Southeastern Pacific Ocean Research May Lead to Better Climate Models for Global Warming, El Niño

One hundred fifty scientists from more than 40 universities in nine countries are starting a coordinated program aimed at gaining new insights about the Earth’s climate and the complex, inter-connected system involving the oceans, atmosphere and the land. They are studying the Southeastern Pacific Ocean, the marine area off South America’s west coast — a region where the interplay among low clouds, strong low level winds, coastal ocean currents, surfacing of deep water, the Andes Mountains, aerosols, and other factors shape the regional climate and affect the global weather in ways that are poorly understood.

“Our research should produce a better understanding of the Southeast Pacific Ocean system, and to improve our global computer climate models, which would lead to more confidence in climate forecasts, including predictions about global warming,” says C. Roberto Mechoso, UCLA professor of atmospheric and oceanic sciences, who chairs the VOCALS (VAMOS Ocean-Cloud-Atmosphere-Land Study) program. “Models currently used for climate change studies have systematic errors concerning the Southeastern Pacific Ocean; because the models are not accurate for such an extensive area, then the El Niños they produce in the Pacific are questionable as well; we hope our research will get rid of, or at least greatly decrease, these uncertainties.”

Variations in the Southeast Pacific climate affects rainfall and temperature worldwide, directly or indirectly, Mechoso believes, but how the system works is not well understood, and therefore cannot be modeled well or predicted accurately.

“Despite its great importance to the Earth’s climate system, the ocean-cloud-atmosphere-land system in the Southeast Pacific has been sparsely observed,” Mechoso says. “With VOCALS, that will change drastically.”

Will VOCALS increase our understanding of how much global warming will occur, and over what period of time?

“Absolutely,” says Mechoso, an expert on El Niño who studies the coasts of Ecuador, Peru and Chile. “We may also produce a better understanding of the dynamics of El Niño. The relation between the Eastern Pacific and El Niño is strong — El Niño develops in the Eastern Pacific — so when the Eastern Pacific is not well represented in climate models, El Niño is not well-represented in the models either.”

VOCALS has a scientific modeling program, which Mechoso heads, which seeks to improve model simulations of key climate processes, and an experimental field component, headed by Robert Wood, assistant professor of atmospheric sciences at the University of Washington. The intensive experimental field program will measure with four aircraft and two research ships containing scientific instruments how thick and deep the clouds are, where and why they open, and a variety of other issues to answer key scientific questions related to the climate system of the Southeast Pacific region. One ship is from the U.S., and the other is from Peru; the scientists expect another ship from either Chile or Ecuador.

“There is tremendous analysis and modeling work that will go along with the field project,” Mechoso says.

VOCALS is supported primarily with federal funding by the National Science Foundation and the National Atmospheric and Oceanic Administration, with additional support by the U.S. Department of Energy and Office of Naval Research, as well as support from Chile and Peru, and a research aircraft from the UK Meteorological Office.

VOCALS, which has a budget of more than $16 million, will continue for three to five years, starting in January 2008; the field program will begin in October 2008, off the coasts of Chile and Peru.

“I believe we have the right questions and the right hypotheses to guide our work,” Mechoso says. “We will learn how the Southeastern Pacific Ocean system works, and find out ways to improve the performance of our climate models.”

Mechoso’s own research project within VOCALS, in collaboration with the National Center for Environmental Prediction, aims to improve the model that is used by the United States for seasonal climate prediction. The “V” in VOCALS represents an acronym: VAMOS, or Variability of the American Monsoon Systems. Mechoso was first chair of this panel of the World Climate Research Program, which identified the Eastern Pacific as an area where improvement in climate models is essential.

The scientists in VOCALS are also trying to learn more about the role of aerosol in cloud behavior and climate.

“The role of aerosol in climate is very complex and we are working very hard to capture aerosol effects in climate models,” Mechoso says. Particles in the atmosphere can directly influence radiation from the sun, but can also have indirect influences on solar radiation by affecting cloud formation. The Intergubernamental Panel on Climate Change (IPCC, a recent Nobel laureate) has emphasized the need to reduce the overall uncertainty in the calculation of climate forcing by aerosol.

Other UCLA faculty participating in the research include James C. McWilliams, UCLA’s Louis B. Slichter Professor of Earth Sciences; Alex Hall, assistant professor of atmospheric and oceanic sciences; and Bjorn Stevens professor of atmospheric and oceanic sciences. Mechoso noted that El Niño was discovered by former UCLA professor Jacob Bjerknes.