Essam Ghamry

Annual and semi-annual Sq variations at 96° MM MAGDAS I and II stations in Africa

The quiet daily variations of the geomagnetic field (Sq) have been studied by using the geomagnetic data of the 10 International Quietest Days. Geomagnetic data from MAGDAS I and II stations—ten stations were selected around the 96° magnetic meridian (MM)—over Africa have been analyzed from September 2008 to August 2009. The analysis of this unique data set clarifies the characteristics of the Sq variations over the African sector for the first time by observational geomagnetic data. In this paper, we found that Sq(H) and Sq(D) show a predominantly annual variation. The most interesting result, and a new finding in the African sector, is the appearance of two vortices in the day lit southern hemisphere during spring. Further data analysis also revealed many other interesting characteristics for the Sq over the African sector.

Effect of SC on frequency content of geomagnetic data using DWT application: SC automatic detection

In this paper, a study is made to determine the effect of sudden commencement (SC) on the power spectrum of geomagnetic data using multiresolution analysis (MRA) of the discrete wavelet transform (DWT). The results of this study provides a guide to develop a new technique to automatically detect the SC because it could be an indicator of the onset of a geomagnetic storm. This new technique divides the original time series into different frequency sub-bands using the MRA of the DWT. Then it detects the change in a certain sub-band which shows a large change due to the SC. The geomagnetic records used in this study were 3-s resolution data collected from the Circum-Pan Pacific Magnetometer Network (CPMN). Using such high-resolution data enables us to minimize the detection error and the processing time to make a decision. The proposed algorithm is tested on one sample every three seconds of data sets collected from the CPMN. The maximum standard deviation of the algorithm detection times is observed to be fifty four seconds of the corresponding arrival times as determined by the National Geophysical Data Center (NGDC).

Geomagnetic Sudden Commencement Automatic Detection via MODWT

It is of great importance to develop an algorithm that autodetects sudden commencement (SC) because it could be an indicator of the onset of the geomagnetic storm. A geomagnetic storm is considered as one of the global processes in the ionosphere-thermosphere-magnetosphere system. Automatic detection of SCs is based on multiresolution analysis of a maximal overlap discrete wavelet transform using a Haar wavelet filter. The proposed algorithm is tested on 1-min-resolution data sets collected from magnetic observatories belonging to the International Real-Time Magnetic Observatory Network. Maximum standard deviation of algorithm detection times is observed to be 1 min of the corresponding arrival times published by the National Geophysical Data Center.

A Wavelet Spectral Analysis Technique for Automatic Detection of Geomagnetic Sudden Commencements

Maximal overlap discrete wavelet transform is used to perform spectral analysis of geomagnetic storm sudden commencements (SCs) (SSCs). This spectral analysis guided us in the development of an automatic SSC detection algorithm. The SC can be an indicator of the onset of a geomagnetic storm; in this case, it is called an SSC. The geomagnetic records used in this study were 3-s resolution data collected from the Circum-Pan Pacific Magnetometer Network. Using such high-resolution data enabled us to achieve a small detection error and short processing time. In addition to these technical merits, we introduce a new algorithm that automatically detects, for the first time, the SC from high-resolution data (sampled at the rate of 1 sample/3 s), unlike previous studies that focused on determining the SSC times automatically using 1-min data. Ninety-three geomagnetic storms were considered for testing the proposed algorithm; it was found that the average and maximum standard deviation of the errors in the detection times determined by the algorithm were 7 and 18 samples, respectively, of the corresponding manually determined arrival times.

Un-decimated discrete wavelet transform based algorithm for extraction of geomagnetic storm sudden commencement onset of high resolution records

The automatic detection of the onset time of the geomagnetic storm sudden commencement (SSC) is of great importance for many applications. The distribution of the power along the frequency axis during the SSC was investigated. This analysis guide us to build an SSC automatic detector, for the first time, of one sample per second data based on the un-decimated discrete wavelet transform (DWT), unlike previous studies that focused on determining the SSC times using one-minute resolution data. Using such high-resolution data enabled us to achieve a small detection error and short processing time. One hundred thirty four geomagnetic storms were considered for testing the proposed algorithm; it was found that the average and maximum standard deviation of the errors in the detection times determined by the algorithm were 35 and 44s, respectively, of the corresponding manually determined onset times. The proposed algorithm tested by using continuous period data (six months). The results show the capability of the algorithm to detect the SSCs successfully with low rate of false detections.

Signatures of the low-latitude Pi 2 pulsations in Egypt

Abstract To study the activities and the physics of the Earth’s magnetosphere, several types of measurements are made with different kinds of instruments both on earth and in space. Ground based data represent the properties of the solar wind, the Earth’s magnetic field and currents in the magnetosphere. Many of the activities occurring in the magnetosphere are a result of changes in the solar wind. It has been known since the 1860s that the Earth’s magnetic field is fluctuating and during that times the fluctuations are periodical. In this study, a special type of magnetic pulsations in the Earth’s magnetic field called Pi 2 (from MAGDAS stations in Egypt) is investigated and analyzed statistically. We carried out our analysis through two different methods: (i) Fourier transformations and (ii) wavelet power spectrum. The result shows that the Pi 2 observed in the main phase of the geomagnetic storm have larger frequency than those observed in the recovery phase. These results excluded the field line resonance and the plasmapause surface as a possible generation mechanism, and suggest the cavity resonance as a possible generation mechanism of the Pi 2 pulsations at low latitude stations in Egypt.

A comprehensive analysis of the geomagnetic storms occurred during 18 February and 2 March 2014

Abstract The Geomagnetic storms are considered as one of the major natural hazards. Egyptian geomagnetic observatories observed multiple geomagnetic storms during 18 February to 2 March 2014. During this period, four interplanetary shocks successively hit the Earth’s magnetosphere, leading to four geomagnetic storms. The storm onsets occurred on 18, 20, 23 and 27 February. A non-substorm Pi2 pulsation was observed on 26 February. This Pi2 pulsation was detected in Egyptian observatories (Misallat and Abu Simbel), Kakioka station in Japan and Carson City station in US with nearly identical waveforms. Van Allen Probe missions observed non-compressional Pc4 pulsations on the recovery phase of the third storm. This Pc4 event is may be likely attributed to the decay of the ring current in the recovery phase.

Geothermal studies in oilfield districts of Eastern Margin of the Gulf of Suez, Egypt

Abstract Results of geothermal studies carried out at 149 onshore oil wells have been used in evaluation of temperature gradient and heat flow values of the eastern shore of the Gulf of Suez. The investigations included temperature logs in boreholes, calculation of amplitude temperature, geothermal gradients and heat flow. The results obtained indicate that geothermal gradient values are in the ranges of 0.02–0.044 °C/m and regionally averaged mean heat flow values are found to fall in the interval of 45–120 mW/m2. Temperature gradients and heat flow values change from low values eastward to high values toward the axial of Gulf of Suez rift. The result of this research work has been highly successful in identifying new geothermal resources eastward of the Gulf of Suez. Additionally, this study shows that the areas with relatively higher temperature gradients have lower oil window, mature earlier, than those with low gradient values. Thus, high temperature gradients cause to expedite the formation of oil at relatively shallow depths and narrow oil windows. On the other hand, low temperature gradient makes the oil window to be quite broad when locate at high depths.

The Egyptian geomagnetic reference field to the Epoch, 2010.0

Abstract The present work is a compilation of two tasks within the frame of the project “Geomagnetic Survey & Detailed Geomagnetic Measurements within the Egyptian Territory” funded by the “Science and Technology Development Fund agency (STDF)”. The National Research Institute of Astronomy and Geophysics (NRIAG), has conducted a new extensive land geomagnetic survey that covers the whole Egyptian territory. The field measurements have been done at 3212 points along all the asphalted roads, defined tracks, and ill-defined tracks in Egypt; with total length of 11,586 km. In the present work, the measurements cover for the first time new areas as: the southern eastern borders of Egypt including Halayeb and Shlatin, the Quattara depresion in the western desert, and the new roads between Farafra and Baharia oasis. Also marine geomagnetic survey have been applied for the first time in Naser lake. Misallat and Abu-Simble geomagnetic observatories have been used to reduce the field data to the Epoch 2010. During the field measurements, whenever possible, the old stations occupied by the previous observers have been re-occupied to determine the secular variations at these points. The geomagnetic anomaly maps, the normal geomagnetic field maps with their corresponding secular variation maps, the normal geomagnetic field equations of the geomagnetic elements (EGRF) and their corresponding secular variations equations, are outlined. The anomalous sites, as discovered from the anomaly maps are, only, mentioned. In addition, a correlation between the International Geomagnetic Reference Field (IGRF) 2010.0 and the Egyptian Geomagnetic Reference Field (EGRF) 2010 is indicated.