The Pre-Depression Investigation of Cloud-Systems in the Tropics (PREDICT) Experiment: Scientific Basis, New Analysis Tools, and Some First Results

Montgomery, Michael T.; Davis, Christopher A.; Dunkerton, Timothy J.; Wang, Zhuo; Velden, Christopher S.; Torn, Ryan D.; Majumdar, Sharanya J.; Zhang, Fuqing; Smith, Roger K.; Bosart, Lance F.; Bell, Michael M.; Haase, Jennifer S.; Heymsfield, Andrew J.; Jensen, J. B.; Campos, T.; Boothe, Mark A.

doi:10.1175/bams-d-11-00046.1

Cited by 152 publications

(144 citation statements)

References 29 publications

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“…Vigh and Schubert (2009) refer to the right-hand side of the geopotential tendency equation as the "cyclogenesis function". Since observations show clearly that tropical cyclogenesis is not an axisymmetric process (e.g., Dunkerton et al, 2009;Montgomery et al, 2012), we believe a more appropriate term for this quantity is the "spin-up function" (S). For the remainder of this paper we will adhere to this latter terminology.…”

Section: Figmentioning

confidence: 99%

Asymmetric and axisymmetric dynamics of tropical cyclones

et al. 2013

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Abstract. We present the results of idealized numerical experiments to examine the difference between tropical cyclone evolution in three-dimensional (3-D) and axisymmetric (AX) model configurations. We focus on the prototype problem for intensification, which considers the evolution of an initially unsaturated AX vortex in gradient-wind balance on an f plane. Consistent with findings of previous work, the mature intensity in the 3-D model is reduced relative to that in the AX model. In contrast with previous interpretations invoking barotropic instability and related horizontal mixing processes as a mechanism detrimental to the spin-up process, the results indicate that 3-D eddy processes associated with vortical plume structures can assist the intensification process by contributing to a radial contraction of the maximum tangential velocity and to a vertical extension of tangential winds through the depth of the troposphere. These plumes contribute significantly also to the azimuthally averaged heating rate and the corresponding azimuthal-mean overturning circulation.The comparisons show that the resolved 3-D eddy momentum fluxes above the boundary layer exhibit counter-gradient characteristics during a key spin-up period, and more generally are not solely diffusive. The effects of these eddies are thus not properly represented by the subgrid-scale parameterizations in the AX configuration. The resolved eddy fluxes act to support the contraction and intensification of the maximum tangential winds. The comparisons indicate fundamental differences between convective organization in the 3-D and AX configurations for meteorologically relevant forecast timescales. While the radial and vertical gradients of the system-scale angular rotation provide a hostile environment for deep convection in the 3-D model, with a corresponding tendency to strain the convective elements in the tangential direction, deep convection in the AX model does not suffer this tendency. Also, since during the 3-D intensification process the convection has not yet organized into annular rings, the azimuthally averaged heating rate and radial gradient thereof is considerably less than that in the AX model. This lack of organization results broadly in a slower intensification rate in the 3-D model and leads ultimately to a weaker mature vortex after 12 days of model integration. While azimuthal mean heating rates in the 3-D model are weaker than those in the AX model, local heating rates in the 3-D model exceed those in the AX model and at times the vortex in the 3-D model intensifies more rapidly than AX. Analyses of the 3-D model output do not support a recent hypothesis concerning the key role of small-scale vertical mixing processes in the upper-tropospheric outflow in controlling the intensification process.In the 3-D model, surface drag plays a particularly important role in the intensification process for the prototype intensification problem on meteorologically relevant timescales by helping foster the organization of convection in azimu...

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Section: Figmentioning

confidence: 99%

Asymmetric and axisymmetric dynamics of tropical cyclones

et al. 2013

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“…An end-to-end simulation system is developed to carry out a sensitivity analysis of the modified FSI algorithm, and it is compared with the GO method. The occultation geometry of ARO events used in this simulation study is based on characteristics of the flights in the PRE-Depression Investigation of Cloud-systems in the Tropics (PREDICT) field campaign over the tropical Atlantic during August-September of 2010 (Montgomery et al, 2012;Haase et al, 2014;Murphy et al, 2015). During the PREDICT campaign, the Global Navigation Satellite System (GNSS) Instrument System for Multistatic and Occultation Sensing (GISMOS) was deployed on the Gulfstream-V High-performance Instrumented Airborne Platform for Environmental Research (GV HIAPER) aircraft (Garrison et al, 2007).…”

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confidence: 99%

Application of the full spectrum inversion algorithm to simulated airborne GPS radio occultation signals

2016

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Abstract. With a GPS receiver on board an airplane, the airborne radio occultation (ARO) technique provides dense lower-tropospheric soundings over target regions. Large variations in water vapor in the troposphere cause strong signal multipath, which could lead to systematic errors in RO retrievals with the geometric optics (GO) method. The spaceborne GPS RO community has successfully developed the full-spectrum inversion (FSI) technique to solve the multipath problem. This paper is the first to adapt the FSI technique to retrieve atmospheric properties (bending and refractivity) from ARO signals, where it is necessary to compensate for the receiver traveling on a non-circular trajectory inside the atmosphere, and its use is demonstrated using an end-to-end simulation system.The forward-simulated GPS L1 (1575.42 MHz) signal amplitude and phase are used to test the modified FSI algorithm. The ARO FSI method is capable of reconstructing the fine vertical structure of the moist lower troposphere in the presence of severe multipath, which otherwise leads to large retrieval errors in the GO retrieval. The sensitivity of the modified FSI-retrieved bending angle and refractivity to errors in signal amplitude and errors in the measured refractivity at the receiver is presented. Accurate bending angle retrievals can be obtained from the surface up to ∼ 250 m below the receiver at typical flight altitudes above the tropopause, above which the retrieved bending angle becomes highly sensitive to the phase measurement noise. Abrupt changes in the signal amplitude that are a challenge for receiver tracking and geometric optics bending angle retrieval techniques do not produce any systematic bias in the FSI retrievals when the SNR is high. For very low SNR, the FSI performs as expected from theoretical considerations. The 1 % in situ refractivity measurement errors at the receiver height can introduce a maximum refractivity retrieval error of 0.5 % (1 K) near the receiver, but the error decreases gradually to ∼ 0.05 % (0.1 K) near the surface. In summary, the ARO FSI successfully retrieves the fine vertical structure of the atmosphere in the presence of multipath in the lower troposphere.

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“…1 The new cyclogenesis model and accompanying scientific hypotheses were established observationally in the Atlantic and eastern Pacific sectors by DMW09. The new models find additional support in idealized numerical modeling simulations (Wang et al, 2010a, b;Montgomery et al, 2010a;Nicholls and Montgomery, 2013), recent case studies in the field in the western North Pacific during the Tropical Cyclone Structure Experiment 2008 (TCS08, Montgomery et al, 2010b;Lussier III, 2010;Montgomery et al, 2012;Raymond and López-Carrillo, 2011;Lussier III et al, 2014), in the Atlantic during the Pre-Depression Investigation of Cloud Systems in the Tropics (PREDICT) campaign in 2010 Smith and Montgomery, 2012;Ahijevych, 2012, 2013), in NASA's ongoing Hurricane and Severe Storm (HS3) missions (2012)(2013)(2014)(2015)(2016) and the case of Hurricane Sandy (Lussier III et al, 2015). The field data afford a resolved view of horizontal and vertical structure in the wave pouch and its immediate surroundings, valuable for system centering, circulation magnitude, vortic-8512 T. M. Freismuth et al: Why did the storm ex-Gaston (2010) fail to redevelop?…”

Section: Introductionmentioning

confidence: 74%

Why did the storm ex-Gaston (2010) fail to redevelop during the PREDICT experiment?

et al. 2016

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Abstract. An analysis is presented of the failed redevelopment of ex-Gaston during the 2010 PREDICT field campaign based on the European Centre for Medium Range Weather Forecast (ECMWF) analyses. We analyze the dynamics and kinematics of ex-Gaston to investigate the role of dry, environmental air in the failed redevelopment. The flow topology defined by the calculation of particle trajectories shows that ex-Gaston's pouch was vulnerable to dry, environmental air on all days of observations. As early as 12:00 UTC 2 September 2010, a dry layer at and above 600 hPa results in a decrease in the vertical mass flux and vertical relative vorticity. These findings support the hypothesis that entrained, dry air near 600 hPa thwarted convective updraughts and vertical mass flux, which in turn led to a reduction in vorticity and a compromised pouch at these middle levels. A compromised pouch allows further intrusion of dry air and quenching of subsequent convection, therefore hindering vorticity amplification through vortex tube stretching. This study supports recent work investigating the role of dry air in moist convection during tropical cyclogenesis.

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The Pre-Depression Investigation of Cloud-Systems in the Tropics (PREDICT) Experiment: Scientific Basis, New Analysis Tools, and Some First Results

Cited by 152 publications

References 29 publications

Asymmetric and axisymmetric dynamics of tropical cyclones

Asymmetric and axisymmetric dynamics of tropical cyclones

Application of the full spectrum inversion algorithm to simulated airborne GPS radio occultation signals

Why did the storm ex-Gaston (2010) fail to redevelop during the PREDICT experiment?

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