CAS Research

The mission of the Climate Analysis Section is to increase the understanding of the atmosphere and climate system through empirical studies and diagnostic analyses of the atmosphere and its interactions with the Earth's surface and oceans on a wide range of scales with a particular goal of contributing to the building of a climate information system.

Emphasis of research is on the atmospheric and oceanic general circulations, meteorological phenomena such as tropical cyclones, global warming, the hydrological cycle, and climate variations over several time scales. Research has focused on interannual variations, such as the El Nino-Southern Oscillation and the North Atlantic Oscillation phenomena; decadal variations, such as the Pacific Decadal Oscillation; and longer-period trends, and their climate forcings. Attribution and mitigation of climate change are also topics of in-depth research.

Highlights

Climate change and other factors are drying up many of the world's rivers.
Many of the world's big rivers are drying out, with no sign of relief. Kevin Trenberth of the National Center for Atmospheric Research and his colleagues analyzed 925 rivers around the globe, from 1948 to 2004. Trenberth says a third of these rivers showed significant changes. And the majority of those that changed have gotten drier. [radio interview]

Press Release: 21 April 2009
Water Levels Dropping in Some Major Rivers as Global Climate Changes
Rivers in some of the world's most populous regions are losing water, according to a new comprehensive study of global stream flow. The study suggests that in many cases the reduced flows are associated with climate change. Staff: A. Dai and K. Trenberth

First International Meeting on Attribution of Climate Events
To kick off the ACE activity, a one day meeting was held at NCAR on 26 January 2009 to discuss the research needed to provide authoritative assessments of the causes of anomalous climate conditions and extreme weather events.
Staff: A. Dai, C. Deser, J. Hurrell, and K. Trenberth

Recent Publications

Global warming due to increasing absorbed solar radiation
Global climate models used in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) are examined for the top-of-atmosphere radiation changes as carbon dioxide and other greenhouse gases build up from 1950 to 2100. There is an increase in net radiation absorbed, but not in ways commonly assumed. [article] [abstract]

Effect of the Atlantic hurricanes on the oceanic meridional overturning circulation and heat transport
Hurricanes have traditionally been perceived as intense but relatively small scale phenomena, with little effect on the large scale climate system. However, recent evidence has suggested that hurricanes could play a much more significant role in global climate. [article] [abstract]

The Mid-1970s Climate Shift in the Pacific and the Relative Roles of Forced versus Inherent Decadal Variability
A significant shift from cooler to warmer tropical Pacific sea surface temperatures (SSTs), part of a pattern of basinwide SST anomalies involved with a transition to the positive phase of the Interdecadal Pacific Oscillation (IPO), occurred in the mid-1970s with effects that extended globally. [article] [abstract]