Environmental Science Division (EVS)a Division of Argonne National Laboratory

ARM mobile facility completes aerosol campaign in India

May 31, 2012

The U.S. Department of Energy’s Atmospheric Radiation Measurement (ARM) Program mobile observing facility, AMF1, recently completed its deployment in Nainital, India, in support of the Ganges Valley Aerosol Experiment (GVAX). Argonne National Laboratory atmospheric scientist Rao Kotamarthi led the one-year campaign. Kotamarthi is the first national lab scientist to be awarded use of the ARM mobile facility.

The GVAX campaign is the first long-term collaborative climate research effort between the DOE and India's science-related agencies. The Indo-U.S. collaborative project deployed a full set of instruments to continuously measure atmospheric state, energy budgets, clouds, and aerosol properties in the Indo-Gangetic Plain. The data gathered during this campaign will allow researchers to study, among other things, the effects of aerosols on the plain’s hydrologic cycle. This region encompasses most of northern and eastern India and is bounded on the north by Himalaya Mountains that feed its numerous rivers—including the Ganges River that many millions of people rely on every day.

“Aerosols over the Indo-Gangetic basin is characterized by a mixture of most aerosol types,” said S.K. Satheesh, an assistant professor at the Centre for Atmospheric and Oceanic Sciences, Indian Institute of Science (IISc), Bangalore. “It is one of the best locations to study aerosol radiative impacts as well as aerosol-cloud relationships because of strong seasonal dependence on aerosol composition.”

Argonne’s Kotamarthi worked closely with colleagues from the IISc and the Aryabhatta Research Institute of Observational Sciences (ARIES) to gather a comprehensive set of measurements during pre-monsoon, monsoon, and post-monsoon seasons. The goal of the GVAX program is to gain a better understanding of the impact of these aerosols on the regional climate in general and on the monsoons in particular. The data set collected by the program thus has the potential of not only helping advance basic climate science, but also benefiting local communities by increasing the understanding of how the chemical and physical characteristics of the aerosols could affect them directly.

“Most models either assume uniform distribution of aerosols in the lower part of the atmosphere or that all the aerosols are above the atmospheric boundary layer with a smooth decay,” said Kotamarthi. “As a result of our research, we now have data that shows significantly distinct heating profiles from aerosols in the atmosphere.”

Researchers involved in GVAX campaign recently presented some preliminary data at the Atmospheric System Research Science Team Meeting in Crystal City, Virginia. Highlights included measurements of the subtropical jetstream over the Ganges Valley region, cloud cover and cloud heights for the monsoon period, and water vapor profiles through the various seasons.

ARM Facility in Nainital, India.
ARM Facility in Nainital, India. [Source: Argonne National Laboratory]
portrait of V. Rao Kotamarthi