Tropical Circulation Systems and Monsoons

Saha, Kshudiram

doi:10.1007/978-3-642-03373-5

Cited by 29 publications

(23 citation statements)

References 65 publications

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“…At first sight, REMO is able to reproduce the observed patterns in an excellent way (cf. Saha and Saha 2001). Note that no postprocessing (model output statistics) of the model data is done.…”

Section: Model Validationmentioning

confidence: 99%

Regional Climate Change in Tropical and Northern Africa due to Greenhouse Forcing and Land Use Changes

et al. 2009

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Human activity is supposed to affect the earth's climate mainly via two processes: the emission of greenhouse gases and aerosols and the alteration of land cover. While the former process is well established in state-of-the-art climate model simulations, less attention has been paid to the latter. However, the low latitudes appear to be particularly sensitive to land use changes, especially in tropical Africa where frequent drought episodes were observed during recent decades. Here several ensembles of long-term transient climate change experiments are presented with a regional climate model to estimate the future pathway of African climate under fairly realistic forcing conditions. Therefore, the simulations are forced with increasing greenhouse gas concentrations as well as land use changes until 2050. Three different scenarios are prescribed in order to assess the range of options inferred from global political, social, and economical development. The authors find a prominent surface heating and a weakening of the hydrological cycle over most of tropical Africa, resulting in enhanced heat stress and extended dry spells. In contrast, the large-scale atmospheric circulation in upper levels is less affected, pointing to a primarily local effect of land degradation on near-surface climate. In the model study, it turns out that land use changes are primarily responsible for the simulated climate response. In general, simulated climate changes are not concealed by internal variability. Thus, the effect of land use changes has to be accounted for when developing more realistic scenarios for future African climate.

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Section: Model Validationmentioning

confidence: 99%

Regional Climate Change in Tropical and Northern Africa due to Greenhouse Forcing and Land Use Changes

et al. 2009

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“…The ITCZ reaches its southernmost position near the north coast of Australia sometime in February and northernmost position in the East China Sea in July (Saha, 2010).…”

Section: Introductionmentioning

confidence: 99%

Extreme Intertropical Convergence Zone shifts over Southern Maritime Continent

Freitas

Aímola

Ambrizzi³

et al. 2016

Atmospheric Science Letters

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This study investigated the Intertropical Convergence Zone (ITCZ) extreme shifts in the Southern Maritime Continent (SMC) region in austral spring during the period 1979-2015. The results have shown that the ITCZ Southern Boundary (SB) presents great correlations with a meridional Sea Surface Temperature (SST) gradient and Indian Ocean Dipole (IOD) events. However, besides these local forcing, the extreme ITCZ shifts are also influenced by El Niño-Southern Oscillation (ENSO) events and an associated zonal SST gradient. The extreme shifts are due mainly to the combination of changes in Walker Circulation (WC) in the Pacific and Indian Ocean (IO) and local SST anomalies. Therefore, during ITCZ southward extreme shifts, the WC is stronger leading to the strengthening of the northwest equatorial winds in the IO, which pumps moist air and boosts the diabatic heating in the SMC due to the local positive SST anomalies present in this region. Otherwise, during northward extreme shifts, the WC is weaker, not allowing the performance of the northwest equatorial winds in the IO, which associated with the local negative SST anomalies, leads to drier conditions in the SMC region. Another interesting result found here is that a strong meridional or zonal index not necessarily implies a larger shift. The combination of very strong ENSO and IOD events can lead to greater ITCZ SB shifts. Besides, the ITCZ SB shifts can act as a bridge linking IOD and ENSO.

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“…These are the Asia-Australia, Africa, and American continents. Based on the monsoon's seasonal movement, they are further subdivided into regions (Saha, 2010) as shown in Table 2.…”

Section: Discussionmentioning

confidence: 99%

Volcanoes magnify Metro Manila's southwest monsoon rains and lethal floods

et al. 2015

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Many volcanoes worldwide are located near populated cities that experience monsoon seasons, characterized by shifting winds each year. Because of the severity of flood impact to large populations, it is worthy of investigation in the Philippines and elsewhere to better understand the phenomenon for possible hazard mitigating solutions, if any. During the monsoon season, the change in flow direction of winds brings moist warm air to cross the mountains and volcanoes in western Philippines and cause lift into the atmosphere, which normally leads to heavy rains and floods. Heavy southwest monsoon rains from 18-21 August 2013 flooded Metro Manila (population of 12 million) and its suburbs paralyzing the nation's capital for an entire week. Called the 2013 Habagat event, it was a repeat of the 2012 Habagat or extreme southwest monsoon weather from 6-9 August, which delivered record rains in the mega city. In both the 2012 and 2013 Habagat events, cyclones, the usual suspects for the delivery of heavy rains, were passing northeast of the Philippine archipelago, respectively, and enhanced the southwest monsoon. Analysis of Doppler data, rainfall measurements, and Weather Research and Forecasting (WRF) model simulations show that two large stratovolcanoes, Natib and Mariveles, across from Manila Bay and approximately 70 km west of Metro Manila, played a substantial role in delivering extreme rains and consequent floods to Metro Manila. The study highlights how volcanoes, with their shape and height create an orographic effect and dispersive tail of rain clouds which constitutes a significant flood hazard to large communities like Metro Manila.

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Tropical Circulation Systems and Monsoons

Cited by 29 publications

References 65 publications

Regional Climate Change in Tropical and Northern Africa due to Greenhouse Forcing and Land Use Changes

Regional Climate Change in Tropical and Northern Africa due to Greenhouse Forcing and Land Use Changes

Extreme Intertropical Convergence Zone shifts over Southern Maritime Continent

Volcanoes magnify Metro Manila's southwest monsoon rains and lethal floods

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