A Multiplicity of Model Biases in NCEP's Climate Forecast System: How Do They Propagate in Modeling the Indian Summer Monsoon?
Chaudhari, H.S., Pokhrel, S., Saha, S.K., Dhakate, A., Yadav, R.K., Salunke, K., Mahapatra, S., Sabeerali, C.T. and Rao, S.A. 2013. Model biases in long coupled runs of NCEP CFS in the context of Indian summer monsoon. International Journal of Climatology 33: 1057-1069.
According to the nine researchers, the model  shows dry (wet) rainfall bias concomitant with cold (warm) SST bias over the east (west) equatorial Indian Ocean; and they say that these biases of SST and rainfall  affect both lower- and upper-level circulations in a feedback process, which in turn  regulates the SST and rainfall biases by maintaining a coupled feedback process. Subsequently, a dry (wet) rainfall bias over the east (west) Indian Ocean  induces anomalous low level easterlies over the tropical Indian Ocean and  causes cold SST bias over the east Indian Ocean by triggering evaporation and warm SST bias over the west Indian Ocean through advection of warm waters. The persistent SST bias then  retains the zonal asymmetric heating and meridional temperature gradient resulting in a circum-global subtropical westerly jet core, which in turn  magnifies the mid-latitude disturbances and  decreases the Mascarene high, which in its turn  diminishes the strength of monsoon cross-equatorial flow and  results in less upwelling as compared to that in the observations, which latter phenomenon  increases the SST bias over the West Indian Ocean.
And thus it is, in the words of Chaudhari et al., that "the coupled interaction among SST, rainfall and circulation works in tandem through a closed feedback loop to maintain the model biases over the tropical Indian Ocean." And once significant biases worm their way into the innards of today's complex climate models, they are extremely difficult to expel.