Effect of spatio-temporal sampling of altimeter observations in the north Indian Ocean: A synthetic study using ocean model and SWOT simulator

Neeraj Agarwal (ISRO, India)

CoAuthors

Aditya Chaudhary (ISRO, India); Rashmi Sharma (ISRO, India); Raj Kumar (ISRO, India)

Event: 2019 Ocean Surface Topography Science Team Meeting

Session: The Future of Altimetry

Presentation type: Type Poster

Surface water and ocean topography (SWOT) mission, which is proposed to be launched in 2022, will provide synoptic coverage of oceanic mesoscale and sub-mesoscale features that are not seen in conventional nadir altimeter observations. These observations are expected to enrich the existing knowledge of the ocean dynamics and fill the gaps in the conventional measurements. In addition, it is also expected that the simulations from numerical ocean models would improve when observations from SWOT will be used to constrain these models.
In this paper, an attempt has been made to comment on the optimum number and type (nadir or/and SWOT) of altimeter based space borne instruments to correct a high-resolution ocean model for the north Indian ocean by means of data assimilation. Synthetic observations are generated for SWOT and nadir altimeter tracks in different combinations (single, two or more nadir and SWOT combined) using sea level anomaly fields from a data assimilative, state-of-the-art numerical ocean model and SWOT simulator. The noise levels similar to those of existing Ka band altimeters such as Jason-2, 3, sentinel and Ku band SARAL/AltiKa and upcoming SWOT mission are added while generating these synthetic observations. These observations are then assimilated in a high resolution numerical ocean model for the north Indian ocean. Several assimilation experiments are performed wherein observations from single, multiple nadir altimeters in combination with SWOT observations are used. A hypothetical scenario with two SWOT mission type instruments separated by a gap of 10 days is also generated and the observations are assimilated in the model. The simulated state variables (Temperature, salinity, sea level and currents) from these experiments are then compared with the fields obtained from the same model using which the pseudo-observations were generated. It is expected that these experiments will provide an insight on how many nadir/SWOT altimeters would be required in future to constrain numerical ocean models for accurate ocean state estimation.

 

Poster show times:

Room Start Date End Date
The Gallery Tue, Oct 22 2019,16:15 Tue, Oct 22 2019,18:00
The Gallery Thu, Oct 24 2019,14:00 Thu, Oct 24 2019,15:45
Neeraj Agarwal
ISRO
India
neeraj@sac.isro.gov.in