Monsoon

About: Monsoon is a research topic. Over the lifetime, 16087 publications have been published within this topic receiving 599888 citations.

Historical trends and future predictions of climate variability in the Brahmaputra basin

Abstract: An innovative approach is developed and presented to assess historical climate variations and to quantify future climate change for the entire Brahmaputra basin. Historical trends in temperature and precipitation are analysed from 1900 to 2002 for the Tibetan plateau (TP), the Himalayan belt and the floodplains (FP) using a global 100 year monthly high resolution dataset. Temperature patterns are consistent with global warming and out of the 10% warmest years from 1900 to 2002 six occurred between 1995 and 2002. No clear trends in precipitation were found and annual precipitation in the basin is mainly determined by the strength of the monsoon. Regression analysis is used to further explain monsoon precipitation. A significant inverse relation is found between air temperature differences between the FP and the TP and the strength of the monsoon, whereas the El Nino Southern Oscillation teleconnection does not have a prominent role in explaining variation in monsoon precipitation. Simulation results of six general circulation models are statistically downscaled to the spatial resolution of the observed dataset for two future storylines. The analysis predicts accelerated seasonal increases in both temperature and precipitation from 2000 to 2100. The largest changes occur on the TP and the smallest on the FP. Multiple regression analysis shows a sharp increase in the occurrence of average and extreme downstream discharges for both storylines. The strongest increases are projected for the monsoon season and the largest threat of climate change lies in the associated flooding in the densely populated FP. Copyright © 2007 Royal Meteorological Society

An Intensity Index for the East Asian Winter Monsoon

Abstract: The thermal contrast betweenthe Asian continentand the adjacent oceans is the primary aspect of the East Asian winter monsoon (EAWM) that can be well represented in the sea level pressure (SLP) field. Based on this consideration, a new SLP-based index measuring the intensity of the EAWM is proposed by explicitly taking into account both the east‐west and the north‐south pressure gradients around East Asia. The new index can delineate the EAWM-related circulation anomalies well, including the deepened (shallow) midtropospheric East Asian trough, sharpened and accelerated (widened and decelerated) upper-tropospheric East Asian jet stream, and enhanced (weakened) lower-tropospheric northerly winds in strong (weak) EAWM winters. Compared with previous indices, the new index has a very good performance describing the winter-mean surface air temperature variations over East Asia, especially for the extreme warm or cold winters. The index is strongly correlated with several atmospheric teleconnections including the Arctic Oscillation,theEurasianpattern,andtheNorthPacificOscillation/westernPacificpattern,implyingthepossible internal dynamics of the EAWM variability. Meanwhile, the indexis significantly linked to El Ni~ Oscillation (ENSO) and the sea surface temperature (SST) over the tropical Indian Ocean. Moreover, the SST anomalies over the tropical Indian Ocean are more closely related to the index than ENSO as an independent predictor. This adds further knowledge to the prediction potentials of the EAWM apart from ENSO. The predictability of the index is high in the hindcasts of the Centre National de Recherches M�� (CNRM) model from Development of a European Multimodel Ensemble System for Seasonal-to-Interannual Prediction (DEMETER). Hence, it would be a good choice to use this index for the monitoring, prediction, and research of the EAWM.

Warming of the Eurasian Landmass is Making the Arabian Sea More Productive

Abstract: The recent trend of declining winter and spring snow cover over Eurasia is causing a land-ocean thermal gradient that is particularly favorable to stronger southwest (summer) monsoon winds. Since 1997, sea surface winds have been strengthening over the western Arabian Sea. This escalation in the intensity of summer monsoon winds, accompanied by enhanced upwelling and an increase of more than 350% in average summertime phytoplankton biomass along the coast and over 300% offshore, raises the possibility that the current warming trend of the Eurasian landmass is making the Arabian Sea more productive.

Climate change and coral reefs: different effects in two high-latitude areas (Arabian Gulf, South Africa)

Abstract: The findings in this paper show that Arabian Gulf (Abu Dhabi, Dubai, Sharjah) corals have already been measurably affected by climate change and further negative impacts are expected. Corals in South Africa have been only weakly impacted and are expected to persist in this likely refuge. The Arabian Gulf has recently experienced high-frequency recurrences of temperature-related bleaching (1996, 1998, 2002). First evidence may suggest that bleaching patterns in corals changed due to phenotypic adaptation after two strong bleaching events in rapid succession, because Acropora, which during the 1996 and 1998 events always bleached first and suffered heaviest mortality, bleached less than all other corals in 2002 at Sir Abu Nuair and recovered at Jebel Ali and Ras Hasyan. In South Africa, reef corals largely escaped the mass mortalities observed across the tropics in the late 1990s, although bleaching has also increased since 1999. These reefs are protected by local small-scale upwelling events in summer that, if they occur at the right time, keep temperatures below bleaching levels. Both areas, the Arabian Gulf and South Africa, have rich coral faunas but little to no recent reef-framework production. It is possible that many reefs worldwide may have similar dynamics in the future, if the changed climate (recurrence of temperature anomalies, changes in aragonite saturation state, etc.) suppresses sustained reef building at least temporarily. Global climate models predict the possibility of significant environmental changes, including increases in atmospheric temperature, sea-surface temperature (SST), and sea level. Monsoon and El Nino Southeastern Oscillation (ENSO) patterns might change, but climate models are not conclusive. Sea-level rise by up to 0.88 m is expected to be a problem in some low-lying areas, like the southern Arabian Gulf. Ocean aragonite saturation state is predicted to fall throughout the ocean but may not change reef dynamics in the two study areas.