Water vapor budget of the Indian monsoon depression

Yoon, Jin‐Ho; Chen, Tsing-Chang

doi:10.3402/tellusa.v57i5.14737

Cited by 68 publications

(51 citation statements)

References 28 publications

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“…We also explored the extent to which the intensified BOB monsoon trough may facilitate increases in TC intensity, by examining the moisture transport. In order to depict the precipitation maintenance process, we followed Yoon and Chen []’s water vapor budget analysis for the Indian monsoon depression, by computing the SF and potential function of the column‐integrated water vapor flux, Q , referred to as SFQ and VPQ respectively:

SFQ = \nabla^{- 2} (\overset{true\to}{k} \cdot \nabla \times Q)

and

VPQ = \nabla^{- 2} (\nabla ·Q) .

…”

Section: Changes In Environmental Factorsmentioning

confidence: 99%

Intensification of premonsoon tropical cyclones in the Bay of Bengal and its impacts on Myanmar

et al. 2013

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[1] We analyze multiple global reanalysis and precipitation datasets in order to explain the dynamic mechanisms that lead to an observed intensification of the monsoon trough and associated tropical cyclone (TC) activity over the Bay of Bengal (BOB) during the premonsoon month of May. We find that post-1979 increases in both premonsoon precipitation and TC intensity are a result of enhanced large-scale monsoon circulation, characterized by lower-level cyclonic and upper-level anticyclonic anomalies. Such circulation anomalies are manifest of the tropospheric expansion that is caused by regional warming. The deepened monsoon trough in the BOB not only affects TC frequency and timing, but also acts to direct more cyclones towards Myanmar. We propose that increasing sea surface temperature in the BOB has contributed to an increase in cyclone intensity. Our analyses of the Community Earth System Model single-forcing experiments suggest that tropospheric warming and a deepening of the monsoon trough can be explained by two discreet anthropogenic causes-an increase in absorption due to aerosol loading and an increase in the land-ocean thermal contrast that results from increased greenhouse gases. The ensuing circulation changes provide favorable conditions for TCs to grow and to track eastward towards Myanmar.

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SFQ = \nabla^{- 2} (\overset{true\to}{k} \cdot \nabla \times Q)

and

VPQ = \nabla^{- 2} (\nabla ·Q) .

…”

Section: Changes In Environmental Factorsmentioning

confidence: 99%

Intensification of premonsoon tropical cyclones in the Bay of Bengal and its impacts on Myanmar

et al. 2013

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“…Monsoon depressions generally form over the northern part of the BoB (some form over land also) and propagate westward or northwestward with a typical life span of 3 to 6 days and bring a substantial amount of rainfall to the core monsoon region along their tracks. Previous studies [ Krishnamurti , ; Yoon and Chen , ] reported that monsoon depressions can be responsible for up to half of the monsoon rainfall over core monsoon region. It can thus be expected that any change in the frequency of these depressions can lead to a significant change in total monsoon rainfall, particularly over the core monsoon region.…”

Section: Introductionmentioning

confidence: 99%

Influence of the Atlantic zonal mode on monsoon depressions in the Bay of Bengal during boreal summer

et al. 2014

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The influence of the Atlantic Zonal Mode (AZM) or the Atlantic Niño on monsoon depressions in the Bay of Bengal during the boreal summer (June-August) is studied. Our analysis shows that there is a statistically significant difference in the number of monsoon depressions in the Bay of Bengal between the warm and cold phases of the AZM; more (fewer) monsoon depressions form during the cold (warm) phase of AZM. It also shows that there are differences in spatial pattern of trajectories of monsoon depressions; during the cold phase of AZM, the tracks are relatively long and seem to cluster along the axis of core monsoon region compared to the warm phase of AZM. The analysis indicates an increase (a reduction) in low-level cyclonic vorticity and midtropospheric humidity but a reduction (an increase) in vertical wind shear due to anomalous circulation pattern. All of these changes are favorable for the enhancement (suppression) of monsoon depressions during the cold (warm) phase of the AZM. Our analysis further shows a teleconnection pathway by which the AZM can influence the remote Indian Ocean. This could have implications for enhancing monsoon prediction skill, especially during non-El Niño-Southern Oscillation years.

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“…Fluctuations of the Eurasian teleconnection–propagating Rossby wave trains across Eurasia and East Asia–also modulate the northern part of the Indian monsoon [ Ding and Wang , 2007]. Moreover, summer rains in northern Pakistan can be triggered by monsoon depressions tracking northwest from the Bay of Bengal and into the monsoon trough [ Muhammad , 2005; Yoon and Chen , 2005]. In 2010, several such monsoon depressions moved across India and enhanced moisture pooling in Pakistan during the late July rainstorms [ Houze et al , 2011].…”

Section: Introductionmentioning

confidence: 99%

Pakistan's two-stage monsoon and links with the recent climate change

et al. 2011

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[1] Meteorological conditions related to the Pakistan floods of 2010 were examined in the context of monsoon dynamics and large-scale circulations. Case and climatological analyses suggest that summer precipitation in northern Pakistan comprises two distinct phases: (1) a premonsoon trough phase (July) whose rainfall is more episodic and intense, occurring prior to arrival of the monsoon trough, and (2) a monsoon trough phase (August) whose rainfall is persistent, yet less episodic, driven by northward migration of the monsoon trough. Analyses of conditional instability, moisture flux, and circulation features support a persistent increase in conditional instability during the July premonsoon trough phase, accompanied by increased frequency of heavy rainfall events. Conversely, evidence does not support intensification of the August monsoon trough phase. The increased convective activity during the premonsoon trough phase agrees with the projected increase in the intensity of heavy rainfall events over northern Pakistan. Largescale circulation analysis reveals an upper-level cyclonic anomaly over and to the west of Pakistan-a feature empirically associated with weak monsoon. The analysis also suggests that the anomalous circulation in 2010 is not sporadic but rather is part of a long-term trend that defies the typical linkage of strong monsoons with an anomalous anticyclone in the upper troposphere.

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Water vapor budget of the Indian monsoon depression

Cited by 68 publications

References 28 publications

Intensification of premonsoon tropical cyclones in the Bay of Bengal and its impacts on Myanmar

Intensification of premonsoon tropical cyclones in the Bay of Bengal and its impacts on Myanmar

Influence of the Atlantic zonal mode on monsoon depressions in the Bay of Bengal during boreal summer

Pakistan's two-stage monsoon and links with the recent climate change

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