Investigation of the relation between space-weather parameters and Forbush decreases automatically selected from Moscow and Apatity cosmic ray stations during solar cycle 23

We present the results of an investigation of the relation between space-weather parameters and cosmic ray (CR) intensity modulation using algorithm-selected Forbush decreases (FDs) from Moscow (MOSC) and Apatity (APTY) neutron monitor (NM) stations during solar cycle 23. Our FD location program detected 408 and 383 FDs from MOSC and APTY NM stations respectively. A coincident computer code employed in this work detected 229 FDs that were observed at the same Universal Time (UT) at the two stations. Out of the 229 simultaneous FDs, we formed a subset of 139 large FDs(%) ≤ − 4 at the MOSC station. We performed a two-dimensional regression analysis between the FD magnitudes and the space-weather data on the two samples. We find that there were significant space-weather disturbances at the time of the CR flux depressions. The correlation between the space-weather parameters and decreases in galactic cosmic ray (GCR) intensity at the two NM stations is statistically significant. The implications of the present space-weather data on CR intensity depressions are highlighted.

The Mansurov Effect: Real or a statistical artefact?

<p>The Mansurov Effect is related to the interplanetary magnetic field (IMF) and its ability to modulate the global electric circuit, which is further hypothesized to impact the polar troposphere through cloud generation processes. In this paper we investigate the connection between IMF By-component and polar surface pressure by using daily ERA5 reanalysis for geopotential height since 1980. Previous studies have shown to produce a significant 27-day cyclic response during solar cycle 23. However, when appropriate statistical tests are applied, the correlation is not significant at the 95% level. Our results also show that data from three other solar cycles, which have not been investigated before, produce similar cyclic responses as during solar cycle 23, but with seemingly random offset in the timing of the signal. We examine the origin of the cyclic pattern occurring in the super epoch/lead lag regression methods commonly used to support the Mansurov hypothesis in all recent papers, as well as other phenomena in this community. By generating random normally distributed noise with different levels of temporal autocorrelation, and using the real IMF By-index as forcing, we show that the methods applied to support the Mansurov hypothesis up to now, are highly susceptible, as cyclic patterns always occurs as artefacts of the methods. This, in addition to the lack of significance, suggests that there is no adequate evidence in support of the Mansurov Effect.</p>

Sunspots Influence on Climatic Variability of Karachi and Rohri

The Sun is undoubtedly the most important thrust of the climate system. However, only little is known how variable this force is acting on different time scales ranging from minutes to millennia and how the climate system reacts to changes in this forcing. In the present study possible effect of solar activity on maximum temperature T (max) and minimum temperature T (min), humidity and precipitation have been investigated. The analysis comprises over a period of 2000-2015 that consists of the decreasing phase of solar cycle-23 and the increasing phase of solar cycle-24. To optimize the number of signicant trends, different phases of solar activity have been implemented there to observe the variation in climate of Karachi and Rohri in response of it. These detection and adjustment are carried out using the computer software Statistica and Minitab. Correlation analysis for different seasons of these two regions is performed in this study.

The Statistical Analysis of Characteristics of Coronal Mass Ejection During the Descending Phase of Solar Cycle 23 and 24

The characteristics of CMEs we studied are angular width, linear speed, and acceleration for all categories of CMEs such as narrow (W ≤20°), intermediate (20°< W<200°), wide (W ≥ 200°) and linear speed <500 km/s during the descending phase of solar cycle 23 and 24 and compared them. We have found that there are 1951 narrow CMEs during solar cycle 23 that is 1.9 times greater than in solar cycle 24 (1047). On the other side, the number of intermediate CMEs during solar cycle 24 (1571) is 1.14 times more than solar cycle 23 (1162). We observed no noticeable difference between the number of wide CMEs of solar cycle 23 (29) and 24 (36). The angular width of CMEs during the descending phase of solar cycle 23 and solar cycle 24, predominately distributed around 100-600. The fascinating result is that the angular width distributions for the descending phase of solar cycles are approximately identical. On comparing the results of linear speed of both solar cycle, we can say that, (i) 93.7% (1729) and 87.7% (908) of narrow CMEs, (ii) 97% (1328) and 94% (1479) of intermediate CMEs and (iii) 44% (13) and 42% (15) of wide CMEs have speed of <500 km s-1, respectively. Mostly the fractions of narrow and intermediate CMEs decline sharply at the speeds greater than 500 km s-1. The maximum speed observed during the 23rd cycle is 1994 km/s (wide CME) and the 24th cycle is 3163 km/s (wide CME) respectively. It was noticed that the speed of the 24th solar cycle CME is higher than the 23rd solar cycle CME. The major fraction of CMEs has acceleration in the range of -20 to 20 km s-2, all types of CMEs. The narrow and intermediate CMEs mostly show acceleration while wide CMEs show deceleration.