Topic
Monsoon
About: Monsoon is a research topic. Over the lifetime, 16087 publications have been published within this topic receiving 599888 citations.
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TL;DR: It is found that the observed precipitation decrease can be attributed mainly to human-influenced aerosol emissions, providing compelling evidence of the prominent role of aerosols in shaping regional climate change over South Asia.
Abstract: Observations show that South Asia underwent a widespread summertime drying during the second half of the 20th century, but it is unclear whether this trend was due to natural variations or human activities. We used a series of climate model experiments to investigate the South Asian monsoon response to natural and anthropogenic forcings. We find that the observed precipitation decrease can be attributed mainly to human-influenced aerosol emissions. The drying is a robust outcome of a slowdown of the tropical meridional overturning circulation, which compensates for the aerosol-induced energy imbalance between the Northern and Southern Hemispheres. These results provide compelling evidence of the prominent role of aerosols in shaping regional climate change over South Asia.
790 citations
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TL;DR: Values for the precession and obliquity of the earth 9000 years ago indicate that the global average solar radiation for July 9000 years earlier was 7 percent greater than at present.
Abstract: Values for the precession and obliquity of the earth 9000 years ago indicate that the global average solar radiation for July 9000 years ago was 7 percent greater than at present. When the estimated solar radiation values are used in a low-resulation climate model, the model simulates an intensified continent-scale monsoon circulation. This result agrees with paleoclimatic evidence from Africa, Arabia, and India that monsoon rains were stronger between 10,000 and 5000 years ago than they are today.
779 citations
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TL;DR: In this paper, the authors reviewed recent research progress in the climate changes and explored their impacts on the Plateau energy and water cycle, based on which a conceptualmodeltosynthesize these changes was proposed andurgent issues to be explored were summarized.
775 citations
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TL;DR: In this paper, the authors studied the basic state of the summertime circulation and rainfall over South America using assimilation products from the data assimilation system of Goddard Earth Observing System-1 (GEOS-1) and satellite-derived rainfall.
Abstract: The climatology and the basic state of the summertime circulation and rainfall over South America are studied using assimilation products from the data assimilation system of Goddard Earth Observing System-1 (GEOS-1) and satellite-derived rainfall. Results indicate the existence of a regional summer monsoon circulation regime induced by strong diabatic heating over the subtropical South American highland centered at the Altiplano Plateau. Sensitivity of the results to the assimilation scheme is tested by comparing that with the National Centers for Environmental Prediction (NCEP) reanalysis and with satellite rainfall estimates. Results show general agreement between the model produced rainfall anomaly and the satellite estimates, as well as consistency between the basic circulation features in the GEOS-1 and the NCEP reanalyses. A case study of 1989–90 South American summer monsoon (SASM) reveals the following characteristics. 1) In late spring, the onset of SASM is signaled by an abrupt merging...
772 citations
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TL;DR: In this paper, spatial and temporal variability of the stable isotope composition of precipitation in the southeast Asia and western Pacific region is discussed, with emphasis on the China territory, based on the database of the International Atomic Energy Agency/World Meteorological Organization Global Network Isotopes in Precipitation and the available information on the regional climatology and atmospheric circulation patterns.
Abstract: Spatial and temporal variability of the stable isotope composition of precipitation in the southeast Asia and western Pacific region is discussed, with emphasis on the China territory, based on the database of the International Atomic Energy Agency/World Meteorological Organization Global Network Isotopes in Precipitation and the available information on the regional climatology and atmospheric circulation patterns. The meteorological and pluviometric regime of southeast Asia is controlled by five different air masses: (1) polar air mass originating in the Arctic, (2) continental air mass originating over central Asia, (3) tropical-maritime air mass originating in the northern Pacific, (4) equatorial-maritime air mass originating in the western equatorial Pacific, and (5) equatorial-maritime air mass originating in the Indian Ocean. The relative importance of different air masses in the course of a given year is modulated by the monsoon activity and the seasonal displacement of the Intertropical Convergence Zone (ITCZ). Gradual rain-out of moist, oceanic air masses moving inland, associated with monsoon circulation, constitutes a powerful mechanism capable of producing large isotopic depletions in rainfall, often completely overshadowing the dependence of δ 18 O and δ 2 H on temperature. For instance, precipitation at Lhasa station (Tibetan Plateau) during rainy period (June-September) is depleted in 18 O by more than 6 ‰ with respect to winter rainfall, despite of 10°C higher surface air temperature in summer. This characteristic isotopic imprint of monsoon activity is seen over large areas of the region. The oceanic air masses forming the two monsoon systems, Pacific and Indian monsoon, differ in their isotope signatures, as demonstrated by the average δ 18 O of rainfall, which in the south of China (Haikou, Hong Kong) is about 2.5‰ more negative than in the Bay of Bengal (Yangoon). Strong seasonal variations of the deuterium excess values in precipitation observed in some areas of the studied region result from a complete reversal of atmospheric circulation over these areas and changing source of atmospheric moisture. High d-excess values observed at Tokyo and Pohang during winter (15-25‰) result from interaction of dry air masses from the northern Asian continent passing the Sea of Japan and the China Sea and picking up moisture under reduced relative humidity. The isotopic composition of precipitation also provides information about the maximum extent of the ITCZ on the continent during summer.
765 citations