scholarly journals Local and Time Changes over a 66-Year Period and Annual Relocation of Saudi Arabian Subtropical High Pressure

2016 ◽  
Vol 06 (09) ◽  
pp. 1080-1095 ◽  
Author(s):  
Hasan Lashkari ◽  
Ali Akbar Matkan ◽  
Zainab Mohammadi
Keyword(s):  
High Pressure ◽  
Saudi Arabian ◽  
Subtropical High ◽  
Time Changes

scholarly journals Climatic Change in Australia Since 1880

1953 ◽  
Vol 6 (2) ◽  
pp. 209 ◽  
Author(s):  
EL Deacon
Keyword(s):  
High Pressure ◽  
Climatic Change ◽  
Atmospheric Pressure ◽  
Annual Variation ◽  
Summer Rainfall ◽  
Subtropical High ◽  
Daily Maximum ◽  
Climatic Data ◽  
Maximum Temperatures

Australian climatic data show that, for the period 1911?1950, the summer rainfall over much of the southern part of the continent was considerably greater than in the previous 30 years and, for the same season, mean daily maximum temperatures in the interior were appreciably lower. A difference in character of the annual variation of atmospheric pressure between these periods also suggests a shift of mean position of the subtropical high pressure belt.

The Climate System

2009 ◽  
Author(s):  
Andrew Harding ◽  
Jean Palutikof
Keyword(s):  
High Pressure ◽  
Mediterranean Region ◽  
Eastern Mediterranean ◽  
Western Mediterranean ◽  
Subtropical High ◽  
Westerly Wind ◽  
The West ◽  
The North ◽  
Dry Conditions ◽  
The Mediterranean

The Mediterranean region has a highly distinctive climate due to its position between 30 and 45°N to the west of the Euro-Asian landmass. With respect to the global atmospheric system, it lies between subtropical high pressure systems to the south, and westerly wind belts to the north. In winter, as these systems move equatorward, the Mediterranean basin lies under the influence of, and is exposed to, the westerly wind belt, and the weather is wet and mild. In the summer, as shown in Figure 3.1, the Mediterranean lies under subtropical high pressure systems, and conditions are hot and dry, with an absolute drought that may persist for more than two or three months in drier regions. Climates such as this are relatively rare, and the Mediterranean shares its winter wet/summer dry conditions with locations as distant as central Chile, the southern tip of Cape Province in South Africa, southwest Australia in the Southern Hemisphere, and central California in the Northern Hemisphere. All have in common their mid-latitude position, between subtropical high pressure systems and westerly wind belts. They all lie on the westerly side of continents so that, in winter, when the westerly wind belts dominate over their locations, they are exposed to rain-bearing winds. In the Köppen classification (Köppen 1936), these climates are known as Mediterranean (Type Cs, which is subdivided in turn into maritime Csb and continental Csa). The influence of the Mediterranean Sea means that the Mediterranean-type climate of the region extends much further into the continental landmass than elsewhere, and is not restricted to a narrow ocean-facing strip. Nevertheless, within the Mediterranean region climate is modified by position and topographic influences can be important. The proximity of the western Mediterranean to the Atlantic Ocean gives its climate a maritime flavour, with higher rainfall and milder temperatures throughout the year. The eastern Mediterranean lies closer to the truly continental influences of central Europe and Asia. Its climate is drier, and temperatures are hotter in summer and colder in winter than in the west. Annual rainfall is typically around 750 mm in Rome, but only around 400 mm in Athens.

Climatology of the subtropical high-pressure belt

2021 ◽  
Author(s):  
Rajasri Sen Jaiswal ◽  
Siva M. ◽  
Thirumala Lakshmi K. ◽  
Rasheed M.
Keyword(s):  
High Pressure ◽  
Subtropical High

Monitoring Agricultural Drought in Southern Africa

2005 ◽  
Author(s):  
Leonard S. Unganai
Keyword(s):  
High Pressure ◽  
Southern Africa ◽  
Southern Oscillation ◽  
Personal Communication ◽  
Agricultural Drought ◽  
Subtropical High ◽  
Annual Rainfall ◽  
Severe Drought ◽  
Record Keeping ◽  
Orographic Enhancement

Southern Africa lies between 0°S to 35°S latitude and 10°E to 41°E longitude. In this region, annual rainfall ranges from below 20 mm along the western coastal areas of Namibia to as high as 3000 mm in some highland areas of Malawi. Rainfall generally increases from south to north in response to topography and the main rain-bearing systems affecting the subregion. In the southwest sections of the sub-region, annual rainfall averages below 400 mm, whereas the high-altitude areas receive up to 3000 mm due to orographic enhancement. Two important features that control the climate of southern Africa are the semipermanent subtropical high-pressure cells centered in the southeast Atlantic and the southwest Indian Ocean. These subtropical high pressure cells are associated with widespread and persistent subsidence (Lockwood, 1979). Part of southern Africa is under the downward leg of the Hadley Cell, superposed on the zonal Walker cell. The complex interaction of these cells, particularly during warm El Niño/Southern Oscillation (ENSO) episodes, is usually associated with drier than normal austral summers over much of southern Africa. Much of southern Africa is therefore semiarid and prone to recurrent droughts. In South Africa, for operational purposes, a drought is broadly defined as occurring when the seasonal rainfall is 70% or less of the long-term average (Bruwer, 1990; Du Pisani, 1990). It becomes a disaster or severe drought when two or more consecutive rainfall seasons experience drought. Drought affects some part of southern Africa virtually every year. Southern Africa has suffered recurrent droughts since record keeping began (Nicholson, 1989; Unganai, 1993). Severe drought periods included 1800– 30, 1840–50, 1870–90, 1910–15, 1921–25, 1930–50, 1965–75, and 1980–95. During some of these drought periods, rivers, swamps, and wells dried up and well-watered plains turned into barren lands. For Zimbabwe, the worst drought years were 1911–12, 1923–24, 1946–47, 1972–73, 1981–82, 1982–83, 1986–87, and 1991–92 (Zimbabwe Department of Meteorological Services, personal communication, 2002). During the severe and recurrent droughts of the 1980s and 1990s, the impact on vulnerable communities and the environment was catastrophic.

scholarly journals Drastic shrinking of the Hadley circulation during the mid-Cretaceous supergreenhouse

2011 ◽  
Vol 7 (1) ◽  
pp. 119-151 ◽  
Author(s):  
H. Hasegawa ◽  
R. Tada ◽  
X. Jiang ◽  
Y. Suganuma ◽  
S. Imsamut ◽  
...  
Keyword(s):  
High Pressure ◽  
Global Climate ◽  
Surface Wind ◽  
Hadley Circulation ◽  
Temporal Changes ◽  
Subtropical High ◽  
Data Sets ◽  
Oceanic Circulation ◽  
Meridional Heat Transport ◽  
Spatio Temporal

Abstract. Understanding the behaviour of the global climate system during extremely warm periods is one of the major themes of paleoclimatology. Proxy data demonstrate that the equator-to-pole temperature gradient was much lower during the mid-Cretaceous "supergreenhouse" period than at present, implying larger meridional heat transport by atmospheric and/or oceanic circulation. However, reconstructions of atmospheric circulation during the Cretaceous have been hampered by a lack of appropriate data sets based on reliable proxies. Desert distribution directly reflects the position of the subtropical high-pressure belt, and the prevailing surface-wind pattern preserved in desert deposits reveals the exact position of its divergence axis, which marks the poleward margin of the Hadley circulation. We reconstructed temporal changes in the latitude of the subtropical high-pressure belt and its divergence axis during the Cretaceous based on spatio-temporal changes in the latitudinal distribution of deserts and prevailing surface-wind patterns in the Asian interior. We found a poleward shift in the subtropical high-pressure belt during the early and late Cretaceous, suggesting a poleward expansion of the Hadley circulation. In contrast, an equatorward shift of the belt was found during the mid-Cretaceous "supergreenhouse" period, suggesting drastic shrinking of the Hadley circulation. These results, in conjunction with recent observations, suggest the existence of a threshold in atmospheric CO2 level and/or global temperature, beyond which the Hadley circulation shrinks drastically.

The Influence of the Subtropical High-Pressure Ridge on the Western Australian Wave Climate

2016 ◽  
Vol 75 (sp1) ◽  
pp. 567-571 ◽  
Author(s):  
Moritz Wandres ◽  
Charitha Pattiaratchi ◽  
E.M.S Wijeratne ◽  
Yasha Hetzel
Keyword(s):  
High Pressure ◽  
Wave Climate ◽  
Subtropical High ◽  
Pressure Ridge ◽  
Western Australian
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