Strong Storm Research Articles

Extreme and severe convective weather disasters: A dual-polarization radar nowcasting method based on physical constraints and a deep neural network model

It is difficult for traditional methods, such as the PySTEPS method, which is based on optical flows, and the UNet method, which is based on convolutional neural networks, to predict extreme weather events (e.g., hail, heavy rain, lightning and mesoscale cyclones) 0–60 min in advance because these events have short life cycles, occur at small scales, rapidly develop and are highly nonlinear. Based on the structural characteristics of severe weather, we propose a physically constrained generative adversarial deep neural network nowcasting model to improve the prediction accuracy and blurry data problem associated with nowcasting extreme convective weather within the 0–60 min interval. The improved TITAN algorithm is used to quickly identify and match strong storm cells in three dimensions, and the convection-diffusion constraint equation is established. Additionally, reflectivity (Zh), differential reflectivity (Zdr), the range derivative-specific differential phase (Kdp), correlation coefficient (cc), precipitation particle phase, and velocity divergence are considered when training the model with a large sample set, and constraint equations are used for optimization. The critical success index, false alarm ratio and miss probability scores of the nowcasting results obtained with this method are better than the PySTEPS and UNet results. Additionally, the root mean square error of a hailstorm nowcasted with a 30-min lead time is significantly better than that of the other methods, and the blurry data problem that appears over time is mitigated. We show that our model can provide nowcasts with high precision to support operations at various resolutions and lead times in cases for which alternative methods struggle.

Comparison on two different methods for assessment of population fertility of the Okhotsk herring on the data of standard roe survey

The main part of the spawning grounds of herring in the northwestern Okhotsk Sea, from the Ayan Bay to the Eirineiskaya Bay, was surveyed on June 3–21, 2022 using standard methods of the roe diving survey. In order to rationalize the survey methodology, the herring population fertility (PF) was evaluated using two different approaches. The first is a standard method (described by Farkhutdinov, 2005) with calculation of the spawning ground areas and the roe density (RD) for each of them. The second method is based on the relationship between the total area of spawning grounds and PF detected previously by Dulenin and Didenko (2021). The spawning conditions for Okhotsk herring were abnormal in 2022. Just before the mass spawning, a strong storm had destroyed many spawning substrates and redistributed the spawning shoals of herring in the coastal zone. As the result, mean RD was extremely low – 1075318 eggs/m2 (long-term average value was 4170320 eggs/m2), but herring spawned in new areas, additionally to usual spawning grounds, so the total area of surveyed spawning grounds was rather large, as 38.68 km2. The population fertility calculated for this total area using the relationship between these indices was 182 . 1012 eggs that corresponded to the spawning stock number (SSN) of 6.513 . 109 ind. and the spawning stock biomass (SSB) of 1.823 . 106 t. These estimates match well with results of the stock assessment by other methods. On the contrary, unrealistic low assessments were provided using the routine method with calculation of RD on the annually surveyed spawning grounds (PF 51 . 1012 eggs, SSN 1.936 . 109 ind., SSB 0.542 . 106 t), because the spawning on destructed substrate could not represent adequately the state of the herring population during 2–3 years, until restoration of the algae belt. Besides, the standard method for data processing of the roe diving surveys is based on a number of non-formalized subjective assessments and assumptions that cannot ensure verification of the survey results. In opposite to this disadvantage, the calculation of PF by the area of spawning grounds is methodologically simple and allows to use remotely operated underwater vehicles, unmanned aerial vehicles and geographic information systems, with complete hardware and software documentation of survey materials. Thus, the PF evaluation using its relationship with the total area of spawning grounds is recommended for introduction as the main method of the Okhotsk herring stock assessment.

Critical Pre-Formation Decision Flowchart to Apply Tropical Cyclone Lifecycle Predictions in Eastern North Pacific

We have previously demonstrated that the ECMWF ensemble (ECEPS) provides early forecasts not only of the Time-to-Tropical Storm (T2TS) and of the Time-to-Hurricane (T2HU), but also of the Time-Ending-Hurricane (TEHU) and Time-Ending-Tropical Storm (TETS) times and positions along those 15-day ECEPS track forecasts, which then provides an opportunity for high-wind warnings along the path during the entire lifecycle of these Hurricanes. The focus in this study is the Decision Flowchart that has been developed to assist the forecasters to select the pre-formation disturbance that is most likely to become the next Tropical Storm with the potential to become a Hurricane. The most crucial decision is to detect and eliminate any disturbance that likely originated from a precursor Caribbean false alarm circulation. Summaries of other steps in the Decision Flowchart “To Watch”, or to reject, other storm options in the twice-daily ECEPS forecasts are provided for Hurricanes Enrique and Felicia, and for strong Tropical Storm Guillermo and weak Tropical Storm Jimena. The first detections in the ECEPS forecasts for the Tropical Storms during the 2021 season averaged 6 days, 18 h in advance with a range of only 2 days, 6 h in advance for TS Terry to 9 days, 18 h in advance for TS Sandra.

Simulating a Strong Magnetic Storm Impact on Russia’s Interconnected Power System of Center

Studying of a negative impact of the space weather and magnetic storms as its special case, on the performance of a critical technological infrastructure, with development of methods and means for protecting it is a relevant but difficult task. Many advanced countries, primarily the United States, are dealing with this problem. The article presents the results of elaborating a methodology for computational simulation of the impact of geomagnetically induced currents on large electric power systems. The developed methodology makes it possible to take into account the influence of changes in the reactive power and temperature of power transformer structural elements caused by magnetic biasing of their core, as well as the operation of relay protection. The impact of the geomagnetically induced currents expected during a strong magnetic storm on Russia’s Interconnected Power System of Center, including the power systems of Moscow, Leningrad and other major administrative and industrial regions of the country has been simulated for the first time. It is shown that such impact gives rise to a set of factors that can cause the development of a system-wide accident: a significant decrease in voltage at a number of power system facilities, mass-scale disconnection of power lines by their relay protections, and unacceptable heating of structural elements of some power transformers.

Storm Time Electrified MSTIDs Observed Over Mid‐Latitude North America

AbstractMedium‐scale Traveling Ionospheric Disturbances (MSTIDs) are prominent and ubiquitous features of the mid‐latitude ionosphere, and are observed in Super Dual Auroral Radar Network (SuperDARN) and high‐resolution Global Navigational Satellite Service (GNSS) Total Electron Content (TEC) data. The mechanisms driving these MSTIDs are an open area of research, especially during geomagnetic storms. Previous studies have demonstrated that nightside MSTIDs are associated with an electrodynamic instability mechanism like Perkins, especially during geomagnetically quiet conditions. However, dayside MSTIDs are often associated with atmospheric gravity waves. Very few studies have analyzed the mechanisms driving MSTIDs during strong geomagnetic storms at mid‐latitudes. In this study, we present mid‐latitude MSTIDs observed in de‐trended GNSS TEC data and SuperDARN radars over the North American sector, during a geomagnetic storm (peak Kp reaching 9) on 7–8 September 2017. In SuperDARN, MSTIDs were observed in ionospheric backscatter with Line of Sight (LOS) velocities exceeding 800 m/s. Additionally, radar LOS velocities oscillated with amplitudes reaching ±500 m/s as the MSTIDs passed through the fields‐of‐view. In detrended TEC, these MSTIDs produced perturbations reaching ∼50 percent of background TEC magnitude. The MSTIDs were observed to propagate in the westward/south‐westward direction with a time period of ∼15 min. Projecting de‐trended GNSS TEC data along SuperDARN beams showed that enhancements in TEC were correlated with enhancements in SuperDARN SNR and positive LOS velocities. Finally, SuperDARN LOS velocities systematically switched polarities between the crests and the troughs of the MSTIDs, indicating the presence of polarization electric fields and an electrodynamic instability process during these MSTIDs.

Global Ionospheric Response to Intense Variations of Solar and Geomagnetic Activity According to the Data of the GNSS Global Networks of Navigation Receivers

The global response of the ionosphere to intense geomagnetic storms and variations of the solaractivity according to the solar flux F10.7 is considered. As a source of information, data on total electron content(TEC) calculated from measurements of the global network of receivers of the global navigation satellitesystems are used. Unlike many publications, where the effects of individual unique geophysical events arestudied in detail (for example, the superstorm of October 28, 2003), we considered the effects of strong storms(Dst ≤ –80 nT) starting from 2005. The main attention was paid to the dependence on the onset time of themain phase of the storm relative to local time/longitude, as well as the dependence of the intensity of the ionosphericresponse on latitude. To display the ionospheric effects of magnetic storms, a visual image was used – atwo-dimensional representation in the day-local time format, which was used to visualize ionospheric earthquakeprecursors. This approach also makes it possible to visualize the effects of solar activity variations accordingto the F10.7 index and to distinguish them from ionospheric variations during geomagnetic storms. As aresult, it was possible to create a generalized global “pattern” of a geomagnetic storm in the Earth’s ionosphere

Influence of Complex Hydraulic Environments on the Mechanical Properties of Pile-Soil Composite Foundation in the Coastal Soft Soil Area of Zhuhai

Based on a plain concrete pile composite foundation project in the coastal area of Zhuhai, considering the complex hydraulic load environment induced by tidal water-level changes, finite element simulations and parameter calibrations were carried out to determine the physical and mechanical properties of plain concrete pile composite foundation. The hardening soil small (HSS) model, which can be used to simulate the complex mechanical behavior of soft soil under small strain, was selected for modeling analysis. Model parameters were calibrated through resonance column tests, triaxial consolidation drainage loading and unloading shear tests. The complex hydraulic loads were analyzed, including the effects of cyclic tidal action and the sudden rise and fall of the water level induced by strong storm surges on the force, deformation of plain concrete piles, and the mechanical seepage properties of soft soil around piles. The results indicate that: (1) Compared with coastal soft soil in Shanghai, Zhoushan, Tianjin, and other areas, the soft soil in the Zhuhai area has a smaller dynamic shear modulus, cohesion and internal friction angle, and worse engineering properties. (2) The sudden rise of water level leads to a sudden change in the pore pressure of the groundwater, which induces a large deformation of the pile-soil composite foundation. If the foundation on the offshore (dike) side exhibits the most prominent deformation and foundation damage, such as uneven settlement is prone to occur. (3) The offshore side pile is most affected by the hydraulic loads. The deformation of the pile body along the pile body is uneven and the deformation of the upper pile body is relatively large, which may cause fracture damage.

Widespread stem snapping but limited mortality caused by a category 5 hurricane on the Caribbean Island of Dominica

Hurricanes are projected to increase in frequency and severity over the coming century, and predicting the effects of strong hurricanes on forest communities requires an understanding of the damage patterns caused to individual trees and what drives those damage patterns. To better understand damage patterns caused by a category 5 hurricane, we censused nine permanent vegetation plots across the island of Dominica, West Indies, nine months after Hurricane Maria took a direct path over the island. We measured size, damage, and mortality for all adult trees, and measured wood density and carbon content for the 44 most common species to calculate biomass and carbon relocation from the hurricane. Despite widespread major tree damage (76% of trees), mortality nine months after the hurricane was relatively low (10% of trees). The most common damage types were stem snapping (40% of trees) and major branch damage (26% of trees), but the damage types with the highest rates of mortality were uprooting and being crushed by a neighboring tree (33% and 47% of uprooted and crushed trees died, respectively). Larger individual trees and species with lower wood density were more susceptible to snapping, uprooting and mortality, and trees on steeper slopes were more prone to being crushed by neighboring trees. Hurricane Maria caused an average loss of 44 Mg ha−1 of aboveground carbon and 90.3 Mg ha−1 of aboveground biomass. Synthesis – Trees in these hurricane-prone forests show a strong ability to survive extremely strong storms even when severely damaged, but substantial amounts of forest carbon are redistributed to the forest floor even when mortality rates are relatively low. Our data suggest that these hurricane-prone forests will continue to shift toward smaller, high wood-density species with increasing hurricane frequency and intensity.

Study of the Impact of Strong Magnetic Storm on the Consolidated Power System of the Center of Russia

Study of the Impact of Strong Magnetic Storm on the Consolidated Power System of the Center of Russia

Modeling the Sea Level Response of the Northern East China Sea to Different Types of Extratropical Cyclones

AbstractSea level response to extratropical cyclones, one of the most disastrous weather systems, varies depending on cyclone types and tracks. This study presents a systematic modeling assessment of storm surge induced by extratropical cyclones in the northern East China Sea using an ocean‐wave coupled model, based on the Coupled Ocean‐Atmosphere‐Wave‐Sediment Transport (COAWST) model system. We identified the type of extratropical cyclone most likely to cause disasters and the areas likely to suffer the worst effects. We conducted sensitivity experiments to analyze the driving mechanisms (such as wind, air pressure, tide, and wave) and influencing mechanisms (such as local and remote meteorological effect and Ekman effect) of storm surge. During strong winds, positive and negative storm surges were consistent with the wind direction, and formed source of coastal trapped waves. When an abnormally high water level occurred in a semi‐enclosed sea area, it propagated mainly along the cyclone direction. The energy of coastal trapped waves was easy to dissipate in case of caps and other locations with large topographic changes. Tide‐surge‐wave interaction and propagation were also greatly affected by coastal trapped waves.

Global Asymmetry in ΔX Variations During the 06 April 2000 Geomagnetic Storm: Relative Roles of IMF Bz and By

AbstractThis investigation is directed to understand the asymmetry in ΔX variations caused due to the relative roles played by Interplanetary Magnetic Field (IMF) Bz and IMF By in a particular interval (22:22–22:55 UT), during the main phase of a strong geomagnetic storm event of 06 April 2000 (Ap = 236). Two pairs of antipodal stations, being part of the SuperMAG network, are considered here. Ionospheric convection maps from SuperDARN network are used to understand spatio‐temporal evolution of the DP2 ionospheric convection patterns over high‐latitudes. The two‐dimensional maps of equivalent currents are used to show signatures of global DP2 currents associated with the interplay effect between the two IMF components. Observations show increases in the difference in ΔX variations between nearly antipodal stations from the Japanese‐European/African sector with respect to the same between the nearly antipodal stations from the Pacific/American‐Indian sector. This asymmetry is observed during the period when the absolute magnitude of IMF By is larger than that of IMF Bz resulting in a significant and conspicuous enhancement in IMF |By/Bz|. It is suggested that the distortions in DP2 cells and associated rotation of electrodynamic day‐night divider, bring one pair of stations under the same DP2 cell and one station of the other pair under a different DP2 cell and throat flow region leading to the asymmetry in ΔX variations between the antipodal stations. Therefore, the work highlights the importance of the interplay between IMF Bz and IMF By in determining the ionospheric impact over low latitudes during strong geomagnetic conditions.

The role of baroclinic activity in controlling Earth’s albedo in the present and future climates

Clouds are one of the most influential components of Earth's climate system. Specifically, the midlatitude clouds play a vital role in shaping Earth's albedo. This study investigates the connection between baroclinic activity, which dominates the midlatitude climate, and cloud-albedo and how it relates to Earth's existing hemispheric albedo symmetry. We show that baroclinic activity and cloud-albedo are highly correlated. By using Lagrangian tracking of cyclones and anticyclones and analyzing their individual cloud properties at different vertical levels, we explain why their cloud-albedo increases monotonically with intensity. We find that while for anticyclones, the relation between strength and cloudiness is mostly linear, for cyclones, in which clouds are more prevalent, the relation saturates with strength. Using the cloud-albedo strength relationships and the climatology of baroclinic activity, we demonstrate that the observed hemispheric difference in cloud-albedo is well explained by the difference in the population of cyclones and anticyclones, which counter-balances the difference in clear-sky albedo. Finally, we discuss the robustness of the hemispheric albedo symmetry in the future climate. Seemingly, the symmetry should break, as the northern hemisphere's storm track response differs from that of the southern hemisphere due to Arctic amplification. However, we show that the saturation of the cloud response to storm intensity implies that the increase in the skewness of the southern hemisphere storm distribution toward strong storms will decrease future cloud-albedo in the southern hemisphere. This complex response explains how albedo symmetry might persist even with the predicted asymmetric hemispheric change in baroclinicity under climate change.

Investigation of Interhemispheric Asymmetry of the Thermospheric Composition Observed by GOLD during the First Strong Geomagnetic Storm in Solar-Cycle 25, 1: IMF By Effects

Investigation of Interhemispheric Asymmetry of the Thermospheric Composition Observed by GOLD during the First Strong Geomagnetic Storm in Solar-Cycle 25, 1: IMF By Effects

Hydrodynamic variations and human activities have influenced sediment fluxes in the pearl river delta since the late holocene

Climate change and human activity can both exert a role in the river discharge and sediment load in river deltas when the sea level remains relatively stable. The Pearl River Delta constitutes the metropolitan region of the Guangdong–Hong Kong–Macau Greater Bay Area, and its evolution in the past and future impacts the sustainable development of this region. In this manuscript, a core situated in the northern South China Sea, adjacent to Qiao Island of Zhuhai city in the Pearl River Delta, was selected to investigate the hydrodynamic variation influenced by tropical processes and the sediment flux imposed by human activities. Using paleosecular variations (PSVs) in geomagnetic field correlations constrained by seven radiocarbon ages, an ∼2.5 kyr chronology was provided for core sediments ∼2.8 m in length. The magnetic fabric results suggest that deposition was influenced by the two types of hydrodynamic-weak energy modulated by El Niño–Southern Oscillation (ENSO) activity and higher energy regulated by high-frequency tropical storms. The cyclic variations in the degree of anisotropy of magnetic susceptibility (P) indicate two periodic changes at approximately 300 and 100 years, which were forced by ENSO activity, while the ratio of lineation with foliation (q value) implies a higher energy flow period of 1.3–1.9 kyr, arising from strong tropical storms. Moreover, the high saturation remanence (SIRM) introduces more sediment flux, which is impacted by growing human activity during the period of 1.0–1.6 kyr.

Modeling of Hydrodynamic and Lithodynamic Coastal Processes in the Harbour Area

One of the problems in the design of ports is the assessment of coastal sediment movements near structures. The article presents materials for assessing the impact of port facilities on the processes of coastal erosion/accumulations in the area of Gelendzhik Bay (Black Sea). All the main processes of interaction of waves, currents and sediment movement occur in the coastal zone, therefore, the study presents the possibilities of complex application of hydrodynamic and lithodynamic models. In this work, the wind wave models Wave Watch III and SWAN were used. As the initial data, the data of the NCEP/NCAR reanalysis of wind fields in the period from 1989 to 2012 were used. To simulate currents, sediment transport and lithodynamic processes, a model of two-dimensional COASTOX–CUR currents generated by waves and wind, COASTOX-SED sediment transport together with the COASTOX–MORPHO bottom reshaping model was used. In the simulation scenario, a sequence of the 5 strongest storms from the period under consideration was considered. Analysis of washout zones/accumulations have shown that areas of intensive bottom reshaping are associated with the most intense currents. It is shown that the construction of the port facilities will not have a significant impact on the lithodynamic processes in the Gelendjik bay.

Amazon windthrow disturbances are likely to increase with storm frequency under global warming

Forest mortality caused by convective storms (windthrow) is a major disturbance in the Amazon. However, the linkage between windthrows at the surface and convective storms in the atmosphere remains unclear. In addition, the current Earth system models (ESMs) lack mechanistic links between convective wind events and tree mortality. Here we find an empirical relationship that maps convective available potential energy, which is well simulated by ESMs, to the spatial pattern of large windthrow events. This relationship builds connections between strong convective storms and forest dynamics in the Amazon. Based on the relationship, our model projects a 51 ± 20% increase in the area favorable to extreme storms, and a 43 ± 17% increase in windthrow density within the Amazon by the end of this century under the high-emission scenario (SSP 585). These results indicate significant changes in tropical forest composition and carbon cycle dynamics under climate change.

The Mean Kinematic Structure of the Tropical Cyclone Boundary Layer and Its Relationship to Intensity Change

Abstract This study investigates the relationship between the azimuthally averaged kinematic structure of the tropical cyclone boundary layer (TCBL) and storm intensity, intensity change, and vortex structure above the BL. These relationships are explored using composites of airborne Doppler radar vertical profiles, which have a higher vertical resolution than typically used three-dimensional analyses and, therefore, better capture TCBL structure. Results show that the BL height, defined by the depth of the inflow layer, is greater in weak storms than in strong storms. The inflow layer outside the radius of maximum tangential wind speed (RMW) is deeper in intensifying storms than in nonintensifying storms at an early stage. The peak BL convergence inside the RMW is larger in intensifying storms than in nonintensifying storms. Updrafts originating from the TCBL are concentrated near the RMW for intensifying TCs, while updrafts span a large radial range outside the RMW for nonintensifying TCs. In terms of vortex structure above the BL, storms with a quickly decaying radial profile of tangential wind outside the RMW (“narrow” vortices) tend to have a deeper inflow layer outside the RMW, stronger inflow near the RMW, deeper and more concentrated strong updrafts close to the RMW, and weaker inflow in the outer core region than those with a slowly decaying tangential wind profile (“broad” vortices). The narrow TCs also tend to intensify faster than broad TCs, suggesting that a key relationship exists among vortex shape, the BL kinematic structure, and TC intensity change. This relationship is further explored by comparisons of absolute angular momentum budget terms for each vortex shape.

Ionospheric Irregularities Responses to Strong Geomagnetic Storms in Hong Kong Region Over The Past Two Solar Cycles (2001–2020)

Using the GNSS data from Hong Kong region, this study comprehensively investigates the ionospheric irregularities responses to strong geomagnetic storms over the past two solar cycles 2001-2020. Based on the geomagnetic index <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Dst</i> , total 64 strong storms are confirmed during 2001-2020. Statistical results indicate that for the total 64 strong storms, only 20 storms are considered to trigger irregularities occurrences. When the occurrence local time of the minimum <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dDst</i> ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dDst_min</i> ) is in 10:00-14:00 LT, no ionospheric irregularities occurred at nighttime although there is total 14 strong storms, while that of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dDst_min</i> is in the nighttime of 18:00-21:00 LT, ionospheric irregularities are detected in 10 out of 12 strong storms. For the two special storms on 19 April 2002 ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dDst_min</i> occurred at 21:00 LT) and 23 May 2002 ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dDst_min</i> occurred at 20:00 LT), they did not trigger the generation of ionospheric irregularities although their <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dDst_min</i> occurred in 18:00-21:00 LT. Based on vertical total electron content (VTEC) derived from GPS measurements, it is found that the westward electric fields during two storms should play a vital role to inhibit the nighttime ionospheric irregularities occurrence. This study suggests that cautions should be taken when the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dDst_min</i> determined local time is used to decide the occurrence of nighttime irregularities.

A STUDY OF IMPACT OF STRONG MAGNETIC STORM ON CONSOLIDATED POWER SYSTEM OF CENTRE OF RUSSIA

This article represents results of simulation of geomagnetically induced current impact on Consolidated power system of Centre of Russia during strong magnetic storm. The paper shows that complex of factors appears during this impact which can induce progress of blackout: significant decrease of voltage on a set of electrical power elements, mass cutoff of power transmission lines under the influence of relay protection and dangerous heating of construction elements of power transformers.

BASIC RESULTS FROM THE PROJECT “INVESTIGATION OF THE GEOMAGNETIC DISTURBANCES PROPAGATION TO MID-LATITUDES AND THEIR INTERPLANETARY DRIVERS IDENTIFICATION FOR THE DEVELOPMENT OF MID-LATITUDE SPACE WEATHER FORECAST”

The project is directed to one of the topical tasks of the solar-terrestrial physics: study of the midlatitude effects of the magnetospheric substorms as a key element of the space weather. The goal of the project was to conduct a comprehensive analysis of the spatiotemporal characteristics of magnetospheric substorms and their effects at midlatitudes depending on space weather conditions. For this purpose, studies of various phenomena related to the development of substorm disturbances and their propagation to midlatitudes were carried out. For the first time, an original catalog of the variations of the magnetic field at the midlatitude Bulgarian station Panagjurishte (PAG) was created for the period 2007 - 2022. A methodology was developed and universal programs were created for processing data from European stations, for obtaining maps of the spatial distribution of magnetic variations, and for calculating the midlatitude positive bay (MPB) index. Analyses of events during quiet and disturbed geomagnetic conditions, during slow flows in the solar wind or high speed streams from coronal holes, were carried out. Some cases of supersubstorms have been studied in detail. The hypothesis of the development of an additional substorm current wedge during supersubstorms was confirmed. The morphological features of the polar substorms were also studied. Catalogs of supersubstorms and polar substorms for the past 20 years have been created. The relationships between the statistical distributions of the MPB index and widely used geomagnetic indices and solar wind parameters were established. Cases of occurrence of intense geomagnetically induced currents (GIC) during several strong magnetic storms were identified and analyzed.