Search Results

You are looking at 1 - 7 of 7 items for

  • Author or Editor: Michael Grose x
  • Refine by Access: All Content x
Clear All Modify Search
Michael R. Grose, Jonas Bhend, Sugata Narsey, Alex Sen Gupta, and Josephine R. Brown

Abstract

Climate warming has large implications for rainfall patterns, and identifying the most plausible pattern of rainfall change over the next century among various model projections would be valuable for future planning. The spatial pattern of projected sea surface temperature change has a key influence on rainfall changes in the tropical Pacific Ocean. Here it is shown that simple indices of the size of the equatorial peak in the spatial pattern of warming and to a lesser extent the hemispheric asymmetry in warming are useful for classifying the surface temperature change in different models from phase 5 of the Coupled Model Intercomparison Project (CMIP5). Models with a more pronounced equatorial warming show a fairly distinct rainfall response compared to those with more uniform warming, including a greater “warmer-get-wetter” or dynamical response, whereby rainfall increases follow the surface warming anomaly. Models with a more uniform warming pattern project a smaller rainfall increase at the equator and a rainfall increase in the southern tropical Pacific, a pattern that is distinct from the multimodel mean of CMIP5. Thus, the magnitude of enhanced equatorial warming and to some extent the hemispheric asymmetry in warming provides a useful framework for constraining rainfall projections. While there is not a simple emergent constraint for enhanced equatorial warming in models in terms of past trends or bias in the current climate, further understanding of the various feedbacks involved in these features could lead to a useful constraint of rainfall for the Pacific region.

Full access
David J. Karoly, Mitchell T. Black, Andrew D. King, and Michael R. Grose
Full access
Michael R. Grose, James S. Risbey, Mitchell T. Black, and David J. Karoly
Full access
Michael R. Grose, Mitchell Black, James S. Risbey, Peter Uhe, Pandora K. Hope, Karsten Haustein, and Dann Mitchell
Open access
Michael R. Grose, James S. Risbey, Aurel F. Moise, Stacey Osbrough, Craig Heady, Louise Wilson, and Tim Erwin

Abstract

Atmospheric circulation change is likely to be the dominant driver of multidecadal rainfall trends in the midlatitudes with climate change this century. This study examines circulation features relevant to southern Australian rainfall in January and July and explores emergent constraints suggested by the intermodel spread and their impact on the resulting rainfall projection in the CMIP5 ensemble. The authors find relationships between models’ bias and projected change for four features in July, each with suggestions for constraining forced change. The features are the strength of the subtropical jet over Australia, the frequency of blocked days in eastern Australia, the longitude of the peak blocking frequency east of Australia, and the latitude of the storm track within the polar front branch of the split jet. Rejecting models where the bias suggests either the direction or magnitude of change in the features is implausible produces a constraint on the projected rainfall reduction for southern Australia. For RCP8.5 by the end of the century the constrained projections are for a reduction of at least 5% in July (with models showing increase or little change being rejected). Rejecting these models in the January projections, with the assumption the bias affects the entire simulation, leads to a rejection of wet and dry outliers.

Full access
Michael Garstang, Edward Zipser, Robert Ellingson, Kenneth Warsh, Peter Grose, Stanley Ulanski, Ronald Holle, Ward Seguin, David Fitzjarrald, Steven Greco, and George D. Emmitt

Abstract

Fifty years ago the Line Islands Experiment was launched to obtain in situ surface, soundings, and aircraft observations in a convectively active region of the tropical oceans close to the nadir point of the new geosynchronous meteorological satellite. Two related tropical field experiments, in 1968 and 1969, followed in the vicinity of Barbados in the western Atlantic. Component parts of these three field experiments are recalled in this presentation that resonated over the subsequent half century.

Full access
Carly R. Tozer, James S. Risbey, Michael Grose, Didier P. Monselesan, Dougal T. Squire, Amanda S. Black, Doug Richardson, Sarah N. Sparrow, Sihan Li, and David Wallom
Free access