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Air mass

About: Air mass is a research topic. Over the lifetime, 2432 publications have been published within this topic receiving 71306 citations.


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Journal ArticleDOI
TL;DR: In this article, the authors used the OTD measurements to construct lightning climatology maps that demonstrate the geographical and seasonal distribution of lightning activity for the globe, and found that lightning occurs mainly over land areas, with an average land/ocean ratio of 10:1.
Abstract: of uncertainty for the OTD global totals represents primarily the uncertainty (and variability) in the flash detection efficiency of the instrument The OTD measurements have been used to construct lightning climatology maps that demonstrate the geographical and seasonal distribution of lightning activity for the globe An analysis of this annual lightning distribution confirms that lightning occurs mainly over land areas, with an average land/ocean ratio of 10:1 The Congo basin, which stands out year-round, shows a peak mean annual flash density of 80 fl km 2 yr 1 in Rwanda, and includes an area of over 3 million km 2 exhibiting flash densities greater than 30 fl km 2 yr 1 (the flash density of central Florida) Lightning is predominant in the northern Atlantic and western Pacific Ocean basins year-round where instability is produced from cold air passing over warm ocean water Lightning is less frequent in the eastern tropical Pacific and Indian Ocean basins where the air mass is warmer A dominant Northern Hemisphere summer peak occurs in the annual cycle, and evidence is found for a tropically driven semiannual cycle INDEX TERMS: 3304 Meteorology and Atmospheric Dynamics: Atmospheric electricity; 3309 Meteorology and Atmospheric Dynamics: Climatology (1620); 3324 Meteorology and Atmospheric Dynamics: Lightning; 3394 Meteorology and Atmospheric Dynamics: Instruments and techniques;

1,117 citations

Journal ArticleDOI
TL;DR: In this paper, a high-resolution air mass transformation (AMT) model is proposed for short-range weather forecasts of the temperature and humidity profiles in the lower atmosphere, the structure of the boundary layer, the boundary layers height, and the amount of boundary layer clouds.
Abstract: This paper describes a high resolution air mass transformation (AMT) model. The model is intended for short-range weather forecasts of the temperature and humidity profiles in the lower atmosphere, the structure of the boundary layer, the boundary layer height, and the amount of boundary layer clouds. The AMT model consists of a one-dimensional, multilayer boundary layer model, which is advected along trajectories from a source region to a receptor point. The trajectories are calculated within a larger scale (limited area) model. The initial profiles for temperature and humidity are obtained from observed radiosondes. The paper describes the physical and dynamical background of the model. With the model we have made case studies of the development of stratocumulus over the North Sea, and have simulated the representation of clear skies over land. The output of the model is compared with the output of the ECMWF model and the current operational bulk AMT model. Sensitivity of the model to boundary ...

966 citations

Journal ArticleDOI
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

Journal ArticleDOI
TL;DR: In this paper, an estimate of the mean vertical profile of fine particle aerosol mass during March and April shows that, on average, pollution is concentrated in the lower 5 km of the atmosphere.

654 citations

Journal ArticleDOI
TL;DR: The isotopic composition of rain in the Levant is a reflection of the modification of continental air masses by interaction with the warm Mediterranean Sea, and the detailed pattern of evolution of Levantine air has been studied by an isotopic survey of rain from twenty coastal and island stations in the eastern Mediterranean Sea area as discussed by the authors.
Abstract: The isotopic composition of rain in the Levant is a reflection of the modification of continental air masses by interaction with the warm Mediterranean Sea. The detailed pattern of evolution of Levantine air has been studied by an isotopic survey of rain from twenty coastal and island stations in the eastern Mediterranean Sea area. The changes in tritium, deuterium, and oxygen 18 concentrations as a function of the distance from the coast usually differ from those calculated for a continuous air mass modification model. Rather, the major changes occur in the Aegean Sea and along the Turkish coast, in an area of major cyclogenesis. A model of convergent air masses, based on the synoptic patterns, is more consistent with the observed isotopic composition of atmospheric waters in the area.

610 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20221
202186
202071
201986
201876
201786