Spatio-temporal variations of chlorophyll from satellite derived data and CMIP5 models along Indian coastal regions

Comparison of chlorophyll data of three sets of CMIP5 models for RCP 4.5 (MPI-ESM-MR, HadGEM2-ES and GFDL-ESM2M) and RCP 6.0 (IPSL-CM5A-LR, HadGEM2-ES and GFDL-ESM2M) were done with satellite derived data (OC-CCI) for the period of 1998–2017 along four Indian coastal regions. The monthly, yearly and zone-wise seasonal comparison between model and satellite data were carried out. Analysis of monthly variations of chlorophyll during 1998–2017 reveals that the satellite data show maximum value of 0.53 mg/m3 in September, whereas all other models show maximum in August. Yearly analysis indicates maximum satellite data in the year 2004, while minimum was observed in 2015. HadGEM2-ES exhibited maximum model value and the lowest was found for IPSL-CM5A-LR. It was observed that the maximum chlorophyll value of 2.56 mg/m3 for satellite data was in the monsoon season and the lowest value of 0.14 mg/m3 was in the pre-monsoon. Seasonal analysis reveals no clear match among model and satellite values in any of the coastal regions. In northwest and northeast regions, the satellite values were found higher than the model values in most of the years, whereas in other regions, the model values were found fluctuating with the satellite values. Owing to the mismatch of the model and the satellite values, the work cautions to apply biases or corrections on usage of RCP model data for regional marine climate change research