scholarly journals Cloud activity on Mars near the equinox: Comparison of the 1937 and 1969 oppositions

1971 ◽  
Vol 40 ◽  
pp. 310-319
Author(s):  
G. de Vaucouleurs
Keyword(s):  
Northern Hemisphere ◽  
Cloud Systems ◽  
The North ◽  
North Polar

Four classes of manifestations of cloud activity observed in 1937 and 1969 near the autumn equinox of the northern hemisphere (165°< Ls < 192°) are discussed: (1) formation of the north polar haze cap, (2) unusual cloud systems on the disk, (3) recurrent or persistent cloud activity at the sunset limb, (4) clouds seen in projection above the sunrise terminator.

Mars: VLA observations of the Northern Hemisphere and the north polar region at wavelengths of 2 and 6 cm

Icarus ◽  
1987 ◽  
Vol 71 (1) ◽  
pp. 159-177 ◽  
Author(s):  
Donald J. Rudy ◽  
Duane O. Muhleman ◽  
Glenn L. Berge ◽  
Bruce M. Jakosky ◽  
Philip R. Christensen
Keyword(s):  
Northern Hemisphere ◽  
Polar Region ◽  
The North ◽  
North Polar

Polar Maps

1949 ◽  
Vol 42 (5) ◽  
pp. 219-226
Author(s):  
John Kinsella ◽  
A. Day Bradley
Keyword(s):  
Northern Hemisphere ◽  
Relative Size ◽  
North Pole ◽  
Focused Attention ◽  
Polar Regions ◽  
The North ◽  
The Earth ◽  
The World ◽  
North Polar

It is time for us to get better acquainted with the top and bottom of the earth. The strategic importance of the North Polar Regions is becoming increasingly evident and recent explorations in Antarctica have focused attention on that part of the world. We are accustomed to looking at maps which either exclude the polar regions or which distort excessively the distances, directions and relative size of areas in these parts of the globe. Many maps in common usage do not indicate clearly that the great circles between many important cities in the Northern Hemisphere pass near the North Pole.

scholarly journals Dynamical mechanisms linking Indian monsoon precipitation and the circumglobal teleconnection

2021 ◽  
Author(s):  
Jonathan D. Beverley ◽  
Steven J. Woolnough ◽  
Laura H. Baker ◽  
Stephanie J. Johnson ◽  
Antje Weisheimer ◽  
...  
Keyword(s):  
North America ◽  
Northern Hemisphere ◽  
Rossby Waves ◽  
Wave Train ◽  
Forecast Model ◽  
Seasonal Forecast ◽  
The North ◽  
Circumglobal Teleconnection ◽  
Rossby Wave Train ◽  
Ecmwf Model

AbstractThe circumglobal teleconnection (CGT) is an important mode of circulation variability, with an influence across many parts of the northern hemisphere. Here, we examine the excitation mechanisms of the CGT in the ECMWF seasonal forecast model, and the relationship between the Indian summer monsoon (ISM), the CGT and the extratropical northern hemisphere circulation. Results from relaxation experiments, in which the model is corrected to reanalysis in specific regions, suggest that errors over northwest Europe are more important in inhibiting the model skill at representing the CGT, in addition to northern hemisphere skill more widely, than west-central Asia and the ISM region, although the link between ISM precipitation and the extratropical circulation is weak in all experiments. Thermal forcing experiments in the ECMWF model, in which a heating is applied over India, suggest that the ISM does force an extratropical Rossby wave train, with upper tropospheric anticyclonic anomalies over east Asia, the North Pacific and North America associated with increased ISM heating. However, this eastward-propagating branch of the wave train does not project into Europe, and the response there occurs largely through westward-propagating Rossby waves. Results from barotropic model experiments show a response that is highly consistent with the seasonal forecast model, with similar eastward- and westward-propagating Rossby waves. This westward-propagating response is shown to be important in the downstream reinforcement of the wave train between Asia and North America.

scholarly journals Summer Westerly Jet in Northern Hemisphere during the Mid-Holocene: A Multi-Model Study

Atmosphere ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1193
Author(s):  
Chuchu Xu ◽  
Mi Yan ◽  
Liang Ning ◽  
Jian Liu
Keyword(s):  
Temperature Gradient ◽  
Northern Hemisphere ◽  
Hadley Cell ◽  
Dynamic Processes ◽  
Jet Stream ◽  
Meridional Temperature Gradient ◽  
The North ◽  
Westerly Jet ◽  
Poleward Shift ◽  
Thermodynamic Processes

The upper-level jet stream, a narrow band of maximum wind speed in the mid-latitude westerlies, exerts a considerable influence on the global climate by modulating the transport and distribution of momentum, heat and moisture. In this study by using four high-resolution models in the Paleoclimate Modelling Intercomparison Project phase 3, the changes of position and intensity of the northern hemisphere westerly jet at 200 hPa in summer during the mid-Holocene (MH), as well as the related mechanisms, are investigated. The four models show similar performance on the westerly jet. At the hemispheric scale, the simulated westerly jet has a poleward shift during the MH compared to the preindustrial period. The warming in arctic and cooling in the tropics during the MH are caused by the orbital changes of the earth and the precipitation changes, and it could lead to the weakened meridional temperature gradient and pressure gradient, which might account for the poleward shift of the westerly jet from the thermodynamic perspective. From the dynamic perspective, two maximum centers of eddy kinetic energy are simulated over the North Pacific and North Atlantic with the north deviation, which could cause the northward movement of the westerly jet. The weakening of the jet stream is associated with the change of the Hadley cell and the meridional temperature gradient. The largest weakening is over the Pacific Ocean where both the dynamic and the thermodynamic processes have weakening effects. The smallest weakening is over the Atlantic Ocean, and it is induced by the offset effects of dynamic processes and thermodynamic processes. The weakening over the Eurasia is mainly caused by the dynamic processes.

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