Fig. 1

Summer and autumn averaged spatial distribution of EKE in the Bay of Bengal and its time series from 2000 to 2015, based on SODA (a), OSCAR (b) and AVISO (c) data, respectively. EKE time series averaged in the Bay of Bengal (80°-100°E, 3°-22°N) of those data (d), Filtered result of the time series in (d) on the interannual time scale (2~8 years) (e)"

Fig. 2

Summer and autumn averaged zonal velocity u (positive to the east) (a) and meridional velocity v (positive to the north) (b) of the vertical section along 6°N"

Fig. 3

Spatial distribution of summer and autumn averaged EKE from 2000 to 2015. (a) to (p) corresponding to years 2000 to 2015. The red box in (k) indicates that area (5°-7°30′N, 87°30′-90°E) have large EKE anomaly in some years, marked as area CR"

Fig. 4

DMI Index (bar, corresponding to the left ordinate) and summer and autumn averaged EKE anomaly (black line, corresponding to the right ordinate) in CR area (5°-7°30′N, 87°30′-90°E ) from 2000 to 2015"

Fig. 5

Spatial distribution of summer and autumn averaged eddy field energy (EKE and EPE) and ocean instability (T2, T4). (a~d) are composed by positive IOD years, (e~h) are composed by neutral years, and (i~l) are composed by negative IOD years"

Fig. 6

Surface wind field and sea surface height anomaly in Bay of Bengal of Climatic mean state (a) and composed by positive IOD years (b), negative IOD years (c). Colourful maps are sea surface height anomaly, vectors correspond to wind speed on 1000 hPa isobaric surface in figure (a) and wind speed anomaly in figure (b) and (c), the arrow in the upper right corner corresponds to wind speed of 3 m·s-1"

Fig. 7

Spatial distribution of grids with significant anomalies between climatic mean EKE and summer-averaged EKE (a) and between climatic mean EKE and autumn-averaged EKE (b) composed by negative IOD years. * indicates that it passes the 95% confidence level of t-test"

Fig. 8

Map of 2010 wind anomaly (vector) on 1000 hPa over the Bay of Bengal and sea surface height anomaly (shading) (a). The arrow at the upper-right corner corresponds to wind speed of 3 m·s-1. (b) and (c) correspond to summer and autumn averaged zonal and meridional velocity anomalies along 6°N in 2010"

Fig. 9

Summer and autumn averaged EKE (a), T4 (b), EPE (d), and T2 (e) anomalies along 6°N of the Bay Estuary in 2010. (c) Climatic mean of buoyancy frequency N2, (f) buoyancy frequency N2 anomaly in 2010"

Fig. 10

Monthly time series of all terms in EKE equation in CR area from 2009 to 2011 (a), and monthly time series comparison between the sum of all EKE equation terms and EKE change in CR area from 2000 to 2015 (b). Monthly time series comparison between every single EKE equation term and EKE change in CR area from 2000 to 2015 (c~f)"