Born on 21 February 1927 in Kolkata, Mitra learnt high standards of academics and discipline from his father who was a school teacher. He nurtured and actively practised these values throughout his life. A brilliant student all through his educational career, he stood first in all his examinations. He studied at Bangabasi College and completed his MSc in physics from Calcutta University, before joining Prof. Sisir Kumar Mitra, the doyen of ionospheric research in India, for a DPhil degree. It was Prof. S.K. Mitra who had laid the foundation for ionospheric research in India and his illustrious student and successor A.P. Mitra carried the programme forward. Besides ionospheric research, Mitra’s contributions to science cover many fields that include chemistry of the atmosphere, space research, climate change and global warming.
In 1954, after completingDPhil from Calcutta University,Mitra joined the National Physical Laboratory (NPL), New Delhi, whichmarked the first step of his brilliantscientific career. His early work atNPL involved Earth’s near-spaceenvironment, with both ground-based and space techniques. He setup the Radio Science Division at theNPL and was closely associated with it till his very last days. Mitra waslargely responsible for developingthe Radio Science Division of NPL into one of the front-ranking research centres of the world.
Mitra initiated research in ionospheric physics at the NPL in 1970 when K.S. Krishnan was Director, and contributed significantly to major improvements in radio communication capabilities in the country. Research on the ionosphere has always depended largely on the prevailing technology. In the 1960s the upper atmosphere was probed using rocket-borne payloads. In the 1970s the Satellite Instructional Television Experiment (SITE) used radio beacons to study the upper ionosphere. In the1990s satellites in conjunction with radars, studied the atmosphere from the ground level to heights of 1,000 km. Physical properties like density and temperature were measured at various levels along with a host of other parameters. Mitra coordinated and oversaw all these successful developments and also developed an ionospheric prediction system that has been supporting broadcasting and point-to-point communication systems for more than four decades. He also established an International Radio and Geophysical Warning Centre serving India, West Asia and South East Asia, and established one of the most extensive radio flare detection systems. His work on cosmic radio noise for studying the upper atmosphere led to a series of discoveries in ionosphere, solar physics and cosmic rays.
Mitra was the driving force behind the Indian programme of the International Geophysical Year (IGY) during 1957-58, and the International Quiet Sun Year (IQSY), 1964-65. In the 1970s, Mitra introduced radio research in the troposphere region which contributed significantly to India’s radio communication capability. By introducing tropospheric radio research in India, he contributed to major improvements in radio communication capabilities in the India. He helped the Indian Air Force’s radar communication systems, which gave them superior detection capability. He spearheaded the Indian Middle Atmosphere Programme (IMAP), which started in 1982 to examine the role of middle atmosphere in determining climatic change. This was the beginning of climate change research in India. The IMAP saw extensive use of balloons and rockets to carry equipment up to ionospheric levels.
During the 1990s, Mitra focused on understanding global environmental changes due to human activities and their consequences on the biosphere and provided leadership to several on global change related programmes. He also helped formulate the Indian response to climate change. His landmark contributions in studying the ozone layer, atmospheric chemistry and measuring greenhouse gases in India had an international impact. He was of the opinion that the Intergovernmental Panel on Climate Change was far behind in its research. He was a leading figure in the widely known international programmes ‘Indian Ocean Experiment (INDOEX)’ and the earlier ‘Asian Least Cost Greenhouse Gas Abatement Strategy (ALGAS)’Programme.
Mitra wanted climate studies to be based on good home-grown science. As P.K. Gautam of Institute of Defence Studies and Analysis reminisces, “Mitra believed that foreign-funded research agencies in the region always carried an agenda suited to their own national interests. He was keen that a South Asian Association for Regional Cooperation (SAARC) network be established with India assuming the leadership role.” With this objective, he was keen to set up a new high-altitude lab at Hanle in Ladakh with a great potential for studying atmospheric data. There was a station in Darjeeling in West Bengal located in the house of J.C. Bose; one in the Sunderbans in West Bengal set up by Jadavpur University, Kolkata; and another station in Port Blair in Andaman & Nicobar Islands to collect atmospheric data on a regular basis. Mitra was keen to involve the army in this work, especially in the rugged, remote and high-altitude region of Eastern Himalayas, which he felt did not have adequate number of stations to collect atmospheric data.
Mitra played a key role in setting up some large National and International facilities like the mesospheric-stratospheric-tropospheric, or MST Radar at Tirupati, Free Air Carbon Dioxide Enrichment (FACE) facility at the Indian Agriculture Research Institute, New Delhi, and the Bose Institute of High Altitude Centre for Astro-particle Physics and Space Science in Darjeeling. He was instrumental in developing both institutional and individual capacities across the South Asian Region in the area of global climate change research. He was the chairman of South Asian START Committee (SASCOM) during 1994-98, but continued as the Director of the South Asian START Regional Centre (SAS RC) located at NPL until his death.
Mitra’s concern for global climate change comes out in the following statement made in Kolkata in 2006: “The most precious commodity in this changing world is a stable climate. This in the changing world is a resource. The question of equity is raised. Every citizen should in the long run have an equal emission quota. A new approach is the concept of Contraction and Convergence. It is a policy that to us seems reasonable. It urges that global emissions be cut from the present global average of 1 tonne CO2 per capita to 1/3rd of this value, equally shared, by 2040.” Although a brilliant student himself, Mitra was against laying too much stress on exam results. He said “We lay too much emphasis on academic excellence in student life. We should see how a researcher fares and stop looking for just rank holders.” Known to be assertive, Mitra combined the qualities of an administrator and a scientist well during his tenure as Director of the National Physical Laboratory and Director General, CSIR. But he treated his juniors and research students with lot of care and was always available for discussion and guidance.
Mitra occupied top positions in several international bodies. He was President of the International Union of Radio Science (URSI) during 1984-87. He was the first Indian and second Asian to be elected to this high office. He was a member of the General Committee of International Council of Scientific Union (ICSU) during 1984-88 and was associated with several policy-making bodies. He also served on the Committee on Space Research (COSPAR) in various capacities.
He was elected Fellow of the Royal Society of London in 1989. He was a Fellow of all the three national academies of India, but also of some of the most prestigious academies of the world including the Russian Academy of Sciences, the Third World Academy of Sciences (TWAS), and of the International Academy of Astronautics. He was President of the National Academy of Sciences and Secretary, INSA during 1979-82.Mitra had been bestowed with several awards and medals. He was winner of the Bhatnagar Award, besides the C.V Raman Award, FICCI Award, G.M. Modi Award, and MeghnadSaha Award, to name a few. He had over 200 publications to his credit and had also written and edited several books and monographs. He was awarded the Padma Bhushan by Government of India in 1987. He was a multifaceted scientist-administrator who has left his mark on a wide range of international issues and put India in a leading position in global climate change research.