A P Dimri

Summary of Scientific Contributions
Prof. A. P. Dimri is actively working in the field of Atmospheric Science from the past three decades. His main research interest is on winter weather and climate using observations and modeling tools. His other research interests include regional climate dynamics and its variability, statistical and dynamical downscaling of numerical model outputs, extreme events and their physical understanding as well as Western Disturbances. His doctoral thesis was themed on winter circulation characteristics over western Himalaya.
Through many publications over the decades he has provided comprehension and dynamics of Indian winter (DJF) monsoon. This brought new dimension in Indian meteorology and provided bench mark new initiative to, thus understand, linkages with the Himalayan glacier and associated water/hydrological budget.
Through multiple collaborations over the years, he has explored the winter time precipitation in the Indian meteorological parlance. He is a leading expert on winter time extra-tropical cyclones called ‘Western Disturbances’, their manifestation and interplay with existing Himalayan topography. He has aimed to understand multiple facets of this field of study with specific reference to numerical simulation, to analyze the dynamical and thermodynamical processes associated with these events. The study of Western Disturbances is intended towards the understanding of the initiation, propagation and ultimately desiccation of these cyclonic movements. The associated orographic precipitation occurrence over the north India has been studied in great detail by him. In changing global context, he has defined the term ‘Indian Winter Monsoon’ to explain the precipitation occurring during winter. His emphasis on studies of the snowfall during the winters leading to glacier replenishment provides an insight for recharging of the snow-fed rivers and overall ecology of the region.
Recently he proposed a novel method to study the temperature distribution over mountains in the form of Slope Environmental Lapse Rate modeling specific to the monsoon glacio-hydrological regime of Himalaya. He also specializes in study of Himalayan environment, its climatology and the effect of future climate scenarios on energy and hydrological budget. He has studied a much less investigated spring predictability barrier in the context of Indian Summer Monsoon. He found that the secular behavior of El Nino-Southern Oscillation (ENSO) during preceding spring of monsoon months gets reversed in the succeeding spring. A new dimension to his research is on the variability of Indian Summer Monsoon on intra-seasonal, inter-annual and inter-decadal time scales in relation with different atmospheric forcings such as Potential Vorticity, Quasi-biennial Oscillation (QBO) as well as solar cycle. He established the relation between different phases of QBO and Indian Summer Monsoon rainfall (ISM), and found the good ISM rainfall during west phase in comparison to east phase of QBO. This is particularly important in the context of predicting the ISM rainfall. In another work he established a close linkage of inter-annual changes in ISM with ENSO in the past and showed a weakening of ISM intensity in the last 180 years. In addition, he has worked on evaluation of the latest generation of multiple regional climate models under CORDEX-South Asia project. Using this ensemble of models, changes in future Indian Summer Monsoon characteristics have been assessed by him.
Importantly defined cloudburst (qualitatively discussed so far) as convective initiated trigger by orographic locking in and around the western and central Himalayas. Thus, providing exact definition of it, which was elusive thus so far.
He is involved in various national projects pertaining broadly on understanding of glacio-hydrological regime of Himalaya, extreme precipitation events such as cloudburst, microphysical characterization of winter fog as well as mass balance modeling of Gangotri glacier. He currently has 75 publications in leading national/ international peer reviewed journals as well as 7 books/ chapters in books to his name. Along with these scientific contributions he is also a member of several prestigious organizations such as Indian Meteorological Society and American Geophysical Union. He served as a council member of the Indian Geophysical Union from 2014-16 and has been awarded with various fellowships.

Joined 2020

Organisation

JNU