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Air mass

About: Air mass is a(n) research topic. Over the lifetime, 2432 publication(s) have been published within this topic receiving 71306 citation(s). more


Open accessJournal ArticleDOI: 10.1029/2002JD002347
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; more

Topics: Distribution of lightning (68%), Upper-atmospheric lightning (66%), Lightning (58%) more

996 Citations

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 ... more

Topics: Boundary layer (58%), Radiosonde (53%), Air mass (53%) more

890 Citations

Open accessJournal ArticleDOI: 10.1029/98JD02582
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. more

Topics: Air mass (66%), East Asian Monsoon (63%), Monsoon (63%) more

682 Citations

Journal ArticleDOI: 10.1016/0004-6981(86)90180-0
Leonard A. Barrie1Institutions (1)
Abstract: From December to April, the Arctic air mass is polluted by man-made mid-latitudinal emissions from fossil fuel combustion, smelting and industrial processes. In the rest of the year, pollution levels are much lower. This is the outcome of less efficient pollutant removal processes and better south (S) to north (N) transport during winter. In winter, the Arctic air mass covers much of Eurasia and N. America. Meteorological flow fields and the distribution of anthropogenic SO2 emissions in the northern hemisphere favor northern Eurasia as the main source of visibility reducing haze. Observations of SO42− concentrations in the atmosphere throughout the Arctic yield, depending on location and year, a January–April mean of 1.5–3.9 μg m−3 in the Norwegian Arctic to 1.2–2.2 μg m−3 in the N. American Arctic. 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. Not only are anthropogenic particles present in the Arctic atmosphere but also gases such as SO2, perfluorocarbons and pesticides. The acidic nature and seasonal variation of Arctic pollution is reflected in precipitation, the snowpack and glacier snow in the Arctic. A pH of 4.9–5.2 in winter and ~ 5.6 in summer is expected in the absence of calcareous wind blown soil. Glacial records indicate that Arctic air pollution has undergone a marked increase since the mid 1950s paralleling a marked increase in SO2 and NOx emissions in Europe. Effects of Arctic pollution include a reduction in visibility and perturbation of the solar radiation budget in April–June. Potential effects are the acidification and toxification of sensitive ecosystems. more

Topics: Arctic haze (74%), Arctic (70%), Arctic geoengineering (69%) more

630 Citations

Open accessBook
01 Jan 1985-
Abstract: 1. Earth and Its Atmosphere. 2. Energy: Warming the Earth and the Atmosphere. 3. Seasonal and Daily Temperatures. 4. Atmospheric Humidity. 5. Condensation: Dew, Fog, and Clouds. 6. Stability and Cloud Development. 7. Precipitation. 8. Air Pressure and Winds. 9. Wind: Small-Scale and Local Systems. 10. Wind: Global Systems. 11. Air Masses and Fronts. 12. Middle-Latitude Cyclones. 13. Weather Forecasting. 14. Thunderstorms. 15. Tornadoes. 16. Hurricanes. 17. Earth's Changing Climate. 18. Global Climate. 19. Air Pollution. 20. Light, Color, and Atmospheric Optics. more

Topics: Weather front (63%), Air mass (63%), Thunderstorm (61%) more

572 Citations

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Topic's top 5 most impactful authors

Donald R. Blake

25 papers, 1.9K citations

Colin D. O'Dowd

14 papers, 963 citations

Markku Kulmala

14 papers, 813 citations

Heini Wernli

12 papers, 534 citations

Andreas Stohl

9 papers, 745 citations

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