MMM SEMINAR NCAR
George N.
Kiladis
Aeronomy Laboratory, NOAA
Tropical convection is organized over a wide range of spatial and temporal scales, from Mesoscale Convective Systems (MCS) on up to hemispheric equatorial waves such as the Madden-Julian Oscillation (MJO). An intriguing feature of organized envelopes of tropical convection is the fact that they tend to be composed of smaller scale, higher frequency disturbances. For example, it is well-known that the slowly eastward propagating MJO actually comprises a broad spectrum of higher frequency waves propagating both eastward and westward, such as Kelvin and mixed Rossby-gravity waves. These disturbances are in turn made up of even smaller features, and so on down to the scale of individual cumulus clouds. A fundamental question in tropical meteorology concerns how these individual disturbances might conspire to produce selfsimilar structures across such a wide range of scales. One clue may lie in the fact that the evolution of cloud morphology within MCS and equatorial waves displays a surprising degree of self-similarity across scales, generally characterized by shallow convection along their leading edges, a combination of deep convection and stratiform rainfall in their centers, followed by a preponderance of stratiform rainfall along their trailing edges. The observed vertical structures of these organizations also display a high degree of scale invariance, particularly in temperature and moisture fields. Understanding the nature of these interactions may be crucial to the improvement of convective parameterization in atmospheric general circulation models. One potentially unifying theme discussed in this talk is related to the concept of "gross moist stability".
Thursday, 7 April 2005, 3:30
PM
Refreshments 3:15 PM
NCAR-Foothills Laboratory
3450 Mitchell Lane
Bldg 2 Auditorium (Rm1022)