Search results for "Monsoon"
showing 10 items of 117 documents
Middle-late Pleistocene eastern Mediterranean nutricline depth and coccolith preservation linked to Monsoon activity and Atlantic meridional overturn…
2022
Altres ajuts: Unidad de excelencia María de Maeztu CEX2019-000940-M; Universidade de Vigo's programme to attract excellent research talent (RR04092017) The eastern Mediterranean Sea lies under the influence of high- and low-latitude climatic systems. The northern part of the basin is affected by Atlantic depressions and continental and polar air masses that promote intermediate and deep-water formation. The southern part is influenced by subtropical conditions and monsoon activity. Monsoon intensification results in enhanced freshwater discharge from the Nile River and other (now dry) systems along the North African margin. This freshwater influx into the Mediterranean Sea reduces surface w…
A Tropical Archipelago
2017
The tropical maritime climate of the Philippines is marked by high temperature and abundant rainfall. The chapter first examines the major characteristics of the climate, dominated by the seasonal alternation of the Amihan and Habagat monsoons, leading to sharp differences between regions for their patterns of rainy seasons. Typhoons from the western Pacific hit the islands with brutal force, even if some years are more prone than others to the onslaught of tropical storms, depending on the general atmospheric circulation and the strength—or absence—of El Nino or La Nina. Typhoons not directly hitting the Philippines can still generate high levels of rainfall and enhance flooding, due to th…
Paleolakes in the Gobi region of southern Mongolia
2018
Abstract Numerous lakes and remnants of paleolakes exist in western and southern Mongolia. For six basins in the area, detailed geomorphological maps were compiled, based on extensive field studies and remote sensing datasets. Several phases of high and low lake levels were reconstructed and dated by radiocarbon and optically stimulated luminescence. During the marine isotope stage (MIS) 6 lakes in southern and western Mongolia mostly disappeared. In contrast, large paleolakes existed during the last interglacial (MIS 5e) and lasted probably until the beginning of the last glacial. These huge lakes were caused by a strong East Asian summer monsoon, which reached southern and even western Mo…
Palaeoenvironmental changes in the arid and subarid belt (Sahara-Sahel-Arabian peninsula) from 150 kyr to present
2004
The PEP III Arid to Subarid Belt includes the largest hot desert in the world, the Sahara- Arabian desert and the Sahel zone. The region of interest extends south of the Atlas Mountains and south and east of the Mediterranean Sea to approximately 10 °N and shows a broadly zonal pattern with a varying seasonal distribution of precipitation. In the north (ca. 20–23 °N), rainfall results from the southward displacement of the midlatitude westerlies during winter whereas the south is governed by seasonal northward migration of the Intertropical Convergence Zone (ITCZ). Contraction and expansion phases of these presently semi-arid to hyper-arid desert areas result from significant changes in loc…
Surface hydrographic changes at the western flank of the sicily channel associated with the last sapropel
2021
Abstract In the eastern Mediterranean Sea, the early Holocene was characterized by major climatic and oceanographic changes that led to the formation of the last sapropel (S1) between 10.8 and 6.1 kyr cal. BP. These hydrographic changes might have altered the water exchange between the eastern and western Mediterranean sub-basins through the Strait of Sicily, but the existing evidences are inconclusive. In the present study we show new evidence from sediment core NDT-6-2016 located at the western flank of the Sicily channel, a key location to monitor the surface/intermediate water exchange between the two Mediterranean sub-basins. We perform paleo-hydrographic reconstructions based on plank…
Influence of the Mediterranean Sea on the West African monsoon: Intraseasonal variability in numerical simulations
2010
[1] The influence of May to September sea surface temperature (SST) anomalies in the Mediterranean Sea on the West African monsoon is investigated, analyzing the outputs of numerical sensitivity experiments performed using three atmospheric general circulation models (Action de Recherche Petite Echelle Grande Echelle, European/Hamburg, and University of California, Los Angeles) in the framework of the African Monsoon Multidisciplinary Analysis project. The precipitation and atmospheric dynamics response to the SST forcing is explored, in terms of intraseasonal variability, evaluating the results from the individual models and from the multimodel mean. A positive precipitation response to wa…
African monsoon variability during the previous interglacial maximum.
2002
Little is known about centennial- to millennial-scale climate variability during interglacial times, other than the Holocene. We here present high-resolution evidence from anoxic (unbioturbated) sediments in the eastern Mediterranean Sea that demonstrates a sustained V800-yr climate disturbance in the monsoonal latitudes during the Eemian interglacial maximum (V125 ka BP). Results imply that before and after this event, the Intertropical Convergence Zone (ITCZ) penetrated sufficiently beyond the central Saharan watershed (V21n) during the summer monsoon to fuel flooding into the Mediterranean along the wider North African margin, through fossil river/wadi systems that to date have been cons…
Interacción entre el Monzón de África Occidental y el clima Mediterráneo en verano: Artículo de revisión
2014
Although in the framework of the global climate research the Mediterranean climate variability and the West African Monsoon (WAM) dynamics have been considered for a long time as “passive” systems, i.e., prone to the influence of large scale ocean and atmospheric variability, over the last decade many studies have been dedicated to the WAM-Mediterranean interaction and the active role of these climate systems has been highlighted. This article presents the WAM-Mediterranean teleconnection through an overview of the recent literature, describing the observational evidences and the dynamical mechanisms underlying this climate teleconnection. The influence of the Mediterranean Sea thermal anom…
Monsoon onset over Sudan-Sahel: Simulation by the regional scale model MM5.
2006
[1] The Mesoscale Model MM5 is used to study the regional features of the West African Monsoon onset. In order to increase the results, simulations are carried out for eight consecutive seasons (March to September) of the years 1994 to 2001. The results show that the model can reproduce the dynamical features of the monsoon in a reasonably good manner but the seasonal cycle seems enhanced. It is hypothesized that overestimated rainfall amounts could be related to a poor representation of the land surface characteristics. Nevertheless, the mean simulated monsoon onset dates are similar to those find in the CMAP data set. The onset is characterized by an apparent increase in zonal flow that c…
Forecasting the vegetation photosynthetic activity over the Sahel: a Model Output Statistics approach
2009
The predictability of the mean August–September photosynthetic activity of vegetation over the Sahel for the period 1982–2002 is explored through a Model Output Statistics approach using ECHAM4.5 retrospective forecasts. Given the poor ability of Atmospheric General Circulation Models (AGCMs) to correctly simulate rainfall over the Sahel, the stress is put on using atmospheric dynamics alone. The mean July–September predicted fields of zonal wind at 600 hPa, and humidity flux at 850 hPa, are selected because of their key role in the West African Monsoon system and their consistency in AGCMs. Coupled modes of NDVI/atmospheric dynamics are extracted using Canonical Correlation Analyses perfor…