Variations in Quiet Sun Radiation at Centimetre Wavelengths during Solar Maximum Period

1986 ◽  
pp. 27-32
Author(s):  
B. Lokanadham ◽  
P. K. Subramanian
Keyword(s):  
Solar Maximum ◽  
Quiet Sun ◽  
Maximum Period

Variations in quiet sun radiation at centimetre wavelengths during solar maximum period

1986 ◽  
Vol 119 (1) ◽  
pp. 27-32 ◽  
Author(s):  
B. Lokanadham ◽  
P. K. Subramanian
Keyword(s):  
Solar Maximum ◽  
Quiet Sun ◽  
Maximum Period

Analysis of ionosphere variability over low-latitude GNSS stations during 24th solar maximum period

2017 ◽  
Vol 60 (2) ◽  
pp. 419-434 ◽  
Author(s):  
D. Venkata Ratnam ◽  
G. Sivavaraprasad ◽  
N.S.M.P. Latha Devi
Keyword(s):  
Solar Maximum ◽  
Low Latitude ◽  
Maximum Period

scholarly journals The bottomside parameters <i>B0</i>, <i>B1</i> obtained from incoherent scatter measurements during a solar maximum and their comparisons with the IRI-2001 model

2002 ◽  
Vol 20 (6) ◽  
pp. 817-822 ◽  
Author(s):  
N. K. Sethi ◽  
K. K. Mahajan
Keyword(s):  
Solar Maximum ◽  
Local Times ◽  
Iri Model ◽  
Density Profiles ◽  
Incoherent Scatter ◽  
Ionosphere Modeling ◽  
Resolution Electron ◽  
Maximum Period ◽  
Modeling And Forecasting ◽  
Electron Density Profiles

Abstract. High resolution electron density profiles (Ne) measured with the Arecibo (18.4 N, 66.7 W), Incoherent Scatter radar (I. S.) are used to obtain the bottomside shape parameters B0, B1 for a solar maximum period (1989–90). Median values of these parameters are compared with those obtained from the IRI-2001 model. It is observed that during summer, the IRI values agree fairly well with the Arecibo values, though the numbers are somewhat larger during the daytime. Discrepancies occur during winter and equinox, when the IRI underestimates B0 for the local times from about 12:00 LT to about 20:00 LT. Furthermore, the IRI model tends to generally overestimate B1 at all local times. At Arecibo, B0 increases by about 50%, and B1 decreases by about 30% from solar minimum to solar maximum.Key words. Ionosphere (equational ionosphere; modeling and forecasting)

Alfvénicity of Quiet-Sun-associated Wind during Solar Maximum

2019 ◽  
Vol 871 (2) ◽  
pp. 204 ◽  
Author(s):  
Xin Wang ◽  
Liang Zhao ◽  
Chuanyi Tu ◽  
Jiansen He
Keyword(s):  
Solar Maximum ◽  
Quiet Sun

scholarly journals Signature of the 27-day solar rotation cycle in mesospheric OH and H<sub>2</sub>O observed by the Aura Microwave Limb Sounder

2011 ◽  
Vol 11 (10) ◽  
pp. 28477-28498 ◽  
Author(s):  
A. V. Shapiro ◽  
E. Rozanov ◽  
A. I. Shapiro ◽  
S. Wang ◽  
T. Egorova ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Solar Irradiance ◽  
Solar Minimum ◽  
Solar Maximum ◽  
Solar Rotation ◽  
Time Lag ◽  
Correlation Coefficients ◽  
Maximum Period ◽  
First Time ◽  
Zero Time

Abstract. The mesospheric hydroxyl radical (OH) is mainly produced by the water vapor (H2O) photolysis and could be considered as a proxy for the influence of the solar irradiance variability on the mesosphere. We analyze the tropical mean response of the mesospheric OH and H2O data as observed by the Aura Microwave Limb Sounder (MLS) to 27-day solar variability. The analysis is performed for two time periods corresponding to the different phases of the 11-yr cycle: from December 2004 to December 2005 ("solar maximum" period with a pronounced 27-day solar cycle) and from November 2008 to November 2009 ("solar minimum" period with a vague 27-day solar cycle). We demonstrate, for the first time, that in the mesosphere the daily time series of OH concentrations correlate well with the solar irradiance (correlation coefficients up to 0.79) at zero time-lag. At the same time H2O anticorrelates (correlation coefficients up to −0.74) with the solar irradiance at non-zero time-lag. We found that the response of OH and H2O to the 27-day variability of the solar irradiance is strong for the solar maximum and negligible for the solar minimum conditions. It allows us to suggest that the 27-day cycle in the solar irradiance and in OH and H2O are physically connected.

scholarly journals Validation of COSMIC ionospheric peak parameters by the measurements of an ionosonde chain in China

2014 ◽  
Vol 32 (10) ◽  
pp. 1311-1319 ◽  
Author(s):  
L. Hu ◽  
B. Ning ◽  
L. Liu ◽  
B. Zhao ◽  
G. Li ◽  
...  
Keyword(s):  
Electron Density ◽  
Solar Maximum ◽  
Correlation Coefficients ◽  
Peak Height ◽  
Retrieval Algorithm ◽  
The North ◽  
F Region ◽  
Maximum Period ◽  
Electron Density Profiles ◽  
Mean Square Errors

Abstract. Although the electron density profiles (EDPs) from Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) measurement have been validated by ionosonde data at a number of locations during the solar minimum period, the performance of COSMIC measurements at different latitudes has not been well evaluated, particularly during the solar maximum period. In this paper the COSMIC ionospheric peak parameters (peak electron density of the F region – NmF2; peak height of the F region – hmF2) are validated by the ionosonde data from an observation chain in China during the solar maximum period of 2011–2013. The validations show that the COSMIC measurement generally agrees well with the ionosonde observation. The error in NmF2 from COSMIC and ionosonde measurements varies with latitude. At midlatitude stations, the differences between COSMIC NmF2s and those of ionosondes are very slight. However, COSMIC NmF2 overestimates (underestimates) that of the ionosonde at the north (south) of the equatorial ionization anomaly (EIA) crest. The relative errors of hmF2s are much lower than those of NmF2s at all stations, which indicates the EDP retrieval algorithm of the COSMIC measurement has a better performance in determining the ionospheric peak height. The root mean square errors (RMSEs) of NmF2s (hmF2s) are higher (lower) during the daytime than during the nighttime at all stations. Correlation analysis shows that the correlations for both NmF2s and hmF2s are comparably good (correlation coefficients > 0.9) at midlatitude stations, while correlations of NmF2 (correlation coefficients > 0.9) are higher than those of hmF2 (correlation coefficients > 0.8) at low-latitude stations.

scholarly journals Characteristics of ionospheric scintillation climatology over Indian low-latitude region during the 24th solar maximum period

2019 ◽  
Vol 10 (2) ◽  
pp. 110-117 ◽  
Author(s):  
K. Sahithi ◽  
M. Sridhar ◽  
Sarat K. Kotamraju ◽  
K.Ch. Sri Kavya ◽  
G. Sivavaraprasad ◽  
...  
Keyword(s):  
Solar Maximum ◽  
Ionospheric Scintillation ◽  
Low Latitude ◽  
Maximum Period ◽  
Latitude Region

scholarly journals Solar Microwave Emission in Active Regions

1985 ◽  
Vol 107 ◽  
pp. 225-230
Author(s):  
B. Lokanadham ◽  
P. K. Subramanian ◽  
M. Sateesh Reddy ◽  
B. M. Reddy ◽  
D. R. Lakshmi
Keyword(s):  
Solar Maximum ◽  
Active Regions ◽  
Peak Frequency ◽  
Microwave Emission ◽  
Emission Mechanism ◽  
Strong Magnetic Fields ◽  
X Ray ◽  
Maximum Period ◽  
Solar Microwave ◽  
Microwave Bursts

Multi–frequency Observations of Solar Microwave bursts recorded during solar maximum period 1980–81 are analysed and compared with x–ray data for studying the nature of microwave emissions from active regions. Most of the microwave burst spectra showed that the spectral index below the peak frequency is always less than 2.The magneto-ionic conditions of the burst sources and the electron energies as obtained from these multi-frequency observations of the bursts showed that the centimetric and x-ray observations are satisfactorily explained, if the emitting regions are dense, hot and compact associated with strong magnetic fields of a few hundred gauss, suggesting that the thermal gyroresonance process is the most likely emission mechanism involved in the emission of microwave and x-ray radiations from the active regions of sun.

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