Competing Topographic Mechanisms for the Summer Indo‐Asian Monsoon

Abstract The Indo‐Asian Monsoon (IAM) has changed as the topographies of Asia were assembled into their current configuration. Understanding complex interactions between topography and the IAM through time has been hampered, in part, by poorly resolved topography and atmospheric dynamics in climate...

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Main Authors: R. P. Acosta, M. Huber
Format: Article
Language:English
Published: Wiley 2020-02-01
Series:Geophysical Research Letters
Subjects:
Online Access:https://doi.org/10.1029/2019GL085112
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author R. P. Acosta
M. Huber
author_facet R. P. Acosta
M. Huber
author_sort R. P. Acosta
collection DOAJ
description Abstract The Indo‐Asian Monsoon (IAM) has changed as the topographies of Asia were assembled into their current configuration. Understanding complex interactions between topography and the IAM through time has been hampered, in part, by poorly resolved topography and atmospheric dynamics in climate models. Here, we employ high‐resolution (0.23° × 0.31°) global climate simulations, to more accurately capture these interactions. We find that the Himalayas and Tibet primarily redirect the onshore moisture transport and produce local orographic precipitation. The Iranian Plateau is the primary gatekeeper, insulating the pool of high‐enthalpy air in the Indo‐Gangetic Plain (IGP) from westerly low‐enthalpy advection. But, even when such high‐enthalpy air exists along the IGP, vigorous precipitation in the region (poleward of 25°N) still requires orographic steering and lifting. The large‐scale circulations—largely governed by sea surface temperature gradients—robustly advect water vapor onshore regardless of topography. Thus, neither topography nor localized enthalpy air drives onshore monsoon flow.
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spelling doaj-art-5829cd7e75b34e7e93eb6e2888bd15b12025-08-20T01:50:15ZengWileyGeophysical Research Letters0094-82761944-80072020-02-01473n/an/a10.1029/2019GL085112Competing Topographic Mechanisms for the Summer Indo‐Asian MonsoonR. P. Acosta0M. Huber1Department of Earth, Atmospheric, and Planetary Sciences Purdue University West Lafayette IN USADepartment of Earth, Atmospheric, and Planetary Sciences Purdue University West Lafayette IN USAAbstract The Indo‐Asian Monsoon (IAM) has changed as the topographies of Asia were assembled into their current configuration. Understanding complex interactions between topography and the IAM through time has been hampered, in part, by poorly resolved topography and atmospheric dynamics in climate models. Here, we employ high‐resolution (0.23° × 0.31°) global climate simulations, to more accurately capture these interactions. We find that the Himalayas and Tibet primarily redirect the onshore moisture transport and produce local orographic precipitation. The Iranian Plateau is the primary gatekeeper, insulating the pool of high‐enthalpy air in the Indo‐Gangetic Plain (IGP) from westerly low‐enthalpy advection. But, even when such high‐enthalpy air exists along the IGP, vigorous precipitation in the region (poleward of 25°N) still requires orographic steering and lifting. The large‐scale circulations—largely governed by sea surface temperature gradients—robustly advect water vapor onshore regardless of topography. Thus, neither topography nor localized enthalpy air drives onshore monsoon flow.https://doi.org/10.1029/2019GL085112Asian MonsoonIndian MonsoonHigh‐resolution Climate ModelingTopography‐Atmosphere InteractionsTibetan PlateauHimalayan Mountains
spellingShingle R. P. Acosta
M. Huber
Competing Topographic Mechanisms for the Summer Indo‐Asian Monsoon
Geophysical Research Letters
Asian Monsoon
Indian Monsoon
High‐resolution Climate Modeling
Topography‐Atmosphere Interactions
Tibetan Plateau
Himalayan Mountains
title Competing Topographic Mechanisms for the Summer Indo‐Asian Monsoon
title_full Competing Topographic Mechanisms for the Summer Indo‐Asian Monsoon
title_fullStr Competing Topographic Mechanisms for the Summer Indo‐Asian Monsoon
title_full_unstemmed Competing Topographic Mechanisms for the Summer Indo‐Asian Monsoon
title_short Competing Topographic Mechanisms for the Summer Indo‐Asian Monsoon
title_sort competing topographic mechanisms for the summer indo asian monsoon
topic Asian Monsoon
Indian Monsoon
High‐resolution Climate Modeling
Topography‐Atmosphere Interactions
Tibetan Plateau
Himalayan Mountains
url https://doi.org/10.1029/2019GL085112
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AT mhuber competingtopographicmechanismsforthesummerindoasianmonsoon