Interview with Sulochana Gadgil
The Institute has made many contributions to science. Prof. Satish Dhawan, who was the major architect of the Indian Space Programme, was the director of the Institute from 1962 to 1981. He nurtured science, as well as engineering, in many new areas. He was particularly interested in meteorology and offered our interviewee of this issue, Sulochana Gadgil, a faculty position in the Centre for Theoretical Studies at the Institute, soon after she returned from the Massachussets Institute of Technology (MIT) in the USA. Her work and collaboration with meteorologists from different institutes in the country and her interactions with fluid dynamicists, particularly Prof. R Narasimha, led to the establishment of the Centre for Atmospheric and Oceanic Sciences in 1982. During 1989 to 1996, when she was the chairman of the Centre, several new faculty members were recruited, making it one of the best centres in the country.
Sulochana was born in 1944 in Pune, India. She obtained her M.Sc. in applied mathematics from Pune University in 1965. In 1970, she received her Ph.D., also in applied mathematics from Harvard University (USA). Her thesis dealt with the dynamics of the meanders of the Gulf Stream. Coming from a country where the meteorological phenomenon of monsoon is of vital importance, she decided to learn more about this mighty weather event. She was lucky to have the opportunity to work with Prof. Charney on a postdoctoral fellowship at MIT for one year. Thereafter, she returned to Pune, accepting temporary work at the Indian Institute of Tropical Meteorology and met several scientists with considerable knowledge about monsoon. She joined the Centre for Theoretical Studies at the Indian Institute of Science in 1973. Since then, she has carried out research on many facets of monsoon variability and the nature of the coupling of tropical convection and the oceans, with analysis of conventional and satellite data and theoretical investigations with models, and has also investigated the links between rainfall variability and agricultural productivity in collaboration with several scientists. She has also developed models of interacting populations in collaboration with biologists at the Institute.
In close collaboration with agricultural scientists and farmers, Sulochana has set up a farmers’ network in order to identify acceptable strategies for enhanced production in a variable climate, particularly in rainfed areas on which climate variability is known to have a large impact. With the setting-in of the fatigue of the green revolution in the last decade, enhanced production in rainfed areas has become more important than ever before. Sulochana and her collaborators have worked to develop decision-support systems, based on information and prediction of climate variability, for the rainfed belt. They showed that models which incorporated the indirect impact of climate variability via the triggering of pests/diseases needed to be combined with existing crop models for a realistic simulation of the impact of rainfall variability. Such models will be a major tool for assessing different management options. They found that input from farmers was necessary for model development, as well as elucidation and assessment of management options.
Sulochana has been active in planning climate and global change research and has served on advisory committees of several important institutions in India. She played an important role in the formulation of the Indian Climate Research Programme (ICRP) and was a leader in planning and organizing the first ICRP observational experiment in the Bay of Bengal in 1999.
As regards contacts with WMO, Sulochana was a member of the Joint Scientific Committee (JSC) of the World Climate Research Programme (WCRP) from 1990 to 1998 and Officer from 1994 to 1998. According to several members of that committee, she was extremely effective in that role. She was involved in WCRP monsoon activities and the Atmospheric Model Intercomparison Project (AMIP). She participated in the WCRP International Conference on Monsoon Variability and Prediction in Trieste, Italy (May 1994) and in the International AMIP Scientific Conference in Monterrey, Mexico (May 1995). She played an important role in the Global Change System for Analysis, Research and Training (START) Climate Prediction and Agriculture (CLIMAG) project. At present, Sulochana is a co-chair of the START Scientific Steering Committee.
Sulochana has close professional ties with her husband, Madhav Gadgil, a professor of biology at the same Institute. They have always shared their scientific interests. She says that they have enjoyed the most fulfilling family life.
This April edition of the WMO Bulletin is dedicated to women working in meteorology and hydrology and I consider myself fortunate to have been able to interview Sulochana, a great lady and eminent scientist, for this issue. Her scientific career, her interests in so many topics related to monsoon, agriculture, climate, ecology and evolutionary biology and her modelling work in all these domains make her unique. Moreover, this remarkable lady has skillfully combined her family life with a successful scientific career. She is generous, sharing her knowledge with her students and colleagues, and is kind and agreeable. I enjoyed my contacts with her on the occasion of this interview and am grateful to her for her collaboration.
H.T — Please tell us the date and place of your birth, your parents and the environment you lived in.
S.G. — I was born in 1944 in Pune (also known as Poona). My great-grandfather was an engineer who served as a Minister in the state of Tonk (north-west India). I heard the tales of his heroic efforts to help the people during the severe droughts that are so common in that part of the country from my grandfather. Both my grandfather and my father were respected physicians. My grandfather was also a freedom fighter and several active participants of the struggle against colonial rule were guests at our house. Even after independence, one of the important leaders from Maharashtra, Senapati Bapat, stayed with us every year. I was thus exposed to tales of colonial rule and the struggle for freedom throughout my childhood. My father not only had an M.D. degree in allopathy, but also studied the Indian systems of medicine, Ayurveda and Yoga, in depth. My mother was one of a thriving group of women writers in Marathi, our local language. I was the third of four daughters. My parents encouraged us all to study and take to learned professions; two of my sisters are physicians.
H.T. — Perhaps you could also tell readers something about Pune in a geographical and historical context.
S.G. — Pune was the erstwhile capital of the Maratha kingdom that held out to the last against the British. Pune lies just to the east of the crest-line of the Western Ghats, a hill chain that runs parallel to the west coast of India for a distance of 1 000 kilometres from the southern tip of the peninsula. The south-west winds of the summer monsoon blowing over the Arabian Sea rise against the Western Ghats to pour as much as 5 000 mm of rain on the hills in the span of three months. While Pune itself receives much less rain, lying as it does in the lee of the mountains, it is a wonderful place to witness the grandeur of the Indian monsoon and has been a major centre of meteorological research in India for over a century. Indeed, the clocktower of the Weather Observatory, constructed out of black basalt rock, is an important feature of the city.
Pune had been a seat of learning under Maratha rule and quickly emerged as a centre of social reform and Western education soon after the British take-over in 1818. One of the first schools for girls from disadvantaged communities, using the curriculum introduced by the British, was started in Pune in 1848, a stone’s throw away from our ancestral house in the heart of the old city. Laxmibai, a Maratha queen, leading the charge of her army on horse-back, became the most celebrated figure of the 1857 uprising against British rule. In the 1880s, Ramabai, a woman physician trained in Philadelphia, became a leading educator in Pune. The city witnessed the establishment of a women’s university in early 1900s. Many Puneites, including women, took to the newly emerging technical professions.
H.T. — What about your schooling.
S.G. — I studied in Pune, in the Marathi medium, at the elementary school level, in a famous school that had been built on the site of the stables of the Maratha cavalry. The girls were reputed to be as boisterous as the horses they had replaced. I then went on for high-school education in English to Rishi Valley, a boarding school in the neighbouring state of Andhra Pradesh. Rishi Valley was located in beautiful hilly countryside. Lying as it did in the heart of the semi-arid tract at the centre of the southern Indian peninsula, it enjoyed a drier climate than that of Pune. I returned to this setting 40 years later, when I started working with farmers on the question of what they wanted to learn from the meteorologists. At Rishi Valley, we were encouraged to study what we wished, as we wished, without any pressure. I greatly enjoyed learning classical Indian music and dance.
H.T. — What did you study at university?
S.G. — I came back to Pune for my undergraduate studies at Fergusson College, one of the oldest colleges of India, founded by the great nationalist leader, B.G. Tilak. I opted for natural sciences and majored in chemistry, physics and mathematics. I did very well academically, though Madhav, the fellow student whom I eventually married, claims that I caught his attention when jumping out of a high French window of a lecture hall to escape from a boring class! I then went on to do a master’s degree in applied mathematics at Pune University. At this juncture, I became engaged to Madhav and together we decided to pursue scientific careers.
H.T. — How come you went to study in the USA?
S.G. — Madhav and I felt that a sound foundation for a career in scientific research might be laid in good universities abroad, and we applied together to four of the world’s leading universities. Luckily, we were both admitted with scholarships to Harvard, our first choice. In 1965 we married and went to Harvard together. I was a graduate student of applied mathematics and, with my interest in the natural world, shared with Madhav, decided to work in physical oceanography. My guide, A.R. Robinson, was keen for me to have an excellent grounding in applied mathematics and physics in addition to atmospheric and oceanic dynamics, and I took several courses at Harvard. One of them, on planetary fluid dynamics, was taught by Jule Charney, then visiting Harvard from MIT. With that began a fruitful interaction with this great meteorologist, which continued throughout my stay at Cambridge. I also spent a summer at the Woods Hole Oceanographic Institution, where I had the opportunity of meeting Henry Stommel1, George Veronis and Wilhelm Malkus.
For my thesis I worked on the theory of time-dependent topographic meandering of the Gulf Stream; and on the side completed an investigation into the structure of jets in rotating fluids. We had an outstanding and a very active group of geophysical fluid dynamicists between Harvard, MIT and Woods Hole. Some members of the group, George Philander, Eugenia Kalnay and Peter Webster and I have continued to interact to this day. Because of Madhav, I also developed an interest in mathematical ecology and evolutionary biology and began some work in that field.
H.T. — Did you return to India immediately after you obtained your Ph.D.?
S.G. — By the time I completed my Ph.D. thesis in 1970, I had become interested in the monsoon circulation. Jule Charney offered me a postdoctoral fellowship to spend a year with him at MIT to work in tropical meteorology. I jumped at the chance, especially as Madhav had taken a two-year appointment as a lecturer in biology at Harvard after completing his Ph.D. in 1969. Knowing my interest in the monsoon, Charney sent me to visit T.N. Krishnamurti2 at Florida State University. My interaction with TNK and his wife Ruby, who is an outstanding geophysical fluid dynamist, continues to this day. I have learnt a great deal from TNK about the monsoon. After that year at MIT, both of us very much wanted to go back home and we headed back, spending a fortnight en route in the national parks of East Africa.
H.T. — What happened after you returned to Pune?
S.G. — Neither of us had proper jobs on returning to India, but we swam for two years in the Scientific Pool of the Council for Scientific and Industrial Research. Pune was the seat of an important centre of the India Meteorological Department (IMD). Most of the active meteorologists were at IMD or at the Indian Institute of Tropical Meteorology (IITM) that had been set up in Pune after the International Indian Ocean Expedition. I accepted an assignment as a Scientific Pool Officer at the IITM in 1971. This turned out to be most opportune,as the Institute had some of the most active researchers in meteorology such as D.R. Sikka, Y. Ramanathan and H.S Bedi. I learnt a great deal about the monsoon from them and a fruitful collaboration with them continues to this day. My daughter, Gauri, was born in 1972, and soon after that both Madhav and I received offers of Assistant Professorships at the Indian Institute of Science (IISc) in Bangalore.
H.T. — What did the new job entail?
All this meant a relatively modest rate of publications. But today I am happy that I made those choices. They have permitted me to build an excellent broad-based school of atmospheric and oceanic sciences at IISc and help many other groups in the country. They have also permitted me to enjoy a most fulfilling family life.
H.T. — When did you become Professor and how did your activities differ from previous years?
It now has eight full-time faculty members with expertise ranging over radiation and climate, atmospheric thermodynamics and convection, dynamics of the monsoon, ocean and ocean-atmospheric coupling and atmospheric chemistry, who are involved in modelling, field observations and laboratory experiments.
H.T. — You have covered a wide range of scientific activities. You started as a mathematician and then became involved with agriculture and farmers. Have you been able to use your mathematical knowledge in conducting these activities?
S.G. — I was trained as an applied mathematician and had the good fortune to learn from some of the best scientists in the field, including George Carrier and Sydney Goldstein. Carrier gave an outstanding course on the modelling of complex systems, which together with my work on modelling of phenomena relating to the oceans, the atmosphere and evolutionary biology, laid a strong foundation for work on complex natural systems. This has made it possible for me to work on crop models and to develop new models of the triggering of pests and diseases by weather events.
H.T. — Tell us about your studies of monsoon and current knowledge.
S.G. — At MIT I was exposed to Charney’s theories of the tropical convection and particularly the ITCZ. I started learning about the Indian monsoon when I joined IITM in 1971. To begin with, Sikka and I tested a hypothesis proposed by Ramaswamy about the influence of mid-latitude circulation on the breaks in the monsoon. After painstaking data collection from charts (which in itself was educative), we rejected the hypothesis. I also investigated the impact of the topography of the Indian subcontinent on monsoon circulation, a problem addressed in the early years of the century before the development of geophysical fluid dynamics. I then started a detailed study of the daily variation of the zonal cloudbands (generally associated with the ITCZ) over Indian longitudes with the help of NOAA satellite imagery and in collaboration with Sikka, who not only knew a great deal about the monsoon but had studied satellite meteorology as well. This study was to yield rich dividends in terms of elucidating the nature of intraseasonal variation of the monsoon and provided insights into the basic system responsible for its occurrence. We discovered that, throughout the summer, the cloudbands propagate from the equatorial Indian Ocean into the heated subcontinent at intervals of two to six weeks. This basic feature of the intraseasonal variation is seen every year, irrespective of whether there is a drought or whether it is a good monsoon year. We further showed that large-scale monsoon rainfall over the Indian region is associated with a continental ITCZ. During the summer monsoon, an ITCZ also appears intermittently over the equatorial Indian Ocean and there is competition between the two TCZs with active spells of one being associated with weak spells of the other. These results, discovered by subjective analysis of satellite photographs, have been verified subsequently by several scientists using outgoing longwave radiation data.
Around the time that we discovered the northward propagations of the cloudband, a similar feature was observed in the rainbands simulated in a simple climate model (axisymmetric with a continent poleward of 18°N) developed by Peter Webster and his students. This led to collaboration with Peter Webster and J. Srinivasan, who had just joined the Mechanical Engineering Department of IISc, aimed at understanding the underlying mechanisms. Srinivasan is an expert in radiation and has been an active collaborator in various facets of monsoon research. A student of ours, Ravi Nanjundiah, developed a simple climate model, which could simulate the most important features of the intraseasonal variation of the monsoon. Ravi has subsequently joined the faculty of our Centre and continues to collaborate with me in monsoon modelling.
Simulation of the precipitation patterns associated with the Indian monsoon has proved to be a great challenge for the global climate models. This is because there are two favourable locations for the tropical convergence zone; one over the warm waters of the equatorial Indian Ocean and the other over the heated subcontinent. While in nature it occurs intermittently over each of these locations, the models tend to get locked into one of these locations. Our analysis of the simulations of 30 models run under AMIP revealed this.
Even today, most models cannot simulate the interannual variation of the Indian monsoon, even when the SST is specified from observations. More work is required before they can be used for predictions on the intraseasonal or interannual scale.
H.T. — What were your particular interests in your studies of the ocean?
S.G. — I began my career as a student of A.R. Robinson at Harvard, working on the meanders of the Gulf Stream. We developed a simple model for the impact of bottom topography on an eastward current, considering steady, as well as time-dependent, solutions. After a gap of several years (in which I was involved with the monsoon) I worked with my student, Vinayachandran, and a colleague, D. Sengupta, on the simulation of the circulation of the Bay of Bengal with an ocean general circulation model.
H.T. — Then you switched to climate problems. Can you please outline some of the fields of your interest?
H.T. — What about relations between climate and agriculture?
S.G. — Since ancient times, the Indian economy has been a gamble, as agricultural production is linked to the rainfall, and that is why monsoon research has always been supported in the country. However, while most meteorologists employ this fact to talk of the potential use of meteorological predictions, there have hardly been any studies of what sort of predictions are required for farm-level decision-making and the extent to which they can be generated. In fact, even the extensive knowledge of rainfall variability derived from the rich datasets at IMD, cannot be readily used by farmers, since they use 14-day periods linked to appearance of constellations in the sky rather than the pentad or the week that the meteorologists use. Around 1994, I started working with Seshagiri Rao, an ecologist-farmer and my colleague at the centre, K.N. Rao, on using the knowledge and predictions of rainfall variability for farm-level decisions. In talking to the farmers, we realized that it would be possible to enhance production considerably (or reduce risks) if the available knowledge of rainfall variability was used in conjunction with crop models.
Traditional crops/varieties and farming practices must have evolved to be appropriate for the nature of the rainfall variability of the region by years of experience. However, the crops/varieties now grown in most regions are not the traditional ones. Hence, the tailoring of crops/varieties and farming practices to the variability of the region has yet to be achieved. Most of the recommendations generated by agricultural scientists (who do not take rainfall variability into account) are found to be incorrect by farmers. We studied the problem of the optimum planting dates for rainfed peanuts in a semi-arid tract of the Indian peninsula with a crop model run for 100 years, for which rainfall data were available. We found that the risks of failure would be high if the recommendations of the agricultural scientists were accepted; on the other hand, the sowing period currently used by the farmers involved less risk. Within that period, however, later planting would enhance production. This result, not anticipated by the farmers, is now being tested in their fields. The lesson appears to be that participatory research, in which scientists collaborate with farmers, has to replace the top-down approach adopted by scientists so far. We have developed a network of farmers in the region in order to gain from their vast knowledge of the complex ecosystem and understand the possible decision options open to them. In this way, we have been able to develop a model for the triggering of pests and diseases by wet and dry spells.
H.T. — A major factor in all your studies must have been the important question of the atmosphere-ocean system or atmosphere-ocean coupling?
In collaboration with P.V. Joseph at IMD and N.V. Joshi at our Institute, I addressed this problem by analysing the first digitized dataset on satellite-derived cloudiness—the Sadler dataset—together with the dataset on SST of the north Indian Ocean available at the IMD. We found that the relationship between organized cloudiness and SST is complex and highly non-linear. There is a threshold SST of about 27.5°C, above which the propensity of cloudiness increases rapidly. SST being above the threshold is a necessary—but not a sufficient—condition with some fraction of the warm ocean remaining cloud-free because the dynamics is not favourable. This result has been shown to be valid for all the tropical oceans with better datasets on satellite cloudiness. It so happens that the SST of the north Indian Ocean is above the threshold every summer. This has important implications for the mechanisms leading to the interannual variation of convection over the oceans and hence the monsoon.
H.T. — Please tell us about the Indian Climate Research Programme (ICRP)
S.G. — I have worked on many facets of the Indian monsoon, including analysis of conventional and satellite data to understand the nature of its space-time variation and coupling with the oceans and modelling to identify the responsible mechanisms. Several scientists in this field realized that one of the lacunae in the investigations in India was that we had not conducted observational experiments over regions that play a critical role in determining monsoon variability, such as the oceans around the subcontinent. This was clear from the enormous contributions of TOGA and TOGA-COARE to our understanding of ENSO. However, most of the experiments of this type, beginning with IIOE in the mid-1960s and including MONEX in 1979, were led by scientists from outside the region. While the need to change this situation was recognized, such a change could not have been accomplished without the active participation of scientists who were not only interested in the monsoon but were capable of handling state-of-the-art equipment, i.e. who had adequate training in engineering as well. Narasimha’s group of fluid dynamicists fitted the bill and he and D.R. Sikka led a national observational experiment on the monsoon trough boundary layer in 1990. Around the same time, G.S. Bhat, a mechanical engineer who had modelled clouds in the laboratory for his Ph.D. thesis and who was primarily interested in tropical convection and air-sea interactions, joined our Centre as a faculty member. With such expertise available in the country it became possible to think of observational experiments on the monsoon.
In the early 1990s, there was an increasing realization that important contributions by Indian scientists over the years had not been recognized, partly because they were not always published in international journals. There was a need to synthesize what we knew about the monsoon studies which would lead to a deeper understanding and hence better predictions. Thus was born the ICRP, for which I prepared the science plan in collaboration with scientists at our Centre and other institutions in the country. This plan envisaged a multi-pronged attack involving observational experiments, as well as theoretical and empirical studies.
H.T. — Please tell us about the observational experiment you organized over the Bay of Bengal.
S.G. — The Bay of Bengal Monsoon Experiment (BOBMEX) was organized by a group of scientists from different institutions in the country. With the support of all the concerned Government departments, BOBMEX was successfully conducted in July/August 1999. The second experiment under the ICRP, the Arabian Sea Monsoon Experiment (ARMEX), was carried out in June-August 2002. ARMEX and BOBMEX are important achievements. They were completely national efforts from the stage of formulating the problems to be addressed to planning and execution, which was possible because several agencies and institutions collaborated effectively. I believe that these experiments have added a further dimension to meteorological research in India.
H.T. — Can you describe or express your opinion about the links between increasing human population, climate variation and food availability. Do you foresee any immediate problems in this area?
The variability of the monsoon continued to have a particularly large impact over rainfed tracts. A fatigue of the green revolution has been witnessed over the last decade with rate of production growth declining markedly. Hence, the problem of enhancing production in the rainfed tracts (which cannot be reduced beyond 50 per cent of the cultivated area) assumes great importance. The problem is all the more difficult because it involves tailoring crops/varieties and management practices to the rainfall variability of the region and its prediction. We need to work with the farmers if we are to avoid major difficulties in the future.
H.T. — Let us talk about your contacts with WMO. You were associated with the Joint Scientific Committee (JSC) of the WMO World Climate Research Programme (WCRP).
S.G. — I enjoyed working with the JSC, firstly because it was an opportunity to listen to the latest developments in the field (something I had not had the chance to do since coming back to India in 1971) and, secondly, because I learned how international programmes are formulated, launched and executed. These lessons were important for the development and execution of the ICRP. I was deputed by the JSC to serve on the standing committee of START and I have enjoyed that association. With encouragement from Larry Gates (then chair of the JSC) and Hartmut Grassl (then director of the WCRP) and the active participation of the WCRP, the International Geosphere-Biosphere Programme (IGBP) and the International Human Dimensions Programme on Global Environmental Change, Mike Manton (also a member of the JSC), Will Steffen (IGBP) and I helped START to organize a workshop at Bogor in February 1997 to consider an end-to-end approach for modelling climate variability and agriculture. This led to the launch of the START CLIMAG programme with several demonstration projects. START has nurtured the programme over the past five years and a work plan is now being prepared.
H.T. —What sort of research work are you conducting these days?
S.G. — I continue to work on different facets of the monsoon. Our Centre now has such a talented faculty with expertise in different areas and I thoroughly enjoy the interaction with my colleagues. I continue to collaborate with scientists from other institutions as well. Recently, I finished a paper on breaks in the Indian monsoon with P.V. Joseph at Kochi University. Not too long ago, I collaborated with T.N. Krishnamurti on his work on super-ensembles for prediction. In addition, I am working with colleagues at our centre and experts at the Centre for Ecological Sciences of our Institute on climate variability and agriculture. In particular, we are establishing teacher-student-farmer networks in the climate-agriculture work.
H.T. —Can you tell us about one or two most unforgettable events of your professional life?
S.G. — The high points of my professional life have been the discovery of the phenomenon of the northward propagation of cloudbands over India and unravelling of the relationship between convection over the ocean and SST, including the existence of the SST threshold. I also believe that the methodology we have developed for addressing problems of climate variability and agriculture and its application for identifying farming strategies (such as for planting dates) is going to be recognized as a major contribution as it has the potential to help farmers considerably.
H.T. — Would you like to say something about your family?
S.G. — I have been particularly fortunate in having a wonderful family. My husband has complementary interests which have enriched both our lives. I helped him in his modelling work and we have several joint publications in evolutionary biology. With him and our children, I have spent many a happy hour watching birds, butterflies, elephants and other wildlife and enjoying a variety of landscapes from the peaks of the Himalayas and Western Ghats to our beautiful beaches. He has served as Chair of the Global Environment Facility Scientific and Technical Advisory Panel and gained an understanding of global environmental issues. We have just embarked on a collaboration on the issue of adaptation to climate change. He is also interested in the modelling of crop pests and diseases and the use of teacher-student-farmer networks in climate-agriculture work.
My children are grown up now. My lively daughter is a journalist, married to an outstanding mechanical engineer. They live at Pune where my roots are. My son is a mathematician—a topologist who enjoys his mathematics as much as Madhav and I enjoy our research (not more than us, because I cannot imagine anyone enjoying the scientific endeavour any more than we do!). He has just joined the faculty at the Indian Statistical Institute at Bangalore.
H.T. — Your scientific achievements, your skill at harmonizing career and family and your enthusiasm make you a role model for women working in meteorology and related fields. This interview makes an excellent introduction to this special issue of the WMO Bulletin. Thank you.