J. Khanna, D. Medvigy, G. Fisch, TTAT Neves, Regional hydroclimatic variability due to contemporary deforestation in southern Amazonia and associated boundary layer characteristics. Journal of Geophysical Research - Atmospheres, doi:10.1002/2017JD027888, (2018)
J. Khanna, D. Medvigy, S. Fueglistaler and R. Walko, Regional dry-season climate changes due to three decades of Amazonian deforestation. Nature Climate Change, 7, 200-204, doi: 10.1038/nclimate3226, (2017)
R. M. Nagare, P. Bhattacharya, J. Khanna, and R. A. Schincariol, Coupled cellular automata for frozen soil processes, SOIL, 1, 103-116, doi:10.5194/soil-1-103-2015, (2015)
J. Khanna, D. Medvigy, Strong control of surface roughness variations on the simu- lated dry season regional atmospheric response to contemporary deforestation in Rondonia, Brazil., Journal of Geophysical Research - Atmospheres, 119, 13, 067-13,078, doi:10.1002/2014JD022278, (2014)
J. Khanna, J. Bandoro, R. J. Sica, C. T. McElroy, New technique for retrieval of at- mospheric temperature profiles from Rayleigh-scatter lidar measurements using nonlinear inversion, Applied Optics. 51, 33, 7945-7952, doi:10.1364/AO.51.007945, (2012)
J. Khanna, K. Cook and E. Vizy. Wet and dry tropical/subtropical regions show opposite sensitivities to observed greenhouse gas warming. 31st Conference on Climate Variability and Change, AMS Annual Meeting, Austin, USA. 537 (jan 2018)
K. Cook, E. Vizy and J. Khanna. One Drier, One Wetter: A Tale of Two Rainforests. 31st Conference on Climate Variability and Change, AMS Annual Meeting, Austin, USA. 17B.1 (jan 2018)
J. Khanna and D. Medvigy. Land use induced hydroclimatic variability over large de- forested areas in southern Amazon rainforest. AGU Fall Meeting, New Orleans, USA. A41M-06 (dec 2017)
D. Medvigy and J. Khanna. Regional hydroclimatic impacts of contemporary Amazonian deforestation and their spatiotemporal variability - An integrated study using remotely sensed data and numerical tools. AGU Fall Meeting, San Francisco, USA. H31I-04, (dec 2016)
J. Khanna, D. Medvigy, S. Fueglistaler and R. Walko. Regional hydro-climatic changes due to three decades of Amazonian deforestation. AGU Fall Meeting, San Francisco, USA. B31A-0535, (dec 2015)
J. Khanna, and D. Medvigy. Surface roughness variations control the regional atmospheric response to contemporary scale deforestation in Rondonia, Brazil. EGU General Assembly, Vienna, Austria. 4145, (april 2015)
J. Khanna, and D. Medvigy. Surface roughness variations control the regional atmo- spheric response to contemporary deforestation in Rondonia, Brazil. AGU Fall Meeting, San Francisco, USA. GC13J-0822, (dec 2014)
J. Khanna, and D. Medvigy. Costs and benefits of simulating the hydro-climatological ef- fects of Amazonian deforestation at different resolutions. AGU Fall Meeting, San Francisco, USA. A33E-0268, (dec 2013)
J. Khanna, and D. Medvigy. Links between land use change and recent dry season droughts in Amazonia. AGU Fall Meeting, San Francisco, USA. H54B-05, (dec 2012).
J. Khanna, R. J. Sica, and C. T. McElroy. Atmospheric temperature retrievals from lidar measurements using techniques of non-linear mathematical inversion. AGU Fall Meeting, San Francisco, USA. SA51B-1935, (dec 2011)
R. Wing, et al. First results from the relocated and enhanced Purple Crow lidar. AGU Fall Meeting, San Francisco, USA. SA51B-1945, (dec 2011)
R. J. Sica, et al. The new and improved Purple Crow lidar. AGU Fall Meeting, San Francisco, USA. A11A-0027, (dec 2010)
J. Khanna Land-atmosphere interactions and regional hydroclimatic impacts induced by anthropogenic land cover and climate change in wet tropical regions. Center for Atmospheric and Oceanic Sciences, Indian Institute of Science, Bangalore, Karnataka, India, (nov 2017)
J. Khanna, D. Medvigy, S. Fueglistaler and R. Walko. Identification of regional climatic changes due to three decades of Amazonian deforestation. Lamont Doherty Earth Observatory, Columbia University, Palisades, N.Y., USA, (jan 2016)
PhD (2011 to 2016), Programme in Atmospheric and Oceanic Sciences, Princeton University, USA
M.S. in Physics and Environment and Sustainability (2009 to 2011), Department of Physics and Astronomy, University of Western Ontario, Canada
M.Sc. in Physics (2006 to 2008), Department of Physics, Indian Institute of Technology, Roorkee, India
B. Sc. in Physics (with Hons.) (2003 to 2006), Department of Physics, Banaras Hindu University, India
Atmospheric physics, physical processes of land-atmosphere coupling, regional climatology, deforestation impacts in tropical rainforests, convective processes, boundary layer processes
Invited participant in the workshop “The economic value of climate stability from forests: The case of the Brazilian agricultural frontier” organized by The National Socio-Environmental Syn- thesis Center in University of Maryland, USA. (March 2018)
Vegetation, the lowest occupant of our food chain, serves as the base of the pillar of life on Earth. But, although not apparent, vegetation also plays a big role in regulating the Earth’s climate, most apparently by the atmospheric regulation of - CO2 through photosynthesis, atmospheric moisture through evapotranspiration and absorbed energy through surface albedo. But what spatial scales does this regulation become substantial enough to cause a detectable modification to the climate? I am interested in investigating the regional hydro-climatological impacts of vegetation. In the past I have worked on deforestation impacts in the Amazon rain forest and my recent interests have evolved to also include such studies in forests in India like the ones in the Himalayas.
Regional Scale Convective Processes
One of the challenges for accurate climate change prediction is the adequate representation of convection. Convection and clouds appear in a myriad of spatial scales in our atmosphere. On top of that, a myriad of thermodynamic and radiative processes are involved in convection and cloud development. Not all of this region-specific complexity is understood and even less is represented in climate models. For example, convection in the tropics is traditionally represented based on the thermodynamic state of the large scale atmosphere which results in inaccurate convective triggering and precipitation in numerical models. I share my research interest with several active efforts that aim at improving our understaning of convection on regional scales. In particular I am investigating such processes over densely vegetated areas in the Amazon and in India.
Extreme Heat Events under Climate Change
Climate projections for the Indian subcontinent show an alarming increase in extreme heat events throughout the Indo-Gangetic plains and some parts of south eastern India. The extreme events are intriguing because the observed temperature records from India do not show a significant increasing trend in daily peak temperatures despite the overall increasing trend in daily average temperature. Studies have suggested the crucial role of increased near surface humidity in increasing the 'perception' of heat during heat waves. But water vapor in the atmosphere can have other physical and dynamical impacts as well which could ultimately manifest in to heat wave sensitivity on the surface. Understanding such under-lying processes is another research direction I am currently pursuing.
January 2019 Department of Hydrology, IIT Roorkee, India
Instructor for graduate course HY-513 - Hydrometeorology and Climate Change.
2017 - The McGraw Center for Teaching and Learning, Princeton University, USA Certificate from the Teaching Transcript Program.
September 2014 to January 2015 - Princeton University, USA
Assistant in teaching for GEO415 - Introduction to Atmospheric Sciences.
September 2009 to August 2011 - University of Western Ontario, Canada
Instructor for Physics 1301A/1302B - Introductory Physics 1/2 (undergraduate laboratory course).
August 2008 to May 2009 - Indian Institute of Technology, Roorkee, India
Teaching Assistant for Undergraduate Introductory Physics lecture course and physics laboratory training course.