Regional Circulation Systems

Hastenrath, Stefan

doi:10.1007/978-94-009-5388-8_6

Cited by 4 publications

(6 citation statements)

References 150 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Dallmeyer et al (2010) also show a precipitation increase on the southern rim of the Himalayas. In EC-Earth, precipitation increase over continental Asia is mostly related to a redistribution of precipitation between ocean and land, as well as the increased moisture transport from the southern equatorial Indian Ocean (corroborated by Hastenrath, 1991;Clemens et al, 1991;Marzin and Braconnot, 2009a). Local recycling over land does not play a role, which is opposite to the findings of Marzin and Braconnot (2009a) and Dallmeyer et al (2010).…”

Section: The Asian Monsoonsmentioning

confidence: 85%

“…Generated by the asymmetric heating of continents and oceans, they are characterised by seasonal reversals in atmospheric circulation and associated precipitation (Hastenrath, 1991;Webster, 1987a;Webster et al, 1998). The strength of monsoons varies on inter-seasonal to inter-decadal timescales, through interactions with different components of the climate system (e.g., Webster, 1987b;Shukla, 1987).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Monsoonal response to mid-holocene orbital forcing in a high resolution GCM

et al. 2012

View full text Add to dashboard Cite

Abstract.In this study, we use a sophisticated highresolution atmosphere-ocean coupled climate model, ECEarth, to investigate the effect of Mid-Holocene orbital forcing on summer monsoons on both hemispheres. During the Mid-Holocene (6 ka), there was more summer insolation on the Northern Hemisphere than today, which intensified the meridional temperature and pressure gradients. Over North Africa, monsoonal precipitation is intensified through increased landward monsoon winds and moisture advection as well as decreased moisture convergence over the oceans and more convergence over land compared to the pre-industrial simulation. Precipitation also extends further north as the ITCZ shifts northward in response to the stronger poleward gradient of insolation. This increase and poleward extent is stronger than in most previous ocean-atmosphere GCM simulations. In north-westernmost Africa, precipitation extends up to 35 • N. Over tropical Africa, internal feedbacks completely overcome the direct warming effect of increased insolation. We also find a weakened African Easterly Jet. Over Asia, monsoonal precipitation during the Mid-Holocene is increased as well, but the response is different than over North-Africa. There is more convection over land at the expense of convection over the ocean, but precipitation does not extend further northward, monsoon winds over the ocean are weaker and the surrounding ocean does not provide more moisture. On the Southern Hemisphere, summer insolation and the poleward insolation gradient were weaker during the Mid-Holocene, resulting in a reduced South American monsoon through decreased monsoon winds and less convection, as well as an equatorward shift in the ITCZ. This study corroborates the findings of paleodata research as well as previous model studies, while giving a more detailed account of Mid-Holocene monsoons.

show abstract

Section: The Asian Monsoonsmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Monsoonal response to mid-holocene orbital forcing in a high resolution GCM

et al. 2012

View full text Add to dashboard Cite

show abstract

“…Monsoon systems play a key role in the climate of the tropics and subtropics. Generated by the asymmetric heating of continents and oceans, they are characterised by seasonal reversals in atmospheric circulation and associated precipitation (Hastenrath, 1991;Webster, 1987a;Webster et al, 1998). The strength of monsoons varies on inter-seasonal to inter-decadal timescales, through interactions with different components of the climate system (e.g., Webster, 1987b;Shukla, 1987).…”

Section: Introductionmentioning

confidence: 99%

Monsoonal response to mid-holocene orbital forcing in a high resolution GCM

Bosmans¹,

Drijfhout²,

Tuenter³

et al. 2011

Preprint

View full text Add to dashboard Cite

In this study we use a sophisticated high-resolution atmosphere-ocean coupled climate model, EC-Earth, to investigate the effect of Mid-Holocene orbital forcing on summer monsoons on both hemispheres. During the Mid-Holocene (6 ka), there was more summer insolation on the Northern Hemisphere than today, which intensified the meridional temperature and pressure gradients. Over North Africa, monsoonal precipitation is intensified through increased landward monsoon winds and moisture advection as well as decreased moisture convergence over the oceans and more convergence over land compared to the pre-industrial simulation. Precipitation also extends further north as the ITCZ shifts northward in response to the stronger poleward gradient of insolation. This increase and poleward extent is stronger than in most previous ocean-atmosphere GCM simulations. In north-westernmost Africa, precipitation extends up to 35° N. Over tropical Africa, internal feedbacks completely overcome the direct warming effect of increased insolation. We also find a weakened African Easterly Jet. Over Asia, monsoonal precipitation during the Mid-Holocene is increased as well, but the response is different than over North-Africa. There is more convection over land at the expense of convection over the ocean but precipitation does not extend further northward, monsoon winds over the ocean are weaker and the surrounding ocean does not provide more moisture. On the Southern Hemisphere, summer insolation and the poleward insolation gradient were weaker during the Mid-Holocene, resulting in a reduced South American monsoon through decreased monsoon winds and less convection, as well as an equatorward shift in the ITCZ. This study corroborates the findings of paleodata research as well as previous model studies, while giving a more detailed account of Mid-Holocene monsoons

show abstract

“…By using the NCEP/NCAR reanalysis data from 1979 to 1990, Sathiyamoorthy et al [2007] showed the intraseasonal variability of the TEJ over the Asian region with an intense TEJ migrating over the Indian peninsular region during the ASM. The phenomenon of seasonal reversal of winds during the ISM (June-September) due to land-sea interaction is well reported in the literature [e.g., Hastenrath, 1991]. This aspect can play an important role in transport of upper tropospheric humidity and the formation of tropical cirrus over those areas during the NH summer [Hartmann, 1994;Ahrens, 2003].…”

Section: Resultsmentioning

confidence: 82%

“…The TEJ is generally maintained by the thermal gradient present in the upper troposphere between the heated Asian landmasses of the Tibetan high plateau and relatively cooler Indian Ocean during the ASM season [ Koteswaram , 1958]. The TEJ formed over the South Asia–Pacific region lies at heights of 200–100 hPa pressure levels with wind speeds reaching up to 40 m s −1 [ Hastenrath , 1991]. It can redistribute the water vapor including liquid/ice particles brought up by deep convection and can form high‐altitude clouds [ Ahrens , 2003; Sathiyamoorthy et al , 2004].…”

Section: Introductionmentioning

confidence: 99%

Influence of tropical easterly jet on upper tropical cirrus: An observational study from CALIPSO, Aura-MLS, and NCEP/NCAR data

2011

View full text Add to dashboard Cite

The role of the redistribution of tropical upper tropospheric humidity in the formation of tropical cirrus is studied using three years (June 2006 to December 2008) of observations with the Cloud‐Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument onboard the Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) as well as the Microwave Limb Sounder (MLS) onboard the Aura satellite. The National Centers for Environmental Prediction and Atmospheric Research reanalysis data are also used. Results show that the redistribution of upper tropospheric humidity from a highly convective zone to the Indian peninsular region leads to the formation of the tropical cirrus. Advection of upper layer humidity is caused by the tropical easterly jet (TEJ) associated with the Asian summer monsoon (ASM). Thus the present analysis brings out, for the first time, the role of the TEJ in the redistribution of upper tropospheric humidity and consequently in the formation of tropical cirrus. As little observational evidence exists in support of the generative mechanisms of the cirrus, the present results can be useful in quantifying the formation process of these clouds, which have implications for Earth's radiation budget and improving global climate models.

show abstract

Regional Circulation Systems

Cited by 4 publications

References 150 publications

Monsoonal response to mid-holocene orbital forcing in a high resolution GCM

Monsoonal response to mid-holocene orbital forcing in a high resolution GCM

Monsoonal response to mid-holocene orbital forcing in a high resolution GCM

Influence of tropical easterly jet on upper tropical cirrus: An observational study from CALIPSO, Aura-MLS, and NCEP/NCAR data

Contact Info

Product

Resources

About