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

Comment on "Influence of the Southern Oscillation on tropospheric temperature" by J. D. McLean, C. R. de Freitas, and R. M. Carter
McLean et al. [2009] (henceforth MFC09) claim that the El Niño/Southern Oscillation (ENSO), as represented by the Southern Oscillation Index (SOI), accounts for as much as 72% of the global tropospheric temperature anomaly (GTTA) and an even higher 81% of this anomaly in the tropics. They conclude that the SOI is a "dominant and consistent influence on mean global temperatures," "and perhaps recent trends in global temperatures". However, their analysis is incorrect in a number of ways... [submitted abstract]

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]