude grid, with now 20 levels in the vertical. Various parametrizations have been modified to adapt to the increased resolution and to align the simulated bottom pressure variability with various observational data-sets.
The initial state of the model was based on temperature and salinity climatologies obtained from the World Ocean Atlas 2001 (WOA01; Conkright, 2002). The model has been subsequently forced by annually varying climatological fields (winds, pressure, 2m-temperatures and freshwater fluxes) for 10 years, followed by 6-hourly real-time forcing from ERA Interim (Dee et al., 2011) covering the period 1989-2000, and finally operational ECMWF data since January 2001.
Figure 1: Variability of sea surface pressure (left) and ocean bottom pressure (right) as averaged over the last 30 days (top) and the period 2001-2010 (bottom) relative to mean fields for the period 2001+2002.
Bottom pressure variability
The following figures contain information about different characteristics of the simulated bottom pressure fields. Figures are updated daily and represent averages over the most recently simulated 30 days.
Figure 2: Animation of sea surface pressure anomalies (left) and simulated ocean bottom pressure anomalies (right) relative to mean fields for 2001+2002 for the last 30 days. Please click on the figures to start the animation.
Figure 4: Area-mean bottom pressure anomalies relative to a mean field for 2001+2002 for the Hudson Bay (middle left), the Baltic Sea (middle right), the Mediterranean Sea (bottom left), and the coastal waters around Antarctica southwards of the Southern ACC front (bottom right). Shape and geographical extent of the averaging regions might be obtained from the upper panel.
Figure 5: Mean amplitudes of diurnal atmospheric tides in atmospheric surface pressure (left), as well as its corresponding response in ocean bottom pressure (right) averaged over the last 30 days (top) and for the time period 2001-2010 (bottom).
Figure 6: Mean amplitudes of semidiurnal atmospheric surface pressure (left), as well as its corresponding response in ocean bottom pressure (right) averaged over the last 30 days (top) and for the time period 2001-2010 (bottom). Note that semidiurnal variability at the S2 frequency has been largely removed by means of an correction model, since S2 bottom pressure variability due to atmospheric pressure forcing is already included in altimetry-based ocean tide models applied in the GRACE gravity field processing. Semidiurnal variability present here merely represents residual amplitudes related to seasonal modulations or (eventually) long-term changes in the atmospheric tides.