Showing papers on "Space weather published in 1975"

Possible relationships between solar activity and meteorological phenomena

Abstract: A symposium was conducted in which the following questions were discussed: (1) the evidence concerning possible relationships between solar activity and meteorological phenomena; (2) plausible physical mechanisms to explain these relationships; and (3) kinds of critical measurements needed to determine the nature of solar/meteorological relationships and/or the mechanisms to explain them, and which of these measurements can be accomplished best from space.

The Response of the Magnetosphere to the Solar Wind

Abstract: Almost seventeen years have elapsed since the first probes were sent into the Earth’s magnetosphere. Since that time, our understanding of the magnetosphere has gradually evolved to the point that now we have a clear, although at times qualitative, understanding of the dominant physical mechanisms at work in the terrestrial magnetosphere. Many of these processes undoubtedly occur in the magnetosphere of Jupiter also. While their relative importance will be altered by the different scales of the parameters in the Jovian magnetosphere, our understanding of Jupiter will be hastened by our experience in studying the Earth.

The Earth's magnetosphere

Abstract: The growth of satellite observations over the last 15 years, together with increasingly sophisticated ground‐based measurements, has brought the study of Earth's electromagnetic environment to a new era of development. This study has grown to a broad discipline that overlaps magnetism, astrophysics and plasma physics. Important understandings have been achieved in many areas including auroral phenomena, distributions and interactions of plasmas and waves in the magnetosphere, the physics of wave–energetic‐particle interactions, and the identification of magnetic‐field‐aligned currents.

Geomagnetic crochets associated with proton flares.

Abstract: age increase in r, versus vT/r eFig. I also shows that even for vT=2r. the ratio re'/re= 1'34 whereas according to the correction suggested by Rees this ratio should be 2; amounting to 100% error when vT is neglected. Fig. 2 shows the profile of B(P) for vT=2r. compared with the brightness profile B(P) for vT=O. It is seen that except for increased effective width r/, the gaussian nature of the profile is not measurably distorted. One feature not shown in Fig. 2 is the shift of the position of central peak brightness through ; vT. To get a closer insight into the process leading to increased effective half-width, the effect of finite exposure and finite wind velocity on the measured brightness distribution can also be looked upon in the following way. When plotted in units of r. the instantaneous brightness profile (assumed gaussian) is a normal curve with half-width equal to unity. Effect of finite vand T can now be considered as scanning of this normal curve with a rectangular window v'F]r •• This also explains why percentage increase in r; is a function of v'F[r, only. It may finally be concluded that for usual photographic exposures of about 10 see and for atmospheric winds upto 100 m/sec, the correction to the effective half-width is quite small, except for the very early parts of observations (where, however, one does not use exposure as long as 10 see). In any case Fig. 1 may be used to correct for the effect of winds and of the exposure time.

Extreme space weather events as seen in the historical geomagnetic records of colaba, india and their estimation of interplanetary conditions

Abstract: Geomagnetic variations recorded at ground can well project the role of electromagnetic fields and currents in the ionosphere. Active regions in the sun give rise to flares, coronal mass ejections and several major solar energetic particle events of varying amplitudes and characteristics resulting in geomagnetic disturbances. Solar flares and Coronal Mass Ejections (CMEs) are the most prominent and violent manifestation of the solar activity. When the ejecta from solar flares and CMEs hit the Earth's magnetosphere, they often lead to intense magnetic storms. The geomagnetic data from Colaba Magnetic Observatory consisted of systematic hourly eye observations using Grubb’s magnetometer from 1847 to 1872 in continuation of the earlier series of observations at Colaba since 1841. The regular daily photographic records of the geomagnetic components are available since 1872 to 1905 from Colaba. The geomagnetic records from Colaba-Alibag observatories in India, contain historically the longest and continuous observations recorded on photographic paper since 1872 to the present day digital data using modern magnetometers. Data reduction and analysis techniques evolved at various stages of data processing. Some of the super intense space weather events are investigated using old preserved historical records of Colaba, India. The study of super intense storms after 1900 as recorded at Alibag Observatory will provide important insights into plausible interplanetary conditions for intense geomagnetic storms and probable frequency of their occurrence. Following the Burton et al. [1975], an empirical relationship is derived for estimation of interplanetary electric field (IEFy) from the variations of Dst index and ΔH at Colaba-Alibag observatories. The estimated IEFy values using Dst and ΔHABG variations agree well with the observed IEFy, calculated using ACE (Advanced Composition Explorer) satellite observations for intense geomagnetic storms in solar cycle 23. This study will provide the uniqueness of each event and provide important insights into possible interplanetary conditions for intense geomagnetic storms and probable frequency of their occurrence. The WDC Mumbai activities and data preserving, digitization process will be presented as a member of WDS.

The solar situation preceding the generation of the geomagnetic storm of June 17–20, 1973

Abstract: A photograph of the space laboratory SKYLAB, taken on June 10, 1973, was used to analyse the causes of the generation of the geomagnetic storm which occured after the CMP of a region, related to an eastern coronal stream. It was found that our assumptions about the existence of a coronal stream above the prominences, distributed along the meridian, as well as the densification of the formation above unstable effects, were proved. The agreement between reality and forecasts of geomagnetic activity constitutes further proof thereof. It was also found that the coronal formation lasted over several rotations, a fact with which we usually reckon under certain circumstances.