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|Title:||Assimilation of satellite altimeter data in a multilayer Indian Ocean circulation model|
Agarwal, Vijay K.
|Keywords:||Altimeter data;assimilation;forecast;Indian Ocean circulation model|
|Abstract:||The present study was dictated by a curiosity to examine whether the forecast capability of a multilayer Indian Ocean circulation model can be improved by assimilating satellite altimeter data into the model. In the present investigation we have studied the assimilation of Topex/Poseidon (T/P) altimeter observed sea level anomaly data in a 2 1/2 layer thermodynamic model of the Indian Ocean. The model has been spun up for 7 years with climatological winds and heat fluxes obtained by 5 years average of monthly mean winds and heat fluxes from the National Centre for Environmental Prediction (NCEP) to achieve steady annual cycle. Thereafter, the model has been run further for 5 years (1995-1999) with interannually varying daily NCEP winds and heat fluxes so as to reach the initial state corresponding to 1st January of the experimental year 2000. Subsequently, the model has been run for the experimental year 2000. It has been able to produce the known patterns of current and SST in the Indian Ocean reasonably well. However, the model simulated sea level anomalies (SLA) do not compare well with observations. An attempt has been made to improve the simulation of SLA by assimilating highly accurate T/P altimeter data into the model using the techniques of blending and nudging. Both monsoon and non-monsoon cases have been studied. From the study it can be concluded that it is possible to provide reasonably accurate forecast of oceanic sea level variations in the short time scale (about 5 to 10 days) using this model of intermediate complexity forced by good quality forecast winds if satellite data can be properly assimilated into the model.|
|Appears in Collections:||IJMS Vol.32(3) [September 2003]|
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