Nasa's Tropical Cloud Systems and Processes Experiment

Halverson, Jeffrey B.; Black, Mark M.; Braun, Scott A.; Cecil, Dan; Goodman, Michael; Heymsfield, Andrew J.; Heymsfield, Gerald M.; Hood, Robbie E.; Krishnamurti, T. N.; McFarquhar, Greg M.; Mahoney, Michael J.; Molinari, John; Rogers, Robert F.; Turk, J.; Velden, Christopher S.; Zhang, Da‐Lin; Zipser, Edward J.; Kakar, Ramesh K.

doi:10.1175/bams-88-6-867

Cited by 56 publications

(33 citation statements)

References 21 publications

(27 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The notion of bottom-up development (Halverson et al, 2007) is advanced as a counterpart to the more familiar "topdown" scenario advocated by Bister and Emanuel (1997) and Ritchie and Holland (1997), respectively; see also Ritchie et al (2003). (This perspective was in vogue when M06 was written.…”

Section: Three New Hypotheses Regarding the Wave-vortex Hybridmentioning

confidence: 99%

Tropical cyclogenesis in a tropical wave critical layer: easterly waves

2009

View full text Add to dashboard Cite

Abstract. The development of tropical depressions within tropical waves over the Atlantic and eastern Pacific is usually preceded by a "surface low along the wave" as if to suggest a hybrid wave-vortex structure in which flow streamlines not only undulate with the waves, but form a closed circulation in the lower troposphere surrounding the low. This structure, equatorward of the easterly jet axis, is identified herein as the familiar critical layer of waves in shear flow, a flow configuration which arguably provides the simplest conceptual framework for tropical cyclogenesis resulting from tropical waves, their interaction with the mean flow, and with diabatic processes associated with deep moist convection. The recirculating Kelvin cat's eye within the critical layer represents a sweet spot for tropical cyclogenesis in which a proto-vortex may form and grow within its parent wave. A common location for storm development is given by the intersection of the wave's critical latitude and trough axis at the center of the cat's eye, with analyzed vorticity centroid nearby. The wave and vortex live together for a time, and initially propagate at approximately the same speed. In most cases this coupled propagation continues for a few days after a tropical depression is identified. For easterly waves, as the name suggests, the propagation is westward. It is shown that in order to visualize optimally the associated Lagrangian motions, one should view the flow streamlines, or stream function, in a frame of reference translating horizontally with the phase propagation of the parent wave. In this co-moving frame, streamlines are approximately equivalent to particle trajectories. The closed circulation is quasi-stationary, and a dividing streamline separates air within the cat's eye from air outside. The critical layer equatorward of the easterly jet axis is important to tropical cyclogenesis because its cat's eye provides (i) a region of cyclonic vorticity and weak deformation by Correspondence to: T. J. Dunkerton (tim@nwra.com) the resolved flow, (ii) containment of moisture entrained by the developing gyre and/or lofted by deep convection therein, (iii) confinement of mesoscale vortex aggregation, (iv) a predominantly convective type of heating profile, and (v) maintenance or enhancement of the parent wave until the vortex becomes a self-sustaining entity and emerges from the wave as a tropical depression. The entire sequence is likened to the development of a marsupial infant in its mother's pouch. These ideas are formulated in three new hypotheses describing the flow kinematics and dynamics, moist thermodynamics and wave/vortex interactions comprising the "marsupial paradigm". A survey of 55 named tropical storms in 1998-2001 reveals that actual critical layers sometimes resemble the ideal east-west train of cat's eyes, but are usually less regular, with one or more recirculation regions in the co-moving frame. It is shown that the kinematics of isolated protovortices carried by the wave also can be visualized in a fra...

show abstract

Section: Three New Hypotheses Regarding the Wave-vortex Hybridmentioning

confidence: 99%

Tropical cyclogenesis in a tropical wave critical layer: easterly waves

2009

View full text Add to dashboard Cite

show abstract

“…These include the Tropical Cloud Systems and Processes (TCSP) in 2005 (Halverson et al, 2007) and the NASA AMMA project in 2006. Adding in the results of earlier efforts such as the Tropical Experiment in Mexico (TEXMEX; Bister and Emanuel, 1997;Raymond et al, 1998) and even serendipitous observations of the early development of hurricane Ophelia in RAINEX (Houze et al, 2006(Houze et al, , 2009 and occasionally from reconnaissance aircraft (Reasor et al, 2005),…”

Section: Appendix a Initialization Via The Reverse Balance Equationsmentioning

confidence: 99%

Coarse, intermediate and high resolution numerical simulations of the transition of a tropical wave critical layer to a tropical storm

2010

View full text Add to dashboard Cite

Abstract. Recent work has hypothesized that tropical cyclones in the deep Atlantic and eastern Pacific basins develop from within the cyclonic Kelvin cat's eye of a tropical easterly wave critical layer located equatorward of the easterly jet axis. The cyclonic critical layer is thought to be important to tropical cyclogenesis because its cat's eye provides (i) a region of cyclonic vorticity and weak deformation by the resolved flow, (ii) containment of moisture entrained by the developing flow and/or lofted by deep convection therein, (iii) confinement of mesoscale vortex aggregation, (iv) a predominantly convective type of heating profile, and (v) maintenance or enhancement of the parent wave until the developing proto-vortex becomes a self-sustaining entity and emerges from the wave as a tropical depression. This genesis sequence and the overarching framework for describing how such hybrid wave-vortex structures become tropical depressions/storms is likened to the development of a marsupial infant in its mother's pouch, and for this reason has been dubbed the "marsupial paradigm".Here we conduct the first multi-scale test of the marsupial paradigm in an idealized setting by revisiting the Kurihara and Tuleya problem examining the transformation of an easterly wave-like disturbance into a tropical storm vortex using the WRF model. An analysis of the evolving winds, equivalent potential temperature, and relative vertical vorticity is presented from coarse (28 km), intermediate (9 km) and high resolution (3.1 km) simulations. The results are found to support key elements of the marsupial paradigm by demonstrating the existence of a rotationally dominant region with minimal strain/shear deformation near the center of the critical Correspondence to: M. T. Montgomery (mtmontgo@nps.edu) layer pouch that contains strong cyclonic vorticity and high saturation fraction. This localized region within the pouch serves as the "attractor" for an upscale "bottom up" development process while the wave pouch and proto-vortex move together.Implications of these findings are discussed in relation to an upcoming field experiment for the most active period of the Atlantic hurricane season in 2010 that is to be conducted collaboratively between the National Oceanic and Atmospheric Administration (NOAA), the National Science Foundation (NSF), and the National Aeronautics and Space Adminstration (NASA).

show abstract

“…One reason for the lack of understanding is undoubtedly the fact that genesis occurs over the tropical oceans where conventional observational data such as radar data, radiosonde soundings and surface data are relatively sparse. While there have been a few field experiments directed at documenting cyclogenesis (Bister and Emanuel, 1997;Ritchie and Holland, 1999;Halverson et al, 2007;Elsberry and Harr, 2008;Zipser et al, 2009) and a few serendipitous sets of measurements (Reasor et al, 2005;Houze et al, 2009), many questions remain about the processes involved and their relative importance. A recent review of work over the past few years is given by Montgomery and Smith (2011).…”

Section: Introductionmentioning

confidence: 99%

Observations of the convective environment in developing and non‐developing tropical disturbances

Smith

2012

Quart J Royal Meteoro Soc

View full text Add to dashboard Cite

Analyses of thermodynamic data gathered from airborne dropwindsondes released from the upper troposphere during the Pre-Depression Investigation of Cloud Systems in the Tropics (PREDICT) experiment are presented. We focus on two systems that finally became hurricanes Karl and Matthew, and one system (Gaston) that attained tropical storm status, but subsequently weakened and never redeveloped during five days of monitoring. Data for all events show that the largest values of total precipitable water are collocated with the surface trough and with values of convective available potential energy that seem high enough to support convective organization. These values coincide mostly with low values of convective inhibition. Vertical profiles of virtual potential temperature show little variability between soundings on a particular day, but the system means from day to day show a slight warming. In contrast, vertical profiles of pseudo-equivalent potential temperature, θ e , show much more variability between soundings on a particular day on account of the variability in moisture.In all systems, there was is a tendency for the lower troposphere to moisten, but in the non-developing system, the troposphere became progressively drier in the height range between approximately 2 and 9 km during the five days of observations. In the developing systems, the troposphere moistened. The most prominent difference between the non-developing system and the two developing systems was the much larger reduction of θ e between the surface and a height of 3 km, typically 25 K in the non-developing system, compared with only 17 K in the developing systems. Conventional wisdom would suggest that, for this reason, the convective downdraughts would be stronger in the non-developing system and would thereby act to suppress the development. Here we propose an alternative hypothesis in which the drier air weakens the convective updraughts and thereby the convective amplification of absolute vorticity necessary for development. Copyright

show abstract

Nasa's Tropical Cloud Systems and Processes Experiment

Cited by 56 publications

References 21 publications

Tropical cyclogenesis in a tropical wave critical layer: easterly waves

Tropical cyclogenesis in a tropical wave critical layer: easterly waves

Coarse, intermediate and high resolution numerical simulations of the transition of a tropical wave critical layer to a tropical storm

Observations of the convective environment in developing and non‐developing tropical disturbances

Contact Info

Product

Resources

About