A First Look at the Structure of the Wave Pouch during the 2009 PREDICT–GRIP Dry Runs over the Atlantic

Abstract

A first look at the structure of the wave pouch during the 2009 PREDICT-GRIP dry runs over the Atlantic, Mon. Wea. Rev., 140: 1144Rev., 140: -1163Rev., 140: : 2012 On the other hand, the diagnosis of two nondeveloping waves with a deep pouch suggests that strong vertical shear or dry air intrusion at the middleupper levels (where a wave pouch was absent) can disrupt deep convection and suppress storm development.To sum up, this study suggests that a deep wave pouch extending from the midtroposphere (;600-700 hPa) down to the boundary layer is a necessary condition for tropical cyclone formation within an easterly wave. It is hypothesized also that a deep wave pouch together with other large-scale favorable conditions provides a sufficient condition for sustained convection and tropical cyclone formation. This hypothesized sufficient condition requires further testing and will be pursued in future work.

High resolution simulation of the South Asian monsoon using a variable resolution global climate model

“…Recent studies have pointed out that vortices in the tropical easterly waves over the Atlantic and eastern Pacific can develop into tropical depressions through wave-vortex interaction in a manner similar to the development of a marsupial infant in its mother"s pouch (eg., Dunkerton et.al. 2009, Wang et al 2012. Such a wave-vortex interaction is favored under conditions of weak vortex deformation and moisture containment provided the parent wave is well maintained, so that the above environmental conditions can encourage the aggregation of mesoscale vortices to produce convective heating (Dunkerton et al 2009).…”

Predictability and Genesis of Hurricane Karl (2010) Examined through the EnKF Assimilation of Field Observations Collected during PREDICT

“…Figure 1 summarizes the track and intensity changes of the weather system, starting from the pre-Karl disturbance on 9 September and ending with its decay over Mexico on 18 September. Intensity and track observations of the tropical cyclone are taken from the NHC best-track dataset, while the pregenesis storm positions come from the wave tracking product described in Wang et al (2012). The figure also indicates the positions of PREDICT dropsonde observations that were collected during each flight mission.…”

The importance of low-deformation vorticity in tropical cyclone formation

“…Our new quantity is related, but distinct from, the familiar Galilean-invariant vorticity, which is used in most TC formation diagnostics, and indeed the vertical component 3 is enhanced surrounding the sweet-spots identified by Dunkerton et al and subsequent papers by these authors Montgomery et al, 2010;Wang et al, 2010a, b;Wang, 2012;Wang et al, 2012, hereafter termed DMW papers). However, enhanced vorticity can often extend far from the sweet-spot, which means vorticity alone is insufficient for identifying the sweet-spot.…”