Storms Of Different Intensity Research Articles

Nitric oxide cooling emission during geomagnetic storm: Case studies

The Nitric Oxide (NO) emission at 5.3 µm is the dominating thermospheric coolant in the altitude above ∼ 100 km. It effectively regulates the thermospheric temperature during space weather events. We studied the diurnal response of the Nitric Oxide at 5.3 µm emission to the geomagnetic storms of different intensities by using the NO emission data from the Sounding of Atmosphere using Broadband Emission Radiometry (SABER) instrument onboard NASA’s Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite. We selected eight CME-driven geomagnetic storms with |SYM-H| index ranging from 0 to 500 nT. One of the storms that occurred during 19–22 November 2003 is investigated in details. Other events are used for comparison. The NO flux and the NO power during different phases of the geomagnetic storms are calculated with 24 h-time bins from the storm’s onset. The NO cooling and the cooling power are always higher during the daytime. Although the NO cooling flux and the cooling power increase with the storm intensity, they are not always higher during the stronger storms.

Impacts of Extreme Space Weather Events on September 6th, 2017 on Ionosphere and Primary Cosmic Rays

The strongest X-class solar flare (SF) event in 24th solar cycle, X9.3, occurred on 6 September 2017, accompanied by earthward-directed coronal mass ejections (CMEs). Such space weather episodes are known to cause various threats to human activities ranging from radio communication and navigation disturbances including wave blackout to producing geomagnetic storms of different intensities. In this study, SFs’ ionospheric impacts and effects of accompanied heliospheric disturbances on primary cosmic rays (CR) are investigated. This work offers the first detailed investigation of characteristics of these extreme events since they were inspected both from the perspective of their electromagnetic nature, through very low frequency (VLF) radio waves, and their corpuscular nature of CR by multi-instrumental approach. Aside data recorded by Belgrade VLF and CR stations, data from GOES and SOHO space probes were used for modeling and analysis. Conducted numerical simulations revealed a significant change of ionospheric parameters (sharpness and effective reflection height) and few orders of magnitude increase of electron density. We compared our findings with those existing in the literature regarding the ionospheric response and corresponding parameters. In addition, Forbush decrease (FD) magnitude, corrected for magnetospheric effect, derived from measurements, and one predicted from power exponents used to parametrize the shape of energetic proton fluence spectra at L1 were compared and found to be in good agreement. Presented findings could be useful for investigation of atmospheric plasma properties, particles’ modeling, and prediction of extreme weather impacts on human activities.

Wavelet analysis based VTEC variability over mid-latitude region Sukkur, Pakistan and its comparison with IRI models during 2019-2020

The Total Electron Content (TEC) from the Sukkur GPS station is studied during the final phase of the solar cycle 24 and the initial phase of solar cycle 25 (2019-2020). TEC comparisons are made with three international reference ionospheric models: IRI-2007, IRI-2012 and IRI-2016. The finding of the study indicates that IRI-2016 is better than IRI-2007 and IRI-2012 in monthly values using wavelet transformation. Moreover, the seasonal variations between observed and modelled VTEC were observed maximum during the spring season. Similarly, the IRI-2016 exhibited maximum correlation (i.e., r > 0.8) as compared to the other two models for both solar cycle phases. This study also includes a cross-correlation of GPS-VTEC with several storm indices (Kp, Dst, Ap) via wavelet transformation. In this paper, the wavelet spectrum is analysed for two-year data (2019-2020) to visualize the impact of geomagnetic storm indices on VTEC. Storms of different intensities during 2019-2020 solar activity were also analysed, where maximum correlation from wavelet transformation between GPS VTEC and geomagnetic indices was recorded during the initial solar phase of cycle 25. These kinds of studies assist to correct the measured GPS VTEC and help to improve predicted VTEC over mid-latitude regions.

Timelines as a tool for learning about space weather storms

Space weather storms typically have solar, interplanetary, geophysical and societal-effect components that overlap in time, making it hard for students and novices to determine cause-and-effect relationships and relative timing. To address this issue, we use timelines to provide context for space weather storms of different intensities. First, we present a timeline and tabular description for the great auroral storms of the last 500 years as an example for space climate. The graphical summary for these 14 events suggests that they occur about every 40–60 years, although the distribution of such events is far from even. One outstanding event in 1770 may qualify as a one-in-500-year auroral event, based on duration. Additionally, we present two examples that describe space weather storms using solar, geospace and effects categories. The first of these is for the prolonged storm sequence of late January 1938 that produced low-latitude auroras and space weather impacts on mature technology (telegraphs) and on high frequency radio communication for aviation, which was a developing technology. To illustrate storm effects in the space-age, we produce a detailed timeline for the strong December 2006 geomagnetic storm that impacted numerous space-based technologies for monitoring space weather and for communication and navigation. During this event there were numerous navigations system disturbances and hardware disruptions. We adopt terminology developed in many previous space weather studies and blend it with historical accounts to create graphical timelines to help organize and disentangle the events presented herein.

Evaluating and improving the sand storm numerical simulation performance in Northwestern China using WRF-Chem and remote sensing soil moisture data

This paper aims to test the ability of the WRF-Chem model to simulate sand storms in Northwest China and improve the simulation results by introducing remote sensing soil moisture data into WRF-Chem. We conducted sensitivity tests, including parameterization scheme tests and soil moisture tests using WRF-Chem. By comparing various combinations of parameterization schemes, which have considerable impacts on sand emissions, the most suitable parameterization scheme for WRF-Chem to simulate sand storms in Northwest China was selected for establishing models in future research. Based on the optimal combination of parameterization schemes, the sensitivity of sand emissions to soil moisture was tested, indicating that soil moisture has a substantial influence on sand emissions and revealing a nonlinear relationship between sand emissions and soil moisture. Although sand simulations are sensitive to soil moisture, the sand emission volume does not always increase with decreasing soil moisture content. Moreover, the soil moisture content simulated by WRF-Chem is quite different from that observed by satellites. Therefore, we selected ten sand storms that occurred in Northwest China in 2009–2018, including weak, moderate and strong sand storms, to explore the responses of sand storms of different intensities to soil moisture. Some experiments were conducted in two scenarios: scenario A was simulated only by WRF-Chem, and scenario B was designed by replacing the initial soil moisture field in WRF-Chem with soil moisture satellite data from AMSR2 and AMSR-E. Comparing the simulation results with in-situ ground-based and satellite-based measurements indicates that WRF-Chem can capture strong sand storms and some moderate sand storms, but the ability to simulate weak sand storms needs to be greatly improved. After introducing remote sensing soil moisture data into WRF-Chem, the simulation of sand emissions becomes more accurate, substantially improving the simulation results. Among the ten simulated sand storms, the AOD (aerosol optical depth) and PM10 simulation accuracies are improved for five and seven sand storms, respectively. After this improvement, the AOD correlation coefficient can reach 0.63, and the PM10 correlation coefficient can reach 0.60.

A Comparison of Low-Cost Collector Configurations for Quantifying Ice Accretion

AbstractIce storms are important winter weather events that can have substantial environmental, economic, and social impacts. Mapping and assessment of damage after these events could be improved by making ice accretion measurements at a greater number of sites than is currently available. There is a need for low-cost collectors that can be distributed broadly in volunteer observation networks; however, use of low-cost collectors necessitates understanding of how collector characteristics and configurations influence measurements of ice accretion. A study was conducted at the Hubbard Brook Experimental Forest in New Hampshire that involved spraying water over passive ice collectors during freezing conditions to simulate ice storms of different intensity. The collectors consisted of plates composed of four different materials and installed horizontally; two different types of wires strung horizontally; and rods of three different materials, with three different diameters, and installed at three different inclinations. Results showed that planar ice thickness on plates was 2.5–3 times as great as the radial ice thickness on rods or wires, which is consistent with expectations based on theory and empirical evidence from previous studies. Rods mounted on an angle rather than horizontally reduced the formation of icicles and enabled more consistent measurements. Results such as these provide much needed information for comparing ice accretion data. Understanding of relationships among collector configurations could be refined further by collecting data from natural ice storms under a broader range of weather conditions.

Dynamic wavelet fingerprint for differentiation of tweet storm types

We describe a novel method for analyzing topics extracted from Twitter by utilizing the dynamic wavelet fingerprint technique (DWFT). Topics are derived from 7 different tweet storms analyzed in the study by using a dynamic topic model. Using the time series of each topic, we run DWFT analyses to get a two-dimensional, time-scale, binary image. Gaussian mixture model clustering is used to identify individual objects, or storm cells, that are characteristic to specific local behaviors commonly occurring in topics. The DWFT time series transformation is volume agnostic, meaning we can compare tweet storms of different intensities. We find that we can identify behavior, localized in time, that is characteristic to how different topics propagate through Twitter. The use of dynamic topic models and the DWFT create the basis for future applications as a real-time Twitter analysis system for flagging fake news.

Thermospheric Heating and Cooling Times During Geomagnetic Storms, Including Extreme Events

AbstractWe present the first quantitative calculations of thermospheric heating and cooling times for geomagnetic storms of different intensity, including extreme events. We utilize the neutral mass density database of the CHAllenging Mini‐satellite Payload and Gravity Recovery And Climate Experiment missions to produce thermospheric global system response to geomagnetic storms caused by coronal mass ejections via superposed epoch analysis during May 2001 to December 2015. Storm events are grouped in five different categories based on the minimum value of the SYM‐H index. We calculate the time from storm onset for the thermosphere to reach maximum intensification (heating time) and the time from onset for the thermosphere to recover (cooling time). We find that heating and cooling times decrease as storm intensity increases and the effect is more pronounced for the cooling times. For extreme storms, the thermospheric heating time is 9.5 hr, while the cooling time is 22 hr.

Modeling of GPS-TEC using QR-decomposition over the low latitude sector during disturbed geomagnetic conditions

Given the continuous operation of satellite-based navigation applications, modeling of Total Electron Content (TEC) during magnetic disturbed periods is a significant challenge. The Global Positioning System (GPS)-TEC observations of the Bangalore station (13.02°N, 77.57°E) has been considered and covers the period (2009–2016) of the solar cycle 24. The study emphases on the analysis of TEC variations in eight geomagnetic storms of different intensity: (−223 nT < Dst < −80 nT). The QR decomposition is computed using the Gram-Schmidt (GS) process and is based on observational data from low latitude sectors. For interpolation, the QR model was evaluated on storms that occurred during different periods of solar activity (2009–2016), while for extrapolation the assessment was conducted for the intense storm of March 17, 2015 (St. Patrick's Day storm: Dst −223 nT) in different latitudes, covering the Asian sector between 10°N and 26°N. The R1 and Q1 modes patterns are consistent with changes in the solar proxy index (F10.7) and with regular daily variations and the correlation coefficient is 0.80 and 0.99. The post-residue between the QR model TEC and the GPS- TEC values is ±3 TECU. The QR model captured the TEC responses in consecutive storm cases (18–24, February 2014).The spatial variation of the TEC deviations increases as it moves towards the Equatorial Ionization Anomaly (EIA) crest from the magnetic equator and decreases beyond the crest. The proposed work could be useful for the further study of the Global Navigation Satellite System (GNSS) performance during geomagnetic magnetic disturbed periods.

Ionosphere modeling in the context of Algerian Satellite-based Augmentation System

To guarantee safety-critical implementation of Algerian Satellite-based Augmentation Systems (SBAS), a comprehensive study of the impact of space weather on Global Navigation Satellite Systems (GNSS) over this region is necessary. In this work, three typical ionospheric algorithms: inverse distance weighting (IDW), kriging, and planar-fit were applied on GPS dual-frequency data from seven GPS stations spread over Algerian territory during three major geomagnetic storms of different intensity in addition to a quiet geomagnetic period. The performance of these ionospheric algorithms was investigated based on the broadcast ionospheric vertical delay (Grid Ionospheric Vertical Delay, GIVD) and its corresponding confidence bound error (Grid Ionospheric Vertical Error, GIVE) at two Ionospheric Grid Points (IGPs): (35°N, 5°E) and (30°N, 5°E), located in the Algerian mid-latitudes. The obtained GIVDs were compared to their corresponding delays estimated at nearby user stations as a first reference and to EGNOS messages as a second reference. In addition, the Global Ionospheric Maps (GIMs) from the International GNSS Service (IGS) was incorporated in the analysis. Our results indicate that the studied models provided equivalent accuracy even though kriging slightly outperformed the other models in most of the cases of study. The EGNOS model showed less agreement with the ground truth data during 2013 and 2015, while in 2017 became more accurate after the upgrade. The analysis of estimated GIVEs shows the ability of the three ionospheric models to protect and to safely bound GIVD errors while kriging is intended to provide better availability of Algerian SBAS. In addition, EGNOS GIVEs exhibit effective protection of users at the edge of its service area.

Distribution of intense, moderate and weak geomagnetic storms over the solar cycle

The geomagnetic storms observed during different phases of a solar cycle have distinct primary solar sources. Therefore, we have statistically examined, in the present study, how the geomagnetic storms of different intensities are distributed over a solar cycle. We have considered previous four cycles, viz. cycle 21, 22, 23 and 24. We selected all the storms which were observed during these cycles and classified them into three categories as: intense (Dst ≤ − 100 nT), moderate (− 100 ≤ Dst ≤ − 50) and weak (− 50 ≤ Dst ≤ − 30). We found that geomagnetic storms are distributed in such a way that maximum number of intense storms occur around peak phase of a solar cycle, while maximum number of weak storms occur during the starting and ending phases of a cycle. About 73.20% of intense storms, 58.07% and 47.93% of moderate and weak storms occurred around the peak of a cycle. Therefore, it was concluded that peak phase is dominated by intense and very intense storms due to increase in frequency of occurrence of coronal mass ejections during such periods. At the same time, the ending phase of solar cycle is dominated by the occurrence of weak storms due to the frequent occurrences of fast solar wind streams during such periods. Moreover, the total number of storms occurring during the descending phase is greater than those observed during the ascending phase. The storms with peak Dst ≤ − 200 nT were classified as very intense and designated as outstanding Sun–Earth connections. It was found that 90% of such events occur around the peak phase of solar cycle. Therefore, it was concluded that the high-risk events occur during the peak phase of a solar cycle. Therefore, extreme care must be taken while launching new space missions and operating the existing ones, during this period.

Impact of magnetic storms on the global TEC distribution

Abstract. The study is focused on the analysis of total electron content (TEC) variations during six geomagnetic storms of different intensity: from Dstmin=-46 nT to Dstmin=-223 nT. The values of TEC deviations from its 27-day median value (δTEC) were calculated during the periods of the storms along three meridians: American, Euro-African and Asian-Australian. The following results were obtained. For the majority of the storms almost simultaneous occurrence of δTEC maximums was observed along all three meridians at the beginning of the storm. The transition from a weak storm to a superstorm (the increase of magnetic activity) almost does not affect the intensity of the δTEC maximum. The seasonal effect was most pronounced along the Asian-Australian meridian, less often along the Euro-African meridian and was not revealed along the American meridian. Sometimes the seasonal effect can penetrate to the opposite hemisphere. The character of average δTEC variations for the intense storms was confirmed by GOES satellite data. Though there are some common features of TEC variation revealed during each storm phase, in general no clear dependence of TEC responses on the storm phases was found: the effects were different during each storm at different locations. The behavior of the correlation coefficient (R) between δTEC values along the three meridians was analyzed for each storm. In general, R&gt;0.5 between δTEC values averaged along each meridian. This result is new. The possible reasons for the exceptions (when R&lt;0.5) were provided: the complexity of phenomena during the intense storms and discordance in local time of the geomagnetic storm beginning along different meridians. Notwithstanding the complex dependence of R on the intensity of magnetic disturbance, in general R decreased with the growth of storm intensity.

Dynamics of the ring current–magnetotail currents relationships during geomagnetic storms of different intensity

The results of studying the intensity of fluxes of 30–80 keV ions from the data of measurements of the NOAA (POES) sun-synchronous satellites during geomagnetic storms of different intensity are presented. For 15 geomagnetic storms with |Dst|max from ~37 to ~422 nT, the storm-time maximum ion fluxes in the near-equatorial region (trapped particles) and at high latitudes (precipitating particles) have been considered. It is shown that the maximum fluxes of trapped particles, which are considered a ring-current proxy, increase with the storm power. In this case, if a smooth growth of fluxes is recorded for storms with |Dst|max 250 nT. This may be evidence of both an increasing of the contribution of the ring current relative to magnetotail currents to the development of high-intensity storms and to a nonlinear link between the ring current and ion fluxes at low altitudes in the near-equatorial region. Despite large variations in fluxes of precipitating particles in the polar region above the boundary of isotropization, a decreasing tendency, as a whole, in fluxes of these particles is observed with increasing the storm intensity. This is the evidence of the effect of saturation of magnetotail currents and of an increase in the relative role of the ring current during strong magnetic storms.

Effect of ionospheric irregularities on GPS signals during declining phase of solar cycle 23 at Bhopal

The present investigation is dedicated to the evaluation of GPS performance under disturbed geomagnetic conditions at the equatorial region. When GPS signals encounter the ionospheric irregularities of different size developed during high geomagnetic or solar activity, they undergo rapid changes in their phase and amplitude, known as scintillations. We have studied the occurrence characteristics of scintillation events during geomagnetic storms of different intensity at the crest of equatorial anomaly station Bhopal (23.2N, 77.6E). To accomplish this study we have used two data sets: Disturbed Storm Time (Dst) index and Amplitude Scintillation (S4) index. The geomagnetic storm activity is characterized by the Dst index and the evaluation of GPS performance during disturbed geomagnetic condition is realized through S4 index. We have selected thirty one geomagnetic storms that occurred during the year 2004 and 2005. We then classified these geomagnetic storms and scintillation events into weak, moderate and intense and weak, moderate and strong according to Dst index and S4 index respectively. During all the storm events we observed a good number of scintillation events. We then performed the correlation analysis between the Dst index and S4 index, to find out the impact of storm intensity on the occurrence of scintillation events.

Shifts in biomass and productivity for a subtropical dry forest in response to simulated elevated hurricane disturbances

Caribbean tropical forests are subject to hurricane disturbances of great variability. In addition to natural storm incongruity, climate change can alter storm formation, duration, frequency, and intensity. This model-based investigation assessed the impacts of multiple storms of different intensities and occurrence frequencies on the long-term dynamics of subtropical dry forests in Puerto Rico. Using the previously validated individual-based gap model ZELIG-TROP, we developed a new hurricane damage routine and parameterized it with site- and species-specific hurricane effects. A baseline case with the reconstructed historical hurricane regime represented the control condition. Ten treatment cases, reflecting plausible shifts in hurricane regimes, manipulated both hurricane return time (i.e. frequency) and hurricane intensity. The treatment-related change in carbon storage and fluxes were reported as changes in aboveground forest biomass (AGB), net primary productivity (NPP), and in the aboveground carbon partitioning components, or annual carbon accumulation (ACA). Increasing the frequency of hurricanes decreased aboveground biomass by between 5% and 39%, and increased NPP between 32% and 50%. Decadal-scale biomass fluctuations were damped relative to the control. In contrast, increasing hurricane intensity did not create a large shift in the long-term average forest structure, NPP, or ACA from that of historical hurricane regimes, but produced large fluctuations in biomass. Decreasing both the hurricane intensity and frequency by 50% produced the highest values of biomass and NPP. For the control scenario and with increased hurricane intensity, ACA was negative, which indicated that the aboveground forest components acted as a carbon source. However, with an increase in the frequency of storms or decreased storms, the total ACA was positive due to shifts in leaf production, annual litterfall, and coarse woody debris inputs, indicating a carbon sink into the forest over the long-term. The carbon loss from each hurricane event, in all scenarios, always recovered over sufficient time. Our results suggest that subtropical dry forests will remain resilient to hurricane disturbance. However carbon stocks will decrease if future climates increase hurricane frequency by 50% or more.

Geomagnetic storms, super‐storms, and their impacts on GPS‐based navigation systems

AbstractUsing data of GPS receivers located worldwide, we analyze the quality of GPS performance during four geomagnetic storms of different intensity: two super‐storms and two intense storms. We show that during super‐storms the density of GPS Losses‐of‐Lock (LoL) increases up to 0.25% at L1 frequency and up to 3% at L2 frequency, and up to 0.15% (at L1) and 1% (at L2) during less intense storms. Also, depending on the intensity of the storm time ionospheric disturbances, the total number of total electron content (TEC) slips can exceed from 4 to 40 times the quiet time level. Both GPS LoL and TEC slips occur during abrupt changes of SYM‐H index of geomagnetic activity, i.e., during the main phase of geomagnetic storms and during development of ionospheric storms. The main contribution in the total number of GPS LoL was found to be done by GPS sites located at low and high latitudes, whereas the area of numerous TEC slips seemed to mostly correspond to the boundary of the auroral oval, i.e., region with intensive ionospheric irregularities. Our global maps of TEC slips show where the regions with intense irregularities of electron density occur during geomagnetic storms and will let us in future predict appearance of GPS errors for geomagnetically disturbed conditions.

The Earth’s magnetosphere response to interplanetary medium conditions on January 21–22, 2005 and on December 14–15, 2006

The Earth’s magnetosphere response to interplanetary medium conditions on January 21–22, 2005 and on December 14–15, 2006 has been studied. The analysis of solar wind parameters measured by ACE spacecraft, of geomagnetic indices variations, of geomagnetic field measured by GOES 11, 12 satellites, and of energetic particle fluxes measured by POES 15, 16, 17 satellites was performed together with magnetospheric modeling based in terms of A2000 paraboloid model. We found the similar dynamics of three particle populations (trapped, quasi-trapped, and precipitating) during storms of different intensities developed under different external conditions: the maximal values of particle fluxes and the latitudinal positions of the isotropic boundaries were approximately the same. The main sources caused RC build-up have been determined for both magnetic storms. Global magnetospheric convection controlled by IMF and substorm activity driven magnetic storm on December 14–15, 2006. Extreme solar wind pressure pulse was mainly responsible for RC particle injection and unusual January 21, 2005 magnetic storm development under northward IMF during the main phase.

Variaciones del quimismo del arroyo durante las crecidas en una cuenca de encinar montano

Streamwater changes during storm events are investigated in a small evergreen-oak forested watershed in the Montseny mountains (NE Spain). Results from two storms of different intensities that took place under dry antecedent conditions are discussed in terms of ion sources and runoff mechanisms. Dilution effects were found for conductivity, pH, HC03, Ca2+, Na+ and Mg2+ while K+ and N03 usually increased with discharge, sometimes dramatically. Substantial and sustained in creases of S04 - and elin storm runoff were also observed. A principal component analysis helps in summarizing the data.

Improving Geostationary Satellite Rainfall Estimates Using Lightning Observations: Underlying Lightning–Rainfall–Cloud Relationships

AbstractThis study quantifies the relationships among lightning activity, convective rainfall, and associated cloud properties on both convective-system scale (or storm scale) and satellite-pixel scale (~5 km) on the basis of 13 yr of Tropical Rainfall Measuring Mission measurements of rainfall, lightning, and clouds. Results show that lightning frequency is a good proxy to separate storms of different intensity, identify convective cores, and screen out false convective-core signatures in areas of thick anvil debris. Significant correlations are found between storm-scale lightning parameters and convective rainfall for systems over the southern United States, the focus area of the study. Storm-scale convective rainfall or heavy-precipitation area has the best correlation (coefficient r = 0.75–0.85) with lightning-flash area. It also increases linearly with increasing lightning-flash rate, although correlations between convective/heavy rainfall and lightning-flash rate are somewhat weaker (r = 0.55–0.75). Statistics further show that active lightning and intense precipitation are not well collocated on the pixel scale (5 km); for example, only 50% of the lightning flashes are coincident with heavy-rain cores, and more than 20% are distributed in light-rain areas. Simple positive correlations between lightning-flash rate and precipitation intensity are weak on the pixel scale. Lightning frequency and rain intensity have positive probabilistic relationships, however: the probability of heavy precipitation, especially on a coarser pixel scale (~20 km), increases with increasing lightning-flash density. Therefore, discrete thresholds of lightning density could be applied in a rainfall estimation scheme to assign precipitation in specific rate categories.

Electron flux changes in the outer radiation belt by radial diffusion during the storm recovery phase in comparison with the fully adiabatic evolution

[1] The radial diffusion process can play an important role in redistributing the radiation belt electron fluxes. In this work, we have performed 1-D radial diffusion simulations to examine the evolution of the phase space density (PSD) of the outer radiation belt electrons and to estimate the corresponding fluxes during the storm recovery phase. The key element that distinguishes our simulations from previous works is the initial condition for PSD, which is characterized by a steep radial gradient across the trapping boundary. In our simulations, this condition is formed as a result of the drift loss effect of particles during the storm main phase, and the simulations of radial diffusion were run for the storm recovery phase. We performed the study for three classes of geomagnetic storms of different intensities, i.e., the moderate (−100 nT < Dstmin ≤ −50 nT), strong (−150 nT < Dstmin ≤ −100 nT), and severe (Dstmin ≤ −150 nT) storms. The effects of radial diffusion in PSD are notable in the following respects. First, the radial diffusion process is very significant for the initial few hours of the storm recovery phase. Second, the effect of the radial diffusion occurs in both inward and outward directions, thus affecting a wide range of L regions. The inward diffusion causes the PSD peak to move inward. The regions outside of the initial trapping boundary are refilled with finite PSD by the outward radial diffusion. Consequently, the combination of these effects results in different levels and patterns in the directional and omni-directional fluxes from those expected from a fully adiabatic evolution throughout the entire storm period. Last, the details of the PSD evolution, and thus its effect on the corresponding flux levels and patterns, differ among storms of different intensities. We report these differences in detail.