## 4 Discussion
The relatively strong summer monsoon winds blowing from the southwest of the tropical Indian Ocean region (Figure S7d-f) bring ample water to India. The resultant positive rainfall anomalies generate positive anomalies of soil moisture, reduce the chances of water stress together with cooler air temperature anomalies and, therefore, result in positive anomalies of SIF. Meanwhile, we do not rule out the possibility of reduced rainfall over the central and northern Indian regions in June due to the late onset or late progress of monsoon as a result of positive SST anomalies in the Indian Ocean [73]. This condition can also dampen the photosynthetic activity and produce negative SIF anomalies in India. The SST variations in Nino regions may have influenced SST anomalies of the tropical Indian Ocean in June. However, the rainfall anomalies in India are directly linked to the SST conditions in the tropical Indian Ocean, and the contribution of tropical Indian Ocean SST to the monsoon variability appears more dominant than the Nino SSTs, at least during the onset phase [73]. The observed SIF anomalies in India showed a good degree of coupling with tropical Indian Ocean SST variability. Meanwhile, NINO3 SST anomalies failed to exhibit considerable correlations with SIF anomalies in June, even after considering a time lag of 5 months (Figure S8). Furthermore, the study focuses exclusively on the relationship between SST anomalies in the tropical Indian Ocean regions and SIF anomalies in India and not on the factors contributing to tropical Indian Ocean SST and the monsoon variability in India. The identified ocean-vegetation linkage may be useful to track the vegetation growth anomalies in India concerning the tropical Indian Ocean SST variability. Overall, the local tropical Indian Ocean SST effect was observed mostly in the SIF anomalies across the central and northern Indian regions, where the land largely comprises rain-fed agricultural lands and forest ecosystems, the productivity of which fluctuates according to the monsoon rainfall [33; 74]. Mostly an arid-semi-arid climatic condition persists in the ACZs of this region and, in some areas, shifts to sub-humid climates. Normally, the hydrologic fluctuations control vegetation photosynthesis in arid to semi-arid ecosystems [75; 76], and the net primary productivity of the forest ecosystems in the tropical belt depends on precipitation to a large extent [77]. The Indian Ocean is warming in response to global warming, and the impact of this warming through atmospheric teleconnections should reflect on the functional characteristics of terrestrial vegetation. An attempt is made to infer such a possibility on the basis of the present analyses though no attempt has been made here to understand the influence of the Indian Ocean warming trend. It was found that the warmer years of the Indian Ocean are more influential as compared with the cooler years, indicating a bias of the SST-SIF link to warmer trends. This means a warmer Indian Ocean condition may lead to reduced terrestrial photosynthetic activity in India in the initial phase of the monsoon period. Consequently, the decline in photosynthetic carbon uptake would gradually alter the land-atmosphere interactions and affect the climate over the Indian subcontinent.