Storm Of July Research Articles

Text and Subtext: On the Example of Two Poems by Boris Pasternak

A close reading of two poems by Boris Pasternak (“A Storm in July” and “To the Memory of Demon”). Both poems are considered to be inverted variants (or “antitexts”) of Russian classical poems by Fiodor Tiutchev and Mikhail Lermontov (Tiutchev‘s “Spring Storm” and Lermontov‘s “Demon,” respectively). According to the author, this technique may be typical for many other poetic texts written by Pasternak.

The response of the ionosphere to intense geomagnetic storms in 2012 using GPS-TEC data from East Africa longitudinal sector

The response of the ionosphere to intense magnetic storms has been studied using total electron content (TEC). TEC data recorded by a series of GPS receivers at a longitude ∼35°E covering a wide range of latitudes (32°S to 68°N, geographic) is analyzed to study spatio-temporal modifications of the vertical TEC (vTEC) during storms on 07 and 09 March 2012 and on 14 July 2012. We have observed main phase positive response at equatorial ionization anomaly (EIA) crests and mid latitude regions in all the storms. These main phase positive responses are associated with vertical drift enhancement (intensified equatorial electrojet (EEJ)) and the mechanical effect of equatorward neutral wind after an auroral activity. A daytime substantial depletion of TEC at low latitude region was observed on 08 March 2012. This is due to the combined effects of oversheilding and disturbance dynamo electric field that drive large downward drifts during the day. The low latitude and equatorial ionospheric response in the recovery phase days of March storm is found to be largely associated with the disturbance dynamo field that suppressed the upward E×B drift from EEJ observations. The summer negative and winter positive response in July storm as well as mid latitude positive response in March storm was associated with the composition changes as depicted by the O to N2 ratio from GUVI measurements.

Matroshka DOSTEL measurements onboard the International Space Station (ISS)

This paper presents the absorbed dose and dose equivalent rate measurements achieved with the DOSimetry TElescope (DOSTEL) during the two Matroshka (MTR) experiment campaigns in 2004/2005 (MTR-1) and 2007/2008 (MTR-2B). The comparison between the inside (MTR-2B) and outside (MTR-1) mission has shown that the shielding thickness provided by the International Space Station (ISS) spacecraft hull has a minor effect on the radiation exposure caused by Galactic Cosmic Rays (GCR). The exposure varies with the solar modulation of the GCR, too. Particles from Earth’s radiation belts are effectively shielded by the spacecraft hull, and thus the contribution to the radiation exposure is lower for the inside measurement during MTR-2B. While the MTR-DOSTEL absorbed dose rate shows a good agreement with passive detectors of the MTR experiment for the MTR-2B mission phase, the MTR-1 absorbed dose rates from MTR-DOSTEL measurements are much lower than those obtained by a nearby passive detector. Observed discrepancies between the MTR-DOSTEL measurements and the passive detectors located nearby could be explained by the additional exposure to an enhanced flux of electrons trapped between L-parameter 2.5 and 3.5 caused by solar storms in July 2004.

Effect of the temperature variation between Mediterranean Sea and Syrian deserts on the dust storm occurrence in the western half of Iran

Recent dust storms have caused crises in western Iran, which necessitate the prediction of these storms a few days before their occurrence. This is the first study of its type that analyzes the effect of temperature differences between the Mediterranean Sea surface and Syrian deserts (creation zone of the dusts storms) on the formation of dust storms in the west of Iran. The study also seeks to identify any changes in the atmospheric temperature created by the extreme dust storm of July 5, 2009 in west of Iran (Sanandaj City). In this study, the MODIS images from 2000 to 2008, and particulate matter data of the Sanandaj station from 2008 to 2012 were utilized to identify the dust storm days. The Mediterranean Sea surface temperature data were extracted from NOAA satellites for dust storm days up to four days preceding them. The web site of world weather was used to obtain the temperature of Damascus, Syria station as the selected land station. According to the results, significant differences were acquired between surface temperatures of Damascus station and the Mediterranean Sea in the dust storm days and up to three days before them. As the dust storm days approached, a rising trend was observed in changes of the temperature difference between land and sea. Thermal map analysis of the atmosphere of the Syrian deserts on July 5, 2009 showed significant decrease in the levels of 1000hPa and 500hPa but for the days preceding it no significant changes were observed. It can be concluded that the temperature difference between the Mediterranean Sea surface and the Syrian deserts four days before the dust storm occurrences is the important factor in predicting this event.

A preliminary study of thermosphere and mesosphere wind observed by Fabry‐Perot over Kelan, China

AbstractA Fabry‐Perot interferometer (FPI) system was deployed in Kelan (38.7°N, 111.6°E), center China in November 2011, which observes the airglows at wavelengths of 892.0 nm, 557.7 nm, and 630.0 nm from OH and OI emissions in the upper atmosphere, to derive the wind and temperature at heights around 87 km, 97 km, and 250 km, respectively. From late 2011 through 2013 a series of more than 4500 measurements at each height are validated according to manufacture data quality criteria. By using these data, the morphology of wind in the mesosphere and thermosphere is investigated in this study. Preliminary results are as follows: (1) As for the diurnal variation, meridional and zonal winds at heights of 87 km and 97 km, which are derived through 892.0 nm and 557.7 nm airglows, usually range from −50 m/s to 30 m/s and −50 m/s to 50 m/s, respectively, with typical random errors of about 6–10 m/s at 87 km and 2–3 m/s at 97 km. Meridional winds usually are northward at dusk, southward at middle night, and back to northward at dawn; and zonal winds usually are eastward at dusk, westward at middle night, and back to eastward at dawn. The monthly mean winds are in good agreement with those of HWM93 results. Meridional and zonal winds at a height of 250 km, which are derived through 630.0 nm nightglow, range from −110 m/s to 80 m/s with typical random errors of about 8–10 m/s. Meridional winds usually are northward at dusk, southward at middle night, and back to northward at dawn; and zonal winds usually are eastward at dusk, zero at middle night, and westward at dawn; and they are also well consistent with HWM93 results. (2) As for the seasonal variation, meridional winds at the heights of 87 km and 97 km have a visible annual variation at 12–17 LT and with a little semiannual variation at all other hours, but the zonal winds at the heights of 87 km and 97 km have a semiannual variation all night. The seasonal dependence of the winds, both meridional and zonal winds, at the height of 250 km is generally annual, but isolated cases of semiannual variation are observed. (3) The horizontal winds at 250 km evidently respond to the two storms of July 2012, apparent enhancement of the velocity of the southwestward wind. But no other obvious storm effects can be found from the winds at 87 km and 97 km during the same period.

Combined Sewer Overflows (CSOs) Impact on Water Quality and Environmental Ecosystem in the Harlem River

The Harlem River, a 9.3-mile channel that flows from the Hudson River to the East River, has experienced decades of industrial abuse and remains gritty and industrial. During heavy rains, the pipes discharge raw sewage into the river through combined sewer overflows (CSOs) that can contain bacteria and cause illness. Water samples were collected from CSO discharge point and several adjacent sites along the river in the Bronx side close to River Park Towers at Richman Plaza and Manhattan side at Wards Island. Nutrients, bacteria, polychlorinated biphenyls (PCBs), and fish consumption safety have been analyzed. Results showed that phosphorus, ammonia concentration as well as fecal coliform, E.Coli, enterococcus levels increased significantly during heavy rainstorms. Ammonia concentration was up to 2.725 mg/L during tropical storm Arthur on July 2, 2014 and rainstorm in May 2013, and soluble reactive phosphorus (SRP) or orthophosphate was up to 0.197 mg/L during heavy thunderstorm in April 2011; both nutrients were exceeded EPA regulation for ammonia (0.23 mg/L) and phosphate (0.033 mg/L) for New York City (NYC) waters. The colonies of fecal coliform were more than 5 million MPN/100ml (most probable number per 100 ml) during tropical storm Arthur in July 2014 and heavy rainstorm in April 2014, and fecal coliform was more than 10,000 MPN/100ml during storm in July and November 2013; E.Coli reached more than 5000 MPN/100ml during tropical storm Arthur and storm in May 2013; enterococcus reached more than 10,000 MPN/100ml during tropical storm Arthur and heavy rainstorm in April 2014. These bacteria (pathogen) levels in the Harlem River were significantly higher than EPA standards (fecal coliform: 200 MPN/100ml, E.Coli: 126 MPN/100ml, enterococcus: 104 MPN/100ml), especially during rainstorm/tropical storm. Of particular significance, nutrients and bacteria were analyzed before and after Hurricane Sandy devastated NYC in late October 2012; results determined that bacteria and ammonia concentrations increased after this monumental storm, elucidating the environmental impact of large storm events. PCB 11 (3,3’-dichlorobiphenyl,

Beijing storm of July 21, 2012: observations and reflections

Beijing storm of July 21, 2012: observations and reflections

The effect of energetic electron precipitation on middle mesospheric night‐time ozone during and after a moderate geomagnetic storm

Using a ground‐based microwave radiometer at Troll Station, Antarctica (72°S, 2.5°E,L = 4.76), we have observed a decrease of 20–70% in the mesospheric ozone, coincident with increased nitric oxide, between 60 km and 75 km altitude associated with energetic electron precipitation (E > 30 keV) during a moderate geomagnetic storm (minimum Dst of −79 nT) in late July 2009. NOAA satellite data were used to identify the precipitating particles and to characterize their energy, spatial distribution and temporal variation over Antarctica during this isolated storm. Both the ozone decrease and nitric oxide increase initiate with the onset of the storm, and persist for several days after the precipitation ends, descending in the downward flow of the polar vortex. These combined data present a unique case study of the temporal and spatial morphology of chemical changes induced by electron precipitation during moderate geomagnetic storms, indicating that these commonplace events can cause significant effects on the middle mesospheric ozone distribution.

Some recent extreme wind events in New Zealand

Damaging winds, associated with a variety of weather phenomena, are frequently experienced in New Zealand. Observations and modelling of two recent extreme wind events; the Taranaki tornado outbreak of July 2007, and the Greymouth down-slope easterly wind storm of July 2008 are described in detail here. Post-event engineering damage surveys, rare for New Zealand, were done for these storms and the results are summarized here. Finally, the issue of sampling extreme wind events is raised and the need to include detailed numerical modelling analysis to understand wind gust climatologies at observing sites and extending these to wider regions is discussed.

Relaxation of electron and proton radiation belts of the earth after strong magnetic storms

During strong magnetic storms in July and November of 2004 the fluxes of trapped particles (protons and electrons of MeV energies) in the Earth’s radiation belts have increased by orders of magnitude and then decreased remaining on an enhanced level for several months. These enhancements allowed us to study the processes of relaxation of the radiation belts. Measurements of energetic particles by low-altitude satellites Coronas-F and Servis-1 have shown that predictions of the theory about the rate of pitch-angle diffusion are not always correct, giving both overestimated and underestimated values for the lifetime of energetic particles.

Ground‐based estimates of outer radiation belt energetic electron precipitation fluxes into the atmosphere

AARDDVARK data from a radio wave receiver in Sodankylä, Finland have been used to monitor transmissions across the auroral oval and just into the polar cap from the very low frequency communications transmitter, call sign NAA (24.0 kHz, 44°N, 67°W, L = 2.9), in Maine, USA, since 2004. The transmissions are influenced by outer radiation belt (L = 3–7) energetic electron precipitation. In this study, we have been able to show that the observed transmission amplitude variations can be used to determine routinely the flux of energetic electrons entering the upper atmosphere along the total path and between 30 and 90 km. Our analysis of the NAA observations shows that electron precipitation fluxes can vary by 3 orders of magnitude during geomagnetic storms. Typically when averaging over L = 3–7 we find that the >100 keV POES “trapped” fluxes peak at about 106 el. cm−2 s−1 sr−1 during geomagnetic storms, with the DEMETER >100 keV drift loss cone showing peak fluxes of 105 el. cm−2 s−1 sr−1, and both the POES >100 keV “loss” fluxes and the NAA ground‐based >100 keV precipitation fluxes showing peaks of ∼104 el. cm−2 s−1 sr−1. During a geomagnetic storm in July 2005, there were systematic MLT variations in the fluxes observed: electron precipitation flux in the midnight sector (22–06 MLT) exceeded the fluxes from the morning side (0330–1130 MLT) and also from the afternoon sector (1130–1930 MLT). The analysis of NAA amplitude variability has the potential of providing a detailed, near real‐time, picture of energetic electron precipitation fluxes from the outer radiation belts.

사전재해영향성검토 시 합리적인 홍수유출 모의모형 선정에 관한 연구

도시개발은 불투수면적의 증가를 가져오는 요인이다. 영구저류지는 도시개발 유역의 우수유출을 저감시키는 시설이다. 본 연구에서는 사전재해영향성 제도에서 합리적인 홍수조절방안을 제시하고자 하였다. 먼저 홍수량 계산에서 도달시간 채택에 관한 문제점을 고찰하였다. 홍수유출 모의모형의 적합성 검토는 전원유역과 도시유역에 대하여 수행되었다. 홍수유출 모의모형은 2009년 7월 7일과 9일의 실제 호우 시 측정자료를 통하여 검증되었다. 그 결과, 전원유역과 도시유역에 적합한 모형은 각각 운동파 모형과 SWMM인 것으로 분석되었다. 본 연구에서 수행한 홍수량 산정모형과 합리적인 홍수설계 방안은 국내의 영구저류지 설계 시 기초 자료로 활용될 수 있을 것이다. 수문학적 분석방법은 영구저류지의 합리적인 용량 및 규모산정에 활용될 것으로 사료된다. Urban development is a cause of expansion of impervious area. A permanent storage is operated as a method of reducing runoff of watershed. The purpose of study is to propose reasonable choice of simulation model for rainfall-runoff in the prior review system on disaster effect. First, we indicated problem about concentration time choice in the flood simulation. To test the adequacy of a rainfall-runoff simulation model, We analyzed characteristics of rainfall-runoff about urban and natural watersheds. A simulation model was calibrated with the storm of july 7 to July 9 in 2009. From the result, we proposed that SWMM and kinematic wave method as the flood simulation models for urban and natural watersheds. A simulation model and design method of a permanent storage for flood that is proposed in this study will be useful for practical design of flood simulation. The hydrologic analysis method of the study can be used for capacity evaluation of permanent storage plan.

Solar S-bursts at Frequencies of 10 – 30 MHz

Solar S-bursts observed by the radio telescope UTR-2 in the period 2001 – 2002 are studied. The bursts chosen for a detailed analysis occurred in the periods 23 – 26 May 2001, 13 – 16 and 27 – 39 July 2002 during three solar radio storms. More than 800 S-bursts were registered in these days. Properties of S-bursts are studied in the frequency band 10 – 30 MHz. All bursts were always observed against a background of other solar radio activity such as type III and IIIb bursts, type III-like bursts, drift pairs and spikes. Moreover, S-bursts were observed during days when the active region was situated near the central meridian. Characteristic durations of S-bursts were about 0.35 and 0.4 – 0.6 s for the May and July storms, respectively. For the first time, we found that the instantaneous frequency width of S-bursts increased with frequency linearly. The dependence of drift rates on frequency followed the McConnell dependence derived for higher frequencies. We propose a model of S-bursts based on the assumption that these bursts are generated due to the confluence of Langmuir waves with fast magnetosonic waves, whose phase and group velocities are equal.

Effect of magnetospheric substorms on asymptotic directions of arrival of cosmic ray relativistic protons

The effect of magnetospheric storm on the propagation of relativistic protons has been analyzed. The method of trajectory calculations has been used to estimate changes in the reception cones for 21 stations, caused by the storm of July 19–20, 2000, accompanied by considerable saw-tooth substorm disturbances. It has been indicated that the degree of the substorm effect on the propagation of cosmic ray (CR) relativistic protons, registered with ground detectors, differs for different stations and depends on a distance of the particle trajectory from the localization of a substorm disturbance. The maximal effect for the considered substorm was found at Inuvik and McMurdo stations. Changes in the reception cone, caused by the substorm at these stations, were comparable or even larger than changes caused by the storm. Based on the calculations, the conclusion has been drawn that a disturbance (substorm) localized in space results in the appearance of relatively local zones on the Earth’s surface where characteristics of the asymptotic arrival of relativistic particles are changed.

Longitudinal development of low‐latitude ionospheric irregularities during the geomagnetic storms of July 2004

During the period 22–28 July 2004, three geomagnetic storms occurred due to a sequence of coronal mass ejections. In this paper we present and discuss the ionospheric observations from a set of in situ satellites and ground‐based GPS total electron content and scintillation receivers, a VHF radar, and two chains of ionosondes (∼300°E and ∼120°E, respectively) that provide the evolutionary characteristics of equatorial and low‐latitude ionospheric irregularities versus longitude during these storm periods. It is found that the irregularities occurred over a wide longitudinal range, extending from around 300°E to 120°E on storm days 25 and 27 July 2004. On 25 July plasma bubbles (PBs) began premidnight in America and postmidnight in Southeast Asia. On 27 July the occurrence of irregularities followed the sunset terminator and was observed sequentially after sunset from American to Southeast Asian longitudes. Past studies have reported that storm‐time low‐latitude ionospheric irregularities are mostly confined to a narrower longitude range, <90°, after sunset hours and are associated with the prompt penetration of eastward electric fields (PPEFs) into low latitudes. In June solstice months the occurrence of range‐type spread F or PBs is very low in Southeast Asian and South American sectors. In contrast, the present results indicate that geomagnetic storms triggered the wide longitudinal development of PBs. In the American sector this was probably due to the effects of PPEFs on both storm days. However, in the Southeast Asian sector the PBs on the 2 days probably arose from disturbance dynamo electric field (DDEF), PPEF, and gravity wave seeding effects. This study further shows that under complex storm conditions, besides the long duration or multiple penetrations, the combined effects of PPEFs and DDEFs could result in a wide longitude extent of ionospheric irregularities at times.

O- AND H-ISOTOPE RECORD OF CAPE TOWN RAINFALL FROM 1996 TO 2008, AND ITS APPLICATION TO RECHARGE STUDIES OF TABLE MOUNTAIN GROUNDWATER, SOUTH AFRICA

The O- and H-isotope composition of rainfall collected over a variety of time periods at the University of Cape Town (UCT) between 1996 and 2008 has been determined. A continuous record of monthly rainfall from 1996 to 2008 has a range in δD and δ 18 O values from −57 to +18‰ and −8.1 to +3.5‰, respectively. These data show limited but discernable temperature and amount effects. Daily rainfall between June 2000 to September 2001 ranges in δD and δ 18 O from −57 to + 27‰, and, −9.0 to +6.4‰ respectively, showing only a marginally greater temperature and amount effect than the monthly data. Rainfall collected at 18 O value of 26 and 3.3‰, respectively in as little as 30 minutes during the passage of a cold front. Unusual events such as snow and hail in the area have much lower δD and δ 18 O values (−60 and −10.9‰). The deuterium excess values were significantly higher in the storm samples (average 20.0) and the hail and snow samples (average 30.1) than in the monthly rain samples (average 12.4). The UCT monthly samples define a meteoric water line whose equation is δ= 6.41*δ 18 O + 8.66 (r = 0.88). The daily and hail/snow samples show a better correlation (r = 0.93) due to the greater spread of values, with an equations of the line of best fit of δD = 6.64δ 18 O + 11.89. Rain water collected during two storms in July and August show an excellent correlation between δD and δ 18 O (r = 0.97) with an equation of best fit of δD = 7.89 δ 18 O + 19.35. There has been no systematic change in annual amount, mean temperature or weighted mean isotope composition from 1996 to 2008, but 1996 (16.1°C) was, on average, 1.3°C colder than 1997 to 2008 (ave. 17.3°C). Annual rainfall at UCT has varied from ~1000 mm (1997) to 1700 mm (2001), and the weighted mean annual δD and δ 18 O values calculated from the monthly samples varies from −16 to −7‰ and −3.8 to −2.6‰, respectively. The years 2005 and 2006 showed a significantly lower deuterium excess (~6) compared to typical values of about 16, which suggests that these years experienced less frontal rain. This difference in isotope composition of rainfall is detectable in the isotope composition of water collected from springs on the lower slopes of Table Mountain and suggests that the Table Mountain aquifer(s) are recharged by approximately 50% within three years.

Superconcentration of photospheric sources of the large-scale open solar magnetic field in the main zone of active longitudes, blocking of differential rotation, and origination of the four-sector structure: 2. Geoeffectiveness

The effectiveness of the series of powerful heliospheric storms, originated during the decline phase of cycle 23 owing to the superconcentration of the open field photospheric sources in the main zone of active longitudes, has been studied. The geoeffectiveness of the storm of July 16—27, 2004, was closely related to the origination of the four-sector structure and depended on the destabilization of two activity centers weakly and strongly geoeffective with ARs 10649 and 10652. The first center was localized in one of the new sectors; the second center, in the western surroundings of the zone of active longitudes. The departure of coronal mass ejections from AR 10649 was substantially hindered: they were completely absent after the series of powerful X-ray flares, and a rare phenomenon of “sunquake” was observed: shock waves did not reach the Earth in spite of its favorable position. The Earth was strongly shielded by new sector boundaries from coronal ejections from AR 10652 with a gradual weakening and disappearance of this region, as a result of which the cascade of three near-Earth storms with an increasing power and Ap, indices of 52, 154, and 186 originated. Rare phenomena in AR 10649 and the cascade of solar—terrestrial heliospheric storms made the storm of July 16— 27 a unique phenomenon in cycle 23, and a short-term prediction of its geoeffectiveness was impossible.

Variation in soil characteristics and hydrologic properties associated with historic land use near a recent landslide, Nagano Prefecture, Japan

An unlikely combination of relatively low rainfall intensity and gently sloping topography produced numerous landslides and debris flows during a prolonged storm in July 2006 around Okaya City, Nagano Prefecture, Japan, and indicated the existence of other factors contributing to the landslide initiation. We focused our detailed investigation on a relatively large landslide/debris flow near Okaya City where the highly variable soil characteristics in the landslide scarp led us to examine the variability of physical and hydrological properties throughout the soil profile and within the area above the landslide. The soil in our study area ranges from gravelly loamy sand to loamy silt and is the result of ≈ 10,000 years of erosion processes which have accumulated soil in this geomorphic hollow above a thin residual soil. A zone of black soil found at depths ranging from 20 to 280 cm upslope of the landslide scar is indicative of sequential forest burning practiced during Jomon age hunting and gathering. Previous C-14 dates indicate these anthropogenic practices occurred between 10,200 and 4510 years BP at this site. Based on the average thickness and age of this anthropic soil sequence, the average infilling rate of this geomorphic hollow (primarily by surface erosion) was about 0.45 Mg ha − 1 year − 1 during this ≈ 5700 year period. Saturated hydraulic conductivity (Ks) tended to be higher, but more variable in the upper meter of the soil profile where soils were affected by terracing and agriculture practices of the past 200 years. At depths below 1.4 m, Ks was a bit lower and less variable, especially in the black soil layers (minimum 1.11 × 10 - 5 and maximum 4.03 × 10 - 5 m s - 1 ). Because this black anthropic soil is located near the middle of the profile, it may significantly affect the hydrologic response to rainfall inputs and the resulting slope stability by intercepting infiltrating rain water and developing a temporary perched water table or by absorbing and accumulating large quantities of water and delaying the further deep percolation in subsequent storm events. A detailed auger survey immediately above the landslide scarp revealed that the black layer is quite variable in depth but is thickest near the longitudinal axis of the concave hollow and then thins out and disappears closer to the ridges bounding the hollow. Total soil depth was also variable (1.8 to 4.0 m) and exhibited a similar pattern of distribution within the hollow — i.e., deepest along the concave axis. The variable distribution of the black layer and its association with soil depth may contribute to the location of the landslide. Thus, both the vertical variability and spatial propagation of soil properties appear to suggest the specific site of landslide occurrence. Understanding the genesis of the black layer and the magnitude of anthropogenic effects in this area underline the need to assess historic land use patterns over thousands of years rather than relying only on the effects of recent human practices related to slope stability.

Spatial distribution and frequency of precipitation during an extreme event: July 2006 mesoscale convective complexes and floods in southeastern Arizona

An extreme, multiday rainfall event over southeastern Arizona during 27–31 July 2006 caused record flooding and a historically unprecedented number of slope failures and debris flows in the Santa Catalina Mountains north of Tucson. An unusual synoptic weather pattern induced repeated nocturnal mesoscale convective systems over southeastern Arizona for five continuous days, generating multiday rainfall totals up to 360 mm. Analysis of point rainfall and weather radar data yielded storm totals for the southern Santa Catalina Mountains at 754 grid cells approximately 1 km × 1 km in size. Precipitation intensity for the 31 July storms was not unusual for typical monsoonal precipitation in this region (recurrence interval (RI) < 1 year), but multiday rainfall where slope failures occurred had RI > 50 years and individual grid cells had RI exceeding 1000 years. The 31 July storms caused the watersheds to be essentially saturated following 4 days of rainfall.

The recovery phase of the superstrong magnetic storm of July 15–17, 2000: Substorms and ULF pulsations

The geomagnetic observations, performed at the global network of ground-based observatories during the recovery phase of the superstrong magnetic storm of July 15–17, 2000 (Bastille Day Event, Dst = −301 nT), have been analyzed. It has been indicated that magnetic activity did not cease at the beginning of the storm recovery phase but abruptly shifted to polar latitudes. Polar cap substorms were accompanied by the development of intense geomagnetic pulsations in the morning sector of auroral latitudes. In this case oscillations at frequencies of 1–2 and 3–4 mHz were observed at geomagnetic latitudes higher and lower than ∼62°, respectively. It has been detected that the spectra of variations in the solar wind dynamic pressure and the amplitude spectra of geomagnetic pulsations on the Earth’s surface were similar. Wave activity unexpectedly appeared in the evening sector of auroral latitudes after the development of near-midnight polar substorms. It has been established that the generation of Pc5 pulsations (in this case at frequencies of 3–4 mHz) was spatially asymmetric about noon during the late stage of the recovery phase of the discussed storm as took place during the recovery phase of the superstrong storms of October and November 2003. Intense oscillations were generated in the morning sector at the auroral latitudes and in the postnoon sector at the subauroral and middle latitudes. The cause of such an asymmetry, typical of the recovery phase of superstrong magnetic storms, remains unknown.