Washington — A 2011 U.S. National Oceanic and Atmospheric Administration (NOAA) research paper that tied weaker South Asian summer monsoons to human activities has won an international award from the World Meteorological Organization (WMO).

WMO’s Norbert Gerbier–MUMM International Award for 2013 went to the paper “Anthropogenic Aerosols and the Weakening of the South Asian Summer Monsoon,” which was published in the journal Science in September 2011. The award recognizes an original scientific paper on the influence of meteorology in a particular field of the physical, natural or human sciences, or on the influence of one of these sciences on meteorology.

The winning paper answered an important question about decreasing rainfall during South Asian summer monsoons in the last half of the 20th century by clearly pointing to human influences as the driving force behind decreasing monsoons. Using the latest NOAA Geophysical Fluid Dynamics Laboratory global climate model, the paper compared model simulations with observed monsoon rainfall data and hydrological cycle theory.

The paper showed that increased concentrations of greenhouse gases in the atmosphere were not to blame for decreasing monsoons. Aerosols, or tiny particles emitted by the burning of fossil fuels, were. The research indicated the prominent role that aerosols can play in altering regional climate.

Monsoon rains provide about 80 percent of the precipitation in South Asia, so weaker monsoons could prove harmful to crops, livestock, water resources, and human and economic health. Policymakers and resource managers needed to know whether the decreased rainfall was part of a natural cycle or was influenced by human activity.

The winning paper’s authors are Massimo Bollasina of Princeton University and Yi Ming and V. “Ram” Ramaswamy of the NOAA Geophysical Fluid Dynamics Laboratory (GFDL) in Princeton, New Jersey. Bollasina is an investigator for the Cooperative Institute for Climate Science, a partnership between NOAA and Princeton. He is also with Princeton’s Atmospheric and Oceanic Sciences Program, a collaborative program of GFDL and Princeton.

The three authors will receive the award in the spring of 2013 at the World Meteorological Organization in Geneva. The WMO is the United Nations’ agency for weather, climate, and water. The award was named for the late Norbert Gerbier, who served as president of the WMO Commission for Agricultural Meteorology from 1979 to 1985.

To read more about the paper's findings, visit the GFDL website.