Comparison of gridded multi-mission and along-track mono-mission satellite altimetry wave heights with in situ near-shore buoy data

• Examined applicability of satellite altimetry for nearshore region off Indian coast.
• Gridded multi-mission and along track mono-mission products used for study.
• Multi-mission data for three stations resulted in close agreement with buoy data.
• For mono-mission, better predicted and more collocated points are found for Jason-2.
• Altimeter observations for significant wave height< 0.5 m is unreliable.

The applicability of altimeter data for the coastal region is examined by comparing the gridded multi-mission and along-track mono-mission significant wave height (SWH) data with the in situ buoy measurements at four stations off the east and west coasts of India. Among all of the satellites, a greater number of collocated points and better correlation were found for Jason-2. A comparison of the SWH data from multi-mission products (Jason-1, Jason-2, Envisat, and ERS-2) obtained from AVISO with the measured buoy data shows that all of the satellites overestimated the SWH. Applying a correction factor of 0.75, 0.70 and 0.69 to the altimeter data for stations 1, 2 and 4, respectively, resulted in close agreement with the buoy data (correlation coefficient ~0.9–0.96). Monthly averaged buoy and altimeter SWH values show convincing correlation ranging from 0.97 to 0.98 for three stations. The smallest correlation coefficient (0.6) was found at station 3, where the selected grid points are located close to the coast and are influenced by land contamination and wave decay effects. For waves with a SWH<0.5 m, the correlation coefficient is sparingly low for all stations, which underlines the fact that the altimeter observations for SWH<0.5 m are unreliable.