Search Results

You are looking at 1 - 10 of 20 items for :

  • All content x
Clear All
Oreste Reale, William K. Lau, Kyu-Myong Kim, and Eugenia Brin

latter is the precursor of Helene and will be discussed in section 3c . In Fig. 2 the same Hovmöller diagram is extracted from operational NCEP analyses (interpolated on pressure levels at 1° × 1°) for validation purposes. There is a very good correlation in the vorticity fields, notwithstanding that slightly stronger vorticity values can be seen in the GEOS-5 analyses. As for the moisture, it is intrinsically a very noisy field but the correspondence between the basic features is also very good

Full access
John Molinari and David Vollaro

1. Introduction Molinari and Vollaro (2008 , hereafter MV08) examined the spatial variation of helicity and convective available potential energy (CAPE) in Hurricane Bonnie (1998). They made use of dropsonde data collected during the Third and Fourth Convection and Moisture Experiments (CAMEX-3 and CAMEX-4; Kakar et al. 2006 ) by the National Aeronautics and Space Administration (NASA). An enormous azimuthal variation of helicity over the lowest 3 and 6 km existed with respect to the

Full access
Syed Ismail, Richard A. Ferrare, Edward V. Browell, Gao Chen, Bruce Anderson, Susan A. Kooi, Anthony Notari, Carolyn F. Butler, Sharon Burton, Marta Fenn, Jason P. Dunion, Gerry Heymsfield, T. N. Krishnamurti, and Mrinal K. Biswas

turn can influence cloud microphysics, latent heat release, vertical transport and convection development, and precipitation. Fields of water vapor concentration are a key component for understanding processes of precipitation, evaporation, and latent heat release in cloud systems. The lack of adequate and accurate moisture measurements with sufficient vertical and horizontal resolutions limits the ability of most numerical models to represent these processes. Krishnamurti et al. (1994) found

Full access
Zhuo Wang, M. T. Montgomery, and T. J. Dunkerton

tropical cyclone bottom-up development. The notion of a “vortical” hot tower generalizes the concept of a tall, protected region of undilute ascent ( Riehl and Malkus 1958 ; Riehl and Simpson 1979 ; Simpson et al. 1998 ) to a rotating environment. Montgomery and collaborators showed that in a favorable vorticity- and moisture-rich tropical environment, VHTs quickly emerge as the dominant coherent structures and act as essential building blocks in constructing the tropical cyclone (TC) vortex via

Full access
Wallace Hogsett and Da-Lin Zhang

emphasize that lateral energy fluxes are critical for TC development. It is obvious from Fig. 4 that there are pronounced offsets between the PBL friction (KDIS) and BKE production (KGEN; Fig. 4a ), and between convective consumption (LHR) and moisture supply (LFLX) through the lateral boundaries ( Fig. 4b ). In general, the budget terms increase in magnitude slowly prior to 63 h, although the BKE production (KGEN) is highly variable during the partial eyewall stage. As will be shown in section 6

Full access
Edward K. Vizy and Kerry H. Cook

strong meridional soil moisture gradients that lead to strong positive meridional temperature gradients at the surface and in the lower troposphere. The positive meridional temperature gradient at the surface induces easterly flow over the surface monsoon westerlies, including at the level of the AEJ ( Cook 1999 ). The AEJ can extend westward over the adjacent eastern North Atlantic and intensify, especially during a SAL outbreak. The SAL is a layer of warm, dry Saharan air and dust that advances

Full access
Zhaoxia Pu, Xuanli Li, and Juanzhen Sun

National Aeronautics and Space Administration (NASA) Convective and Moisture Experiment ( Kakar et al. 2006 ), and the 2005 Hurricane Rainband and Intensity Change Experiment ( Houze et al. 2006 ), have been conducted to collect data during intensive observing periods. During July 2005, NASA, in collaboration with NOAA, executed the Tropical Cloud Systems and Processes (TCSP) field experiment ( Halverson et al. 2007 ) based in Costa Rica. The goal of this experiment was to improve the understanding of

Full access
Chanh Q. Kieu and Da-Lin Zhang

associated with the tangential flows). Because the two processes depend on the momentum drag and the heat and moisture exchange coefficients, respectively, Craig and Gray (1996) conducted a series of sensitivity experiments in which these coefficients are varied alternately. Their results confirm the WISHE feedback as the main mechanism for TCG. In fact, we have also seen in Part II that the surface heat fluxes and pressure drops increase sharply during the merging phase, also revealing the important

Full access
Zhuo Wang, M. T. Montgomery, and T. J. Dunkerton

pouch). The results broadly supported the hypotheses proposed by Dunkerton et al. (2009 , hereafter DMW09) for tropical cyclone formation. DMW09 proposed three new hypotheses linking synoptic, subsynoptic, mesoscale, and cloud-scale processes of the tropical troposphere. The cat’s eye region within the easterly wave’s critical layer was hypothesized to be important in TC formation. In the first hypothesis (H1) wave breaking or roll up of the cyclonic vorticity and moisture near the critical

Full access
R. A. Hansell, S. C. Tsay, Q. Ji, N. C. Hsu, M. J. Jeong, S. H. Wang, J. S. Reid, K. N. Liou, and S. C. Ou

important implications for their potential to modulate the heat and moisture surface budgets ( Solomon et al. 2007 ), surface–air exchange processes, and the general circulation of the atmosphere (e.g., Lau et al. 2006 ). It is necessary to understand these regional effects before a comprehensive understanding of its global-scale impact can be achieved. In this paper, the DRE LW of airborne mineral dust during the NASA African Monsoon Multidisciplinary Analysis (NAMMA) 2006 field campaign is

Full access