Monsoon

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

An Observational Study of the South China Sea Monsoon during the 1979 Summer: Onset and Life Cycle

Abstract: The onset and life cycle of the 1979 South China Sea summer monsoon were examined in the context of the 30–60- and 12–24-day monsoon modes. The former intraseasonal mode formed the northward-migrating monsoon trough/ridge, while the latter intraseasonal mode propagated westward in the South China Sea. The monsoon in this region exhibited three cycles over the summer (May–August), with the onset taking place about one cycle ahead of the onset of the Indian and Japanese monsoons. Climatologically, a summer trough line radiated out from the Indian monsoon trough region, across Indochina, to the northern South China Sea. The monsoon onset occurred when the 30–60-day monsoon trough and the 12–24-day low center arrived simultaneously at the northern South China Sea, close to the climatological summer trough line, in the middle of May. The breaks occurred when the 30–60-day monsoon ridge lines and the 12–24-day high center met near 15°–20°N in the northern South China Sea. The South China Sea monsoon wa...

The Field Operations and Early Results of the South China Sea Monsoon Experiment (SCSMEX)

Abstract: The South China Sea Monsoon Experiment (SCSMEX) is an international field experiment with the objective to better understand the key physical processes for the onset and evolution of the Asian summer monsoon in relation to fluctuation of the regional hydrologic cycle over Southeast Asian, southern East Asia, aiming at improving monsoon prediction. In this article, we present a description of the major meteorological observation platforms during the Intensive Observing Periods (IOP) of SCSMEX. We also provide highlights of early results and discussions of the role of SCSMEX in providing valuable in-situ data for calibration of satellite rainfall estimate from the Tropical Rainfall Measuring Mission (TRMM). Preliminary results indicate that there are distinctive stages in the onset of the South China Sea monsoon including possibly strong influences from extratropical systems as well as from convection over the Indian Ocean and the Bay of Bengal. There are some tantalizing evidence of complex interactions between the supercloud cluster development over the Indian Ocean, advancing southwest monsoon flow over the South China Sea, midlatitude disturbances and the western Pacific subtropical high, possibly contributing to the disastrous flood over Yangtze River Basin in China during June 1998.

Model Climatology of the Mexican Monsoon

Abstract: The Mexican monsoon is a significant feature in the climate of the southwestern United States and Mexico during the summer months. Rainfall in northwestern Mexico during the months of July through September accounts for 60% to 80% of the total annual rainfall, while rainfall in Arizona for these same months accounts for over 40% of the total annual rainfall. Deep convection during the monsoon season produces frequent damaging surface winds, flash flooding, and hail and is a difficult forecast problem. Past numerical simulations frequently have been unable to reproduce the widespread, heavy rains over Mexico and the southwestern United States associated with the monsoon. The Pennsylvania State University/National Center for Atmospheric Research mesoscale model is used to simulate 32 successive 24-h periods during the monsoon season. Mean fields produced by the model simulations are compared against observations to validate the ability of the model to reproduce many of the observed features, includ...

Seasonality and interannual variability of particle fluxes to the deep Bay of Bengal: influence of riverine input and oceanographic processes

Abstract: Results from sediment trap experiments conducted from October 1987 until November 1997 in the deep northern, central and southern Bay of Bengal, northern Indian Ocean, revealed significant monsoon-induced seasonal and interannual variations in total and component fluxes. Distinct regional differences occurred related to the variable effect of terrestrial input and the development of relatively small-scaled oceanographic processes. The enormous fluvial input to the Bay during SWM is reflected in the high average content of lithogenic matter between 39% at the northernmost and 12.6% at the most distal sampling site in the southern Bay of Bengal. Generally, the riverine input supports a relative increase in the fluxes of biogenic opal. At the stations nearest to the continent (NBBT-N; CBBT) terrestrial inputs determine seasonal and interannual variabilities. Lateral supply of lithogenic matter from the shelf regions lead to distinct increase of fluxes with depth. High-flux events of >300 mg m −2 d −1 consisting of >50% lithogenics occur in the central Bay of Bengal during NEM and in the northern Bay of Bengal during SWM in response to resuspension of shelf sediments and severe floods. When riverine input by Ganges/Brahmaputra and the offshore propagation of the river plume during SWM is reduced, the advection from an upwelling area along the east coast of India during NE–SW intermonsoon becomes the most prominent control mechanism for both biogenic and lithogenic fluxes at NBBT-N. In the central Bay of Bengal (CBBT) fluxes are characterized by a bimodal pattern. High carbonate-dominated fluxes during SWM and NEM occur mainly due to wind-induced nutrient supply, whereas high, opal-rich fluxes during SW–NE intermonsoon are controlled by both upwelling as well as supply of riverine and shelf-derived matter. Wind forcing is the dominant factor controlling particle fluxes at the most distal stations (NBBT-S; SBBT), leading to distinct maxima during SWM with high abundance of biogenic components. Here, interannual variations of particle fluxes are associated with changes in marine productivity induced by oceanographic processes. This is most obvious for SBBT, where the advection of upwelled water from the west coast of India in some years results in highest SWM fluxes and a distinct shift towards biogenic opal.