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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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Journal ArticleDOI
TL;DR: In this article, the carbon isotopic composition of both soil carbonate and organic matter shifts dramatically starting ca. 7.0 Ma, marking the displacement of largely C3 vegetation, probably semi-deciduous forest, by C4 grasslands.
Abstract: Neogene sediments belonging to the Siwalik Group crop out in the Himalayan foothills along the length of southern Nepal. Carbon and oxygen isotopic analyses of Siwalik paleosols from four long Siwalik sections record major ecological changes over the past ∼11 m.y. The carbon isotopic composition of both soil carbonate and organic matter shifts dramatically starting ca. 7.0 Ma, marking the displacement of largely C3 vegetation, probably semi-deciduous forest, by C4 grasslands. By the beginning of the Pliocene, all the flood plains of major rivers in this region were dominated by monsoonal grasslands. The floral shift away from woody plants is also reflected by the decline and final disappearance of fossil leaves and the decrease in coal logs in the latest Miocene. A similar carbon isotopic shift has been documented in the paleosol and fossil tooth record of Pakistan, and in terrigenous organic matter from the Bengal Fan, showing that the floral shift was probably continentwide. The latest Miocene also witnessed an average change of ∼4‰ in the oxygen isotopic composition of soil carbonate, as observed previously in Pakistan. The reasons for this are unclear; if not diagenetic, a major environmental change is indicated, perhaps related to that driving the carbon isotopic shift. Recently described pollen and leaf fossils from the Surai Khola section show that evergreen forest was gradually displaced by semi-deciduous and dry deciduous forest between 11 and 6 Ma. The gradual nature of this floral shift, which culminated in the rapid expansion of C4 grasses starting ∼7.0 m.y. ago, is difficult to explain by a decrease in atmospheric pCO2 alone (Cerling et al., 1993) but fits well with a gradual onset of monsoonal conditions in the late Miocene in the northern Indian subcontinent. Himalayan uplift, driving both monsoonal intensification and consumption of CO2 through weathering, may be the common cause behind major late Miocene environmental change globally. However, the decline of effective moisture associated with monsoon development has probably slowed, not increased, the rate of consumption of CO2 by chemical weathering of Himalayan sediments.

351 citations

Journal ArticleDOI
TL;DR: In this article, the influence of the Asian monsoon on the δ18O composition of precipitation is investigated on the basis of the ECHAM-4 Atmospheric General Circulation Model (AGCM), fitted with stable isotopic tracers.
Abstract: [1] The influence of the Asian monsoon on the δ18O composition of precipitation is investigated on the basis of the ECHAM-4 Atmospheric General Circulation Model (AGCM), fitted with stable isotopic tracers. The model is forced with prescribed sea surface temperatures (SST) over the last few decades of the 20th century. The simulated climate and climate–stable isotope relationships are validated with observational data from the International Atomic Energy Agency–Global Network of Isotopes in Precipitation (IAEA-GNIP) and reanalysis data. The model shows deficiencies when simulating interannual variations of monsoon precipitation, but the associated monsoon circulation is quite accurately reproduced, in particular when run in a high-resolution (T106) version. The modeled stable isotope distribution is quite similar to observations, but the local climatic controls on δ18O are overestimated. The influence of the Asian monsoon on δ18O is analyzed on the basis of a vertical wind shear index M, indicative of variations in large-scale monsoon strength. The ECHAM model simulates a significant negative relationship between δ18O composition of precipitation and M over most monsoon-affected areas, consistent with the IAEA-GNIP data. Variations in the amount of precipitation provide a first-order explanation for this relationship. Distillation processes during transport and hence increased rainout and depletion of heavy isotopes upstream may also lead to a significant monsoon-δ18O relationship in areas where local precipitation is not affected by monsoon variability. The modern δ18O record from the Dasuopu ice core in the Himalayas is a good indicator of the large-scale monsoon circulation, a relationship that is correctly simulated by the T106 version of the ECHAM model. Our results suggest that δ18O variations in this region are sensitive to fluctuations in Asian monsoon intensity.

350 citations

Journal ArticleDOI
TL;DR: The authors provided a new view of global and regional monsoonal rainfall, and their changes in the 21st century under RCP4.5 and RCP8.5 scenarios as projected by 29 climate models that participated in the Coupled Model Intercomparison Project phase 5.
Abstract: [1] We provide a new view of global and regional monsoonal rainfall, and their changes in the 21st century under RCP4.5 and RCP8.5 scenarios as projected by 29 climate models that participated in the Coupled Model Intercomparison Project phase 5. The model results show that the global monsoon area defined by the annual range in precipitation is projected to expand mainly over the central to eastern tropical Pacific, the southern Indian Ocean, and eastern Asia. The global monsoon precipitation intensity and the global monsoon total precipitation are also projected to increase. Indices of heavy precipitation are projected to increase much more than those for mean precipitation. Over the Asian monsoon domain, projected changes in extreme precipitation indices are larger than over other monsoon domains, indicating the strong sensitivity of Asian monsoon to global warming. Over the American and African monsoon regions, projected future changes in mean precipitation are rather modest, but those in precipitation extremes are large. Models project that monsoon retreat dates will delay, while onset dates will either advance or show no change, resulting in lengthening of the monsoon season. However, models’ limited ability to reproduce the present monsoon climate and the large scatter among the model projections limit the confidence in the results. The projected increase of the global monsoon precipitation can be attributed to an increase of moisture convergence due to increased surface evaporation and water vapor in the air column although offset to a certain extent by the weakening of the monsoon circulation.

350 citations

Journal ArticleDOI
TL;DR: In this paper, a detailed record of changes in East Asian monsoon climate since the late Miocene Epoch was found in Chinese eolian and organic deposits by a shift from cool, humid lateglacial conditions to cold and dry conditions, followed by a return to milder, humid climate at the beginning of the Holocene.

348 citations

Book
01 Jan 1988
TL;DR: Wang et al. as discussed by the authors studied the effect of topography and elevation on the seasonal distribution of precipitation in China and found that the topography of land and sea and the nature of the underlying ground can influence the seasonal variation of precipitation.
Abstract: 1 Introduction.- 1.1 Aims and Concept of the Study.- 1.2 Climate Data.- 1.3 Review of Climate Studies on China.- 2 Controlling Factors of the Climate.- 2.1 Latitude, Longitude and Location.- 2.2 Topography and Landforms.- 2.3 Distribution of Land and Sea and Nature of the Underlying Ground.- 2.4 Seasons.- 3 Circulation.- 3.1 Seasonal Pressure Distribution at Sea Level.- 3.2 Seasonally Prevailing Winds and Air Masses.- 3.3 Winter and Summer Monsoon.- 3.3.1 Characteristics of the Monsoon in General.- 3.3.2 Onset and Duration of the Winter Monsoon.- 3.3.3 Periods of Active and Weak Winter Monsoon.- 3.3.4 Damage Due to Strong Cold Outbreaks of Winter Monsoon.- 3.3.5 Onset and Duration of the Summer Monsoon.- 3.3.6 Some Characteristics of the Summer Monsoon.- 3.4 Frontology.- 3.4.1 Mean Front Position in January and July.- 3.4.2 The Stationary Fronts in February and March as well as in the Pre-Typhoon Season in South China.- 3.4.3 Some Characteristics of the Mei-Yu Front.- 3.5 The Transient Disturbances.- 3.5.1 The Upper Westerly Troughs in the Westerlies.- 3.5.2 Extratropical Cyclones and Anticyclones.- 3.5.3 Typhoons.- 4 Temperature.- 4.1 Mean Annual Air Temperature Distribution.- 4.2 Mean Seasonal Temperature Distribution.- 4.3 Annual Range and Annual Variation of Temperature.- 4.4 Onset and End of Certain Limited Temperatures and Their Duration.- 4.4.1 Mean Daily Air Temperature ? 0 C.- 4.4.2 Mean Daily Air Temperature ? 10 C.- 4.4.3 Maximum Daily Air Temperature ? 35 C.- 4.4.4 Other Extreme Limited Temperatures.- 4.5 Vertical Distribution of Temperature.- 4.6 Comparison of Temperature at the Same Latitude.- 4.7 Diurnal Range of Temperature.- 4.8 Interannual Variability of Temperature.- 4.8.1 Variability of Annual Mean Temperature.- 4.8.2 Variability of Monthly Mean Temperatures.- 4.9 Historical-Climatic Change of Temperature During the last 5,000, 500 and 100 Years.- 5 Precipitation.- 5.1 Mean Annual Precipitation Distribution.- 5.2 Mean Seasonal Precipitation Distribution.- 5.3 Annual Variation of Precipitation.- 5.3.1 Specific Precipitation Types and Their Distribution.- 5.3.2 Variation of Wet and Dry Months over Space and Time.- 5.3.3 Summer Precipitation.- 5.4 Interannual Precipitation Variability.- 5.4.1 Variability of Annual Precipitation.- 5.4.2 Variability of Monthly Precipitation.- 5.4.3 Variability of Annual and Monthly Precipitation at Beijing.- 5.5 Precipitation Frequency Expressed in Rainy Days.- 5.6 Precipitation Intensity.- 5.7 Rainstorms and Certain Events of Heavy Rainfall.- 5.8 Diurnal Variation of Precipitation.- 5.9 Influence of Topography and Elevation on Precipitation.- 5.9.1 Influence of the Exposition of Slopes on Precipitation.- 5.9.2 Effect of Elevation on Prefipitation.- 5.10 Historical Change of Precipitation.- 5.11 Snow.- 5.11.1 Mean Length of Snow Cover Period.- 5.11.2 Number of Snowfall Days.- 5.11.3 Maximum Depth of Snow.- 5.11.4 Altitude of the Snow Line.- 6 Cloudiness and Sunshine.- 6.1 Mean Annual Cloudiness and January and July Amount.- 6.2 Sunshine.- 6.2.1 Annual Sunshine Duration.- 6.2.2 Sunshine Duration in January and July and Annual Variation.- 6.3 Global Radiation.- 6.4 Fog.- 7 Surface Wind.- 7.1 Mean and Extreme Wind Velocities.- 7.2 Local Wind Systems.- 7.2.1 Mountain and Valley Breezes.- 7.2.2 Land and Sea Breezes, Lake Breeze.- 7.2.3 Plateau Monsoon.- 7.2.4 Local Dry and Hot Winds.- 8 Climate Classification and Division of China.- 8.1 General Objectives and Fundamentals of Climate Regionalization.- 8.2 China Within Global Climate Classifications.- 8.3 National Climate Classifications of China.- 8.4 Climate Division of China According to Huang Bing-wei (1986).- 9 Climate Zones of China.- 9.1 Cold Temperate Zone (I).- 9.2 Middle Temperate Zone (II).- 9.3 Warm Temperate Zone (III).- 9.4 Northern Subtropical Zone (IV).- 9.5 Middle Subtropical Zone (V).- 9.6 Southern Subtropical Zone (VI).- 9.7 Peripheral Tropical Zone (VII).- 9.8 Middle Tropical Zone (VIII).- 9.9 Southern Tropical Zone (IX).- 9.10 Alpine Plateau Zone (H0).- 9.11 Subalpine Plateau tone (HI).- 9.12 Temperate Plateau Zone (HII).- Appendix: Climate Tables.- References.

345 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20231,221
20222,355
2021922
2020757
2019749
2018727