Geomagnetic pearl oscillations
1-May-2023: Geomagnetic pearl oscillations increase in the recovery phase of geomagnetic storms
Researchers have traced a very significant increase in special continuous oscillations with pearl-type structures called Geomagnetic Pc1 pearl oscillations on the surface of the Earth in the recovery phase of geomagnetic storms. This study is significant for investigating of precipitation particles during geomagnetic storms and can help us understand the radiation hazard to satellites and astronauts.
Earth’s magnetic field forms a protective shield around us, and various plasma waves are generated in this magnetic field cavity. However, geomagnetic storms often cause a dent in this protection. Energetic particles are either accelerated or lost from the Earth’s radiation belts during these storms. This is responsible for changes in plasma environment leading to growth of low-frequency waves called Electromagnetic ion-cyclotron (EMIC) wave instability which is seen as the magnetic field oscillations (0.1-5 Hz) called as Pc1 pulsations.
The Geomagnetic Pc1 pearl oscillations are amplitude-modulated structured narrow-band signals, which are signatures of low-frequency EMIC waves generated by resonant wave-particle interactions in the Earth’s magnetosphere. The observation of these oscillations is a proxy for the measurement of particle precipitation in the Earth’s magnetosphere.
Evidences of these pulsations are abundant in the mid and high-latitude regions. However, at very low latitude stations, it is not frequent. These waves are an important component of space weather in the near-Earth environment.
A team of scientists at IIG, an autonomous institute of the Department of Science and Technology, along with different Indian and global organization investigated the long-term variability of these pulsations in connection to solar cycles 20-21 and descending phase of solar cycle 24 from very low latitude regions of India.
In the study published in the Journal of Atmospheric and Solar-Terrestrial Physics, the researchers used 13 years of archived records covering solar cycle 20–21 from the equatorial site Choutuppal (CPL, L = 1.03) and 5 years of digital induction coil magnetometer data covering descending phase of solar cycle 24 from the low latitude site Desalpar (DSP, L = 1.07) to investigate the structures of Pc1 waves. The morphological changes during quiet and active geomagnetic conditions were investigated, and the role of ionosphere in bringing the high-latitude EMIC wave to low latitude via ionosphere was modelled.
A clear increase in the number of Pc1 at night was observed compared to the day. This is because the attenuation of Pc1 waves upon propagation via the ionospheric waveguide towards lower latitudes is weaker during night hours. Similarly, during the solar maximum period, the transmission rate of Pc1 waves to the equator was diminished than during the solar minimum. The annual and seasonal patterns of Pc1 occurrence showed an inverse relation with sunspot numbers at both stations. An association of these pulsations with active geomagnetic conditions showed the occurrence of Pc1 increasing significantly in the recovery phase of geomagnetic storms.
The understanding of radiation hazards to satellites and astronauts offered by the study is a great necessity in an era highly dependent on satellite-based communication systems.
Modern Analogue Dataset
29-Apr-2023: Newly developed modern analogue dataset based on biotic and abiotic proxy records could be accurate reference tool for the palaeo-ecological studies in the CGP
Scientists have developed a modern analogue dataset based on biotic and abiotic proxy records from different depositional settings like lakebeds, river beds, forest floors, and croplands across two interfluves of the Central Ganga Plain (CGP) that would be an accurate reference tool for the palaeo-ecological studies in the CGP.
The Central Ganga Plain serves as a food basket for thickly populated India and is undergoing significant upheavals in terms of climatic (monsoonal) variability in recent decades. Future scenario assessment requires rigorous climate models which are built utilizing key data inputs (of this eco-system) emerged from well-dated Palaeo-reconstructions.
A considerable number of records are available from the Central Ganga Plain with restricted information on Palaeo-environmental reconstruction. Modern proxies to distinguish different ecology and depositional environment at the appropriate spatial scale are limited, and generation of such proxies is vital for decoding the past environment in the CGP.
Furthermore, the Ghaghara-Gandak and Ganga-Ghaghara interfluve regions are areas where several meter-thick sediments have been deposited during the Late Quaternary. The interfluve regions are comprised of different depositional environments, such as fluvial, lacustrine, forest, and croplands, so they are important for past environmental and modern analogue studies. The soil/sediment samples can be complemented with biotic (pollen, diatoms, and phytoliths) and abiotic proxies (sediment texture, stable carbon and nitrogen isotopes, XRD/ XRF elements, and magnetic susceptibility parameters).
The BSIP, an autonomous institute of DST, evaluated the strength and weaknesses of biotic and abiotic proxy records of the Ghaghara-Gandak and Ganga-Ghaghara interfluves of CGP.
For the first time, they adopted a holistic approach towards developing multiproxy modern analogues from the two interfluves, which would be an accurate reference tool for the palaeo-ecological studies in the Central Ganga Plain and surrounding areas. The study published in the journal Catena, evaluated both the strength and weaknesses of these proxies and assessed how reliably multiproxy modern analogues can identify different ecological and depositional environments and could be used as a baseline in interpreting Late Quaternary palaeo-environmental and ecological changes more accurately in this region.
The study of biotic and abiotic interactions is important as they aid in building the forest community, food crops, agro-pastoral and human settlements in this region. Consequently, the palaeo-ecological data would assist in better understanding the past and also the sustainable future projections in the Central Ganga Plain.
For example, the inception of human settlement in this region could also be traced through the establishment of marker pollen, phytolith, and diatom taxa. The high/low occurrences of annual herbs like Euphorbiaceae and Convolvulaceae (marker pollen taxa) indicated the monsoonal fluctuation in the Central Ganga Plain. Besides, the different cultural pollen taxa apprised how human-associated changes have reduced the forest cover in the CGP, and hence those forest trees should be plated that can generate and sustain our life-supporting system by giving out oxygen and also combat the rising CO2 levels by carbon sequestration.
The work stands out due to the fact that the fossil pollen represents the plant upto species level and hence could directly trace vegetation changes, and pollen could be an accurate tool for monitoring the large-scale variability in climate change scenarios.
The study would help measure the dynamics of the natural vegetation and the shifts in human occupation over time for future scenario development. This modern comprehensive dataset could provide background information for the Late Quaternary palaeo-ecological reconstruction from the Central Ganga Plain along with the practices for preserving and conserving the endangered biodiversity that flourishes in forests, crops, lakes, and rivers system of this region.
The lakes of the CGP, which were once proliferated with water and supported human settlement, are presently drying up and need to be preserved and cleaned so that the rich biodiversity flourishing in and around the lakes could be used for sustainable future development. Hence the various proxies used in this study helps in generating eco-environmental prospect of wetland and sediments status in this region.
The multiparameter study could also be viewed as an important baseline for conserving different lakes and river systems, often treated as wastelands to be drained, filled, and converted for other purposes.
FM
28-Apr-2023: PM inaugurates 91 new 100W FM Transmitters to enhance FM connectivity in the country
Prime Minister Shri Narendra Modi today commissioned Low Power FM Transmitters of capacity of 100 Watt at 91 locations. These transmitters of have been installed in 84 districts of 20 states. With this the network of transmitters with All India Radio has increased from 524 to 615. The addition will further boost the coverage of AIR to 73.5% of the population of the country.
Left Wing Extremism hit areas, Aspirational Districts and border areas of the country have been given priority for the installation of the transmitters.
Clear sound quality and easy availability of FM receiver equipped mobile phones has increased the demand of FM radio service in the country. In another major step towards meeting this demand and capacity building of the organisation, Government has further approved installation of 63 more FM transmitters in the country.
The Prime Minister congratulated All India Radio on this momentous occasion. Speaking about the significance of the addition, the Prime Minister said that today marks a significant step in the expansion of FM services by All India Radio in the direction of becoming All India FM. He underlined that the beginning of 91 FM transmitters by All India Radio is like a present for 85 districts and 2 crore people of the nation.
The Prime Minister said that the government is continuously working for the democratization of technology. “It is important that no Indian should feel scarcity of opportunity if India has to rise up to its full potential”, the Prime Minister said. Making modern technology accessible and affordable is key to this. He explained this by mentioning optical fiber to all the villages and the cheapest data cost that has eased access to information. He said that this has given a new push to digital entrepreneurship in villages. Similarly, UPI has helped small businesses and street vendors to access banking services.
The Prime Minister underscored the emotional connection of his generation with radio. “For me, there is an added happiness that I have a relationship with radio as a host too”, the Prime Minister said referring to the upcoming 100th episode of Mann Ki Baat. He said “This kind of emotional connect with the countrymen was possible only through the radio. Through this, I remained linked to the strength of the country and the collective power of the duty among the countrymen.” He elaborated on this point by giving examples of the role of the programme in initiatives like Swachh Bharat, Beti Bachao Beti Padhao, and Har Ghar Tiranga which became a people’s movement through Mann Ki Baat. “Therefore, in a way, I am part of your All India Radio Team”, the Prime Minister added.
The Prime Minister underlined that the inauguration of 91 FM transmitters forwards the policies of the government that gives preference to the underprivileged who have been deprived of this facility so far. “Those who were considered to be distant will now get a chance to connect at a greater level”, the Prime Minister said. Listing out the benefits of FM transmitters, the Prime Minister mentioned relaying important information on time, community building efforts, weather updates related to agricultural practices, information on food and vegetable prices for the farmers, discussions about the loss incurred by the use of chemicals in agriculture, pooling of advanced machinery for agriculture, informing women self-help groups about new market practices and assisting the entire community during times of a natural calamity. He also mentioned the infotainment value of the FM.
The Prime Minister touched upon the dimension of linguistic diversity and informed that FM transmission will take place in all the languages and especially in the regions with 27 dialects. “This connectivity does not link just the tools of communications but it connects the people too. This is reflective of the work culture of this government”, said the Prime Minister highlighting the emphasis on social connectivity along with the promotion of physical connectivity.
Concluding the address, the Prime Minister underlined the vision and mission of all communication channels like All India Radio and said that connectivity be it in any form, its purpose is to connect the country and its 140 crore citizens. He expressed confidence that all stakeholders will continue to move forward with this vision resulting in the strengthening of the country through continuous dialogue.
Union Minister Shri Anurag Thakur addressed the gathering from Leh via video conferencing. Speaking about the achievement the Minister said the transmitters will act as a conduit to carry information about the programmes and policies of the government as well as entertainment related content to the corners of the country.
The Minister credited PM Modi for his push for expansion of radio connectivity in India and acknowledged the contribution of his Mann Ki Baat programme in endorsing the importance of Radio, which has been aptly captured in a survey by IIM Rohtak recently.
The Minster underlined that today Akashwani has the largest FM network in India and this network will carry the growth story of New India to every corner of the country.
Background
As part of the government’s commitment to enhancing FM connectivity in the country, 91 new 100W FM transmitters have been installed in 84 districts across 18 States and 2 Union Territories. A special focus of this expansion has been on enhancing coverage in Aspirational Districts and in border areas. The States and UTs which are covered include Bihar, Jharkhand, Odisha, West Bengal, Assam, Meghalaya, Nagaland, Haryana, Rajasthan, Uttar Pradesh, Uttarakhand, Andhra Pradesh, Kerala, Telangana, Chhattisgarh, Gujarat, Madhya Pradesh, Maharashtra, Ladakh and Andaman & Nicobar Islands. With this expansion of AIR’s FM service, an additional 2 crore people will now be covered who did not have access to the medium. It will result in the expansion of coverage in about 35,000 sq km area.