Respond Projects

Ocean Sciences

Satellite altimeter waveform analysis to improve geophysical parameters retrieval

  1. Altimeters are active microwave instruments which provide Sealevel, Wind and significant wave information through the measured waveform characterstics.
  2. Altimeter waveforms are nothing but the variation of received power with respect to time.
  3. Magnitude of the returned waveform power gives you the information of surface wind speed
  4. Slope of the wave form gives the significant wave height information.
  5. Waveform shape and characteristics differ for different targets such as ocean, land and Ice for which different models are needed to understand retrieve geophysical parameters from them.

Satellite altimeter data assimilation in ocean models

  1. Assimilation of satellite derived temp, salinity and sealevel is needed to improve the accuracy ocean model simulations of temp, salinity and currents and their vertical profiles.
  2. Altimeters routinely provide information regarding sealevel, wind and wave information.
  3. Altimeter derived sealevel can be assimilated using variational techniques such as 3D var and 4D var in ocean circulation models such as MOM, ROMS, MITGCM etc.
  4. Altimeter derived significant wave height can be assimilated in ocean wave models such as SWAN, WAVEWATCH etc., for improved prediction of waves along the indian coasts

Derivation of Ocean surface currents utilizing data from SARAL AltiKa and OSCAT. Combining geostrophic currents from SSHA (from Altimeters) and wind driven currents from wind velocities (from Scatterometer), the ocean surface currents can be obtained

The scope of the current observations can be seen in the navigation and optimization of shipping routes, dispersion and drift of pollutants, particularly, algal blooms and oil spills, besides their use in tracing mass and heat distribution across the ocean boundaries. The ocean surface currents of the Global Ocean are estimated combining Ekman Surface Current (ESC) and Surface Geostrophic current (SGC). The ESC is derived from the ocean surface wind fields of Oceansat-2 Scatterometer (OSCAT) data products. The pathwise observations of OSCAT wind vector are used after removing high frequency variations with Data Interpolating Variational Analysis (DIVA). Similarly, the SGC component of the current is estimated using SARAL AltiKa Sea Surface Height (SSH) products.