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1.
Summary The atmospheric electric potential gradient was recorded continuously by a field mill at Fargo, North Dakota, for the period August, 1972–March, 1973. Hourly averages were taken by the equal areas technique to eliminate short period variations. The diurnal variation of monthly averages is shown for the fair weather periods and all weather. In addition, the diurnal variation is shown for all positive values of the potential gradient, which excludes periods of major local space charge generators, but includes periods when the potential gradient might be influenced by regional conditions not otherwise present during fair weather. For a given month the diurnal variation curves are generally similar, with the fair weather curve giving the highest values, and all weather curve giving the lowest values. The months September–November have similar curves with the lowest values and least deviation from the average. The months December–February have similar curves with the highest values.Harmonic analysis is used to compute the times of maxima and contributions to variance of the first four harmonics for each diurnal variation curve. The fair weather first harmonic accounts for the majority of variance and has a maximum near 19.5 h GMT. It is attributed to the global diurnal variation of potential gradient due to thunderstorm activity in the tropics. The second harmonic has one maximum occurring from 9–12 h local time and is attributed to the austausch effect of convection, where ions affect the conductivity of the air locally.The differences in these monthly diurnal variation curves emphasize that the season of year, weather conditions, and length of time over which data is averaged must be specified in atmospheric electricity studies if meaningful conclusions are to be drawn.  相似文献   

2.
Summary For the period February 1967–May 1969, a period of increasing solar activity, unrestricted substantiation was obtained of earlier results which had indicated that subsequent to H-flares potential gradient and air-earth current will increase significantly. A presupposition of this result is that the atmospheric electrical elements are recorded at stations with only minimal local climatic and aerosol physical disturbance factors, and that only meteorologically undisturbed days are used. It was ascertained that the exclusive use of fine weather days is of no influence on the results. The confirmed solar-terrestrial relation is even more pronounced when measurements are based on flares in the vicinity of the central meridian of the sun. It was further substantiated that the frequency of sferics pulses is significantly increased from the flare day on. As the cause for this a solar-triggered increase in thunderstorm frequency is suggested which, in turn, leads to an increase of the potential gradient and earth current. Proton flares have an effect analogous to that of H-flares. If H-flare key days are used on which significant changes were observed in the distribution of pressure over the northern hemisphere, a significant increase of potential gradient and air-earth current is found even with these flare key days. Thus for the first time a connection is made between solar-caused atmospheric electrical effects and synchronous global meteorological changes.  相似文献   

3.
Summary The air-earth current density in the stratosphere, the columnar resistance derived from the measurements of conductivity, and the ionospheric potential were investigated. The data were obtained by radiosonde ascents during the period of 1957–1967.It was found that the local horizontal visibility at the surface is related to the air-earth current density in the stratosphere, and it is expected that the air-earth current density has a seasonal variation. Statistical results show that indeed the air-earth current has a pronounced seasonal variation, high in winter and low in summer. The columnar resistance has also a seasonal variation, reverse to the variation of the air-earth current.The percentage time variation of the air-earth current (1/i) (di/dt) was found to be twice as much as the percentage time variation of the columnar resistance (1/R) (dR/dt) at the Tateno Observatory.The ionospheric potential, deduced from the measurements of the potential gradient by radiosonde ascents, shows no clear seasonal variation at Syowa-Base (Antarctica). Following Ohm's law, however, the above-mentioned results suggest that the seasonal variation of the ionospheric potential would exist on land.
Zusammenfassung Die Vertikalstromdichte in der Stratosphäre, der Säulenwiderstand, berechnet aus Leitfähigkeitsmessungen, und das Ionosphärenpotential wurden untersucht. Die Messergebnisse wurden mittels Radiosonden im Jahrzehnt 1957–1967 erlangt.Es wurde festgestellt, dass die örtliche waagrechte Sichtweite am Erdboden mit der Vertikalstromdichte in der Stratosphäre korreliert ist, und dass erwartet werden muss, dass die Vertikalstromdichte einen jahreszeitlichen Gang aufweist. Tatsächlich lässt sich statistisch zeigen, dass ein solcher jahreszeitlicher Gang der Vertikalstromdichte besteht, mit einem Höchstwert im Winter und einem Mindestwert im Sommer. Auch der Säulenwiderstand zeigt einen jahreszeitlichen Gang, umgekehrt zu dem der Vertikalstromdichte.Die prozentuale zeitliche Änderung der Vertikalstromdichte (1/i) (di/dt) stellte sich als zweimal so gross heraus als die des Säulenwiderstandes (1/R) (dR/dt) gemessen am Observatorium zu Tateno.Wird das Ionosphärenpotential aus den Messungen des Potentialgefälles mit Radiosonden hergeleitet, so stellt sich bei den an der Syowa-Station in der Antarktik angestellten Messungen kein klarer Jahresgang heraus. Die hier zuvor erwähnten Ergebnisse, jedoch, führen zu der Annahme eines Jahresgangs des Ionosphärenpotentials über der genannten Station, wenn man das Ohm'sche Gesetz auf sie anwendet.
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4.
Ionosphere-magnetosphere disturbances at high latitudes, e.g. magnetic substorms, are accompanied by energetic particle precipitation and strong variations of the ionospheric electric fields and currents. These might reasonably be expected to modify the local atmospheric electric circuit. We have analysed air-earth vertical currents (AECs) measured by a long wire antenna at Esrange, northern Sweden during 35 geomagnetic substorms. Using superposed epoch analysis we compare the air-earth current variations during the 3 h before and after the time of the magnetic X-component minimum with those for corresponding local times on 35 days without substorms. After elimination of the average daily variation we can conclude that the effect of substorms on AEC is small but distinguishable. It is speculated that the AEC increases observed during about 2 h prior to the geomagnetic X-component minimum, are due to enhancement of the ionospheric electric field. During the subsequent 2 h of the substorm recovery phase, the difference between substorm and quiet atmospheric currents decreases. The amplitude of this substorm variation of AEC is estimated to be less than 50% of the amplitude of the diurnal variation in AEC during the same time interval. The statistical significance of this result was confirmed using the Van der Waerden X-test. This method was further used to show that the average air-earth current and its fluctuations increase during late expansion and early recovery phases of substorms.  相似文献   

5.
Summary Recordings of potential gradient and air-earth current in fair-weather conditions were made at high-elevation mountain stations; the latter were generally above the vertical-mixing layer and not disturbed by local sources. Both electrical quantities increased significantly from the day of appearance of a solar flare (or a maximum incidence of flares) till the fourth day after the event. Peak potential gradient and air-earth current exceed the normal levels measured during quiet-sun conditions by 50–60% in terms of averages. This result was compared with sferics incidence data and daily geomagnetic coefficients grouped around the selected (flare) dates. Both of the latter quantities show time histories (for the days preceding and following the selected dates) closely correlated with the atmospheric-electrical histories of the same intervals. We may conclude from these results that the total potential between the ground and the upper atmosphere increases for several days after solar flares. The results obtained by previous studies on Mauna Loa confirm this inference. The cause of the phenomenon is presumed to be enhanced thunderstorm activity attendant on solar disturbances.We wish to thank the Deutsche Forschungsgemeinschaft for a grant taht enabled us to carry out the studies described in this paper  相似文献   

6.
There has been considerable interest in estimating secular trends in precipitation data in various regions of the world. It is therefore important to ascertain the manner in which errors of observation affect estimated trends. For this purpose we have compared trends at 1219 stations in the contiguous United States for two data sets: (a) original observations, also called raw observations, and (b) the observations, adjusted to compensate for suspected errors. The adjustments were made at the National Climate Data Center, Asheville (Quinlan et al., 1987;karl andWilliams, 1987), In order to focus on the effects of observational errors we attempted to avoid the effects of filling of missing data by limiting the analysis to the period 1940–1984 for which the number of missing values is much smaller than earlier periods. A least-square linear regression was performed on the raw and adjusted data for each station and the slopes of the fitted lines were compared. The comparison was made for monthly, seasonal and annual precipitation values.The results for annual precipitation showed that 23 percent of the stations have trends of opposite signs in the raw and adjusted data. The trends were identical in annual data at only 11 percent of the stations. When monthly data are combined to form seasonal and annual averages the magnitude of the difference between the slopes of the adjusted and the raw observations generally increases, indicating that the errors in the individual monthly observations are correlated. When the station data were averaged to obtain state-wide averages, the effects of the errors became less pronounced in most of the states. These results indicate that obtaining trends in precipitation from station data is a more difficult problem than has been realized.  相似文献   

7.
Summary In this study, values of the Ångström turbidity coefficient () determined from Solar radiation observations at the National Observatory of Athens over the period 1955–1972 are analysed. Mean daily turbidity lies between 0.020–0.100. Turbidity is higher in summer than in winter. The main factor determining the turbidity is the air mass type. The scavenging by rainfall probably has a considerable effect in determining this distribution. There is some evidence of a trend of increasing turbidity during the period.  相似文献   

8.
Global thunderstorm and shower cloud activity generate the global electric potential difference between the Earth's surface and the lower ionosphere. The finite conductivity of atmospheric air, which arises from cosmic ray and natural radioactive ionisation, permits a vertical conduction current density (1 pA m−2) between the lower ionosphere and the surface during fair-weather conditions; this current provides a physical link between the upper and lower atmospheres. A new instrument system is described to measure the conduction current density at the surface (the “air–Earth current”), which operates on a novel principle using two collecting electrodes of different geometry. Simultaneous measurements from two independent co-located systems using the geometrical principle show close agreement (correlation of 0.96 during 2.5 h of 5 min measurements). The sensor design described is durable and successful measurements in fair and disturbed weather have been obtained in air temperatures between −6 and 35 °C, relative humidity between 44% and 100%, fog, rain and snowfall. The uncertainty in conduction current density determinations is 0.20 pA m−2.  相似文献   

9.
Regional and local characteristics of active fault patterns and elevation variation throughout Honshu, Japan are characterized in terms of their fractal dimensions; this allows variation in these complex variables to be compared directly to the scalar properties of net Quaternary vertical displacement, elevation and 10- and 110-year horizontal strains. The comparisons reveal that, throughout Honshu as a whole, there is significant correlation (r=0.75) between Quaternary vertical displacement, elevation, and its fractal properties. There is poor correlation, however, of elevation and its fractal properties to horizontal crustal strain, and also between Quaternary vertical displacement and horizontal crustal strain. A slight negative correlation is observed between the fractal properties of the active fault system and horizontal crustal strain measured over 10- and 110-year time periods (–0.43 and –0.26, respectively). The correlation between the 10-year (1985–1994) and 110-year (1883–1994) area strains, 0.48, reveals the occurrence of considerable change in the distribution of regional strain over these short time frames. Local computations of the correlation between data sets made for overlapping 160 km length windows of data spaced every 20 km along analysis lines reveal internal fluctuations in the correlation between variables. The local correlation between Quaternary vertical displacement and elevation is highest through central Japan and the Kinki Triangle. There is weak negative correlation between area strain and fractal dimensions of the active fault network. The local correlation between the fractal dimensions of active faults and horizontal area strain over the recent 10-year time period averages about –0.6 through central Japan in an area that extends across the Kinki Triangle through the northern part of central Honshu and northeast across the Itoigawa Shizuoka Tectonic Line. In general, regions of greatest complexity in the active fault network are associated with persistent negative area or compressional strain. Sparsely faulted areas in general coincide with areas of positive or roughly zero area strain. The presence of negative correlation through central Japan and the Kinki Triangle area in the recent 10-year period results from a decrease of area strain within an increasingly complex active fault system that reaches maximum negative values concentrated in the Kinki Triangle during the 1985–1994 time period.  相似文献   

10.
Auroral precipitating electrons pass through an acceleration region before entering the atmosphere. Regardless of what produces it, a parallel electric field is assumed to cause the acceleration. It is well known that from kinetic theory an expression for the corresponding upward field-aligned current can be calculated, which under certain assumptions can be linearized to j = KV. The K constant, referred to as the Lyons-Evans-Lundin constant, depends on the source density and thermal energy of the magnetospheric electrons; it is an important parameter in magnetosphere-ionosphere coupling models. However, the K parameter is still rather unknown, and values are found in a wide range of 10–8–10–10Sim–2. In this study, we investigated how the type of auroral structure affects the K values. We look at onset and westwards-travelling surge (WTS) events and make comparisons with earlier results from observations of more stable auroral arcs. A new analysis technique for studying those magnetospheric parameters using ground-based measurements is introduced. Electron density measurements are taken with the EISCAT radar, and through an inversion technique the flux-energy spectra are calculated. Source densities, thermal energies and potential drops are estimated from fittings of accelerated Maxwellian distributions. With this radar technique we have the possibility to study the changes of the mentioned parameters during the development of onsets and the passage of surges over EISCAT. The study indicates that the linearization of the full Knight formulation holds even for the very high potential drops and thermal temperatures found in the dynamic onset and WTS events. The values of K are found to be very low, around 10–11Sm–2 in onset cases as well as WTS events. The results may establish a new technique where ionospheric measurements are used for studying the ionosphere-magnetosphere coupling processes.  相似文献   

11.
The information content of the 7-year BUV data set has been reexamined by a comparison with a fairly large set of ground Dobson and M-83 instruments. The satellite-ground intercomparison of total ozone was done under different types of ground observation techniques (observation code) and different instrument exposure (exposure code) and for various distances of the subsatellite point from the station. Because of the existing latitudinal gradient in total ozone, at a given station the bias ground-BUV tends to be smaller when the subsatellite point is at a latitude higher than the station's latitude. Knowing the total ozone gradient at a given station, the BUV total ozone has been corrected to account for the ozone gradient and the correlation was calculated with the corresponding ground observations. These correlations seem to offer no improvement when compared with the correlations between the ground ozone and the actual BUV ozone at distances of the subsatellite point from the station within 200 km from the station used in previous studies. The seasonal variation of the BUV-ground correlation reveals information on the noise level of the measurements and the geographical distribution of the percentage mean bias: (Ground-BUV)×100/(Ground) is discussed. Both on short and on longer time scales it appears that the BUV derived recommended total ozone data set is reasonably good and possible instrumental drifts are not large. The analysis includes an extension through April 1977 of the BUV and contour-derived total ozone trends byLondon andLing (1980). Over the northern hemisphere both data sets (contour and BUV) show comparable trends over middle and high latitudes which range from –3 D.U./year to –5 D.U./year during the 7-year period April 1970–April 1977. In the southern hemisphere, however, long-term variation in total ozone cannot be determined from ground observations alone. It is concluded that for unknown reasons during the 7-year period of study, total ozone has been decreasing over most of the globe. The negative growth rates at high latitudes of the northern hemisphere are highly significant.  相似文献   

12.
Riassunto Dalle osservazioni di visibilità verso il mare, eseguite giornalmente a Trieste alle ore 8, 14 e 19, nel ventennio 1931–1950, si deducono le medie mensili, stagionali e annue. La visibilità risulta massima alle ore 14 e nei mesi estivi. Il valore medio annuo è 6.5 del codice internazionale, la visibilità è di 15.000 m ed è classificata mediocre-buona. Nel ventennio l'andamento medio annuo risulta leggermente crescente.
Summary From the visibility-observations towards the sea, effectuated every day at 8h, 14h and 19h, during the period of twenty years (1931–1950), the monthly and annual mean values are calculated. The visibility results maximum at 14h of the summer months. The mean annual value is 6.5 of the International Codex, the visibility is 15.000 m and it is classified middle-good. In the twenty years 1931–1950, the mean annual going results lightly increasing.
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13.
The Gumbel’s third asymptotic distribution (GIII) of the extreme value method is employed to evaluate the earthquake hazard parameters in the Iranian Plateau. This research quantifies spatial mapping of earthquake hazard parameters like annual and 100-year mode beside their 90 % probability of not being exceeded (NBE) in the Iranian Plateau. Therefore, we used a homogeneous and complete earthquake catalogue during the period 1900–2013 with magnitude M w ? ≥?4.0, and the Iranian Plateau is separated into equal area mesh of 1° late?×?1° long. The estimated result of annual mode with 90 % probability of NBE is expected to exceed the values of M w 6.0 in the Eastern part of Makran, most parts of Central and East Iran, Kopeh Dagh, Alborz, Azerbaijan, and SE Zagros. The 100-year mode with 90 % probability of NBE is expected to overpass the value of M w 7.0 in the Eastern part of Makran, Central and East Iran, Alborz, Kopeh Dagh, and Azerbaijan. The spatial distribution of 100-year mode with 90 % probability of NBE uncovers the high values of earthquake hazard parameters which are frequently connected with the main tectonic regimes of the studied area. It appears that there is a close communication among the seismicity and the tectonics of the region.  相似文献   

14.
A comparison of monthly mean values of total ozone at South Pole, Buenos Aires (Argentina), Cachoeira Paulista and Natal (Brazil), and Huancayo (Peru) revealed that whereas South Pole showed an ozone depletion of 45% in October 1987 (as compared to October, 1977), Buenos Aires showed a small decrease (10%) while the other locations showed very small decreases (1–2%). When daily values are considered, the Antarctic ozone hole of October 1987 seems to have caused 10% depletion at Buenos Aires and 5% at Natal and Huancayo in December 1987. However, a large part of this is normal seasonal variation, except at Huancayo, where a residual effect of 5% depletion in December 1987 remains. The QBO effects (5–8% changes in the ozone level in 2–3 years) could cause 10–15% fluctuations in solar UVB on the ground on clear-sky days and could be a possible health hazard unless factors like cloudiness reduce the UVB intensities.  相似文献   

15.
Summary Spectrometric experiments performed, in November 1976, within the framework of the Latitude Survey Mission on board the NASA Convair 990 from Ames Research Center are briefly deseribed. The results presented concern odd nitrogen molecules, HCl and water vapor. In terms of vertical column density, HNO3 is predominant over NO+NO2 at all latitudes higher than 40 degrees. A seasonal variation of NO2 abundance is observed, with larger values in the summer hemisphere at high latitude. The mean zenith column density of HCl above 11 km is 1.5×1015 mol.cm–2, with no evidence for any seasonal or climatic variation. Local number densities as high as 1.4×1010 mol.cm–3 for HNO3 and 5.4×1014 mol.cm–3 for water vapor have been measured during the same flight near 11 km.  相似文献   

16.
Summary Temperature records of a long period (1858–1952) for Athens, in the form of overlapping 30-year intervals, are analyzed with a view to be investigated temperature trends.While the winter temperature has been rising almost continously during the period under consideration, the increase of summer temperature — to which the annual temperature and the annual temperature range as well are rather similar — has occured altogether during the second half of the record. During the first half the summer and annual temperatures and the annual range were all decreasing. The oceanicity increased during the first half and decreased during the second.The total change has been a rise of 0.90 deg. in winter temperature, a fall of 0.7 followed by a rise of 1.00 deg. in summer temperature, and a fall of 0.3 then a rise of 0.70 deg. in annual temperature.The rapid increase of population and also variations in solar activity seem to have partly influenced the Athens temperature trends.Presented at the tenth General Assembly of the International Union of Geodesy and Geophysics in Rome (Italy), September 1954.  相似文献   

17.
The rocketsonde data obtained from the launchings made at Thumba (8°3215N, 76°5148E) during the winter period 1970–71, as already reported, have indicated that warmings of noticeable magnitude occurred at high levels (upper stratosphere and mesosphere) over this tropical station during the period mentioned. The mean monthly radiosonde temperatures of 50, 100 and 300 mb levels at Thumba (Trivandrum) and Delhi (28°35N, 77°12E) during the same period have also pointed out certain anomalies consistent with the warmings referred to above at Thumba. The radiosonde temperatures of the two stations, Thumba (Trivandrum) and Delhi, have now been examined, along with the values of total ozone, for the ten winter periods commencing from 1961–1962. The analysis has pointed out the possibility of high-level warmings also having occurred in the past over the Indian region during the winters of 1963–1964 and 1967–1968, which are also the periods when prominent warmings are definitely known to have occurred at higher latitudes. The behaviour of total ozone has been found to be different in the different years of the warmings. The features noticed have been presented and discussed.  相似文献   

18.
We have used the thermodynamic model of the climate to estimate the effect of variations in the oceanic cloud cover on the surface temperature of the Earth in the North Hemisphere (NH) during the period 1984–1990. We assume that the variations in the cloud cover are proportional to the variation of the cosmic ray flux measured during the same period. The results indicate that the effect in the temperature is slightly noticeable when we consider the surface hemispheric temperature on July 1987, finding an average temperature anomaly between −0.06°C and −0.14°C, along a latitudinal band between 20° and 40°. The surface temperature averaged globally in the NH presents a decrease of 0.01°C in average, which is almost the same for continents and oceans. However, these values are not significant when compared to the overall variability of the time series with and without forcing.  相似文献   

19.
The minimum winter temperature series for the United States Gulf Coast for 1799–1988 (190 values) was subjected to Maximum Entropy Spectral Analysis. Significant periodicities in the QBO region (T-2–3 years) and atT=3.7, 4.5, 5.5, 6.5, 7.5, 12.9, 15.5 and 22 years were detected. Some of these were present in the first half only (1799–1893) while others in the latter half only (1894–1988), indicating a transient nature. Also, more than 50% of the variance was random. Many of the significant periodicities are seen in other geophysical parameters. Some may be harmonics of the 11-year sunspot cycle and the 22-year Hale magnetic sunspot cycle.  相似文献   

20.
Atmospheric electric potential gradient measurments were made near the ground at Vishakapatnam (17°42N, 83°18E). The diurnal variation of potential gradient during fair weather has been studied. The characteristic pattern of potential gradient in different months, different seasons and its annual variation are examined.  相似文献   

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