Variations in Ca-K line profiles and Ca-K line features as a function of latitude and solar cycle during the 20th century

2018 ◽  
Vol 13 (S340) ◽  
pp. 23-26 ◽  
Author(s):  
Jagdev Singh ◽  
M. Priyal ◽  
G. Sindhuja ◽  
B. Ravindra
Keyword(s):  
Solar Cycle ◽  
20Th Century ◽  
Intensity Distribution ◽  
Polar Regions ◽  
Line Profiles ◽  
Threshold Values ◽  
Latitude Belt ◽  
Negligible Amount ◽  
Complex Variation ◽  
Visible Disk

AbstractThe analysis of the Ca-K line spectra as a function of latitude and integrated over the visible disk obtained during the period of 1989–2011 at the Kodaikanal Solar Tower Telescope shows that the FWHM of the K1 distribution at different latitudes varies by negligible amount at about 60° latitude whereas it varies significantly at other latitudes. Findings, especially the fewer variations in mid-latitude belts as compared to polar regions and complex variation in the shift in the activity around 60° latitude belt, will have important implications on the modeling of solar dynamos. Further, we have generated a uniform set of digitized Ca-K line images by selecting images considering the intensity distribution of the images corrected for the instrumental vignetting for the data obtained at Kodaikanal during the 20th century. Then, we have determined the percentage of plage and network areas by using the intensity and area threshold values.

SOLAR CYCLE VARIATIONS OF THE RADIO BRIGHTNESS OF THE SOLAR POLAR REGIONS AS OBSERVED BY THE NOBEYAMA RADIOHELIOGRAPH

2013 ◽  
Vol 780 (2) ◽  
pp. L23 ◽  
Author(s):  
Nariaki V. Nitta ◽  
Xudong Sun ◽  
J. Todd Hoeksema ◽  
Marc L. DeRosa
Keyword(s):  
Solar Cycle ◽  
Polar Regions ◽  
Radio Brightness

Observed Tropospheric Temperature Response to 11-yr Solar Cycle and What It Reveals about Mechanisms

2013 ◽  
Vol 70 (1) ◽  
pp. 9-14 ◽  
Author(s):  
Jiansong Zhou ◽  
Ka-Kit Tung
Keyword(s):  
Solar Cycle ◽  
Large Scale ◽  
Stratospheric Ozone ◽  
Statistical Significance ◽  
Temperature Response ◽  
Polar Regions ◽  
Tropospheric Temperature ◽  
Tropical Ocean ◽  
Global Data ◽  
Difference Projection

Abstract Using 54 yr of NCEP reanalysis global data from 1000 to 10 hPa, this study establishes the existence and the statistical significance of the zonal-mean temperature response to the 11-yr solar cycle throughout the troposphere and parts of the lower stratosphere. Two types of statistical analysis are used: the composite-mean difference projection method, which tests the existence of the solar cycle signal level by level, and the adaptive AR(p)-t test, which tells if a particular local feature is statistically significant at the 95% confidence level. A larger area of statistical significance than that in previous published work is obtained, due to the longer record and a better trend removal process. It reveals a spatial pattern consistent with a “bottom up” mechanism, involving evaporative feedback near the tropical ocean surface and tropical vertical convection, latent heating of the tropical upper troposphere, and poleward large-scale heat transport to the polar regions. It provides an alternative to the currently favored “top down” mechanism involving stratospheric ozone heating.

ON POSSIBLE VARIATIONS OF BASAL Ca II K CHROMOSPHERIC LINE PROFILES WITH THE SOLAR CYCLE

2013 ◽  
Vol 767 (1) ◽  
pp. 56 ◽  
Author(s):  
Alexei A. Pevtsov ◽  
Luca Bertello ◽  
Han Uitenbroek
Keyword(s):  
Solar Cycle ◽  
Line Profiles ◽  
Chromospheric Line

scholarly journals Optical instrumentation for chromospheric monitoring during solar cycle 25 at Paris and Côte d’Azur observatories

2020 ◽  
Vol 10 ◽  
pp. 31
Author(s):  
Jean-Marie Malherbe ◽  
Thierry Corbard ◽  
Kevin Dalmasse
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Space Weather ◽  
Coronal Mass Ejections ◽  
Calibration Method ◽  
Line Profiles ◽  
Short Term ◽  
Optical Instruments ◽  
Dynamic Events

We present the observing program proposed by Paris and Côte d’Azur Observatories for monitoring solar activity during the upcoming cycle 25 and providing near real time images and movies of the chromosphere for space-weather research and applications. Two optical instruments are fully dedicated to this task and we summarize their capabilities. Short-term and fast-cadence observations of the chromosphere will be performed automatically at Calern observatory (Côte d’Azur), where dynamic events, as flare development, Moreton waves, filament instabilities and Coronal Mass Ejections onset, will be tracked. This new set of telescopes will operate in 2021 with narrow bandpass filters selecting Hα and CaII K lines. We present the instrumental design and a simulation of future images. At Meudon, the Spectroheliograph is well adapted to the long-term and low-cadence survey of chromospheric activity by recently improved and optimized spectroscopic means. Surface scans deliver daily (x, y, λ) datacubes of Hα, CaII K and CaII H line profiles. We describe the nature of available data and emphasize the new calibration method of spectra.

scholarly journals The HelMod Monte Carlo Model for the Propagation of Cosmic Rays in Heliosphere

2017 ◽  
Vol 13 (S335) ◽  
pp. 276-279
Author(s):  
Matteo J. Boschini ◽  
Stefano Della Torre ◽  
Massimo Gervasi ◽  
Davide Grandi ◽  
Giuseppe La Vacca ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Solar Cycle ◽  
Diffusion Tensor ◽  
Monte Carlo Model ◽  
Cosmic Ray ◽  
Ecliptic Plane ◽  
Polar Regions ◽  
General Description ◽  
The Earth ◽  
Modulation Model

AbstractThe heliospheric modulation model HelMod solves the transport-equation for Galactic Cosmic Ray propagation through the heliosphere down to Earth. It is based on a 2-D Monte Carlo approach that includes a general description of the symmetric and antisymmetric parts of the diffusion tensor, thus properly treating the particle drift effects as well as convection within the solar wind and adiabatic energy loss. The model was tuned in order to fit 1) the data observed outside the ecliptic plane at several distances from the Earth and 2) the spectra observed near the Earth for both, high and low solar activity periods. Great importance was given to description of polar regions of the heliosphere. We present the flux for protons, antiprotons and helium nuclei computed for solar cycle 23-24 in comparison with experimental observations and prediction for the full solar cycle 24.

scholarly journals Calcium K Line Profiles as a Function of Latitude and Solar Cycle Phase

1990 ◽  
Vol 142 ◽  
pp. 261-261
Author(s):  
Jagdev Singh
Keyword(s):  
Solar Cycle ◽  
Line Profile ◽  
Solar Minimum ◽  
Active Network ◽  
Cycle Phase ◽  
Line Profiles ◽  
Maximum Phase ◽  
Excess Emission ◽  
Limb Darkening ◽  
Network Component

The sun as a star has been studied by many observers by monitoring the calcium K line profile. Skumanich et al (1984) proposed a three component model of the solar cycle variability of calcium K emission using extant contrast and fractional area parameters for (1) cell (2) network and (3) plage components. The computed line profile agreed well with the observed one at the solar minimum by taking the contribution of only cell and network features and using extant limb-darkening laws. The occurrence of plages during the growth of the solar cycle was found to be insufficient to account for the increase in K emission and therefore, they introduced an additional network component, ‘Active network’ in excess of the quiet sun value to explain the observed excess emission during the maximum phase.

scholarly journals Improved characterization and modeling of equatorial plasma depletions

2018 ◽  
Vol 8 ◽  
pp. A38 ◽  
Author(s):  
Estefania Blanch ◽  
David Altadill ◽  
Jose Miguel Juan ◽  
Adriano Camps ◽  
José Barbosa ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Local Time ◽  
Satellite System ◽  
Global Scale ◽  
Electron Content ◽  
Equatorial Anomaly ◽  
Time Duration ◽  
Total Electron ◽  
Latitude Belt ◽  
Independent Observations

This manuscript presents a method to identify the occurrence of Equatorial Plasma Bubbles (EPBs) with data gathered from receivers of Global Navigation Satellite System (GNSS). This method adapts a previously existing technique to detect Medium Scale Travelling Ionospheric Disturbances (MSTIDs), which focus on the 2nd time derivatives of total electron content estimated from GNSS signals (2DTEC). Results from this tool made possible to develop a comprehensive analysis of the characteristics of EPBs. Analyses of the probability of occurrence, effective time duration, depth of the depletion and total disturbance of the EPBs show their dependence on local time and season of the year at global scale within the latitude belt from 35°N to 35°S for the descending phase of solar cycle 23 and ascending phase of solar cycle 24, 2002–2014. These results made possible to build an EPBs model, bounded with the Solar Flux index, that simulates the probability of the number of EPBs and their characteristics expected for a representative day at given season and local time (LT). The model results provided insight into different important aspects: the maximum occurrence of bubbles take place near the equatorial anomaly crests, asymmetry between hemispheres and preferred longitudes with enhanced EPBs activity. Model output comparisons with independent observations confirmed its soundness.

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