Life cycle of cyclones and the polar front theory of atmospheric circulation. By J. Bjerknes and H. Solberg. Kristiania, Geophysisks Publikationer, 3, 1922, No. 1. Pp. 18. 4°. Price 2 kr

1923 ◽  
Vol 49 (206) ◽  
pp. 140-141
Author(s):  
J. S. Dines
2017 ◽  
Vol 30 (1) ◽  
pp. 225-242 ◽  
Author(s):  
Michael R. Grose ◽  
James S. Risbey ◽  
Aurel F. Moise ◽  
Stacey Osbrough ◽  
Craig Heady ◽  
...  

Atmospheric circulation change is likely to be the dominant driver of multidecadal rainfall trends in the midlatitudes with climate change this century. This study examines circulation features relevant to southern Australian rainfall in January and July and explores emergent constraints suggested by the intermodel spread and their impact on the resulting rainfall projection in the CMIP5 ensemble. The authors find relationships between models’ bias and projected change for four features in July, each with suggestions for constraining forced change. The features are the strength of the subtropical jet over Australia, the frequency of blocked days in eastern Australia, the longitude of the peak blocking frequency east of Australia, and the latitude of the storm track within the polar front branch of the split jet. Rejecting models where the bias suggests either the direction or magnitude of change in the features is implausible produces a constraint on the projected rainfall reduction for southern Australia. For RCP8.5 by the end of the century the constrained projections are for a reduction of at least 5% in July (with models showing increase or little change being rejected). Rejecting these models in the January projections, with the assumption the bias affects the entire simulation, leads to a rejection of wet and dry outliers.


2000 ◽  
Vol 54 (3) ◽  
pp. 295-308 ◽  
Author(s):  
Duri Florineth ◽  
Christian Schlüchter

The configuration of Alpine accumulation areas during the last glacial maximum (LGM) has been reconstructed using glacial–geological mapping. The results indicate that the LGM ice surface consisted of at least three major ice domes, all located south of the principal weather divide of the Alps. This implies that the buildup of the main Alpine ice cover during oxygen isotope stage (OIS) 2 was related to precipitation by dominant southerly atmospheric circulation, in contrast to today's prevalent westerly airflow. Such a reorganization of the atmospheric circulation is consistent with a southward displacement of the Oceanic Polar Front in the North Atlantic and of the associated storm track to the south of the Alps. These results, combined with additional paleoclimate records from western and southern Europe, allow an interpretation of the asynchronous evolution of the different European ice caps during the last glaciation. δ18O stages (OIS) 4 and 3 were characterized by location of the Polar Front north of 46°N (Gulf of Biscay). This affected prevailing westerly circulation and thus, ice buildup in western Scandinavia, the Pyrénées, Vosges, and northern Alps. At the LGM, however, the Polar Front lay at ∼44°N, causing dominating southerly circulation and reduced precipitation in central and northern Europe.


2020 ◽  
Vol 33 (6) ◽  
pp. 2183-2200 ◽  
Author(s):  
Peiqiang Xu ◽  
Lin Wang ◽  
Wen Chen ◽  
Guosen Chen ◽  
In-Sik Kang

AbstractThe British–Baikal Corridor (BBC) pattern is the dominant waveguide mode trapped along the summertime polar front jet over northern Eurasia. It consists of four geographically fixed centers over the west of the British Isles, the Baltic Sea, western Siberia, and Lake Baikal, respectively. Its intraseasonal variations and dynamics are investigated based on reanalysis datasets. The BBC pattern has a life cycle of about two weeks. Its precursor could be traced back to an upstream wave packet propagating along the Atlantic jet 10 days before its peak, and its life cycle resembles the evolution of a quasi-stationary Rossby wave train. Diagnosis of the streamfunction tendency equation suggests that the growth and decay of the BBC pattern are primarily driven by the nonlinear processes, whereas the quasi-stationary feature of the BBC pattern arises from the cancellation among the linear processes. Energetics analysis indicates that the energy cycle with the transient eddies (TEs) plays an essential role in the growth and decay of the BBC pattern. The BBC pattern first feeds on the barotropic energy provided by the TEs and then returns the energy to TEs in the form of baroclinic energy. It is this nonlinear interaction with the TEs that poses a tough challenge to the current state-of-the-art models to capture the BBC pattern reasonably.


Author(s):  
Betty Ruth Jones ◽  
Steve Chi-Tang Pan

INTRODUCTION: Schistosomiasis has been described as “one of the most devastating diseases of mankind, second only to malaria in its deleterious effects on the social and economic development of populations in many warm areas of the world.” The disease is worldwide and is probably spreading faster and becoming more intense than the overall research efforts designed to provide the basis for countering it. Moreover, there are indications that the development of water resources and the demands for increasing cultivation and food in developing countries may prevent adequate control of the disease and thus the number of infections are increasing.Our knowledge of the basic biology of the parasites causing the disease is far from adequate. Such knowledge is essential if we are to develop a rational approach to the effective control of human schistosomiasis. The miracidium is the first infective stage in the complex life cycle of schistosomes. The future of the entire life cycle depends on the capacity and ability of this organism to locate and enter a suitable snail host for further development, Little is known about the nervous system of the miracidium of Schistosoma mansoni and of other trematodes. Studies indicate that miracidia contain a well developed and complex nervous system that may aid the larvae in locating and entering a susceptible snail host (Wilson, 1970; Brooker, 1972; Chernin, 1974; Pan, 1980; Mehlhorn, 1988; and Jones, 1987-1988).


Author(s):  
Randolph W. Taylor ◽  
Henrie Treadwell

The plasma membrane of the Slime Mold, Physarum polycephalum, process unique morphological distinctions at different stages of the life cycle. Investigations of the plasma membrane of P. polycephalum, particularly, the arrangements of the intramembranous particles has provided useful information concerning possible changes occurring in higher organisms. In this report Freeze-fracture-etched techniques were used to investigate 3 hours post-fusion of the macroplasmodia stage of the P. polycephalum plasma membrane.Microplasmodia of Physarum polycephalum (M3C), axenically maintained, were collected in mid-expotential growth phase by centrifugation. Aliquots of microplasmodia were spread in 3 cm circles with a wide mouth pipette onto sterile filter paper which was supported on a wire screen contained in a petri dish. The cells were starved for 2 hrs at 24°C. After starvation, the cells were feed semidefined medium supplemented with hemin and incubated at 24°C. Three hours after incubation, samples were collected randomly from the petri plates, placed in plancettes and frozen with a propane-nitrogen jet freezer.


1994 ◽  
Vol 11 (1) ◽  
pp. 47-56
Author(s):  
Virginia C. Day ◽  
Zachary F. Lansdowne ◽  
Richard A Moynihan ◽  
John A. Vitkevich

1978 ◽  
Vol 23 (2) ◽  
pp. 85-86
Author(s):  
BERTRAM J. COHLER
Keyword(s):  

1978 ◽  
Vol 23 (9) ◽  
pp. 697-697
Author(s):  
ALVIN G. BURSTEIN

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