Characterization of the East India Coastal Current using a Drifter, HF
Radars and Altimetry during October -- November 2015
Abstract
This study presents the characterization of the equatorward propagating
East India Coastal Current (EICC) using a drifter during October –
November 2015 (source: NOAA) and the coastal High Frequency Radars
(source: INCOIS and NIOT, India). The altimetry-derived sea surface
height anomaly (SSHA, source: AVISO) and geostrophic currents indicate
that the EICC is associated with three mesoscale cyclonic eddies along
the western Bay of Bengal (BoB). The drifter follows the edges of these
eddies (~0.12 m SSHA contour) on the inshore part of the
EICC. The drifter currents are validated with the geostrophic currents
(daily) as well as the HF Radar-derived surface currents (three hourly).
The speed of the EICC is less (~ 0.6 m/s) on the
north-western BoB, which increases to ~ 1.0 m/s in the
western-central regions and further reaches to ~1.4 m/s
at southern BoB. The comparison of drifter and daily geostrophic
currents show higher correlation (~ 0.93) and lower
errors (~0.16 m/s) when the drifter track is away from
the coast, whereas, comparatively lower correlation (~
0.41) and higher errors (~0.43 m/s) is observed when the
track is near the coastline. This mismatch very near to the coasts is
possibly due to the low quality of altimetry datasets. The drifter
passes through the three HF Radar domains along the Indian coast of the
BoB. The comparisons with HFRs indicate reasonable correlation (0.76,
0.71) and errors (0.19 m/s, 0.32 m/s) at the Odisha and Tamil Nadu
coast.