Impact of solar cycle variation of UV radiation in the Northern Hemisphere winter polar troposphere

2020 ◽  
Author(s):  
In-Sun Song ◽  
Jeong-Han Kim ◽  
Geonhwa Jee
Keyword(s):  
Solar Cycle ◽  
Temperature Gradient ◽  
Gravity Wave ◽  
Uv Radiation ◽  
Northern Hemisphere ◽  
Polar Region ◽  
Solar Maximum ◽  
Polar Regions ◽  
Solar Cycle Variation ◽  
Idealized Model

<p>Solar cycle (SC) induces variations in the UV radiation. The UV variations change the ozone production rate in the middle atmosphere. Responses to the SC-induced variations occur mainly in the equatorial upper stratosphere and the lower mesosphere. It has been reported that zonal mean temperature difference is 1--2 K between solar maximum and minimum. The temperature variation in the equatorial upper stratosphere modifies the meridional temperature gradient between the equatorial region and winter polar region. Change in the temperature gradient induces difference in the strength of the stratospheric polar vortex, which accompanies change in poleward meridional mass circulations and as a result change in the horizontal distribution of the sea-level pressure (SLP) in the winter polar region. In the present study, this mechanism of SC-induced SLP variations in the Northern Hemisphere (NH) winter polar regions is examined using an idealized whole-atmosphere general circulation model. This global model covers from the ground to the lower thermosphere and includes gravity wave drag parameterization and realistic topography. This idealized model is driven by the zonally-averaged radiative equilibrium temperature, but it nevertheless simulates quite realistically atmospheric variabilities such as sudden stratospheric warmings and quasi-biennial oscillations. Perpetual January simulations for solar maximum and minimum show that this idealized model can reproduce the negative SLP anomaly in the NH polar regions in solar maximum, but the magnitude of the anomaly is weak compared with reanalysis studies. Mechanisms of this SLP anomaly are examined through planetary wave dynamics and gravity-wave processes.</p>

Solar Open Magnetic Flux Migration Pattern over Solar Cycles

2019 ◽  
Vol 15 (S354) ◽  
pp. 157-159
Author(s):  
Chia-Hsien Lin ◽  
Guan-Han Huang ◽  
Lou-Chuang Lee
Keyword(s):  
Solar Cycle ◽  
Magnetic Flux ◽  
Solar Observatory ◽  
Migration Pattern ◽  
Polar Regions ◽  
Solar Cycles ◽  
Low Latitude ◽  
Solar Cycle Variation ◽  
Open Magnetic Flux ◽  
Open Flux

AbstractThe objective of this study is to investigate the solar-cycle variation of the areas of solar open magnetic flux regions at different latitudes. The data used in this study are the radial-field synoptic maps from Wilcox Solar Observatory from May 1970 to December 2014, which covers 3.5 solar cycles. Our results reveal a pole-to-pole trans-equatorial migration pattern for both inward and outward open magnetic fluxes. The pattern consists of the open flux regions migrating across the equator, the regions generated at low latitude and migrating poleward, and the regions locally generated at polar regions. The results also indicate the destruction of open flux regions during the migration from pole to equator, and at low latitude regions. The results have been published in Scientific Reports (Huang et al.2017)

scholarly journals Unusual migration of the prominence activities in recent solar cycles

2013 ◽  
Vol 8 (S300) ◽  
pp. 161-167 ◽  
Author(s):  
Masumi Shimojo
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Radial Velocity ◽  
Northern Hemisphere ◽  
Solar Maximum ◽  
The Other ◽  
Occurrence Rate ◽  
Solar Cycles ◽  
Global Magnetic Field ◽  
Cycle 24

AbstractWe investigated the prominence eruptions and disappearances observed with the Nobeyama Radioheliograph during over 20 years for studying the anomaly of the recent solar cycle. Although the sunspot number of Cycle 24 is smaller than the previous one dramatically, the occurrence rate, size and radial velocity of the prominence activities are not changed significantly. We also found that the occurrence of the prominence activities in the northern hemisphere is normal from the duration of the cycle and the migration of the producing region of the prominence activities. On the other hand, the migration in the southern hemisphere significantly differs from that in the northern hemisphere and the previous cycles. Our results suggest that the anomalies of the global magnetic field distribution started at the solar maximum of Cycle 23.

scholarly journals Variations in the occurrence of SuperDARN F region echoes

2014 ◽  
Vol 32 (2) ◽  
pp. 147-156 ◽  
Author(s):  
M. Ghezelbash ◽  
R. A. D. Fiori ◽  
A V. Koustov
Keyword(s):  
Solar Cycle ◽  
Southern Hemisphere ◽  
Local Time ◽  
Northern Hemisphere ◽  
Solar Minimum ◽  
Solar Maximum ◽  
Radar Data ◽  
Occurrence Rate ◽  
Major Focus ◽  
F Region

Abstract. The occurrence of F region ionospheric echoes observed by a number of SuperDARN HF radars is analyzed statistically in order to infer solar cycle, seasonal, and diurnal trends. The major focus is on Saskatoon radar data for 1994–2012. The distribution of the echo occurrence rate is presented in terms of month of observation and magnetic local time. Clear repetitive patterns are identified during periods of solar maximum and solar minimum. For years near solar maximum, echoes are most frequent near midnight during winter. For years near solar minimum, echoes occur more frequently near noon during winter, near dusk and dawn during equinoxes and near midnight during summer. Similar features are identified for the Hankasalmi and Prince George radars in the northern hemisphere and the Bruny Island TIGER radar in the southern hemisphere. Echo occurrence for the entire SuperDARN network demonstrates patterns similar to patterns in the echo occurrence for the Saskatoon radar and for other radars considered individually. In terms of the solar cycle, the occurrence rate of nightside echoes is shown to increase by a factor of at least 3 toward solar maximum while occurrence of the near-noon echoes does not significantly change with the exception of a clear depression during the declining phase of the solar cycle.

scholarly journals North-South Distribution and Asymmetry of GOES SXR Flares during Solar Cycle 24

2020 ◽  
Vol 28 (1) ◽  
pp. 228-235
Author(s):  
Anita Joshi ◽  
Ramesh Chandra
Keyword(s):  
Data Analysis ◽  
Solar Cycle ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Solar Maximum ◽  
X Ray ◽  
The North ◽  
Solar Cycle 24 ◽  
Cycle 24 ◽  
Second Peak

AbstractHere we present the results of the study of the north-south (N-S) distribution and asymmetry of GOES soft X-ray (SXR) flares during solar cycle 24. The period of study includes ascending, maximum and descending phases of the cycle. During the cycle double-peaked (2011, 2014) solar maximum has occurred. The cycle peak in the year 2011 is due to B-class flares excess activity in the northern hemisphere (NH) whereas C and M class flares excess activity in the southern hemisphere (SH) supported the second peak of the cycle in 2014. The data analysis shows that the SXR flares are more pronounced in 11 to 20 degree latitudes for each hemisphere. Cumulative values of SXR flare count show northern excess during the ascending phase of the cycle. However, in the descending phase of the cycle, southern excess occurred. In the cycle a significant SH dominated asymmetry exists. Near the maximum of the cycle, the asymmetry enhances pronouncedly and reverses in sign.

The Hemispheric Sign Rule of Current Helicity during the Rising Phase of Cycle 23

2000 ◽  
Vol 179 ◽  
pp. 303-306
Author(s):  
S. D. Bao ◽  
G. X. Ai ◽  
H. Q. Zhang
Keyword(s):  
Solar Cycle ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Active Regions ◽  
Hemispheric Preference ◽  
Current Helicity

AbstractWe compute the signs of two different current helicity parameters (i.e., αbestandHc) for 87 active regions during the rise of cycle 23. The results indicate that 59% of the active regions in the northern hemisphere have negative αbestand 65% in the southern hemisphere have positive. This is consistent with that of the cycle 22. However, the helicity parameterHcshows a weaker opposite hemispheric preference in the new solar cycle. Possible reasons are discussed.

scholarly journals The solar cycle variation of topological structures in the global solar corona

2014 ◽  
Vol 565 ◽  
pp. A44 ◽  
Author(s):  
S. J. Platten ◽  
C. E. Parnell ◽  
A. L. Haynes ◽  
E. R. Priest ◽  
D. H. Mackay
Keyword(s):  
Solar Cycle ◽  
Solar Corona ◽  
Solar Cycle Variation ◽  
Topological Structures ◽  
Cycle Variation

scholarly journals Extensive reduction of surface UV radiation since 1750 in world's populated regions

2009 ◽  
Vol 9 (20) ◽  
pp. 7737-7751 ◽  
Author(s):  
M. M. Kvalevåg ◽  
G. Myhre ◽  
C. E. Lund Myhre
Keyword(s):  
Uv Radiation ◽  
Correlation Coefficients ◽  
Ultra Violet ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Polar Regions ◽  
Ultra Violet Radiation ◽  
Wide Range ◽  
Extensive Surface ◽  
Year 2000

Abstract. Human activity influences a wide range of components that affect the surface UV radiation levels, among them ozone at high latitudes. We calculate the effect of human-induced changes in the surface erythemally weighted ultra-violet radiation (UV-E) since 1750. We compare results from a radiative transfer model to surface UV-E radiation for year 2000 derived by satellite observations (from Total Ozone Mapping Spectroradiometer) and to ground based measurements at 14 sites. The model correlates well with the observations; the correlation coefficients are 0.97 and 0.98 for satellite and ground based measurements, respectively. In addition to the effect of changes in ozone, we also investigate the effect of changes in SO2, NO2, the direct and indirect effects of aerosols, albedo changes and aviation-induced contrails and cirrus. The results show an increase of surface UV-E in polar regions, most strongly in the Southern Hemisphere. Furthermore, our study also shows an extensive surface UV-E reduction over most land areas; a reduction up to 20% since 1750 is found in some industrialized regions. This reduction in UV-E over the industrial period is particularly large in highly populated regions.

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