Himalayan rainfall and vorticity generation within the Indian summer monsoon

Kennett, E. J.; Toumi, Ralf

doi:10.1029/2004gl021925

Cited by 8 publications

(13 citation statements)

References 21 publications

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“…The vertical gradient of precipitation rate in the Everest region is largely unknown because of a lack of data. Analysis of rain gauges, ERA-40 reanalysis and satellite observations across the Himalaya suggest that there is an approximately exponential decrease of annual precipitation rate with height, limited by available moisture (Kennett and Toumi, 2005). Therefore, the vertical gradient may be approximated by:…”

Section: Mass Balancementioning

confidence: 99%

Response of debris-covered glaciers in the Mount Everest region to recent warming, and implications for outburst flood hazards

Benn

Bolch

Hands³

et al. 2012

Earth-Science Reviews

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539

585

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In areas of high relief, many glaciers have extensive covers of supraglacial debris in their ablation zones, which alters both rates and spatial patterns of melting, with important consequences for glacier response to climate change. Wastage of debris-covered glaciers can be associated with the formation of large moraine-dammed lakes, posing risk of glacier lake outburst floods (GLOFs). In this paper, we use observations of glaciers in the Mount Everest region to present an integrated view of debris-covered glacier response to climate change, which helps provide a long-term perspective on evolving GLOF risks. In recent decades, debris-covered glaciers in the Everest region have been losing mass at a mean rate of 0.32 m yr¹, although in most cases there has been little or no change in terminus position. Mass loss occurs by 4 main processes: (1) melting of clean ice close to glacier ELAs; (2) melting beneath surface debris; (3) melting of ice cliffs and calving around the margins of supraglacial ponds; and (4) calving into deep proglacial lakes. Modelling of processes (1) and (2) shows that Everest-region glaciers typically have an inverted ablation gradient in their lower reaches, due to the effects of a down-glacier increase in debris thickness. Mass loss is therefore focused in the mid parts of glacier ablation zones, causing localised surface lowering and a reduction in downglacier surface gradient, which in turn reduce driving stress and glacier velocity, so the lower ablation zones of many glaciers are now stagnant. Model results also indicate that increased summer temperatures have raised the altitude of the rain-snow transition during the summer monsoon period, reducing snow accumulation and ice flux to lower elevations. As downwasting proceeds, formerly efficient supraglacial and englacial drainage networks are broken up, and supraglacial lakes form in hollows on the glacier surface. Ablation rates around supraglacial lakes are typically one or two orders of magnitude greater than sub-debris melt rates, so extensive lake formation accelerates overall rates of ice loss. Most supraglacial lakes are 'perched' above hydrological base level, and are susceptible to drainage if they become connected to the englacial drainage system. Speleological surveys of conduits show that large englacial voids can be created by drainage of warm lake waters along pre-existing weaknesses in the ice. Roof collapses can open these voids up to the surface, and commonly provide the nuclei of new lakes. Thus, by influencing both lake drainage and formation, englacial conduits exert a strong control on surface ablation rates. An important threshold is crossed when downwasting glacier surfaces intersect the hydrological base level of the glacier. Base-level lakes formed behind intact moraine dams can grow monotonically, and in some cases can pose serious GLOF hazards. Glacier termini can evolve in different ways in response to the same climatic forcing, so that potentially hazardous lakes will form in some situations but no...

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Section: Mass Balancementioning

confidence: 99%

Response of debris-covered glaciers in the Mount Everest region to recent warming, and implications for outburst flood hazards

Benn

Bolch

Hands³

et al. 2012

Earth-Science Reviews

Self Cite

539

585

View full text Add to dashboard Cite

show abstract

“…Meanwhile, Barnett et al (1989) found that the Indian summer monsoon strongly relates with snow deposition in the spring. Studies of the relationship between snow deposition in Eurasia and ISMR variations have been made (Kennett and Toumi, 2005;Rühland et al, 2006).…”

Section: Conclusion and Discussionmentioning

confidence: 99%

The possible influence of solar activity on Indian summer monsoon rainfall

Han

Yin

2007

Appl. Geophys.

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The Indian summer monsoon rainfall (ISMR) plays an important role in the climate system of South Asia. Recently, studies about ISMR variations have been going into more depth. In this present paper, we mainly use the Scargle periodogram and wavelet transform methods to study the periodicity of ISMR changes between 1871 and 2004 and review the possible influence of solar activity on the rainfall. Analysis results show complicated ISMR variations have periodicities with remarkable time-variable characteristics. Investigating a possible connection between the rainfall and solar variations, we believe that solar activity affects the ISMR variations to some extent.

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“…Using the similar modeling configuration as in Yang and Liu (2005), we perform three pairs of PC experiments to explicitly quantify the sensitivity of tropical climate to extratropical forcing. All experiments start from the 800th year of the CTRL and are integrated for 200 yr, when the upper ocean has reached quasiequilibrium.…”

Section: Model and Experimentsmentioning

confidence: 99%

“…FOAM has been used extensively to simulate the global climate in the past, present, and future. Comprehensive analyses of the model simulation can be found, for example, in Wu et al (2003) and Yang and Liu (2005).…”

Section: Model and Experimentsmentioning

confidence: 99%

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Tropical Oceanic Response to Extratropical Thermal Forcing in a Coupled Climate Model: A Comparison between the Atlantic and Pacific Oceans*

Yang

Wang

2011

Journal of Climate

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The tropical oceanic response to the extratropical thermal forcing is quantitatively estimated in a coupled climate model. This work focuses on comparison of the responses between the tropical Atlantic and Pacific. Under the same extratropical forcing, the tropical sea surface temperature responses are comparable. However, the responses in the tropical subsurface in the two oceans are distinct. The tropical subsurface response in the Atlantic can be twice of that in the Pacific. The maximum subsurface temperature change in the tropical Pacific occurs in the eastern lower thermocline, while that in the tropical Atlantic occurs in the west and well below the lower thermocline. The different responses in the tropical Atlantic and Pacific are closely related to the different changes in the meridional overturning circulations. The Pacific shallow overturning circulation, or the subtropical cell, tends to slow down (speed up) in response to the extratropical warming (cooling) forcing. The changes in the upwelling in the eastern equatorial Pacific as well as the shallow subduction from the extratropical southern Pacific along the eastern boundary are accountable for the eastern Pacific temperature change. The Atlantic overturning circulation consists of the shallow subtropical cell and the deep thermohaline circulation. A weakened thermohaline circulation will result in a strengthened northern subtropical cell, in which the change in the lower branch, or the low-latitude North Brazil Current, can cause strong response below the western tropical thermocline. Here the coastal Kelvin wave along the western boundary on the intermediate isopycnal level also plays an important role in the equatorward conveying of the climate anomalies in the mid-to-high-latitude Atlantic, particularly during the initial stage of the extratropical forcing.

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Himalayan rainfall and vorticity generation within the Indian summer monsoon

Cited by 8 publications

References 21 publications

Response of debris-covered glaciers in the Mount Everest region to recent warming, and implications for outburst flood hazards

Response of debris-covered glaciers in the Mount Everest region to recent warming, and implications for outburst flood hazards

The possible influence of solar activity on Indian summer monsoon rainfall

Tropical Oceanic Response to Extratropical Thermal Forcing in a Coupled Climate Model: A Comparison between the Atlantic and Pacific Oceans*

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