Abstract's details
Improving the dynamic atmospheric correction for delayed-time and operational applications of altimetry
CoAuthors
Event: 2015 Ocean Surface Topography Science Team Meeting
Session: Tides, internal tides and high-frequency processes
Presentation type: Type Poster
Contribution: PDF file
Abstract:
Given its current accuracy and maturity, altimetry is considered a fully operational observing system dedicated to various applications such as climate studies or operational oceanography. Altimeter measurements are corrected for several geophysical effects in order to isolate the oceanic variability, and the dynamic atmospheric correction (DAC) is the second most important one after the tide correction; this correction allows for the removal of high frequency variability induced by the atmospheric forcing and aliased by the altimetric measurements.
The high frequency part of the DAC is based on a barotropic model simulation forced by atmospheric pressure and winds (MOG2D; Carrere and Lyard 2003); the low frequency part is an inverse barometer response. A 20-day cutoff-period was chosen because it corresponds to the Nyquist period of T/P-Jason reference altimeters’ sampling and because the variability is mostly barotropic in this high frequency band.
The purpose of the study is to improve the performances of the DAC for all users of altimetry for Delayed-Time (DT) and Near Real Time (NRT) delivery modes.
A recent study (2013) has shown that using a few MOG2D forecasts (forecasts only available until D+2days, 12h) allowed improving the quality of the NRT correction. In this study, operational meteorological forecasts until D+10days have been used, showing a significantly greater improvement on altimeter level-2 products.
The optimal combination of MOG2D and IB at the cutoff-period of 20 days is also checked compared to in situ and altimeter data.
Then in order to improve the DAC correction (DT and NRT) in the high latitudes, the ice cover effect has been implemented in MOG2D model and preliminary results will be presented.
The high frequency part of the DAC is based on a barotropic model simulation forced by atmospheric pressure and winds (MOG2D; Carrere and Lyard 2003); the low frequency part is an inverse barometer response. A 20-day cutoff-period was chosen because it corresponds to the Nyquist period of T/P-Jason reference altimeters’ sampling and because the variability is mostly barotropic in this high frequency band.
The purpose of the study is to improve the performances of the DAC for all users of altimetry for Delayed-Time (DT) and Near Real Time (NRT) delivery modes.
A recent study (2013) has shown that using a few MOG2D forecasts (forecasts only available until D+2days, 12h) allowed improving the quality of the NRT correction. In this study, operational meteorological forecasts until D+10days have been used, showing a significantly greater improvement on altimeter level-2 products.
The optimal combination of MOG2D and IB at the cutoff-period of 20 days is also checked compared to in situ and altimeter data.
Then in order to improve the DAC correction (DT and NRT) in the high latitudes, the ice cover effect has been implemented in MOG2D model and preliminary results will be presented.