Dear Ms. Katzenberger,

Thank you for your careful consideration of and reply to the reviewers' comments. In light of this, and of the reviewers' generally positive views of your paper, I can now invite you to submit your revised manuscript, which I will share with the reviewers for their reconsideration for publication.

Best regards,
Dan Kirk-Davidoff

Dear Ms. Katzenberger,

I've received reports from both reviewers, and am now able to recommend your manuscript for publication subject to minor revisions to improve your introductory description of the interaction of Hadley circulation dynamics and monsoon rainfall, as described by one of the reviewers' comments below. Essentially, the reviewer asks you to include factors specifically driving enhanced precipitation over the Indian Ocean (leading to enhanced subsidence over the Subcontinent, and thus reduced precipitation there) as well as factors directly reducing warming over the subcontinent (such as aerosol pollution) for a more balanced discussion of the origin of the reduced Monsoon precipitation. I look forward to receiving your revised manuscript.

Best regards,
Dan Kirk-Davidoff



Comments from reviewer 2:

The manuscript has been significantly improved. However there are still some parts not clear or partially incorrect. Some changes are still needed.

Ln 59-62: “ The resulting decrease in the land-sea thermal gradient over South Asia opposes the pressure gradient driving the Hadley circulation and consequently subdues the Hadley circulation. Since the Hadley system is responsible for transporting the rainfall to the subcontinent, this is accompanied by a reduction of the rainfall amount during the summer period as observed since the 1950s (Roxy et al., 2015).”

This is too general statement.

First, the Hadley Circulation (HC) that is “transporting” precipitation from Indian Ocean to Asian Continent in JJA, is the cross-equatorial Hadley Circulation, i.e. the strongest one in the Southern Hemisphere (SH). Second, the advection of moist static energy and moisture within the SH HC depends on atmospheric net energy input contrast (and not simply thermal contrasts: that is why the orbital forcing is much stronger driver of monsoons than GHG. See D’Agostino et al., 2019, 2020 where you have mid-Holocene and rcp8.5 net energy input maps!).

The observed reduced Indian rainfall since 1950 as suggested by Roxy et al., might be due to:
decadal-to-multidecadal-centennial variability
SST/ surface fluxes over the Indian Ocean
compensating effect between GHG and Aerosols over land but more likely…
… (and this has been not explicitly mentioned) to a squeezing of the rain belt around the equator. The rain belt under GHG forcing and global warming is expected to be narrower and precipitation more intense (Byrne et al., 2015). So the reduced precipitation over the Indian continent might be simply due to a shift of the rainfall pattern from land to ocean (D’Agostino et al., 2019, 2020).

As also Roxy et al., 2015 said this somewhere “Furthermore, this enhanced upward motion over the ocean is compensated by subsidence of air over the subcontinent (10–20°N), inhibiting convection over the landmass and drying the region, through a modulation of the local Hadley cell (Fig. 5a). This suggests that though the warming ocean engenders enhanced local rainfall due to increased moisture availability, it weakens the monsoon Hadley circulation and reduces the rainfall over the land, ultimately building up a competition among the land and ocean rainfall in the South Asian monsoon domain.”

Try to rephrase here please.

Dear Ms. Katzenberger,

I am now happy to recommend publication of your paper in its current form. Thank you for your careful attention to the reviewers' comments, and for publishing your work with Earth System Dynamics!

Best regards,
Dan Kirk-Davidoff