Blocking Anticyclones Research Articles

Correlation between stratospheric temperature, total ozone, and tropospheric weather systems

The unusual dynamical situation over Europe in the winter 1991/92 caused an unusual behaviour of the total ozone. The strongest negative deviations from the long‐term monthly means occured in January. A very cold middle stratosphere developed at the edge of the polar vortex above a warm anticyclonic block in the troposphere. The corresponding low temperature in the tropopause region was located just beneath the coldest air in the stratosphere.A high positive correlation between the temperature and ozone partial pressure was derived at the edge of the polar stratospheric vortex for the tropopause region and for the middle stratosphere. The physical background was vertical motions changing temperature as well as the ozone content. That means unusually low ozone values can be expected when an elevated tropopause is combined with the adiabatically cooled end of the upwelling branch of an enhanced planetary wave in the middle stratosphere. It is shown that in February 1990, when extremely low total ozone was also observed over Scandinavia during a short anticyclonic blocking, this event was caused by the same process. However, during transient events the tropopause temperature is often anticorrelated with the middle stratospheric temperature (a tropospheric ridge reaching into the stratosphere has a cold high tropopause, but a warm middle stratosphere). The forced vertical motions result in extreme ozone columns only when they are in the same direction in both layers.The enhanced wave activity was connected with a strong polar warming in the upper stratosphere in both winters. At 30 hPa in the middle stratosphere the warm center was situated over Eastern Siberia and the coldest part shifted towards Northern Europe.The same situation was available in 11 cases during the fourteen years series of TOMS data (1979–1992), when total ozone reached values below 225 DU at the edge of the stratospheric polar vortex: enhanced wave activity in the middle stratosphere, polar warming in the upper stratosphere, shift of the coldest part of the polar vortex towards northern Europe over a cold high tropopause of a tropospheric anticyclone.

A Study of the Influence of Satellite Data on GLA Analyses over the Atlantic Ocean during a Period of Blocking Anticyclone Development

This paper presents a statistical diagnosis of the differences between two Goddard Laboratory for Atmospheres analysis representations of temperature and wind speed, one containing satellite data influences (SAT analyses) and one without (NOSAT analyses), for a case of oceanic blocking anticyclone development. Results, obtained using area means and standard deviations of the two fields and correlation coefficients and root-mean-square differences between the two fields, indicate that the inclusion of satellite data can have significant impact on ocean-domain analyses. This is especially evident if one examines higher-order fields that represent gradients in the basic variable fields or contain covariances between two different variables (e.g., advections). More specifically, the inclusion of satellite data resulted in a cold (warm) temperature bias at low (high) levels and weaker temperature gradients, stronger winds, weaker vertical wind shears, and a warm-air advection bias at most levels. The SAT analyses also exhibited larger standard deviations than the NOSAT for wind speed, relative vorticity, vorticity advection, temperature advection, and 500-mb height tendencies, suggesting that for this case the spatial variability of the circulation features were enhanced by the inclusion of satellite data. Even so, since height tendencies forced by vorticity and temperature advection were less sensitive to the addition of satellite data than were the advection quantities themselves, the dynamics of the blocking system was apparently less influenced by the presence of satellite data than was the structure of the system.

ユーラシアのブロッキング高気圧の華中や日本の梅雨に対する影響

ユーラシアのブロッキング高気圧の華中や日本の梅雨に対する影響

The Local Balances of Vorticity and Heat for Blocking Anticyclones in a Spectral General Circulation Model

Abstract Blocking anticyclones that appear in perpetual January simulations of a spectral general circulation model are examined. Blocks in three geographical regions are studied: the North Pacific, the North Atlantic and western North America. Local time-averaged balances of vorticity and heat are evaluated for composite cases of blocking. The following common relationships emerged from these budgets. The time-mean divergence term is, in general, a flat-order term in the vorticity balance throughout the troposphere and its pattern over severe orography is closely related to the underlying topography. Above the surface layer, the horizontal advection of time-mean absolute vorticity by the mean wind mainly balances the divergence term with the net effect of the time-mean vorticity forcing being a tendency for the blocking pattern to propagate downstream. The transient eddy vorticity transports act to shift the block upstream and hence they mainly offset the downstream tendency due to the time-mean flow; th...

A synoptic climatology of major avalanche winters in Norway

AbstractA near continuous record of avalanche deaths in Norway is compiled for 130 years from 1855, and shows a distinct downward trend, but large variations from winter to winter, with a periodicity of 12–13 years. Twelve major avalanche winters are selected, and their synoptic climatology examined using Grosswetterlagen, an index of atmospheric circulation over southern Norway, and monthly sea level pressure anomaly maps. More than one climatological pattern is needed to explain these winters. Major avalanche winters tend to be cold in December and/or January, and have more meridional and less mixed weather types compared with minor avalanche winters. Some have enhanced north or east circulations associated with large anomalies in the semi‐permanent pressure systems. Others display intense anticyclonic blocking near Britain that maintains sustained west to north‐west airflows onto Norway. A switch in circulation pattern from these to a more southerly regime is also important. These aspects of synoptic climatology are related to the mechanisms for producing big avalanches.

A Diagnostic Study of the Potential Vorticity in a Warm Blocking Anticyclone

Abstract Dynamical features of the warm blocking anticyclone which persisted over Europe during the summer of 1976 are studied using National Meteorological Centre analyses. The dynamics am presented from the perspective of quasi-geostrophic potential vorticity q. The block is shown to be a region of anomalously low, almost uniform q¯. Computed balances in the 300 mb monthly mean quasi-geostrophic potential vorticity equation show that the mean flow advection v¯˙∇q¯ and the eddy forciv′˙∇q′ of q¯ are of comparable magnitude and have the tendency to balance one another. It is suggested that transfer by synoptic scale systems acts to maintain the q¯ anomaly against its advection downstream.

Long-Range Tropospheric Transport of Pollution Aerosols into the Alaskan Arctic

Abstract Noncrustal vanadium and manganese are used as chemical tracers for pollution-derived aerosols (collected over a period of four years in the near-surface air at Barrow, Alaska), in order to investigate tropospheric long-range transport of anthropogenic pollution from midlatitudes to the Alaskan Arctic. The analysis is based upon subjectively identifying characteristic transport pathway types using daily circumpolar weather maps. The transport occurs when the midlatitudinal and Arctic atmospheric circulations manifest quasi-persistent circulation patterns. Rapid transport of aerosols, on the order of 7–10 days, is dominated by quasi-stationary anticyclones and takes place along their peripheries where pressure gradients are relatively strong. The seasonal variation in concentration of the Arctic pollution-derived aerosol is related to the seasonal variation in the occurrence and position of midlatitude blocking anticyclones, of the Arctic anticyclone and of the Asiatic anticyclone. The positions of...

The Strong Index Change Period from January 1 to January 7, 1956

In continuation of a recent paper (Defant, Taba, 1957) a seven days period (January 1–7, 1956) has been investigated on a hemispheric scale. During this period strong world wide changes in the circulation type occurred. Such a circulation change from a meridional into a zonal type* has been studied for the first time by means of hemispheric tropopause maps and by using a special technique of dividing the total available material of atmospheric sound ings into three different groups as described in the previous paper. The following points summarize the results:
 1. The hemispheric tropopause maps are most suitable for obtaining a clear picture of three dimensional structure of the atmosphere. The distribution of cold and warm air masses can easily be seen. Breaks in tropopause heights give an immediate impression of the location and the form of the two principal westwind maxima of the westerlies (polarfront jet and subtropical jet). The concentrations in the temperature field of the tropopause level are a further guide for the location of the main wind belts. This temperature field makes it possible to picture the meandering structure of the wind belts and shows the interaction of tropical and mid-latitude circulation. Clear distinction has to be made between subtropical and polar jet.
 2. By the use of this method strong northward displacements of the tropical atmosphere have been shown. At the same time a strong meandering behaviour of the subtropical jet appears. These tropical impulses play a dominating role in producing pronounced changes in mid-latitude circulation and for the generation of large blocking anticyclones.
 3. During the seven days period the character of soundings in the three selected groups (north of the polar jet, between the two jets and south of the subtropical jet) remained nearly unchanged.
 4. Whenever the tropical atmosphere shifted northward stations inside deep troughs having a polar isothermal structure in the stratosphere showed a strong cooling in the higher stratosphere and at the end of the period even the polar stations showed the same feature. It is thought that this cooling is mainly due to advection from the tropical regions, but outgoing radiation and vertical motion may contribute.
 5. A possible cyclic change and three dimensional interaction of the three different parts of the atmosphere is outlined at the end of the paper.
 * meridional and zonal with respect to the form of polarfront jet.

WHITSUN HOLIDAY, 1955: ELEVENTH HOUR RECOVERY OF A ‘BLOCKING ANTICYCLONE’

WeatherVolume 10, Issue 7 p. 237-239 WHITSUN HOLIDAY, 1955: ELEVENTH HOUR RECOVERY OF A ‘BLOCKING ANTICYCLONE’ M. K. Miles, M. K. Miles Meteorological Office, DunstableSearch for more papers by this author M. K. Miles, M. K. Miles Meteorological Office, DunstableSearch for more papers by this author First published: July 1955 https://doi.org/10.1002/j.1477-8696.1955.tb00197.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Volume10, Issue7July 1955Pages 237-239 RelatedInformation