scholarly journals On the characteristics of astronomical refraction in the northern hemisphere

1979 ◽  
Vol 89 ◽  
pp. 103-117
Author(s):  
C. Sugawa ◽  
N. Kikuchi
Keyword(s):  
Northern Hemisphere ◽  
Vertical Structure ◽  
Atmospheric Density ◽  
Height Profile ◽  
Uniform Rate ◽  
Astronomical Refraction ◽  
Equal Temperature

The astronomical refraction mainly depends on the vertical structure or the height profile of atmospheric density. Concerning the vertical structure of atmospheric density, various hypotheses were presented during the last century. Among them Newton's hypothesis of equal temperature and Ivory's one that temperature diminishes at a uniform rate with height appear to represent the height profile of temperature approximately in the lower part of the stratosphere and in the troposphere respectively.

scholarly journals An origin of the variations of astronomical refraction

1979 ◽  
Vol 89 ◽  
pp. 27-33
Author(s):  
Haruo Yasuda ◽  
Rikinosuke Fukaya
Keyword(s):  
Surface Layer ◽  
Correction Term ◽  
Empirical Relation ◽  
Scale Height ◽  
Atmospheric Density ◽  
Analytical Expression ◽  
Temperature And Pressure ◽  
Astronomical Refraction

There exists an empirical relation between the anomalous refraction and the atmospheric density in the surface layer. From the relations the variations of scale height for each night can be determined by the temperature and pressure in the surface layer. A correction term to the refraction table is derived in an analytical expression.

scholarly journals A PV Perspective on the Vertical Structure of Mature Midlatitude Cyclones in the Northern Hemisphere

2012 ◽  
Vol 69 (2) ◽  
pp. 725-740 ◽  
Author(s):  
Jana Čampa ◽  
Heini Wernli
Keyword(s):  
Northern Hemisphere ◽  
Potential Vorticity ◽  
Vertical Structure ◽  
Potential Temperature ◽  
Vertical Cylinder ◽  
Mature Stage ◽  
Extratropical Cyclones ◽  
Surface Acting ◽  
Regional Variability ◽  
Stratospheric Intrusion

Abstract Development of extratropical cyclones can be seen as an interplay of three positive potential vorticity anomalies: an upper-level stratospheric intrusion, low-tropospheric diabatically produced potential vorticity (PV), and a warm anomaly at the surface acting as a surrogate PV anomaly. This study, based on the interim ECMWF Re-Analysis (ERA-Interim) dataset, quantifies the amplitude of the PV anomalies of mature extratropical cyclones in different regions in the Northern Hemisphere on a climatological basis. A tracking algorithm is applied to sea level pressure (SLP) fields to identify cyclone tracks. Surface potential temperature anomalies Δθ and vertical profiles of PV anomalies ΔPV are calculated at the time of the cyclones’ minimum SLP in a vertical cylinder around the surface cyclone center. To compare the cyclones’ characteristics they are grouped according to their location and intensity. Composite ΔPV profiles are calculated for each region and intensity class at the time of minimum SLP and during the cyclone intensification phase. In the mature stage all three anomalies are on average larger for intense than for weak winter cyclones [e.g., 0.6 versus 0.2 potential vorticity units (PVU; 1 PVU = 10−6 K kg−1 m2 s−1) at lower levels, and 1.5 versus 0.5 PVU at upper levels]. The regional variability of the cyclones’ vertical structure and the profile evolution is prominent (cyclones in some regions are more sensitive to the amplitude of a particular anomaly than in other regions). Values of Δθ and low-level ΔPV are on average larger in the western parts of the oceans than in the eastern parts. Results for summer are qualitatively similar, except for distinctively weaker surface Δθ values.

Vertical structure of predictability and information transport over the Northern Hemisphere

2014 ◽  
Vol 23 (2) ◽  
pp. 029202
Author(s):  
Ai-Xia Feng ◽  
Qi-Gang Wang ◽  
Zhi-Qiang Gong ◽  
Guo-Lin Feng
Keyword(s):  
Northern Hemisphere ◽  
Vertical Structure ◽  
Information Transport

Alpha-Effect, Current and Kinetic Helicities for Magnetically Driven Turbulence, and Solar Dynamo

2000 ◽  
Vol 179 ◽  
pp. 387-388
Author(s):  
Gaetano Belvedere ◽  
V. V. Pipin ◽  
G. Rüdiger
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Convection Zone ◽  
Solar Surface ◽  
Momentum Transport ◽  
Angular Momentum Transport ◽  
Magnetic Buoyancy ◽  
Alpha Effect ◽  
Current Helicity

Extended AbstractRecent numerical simulations lead to the result that turbulence is much more magnetically driven than believed. In particular the role ofmagnetic buoyancyappears quite important for the generation ofα-effect and angular momentum transport (Brandenburg & Schmitt 1998). We present results obtained for a turbulence field driven by a (given) Lorentz force in a non-stratified but rotating convection zone. The main result confirms the numerical findings of Brandenburg & Schmitt that in the northern hemisphere theα-effect and the kinetic helicityℋkin= 〈u′ · rotu′〉 are positive (and negative in the northern hemisphere), this being just opposite to what occurs for the current helicityℋcurr= 〈j′ ·B′〉, which is negative in the northern hemisphere (and positive in the southern hemisphere). There has been an increasing number of papers presenting observations of current helicity at the solar surface, all showing that it isnegativein the northern hemisphere and positive in the southern hemisphere (see Rüdigeret al. 2000, also for a review).

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