Different precipitation response over land and ocean to orbital and greenhouse gas forcing

Abstract

Various proxies suggest a nearly in-phase variation of monsoons with local summer insolation. Oceanic proxies of monsoons document a more complex response. Climate model simulations also indicate that the response is different over land and ocean. Here using a transient simulation by a climate model over the last 22,000 years we have unraveled the factors that lead to these differences within the Indian subcontinent. We show that during the deglacial (22–12 ka) precipitation over India and the Bay of Bengal (BoB) are in phase, whereas they are out of phase across the Holocene ( 12 ka to 0 ka). During the deglacial, water vapor amplifies the effect of solar forcing on precipitation over both the regions, whereas contributions from surface latent heat fluxes over the BoB drive an opposite response across the Holocene. We find that greenhouse gas forcing drives similar precipitation response over land and ocean, whereas orbital forcing produces a different response over land and ocean. We have further demonstrated that during periods of abrupt climate change [such as the Bølling–Allerød ( 14 ka)], water vapor affects precipitation mainly through its influence on the vertical stability of the atmosphere. These results highlight the complex nature of precipitation over the BoB and thus has implications for the interpretation of monsoon proxies.

Remote and local drivers of Pleistocene South Asian summer monsoon precipitation: A test for future predictions

“…Hence, idealized simulations indicate a 180° phase difference between the precession-band timing of maximum summer monsoon precipitation over the ocean versus the nearby continents. Jalihal et al (58,65) discuss the mechanisms underlying these simulation results. They find that precipitation over land is more sensitive to radiation forcing (net top of atmosphere long wave and short wave), whereas surface latent heat flux (dominated by winds) and vertical stability are more important over the BoB, again, keeping in mind that IV and GHG forcing are not included in these idealized simulations.…”

Response of the Low‐Level Jet to Precession and Its Implications for Proxies of the Indian Monsoon

“…Thus, indicating that the relationship between LLJ and the monsoon rainfall may be different in different climate regimes. This view is supported by recent studies where it was shown that it is the net energy flux into the atmosphere and water vapor, and not the monsoon winds that account for variability of South Asian monsoon on centennial and longer timescales (Jalihal, Srinivasan, et al., 2019; Jalihal et al., 2020).…”

“…In our previous work Jalihal et al, 2020), using the energetics of monsoons we have shown in the TraCE-21k that net energy flux into the atmosphere (Q div ) and total column water vapor (P wat ) are enough to explain the orbital scale variability of monsoons. Insolation drives fluctuations in monsoons primarily through Q div , whereas greenhouse gases and ice sheets affect the gross moist stability through their impact on P wat .…”

Impact of the Paris Agreement on agriculture, energy, and economy

“…Source: Ministry of Environment, Forest and Climate Change, Government of India, 2018 [9] Because of global warming, more meteorological disasters happen which interpret the normal monsoon rainfall patterns. Based on Jalihal et al [10] investigations, maize and wheat yields are expected to decrease by two to five percent for every degree of temperature increase in India. Thus, the extra gain from increased temperature is not significant to compensate for the devastating loss of the expected yield reduction of the four major crops worldwide.…”