TITLE

The Spatial Variability of Moisture in the Boundary Layer and Its Effect on Convection Initiation: Project-Long Characterization

AUTHOR(S)
Fabry, Frédéric
PUB. DATE
January 2006
SOURCE
Monthly Weather Review;Jan2006, Vol. 134 Issue 1, p79
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
An attempt was made to statistically gauge the importance of moisture variability on convection initiation by analyzing data collected by radar, surface stations, soundings, and airborne in situ sensors over the 7 weeks of the International H2O Project (IHOP_2002). Based on radar refractivity data, the spatial structure of humidity near the surface proved to be very anisotropic, crosswind variability being typically twice as large as along-wind variability, in part as a result of the west-to-east climatological gradient in moisture across the Oklahoma panhandle. Variability in humidity was largest from the afternoon to sunset and smallest a few hours before and after sunrise. At the surface, variograms of refractivity increase almost linearly with scale in the crosswind direction, suggesting that the field of moisture shows little in terms of local maxima and minima. Higher in the boundary layer, moisture variability increases at small scales because of the entrainment of dry capping stable layer air as the daytime boundary layer grows, and the rate of that dry-air entrainment could be used to calculate surface moisture variability. The effect of the observed variability in moisture and temperature in the upper boundary layer on convective inhibition was quantified and contrasted with the effect expected from boundary layer updrafts. At synoptic scales and at the upper end of the mesoscale, the location of convection initiation is most sensitive to the variability in temperature. At smaller scales, storm development becomes extremely sensitive to the strength of updrafts; however, those same updrafts also magnify the effect of moisture and temperature variability, as a result of which the effect of small-scale moisture variability cannot be ignored. Some of the consequences of these findings on the representativeness of radiosonde measurements in the boundary layer and instrumentation needs for convection initiation forecasting are surveyed.
ACCESSION #
19560145

 

Related Articles

  • Observations of the Evolution of the Nocturnal and Convective Boundary Layers and the Structure of Open-Celled Convection on 14 June 2002. Bennett, Lindsay J.; Weckwerth, Tammy M.; Blyth, Alan M.; Geerts, Bart; Qun Miao; Richardson, Yvette P. // Monthly Weather Review;Jul2010, Vol. 138 Issue 7, p2589 

    The Boundary Layer Evolution (BLE) missions of the International H2O Project (IHOP_2002) were designed to provide comprehensive observations of the distribution of water vapor in the quiescent boundary layer and its evolution during the early morning. The case study discussed in this paper...

  • Transitions in Boundary Layer Meso-Ï’ Convective Structures: An Observational Case Study. Kristovich, David A. R.; Laird, Neil F.; Hjelmfelt, Mark R.; Derickson, Russell G.; Cooper, Kevin A. // Monthly Weather Review;Dec99, Vol. 127 Issue 12, p2895 

    Boundary layer rolls over Lake Michigan have been observed in wintertime conditions predicted by many past studies to favor nonroll convective structures (such as disorganized convection or cellular convection). This study examines mechanisms that gave rise to transitions between boundary layer...

  • A New Mixing-Length Formulation for the Parameterization of Dry Convection: Implementation and Evaluation in a Mesoscale Model. Teixeira, J.; Ferreira, J. P.; Miranda, P. M. A.; Haack, T.; Doyle, J.; Siebsema, A. P.; Salgado, R. // Monthly Weather Review;Nov2004, Vol. 132 Issue 11, p2698 

    A realistic representation of the evolution of the dry convective boundary layer in mesoscale and large-scale atmospheric models has been an elusive goal for many years. In this paper the performance of a new mixing-length formulation for the dry convective boundary layer is evaluated in the...

  • A High-Resolution Modeling Study of the 24 May 2002 Dryline Case during IHOP. Part I: Numerical Simulation and General Evolution of the Dryline and Convection. Xue, Ming; Martin, William J. // Monthly Weather Review;Jan2006, Vol. 134 Issue 1, p149 

    Results from a high-resolution numerical simulation of the 24 May 2002 dryline convective initiation (CI) case are presented. The simulation uses a 400 km × 700 km domain with a 1-km horizontal resolution grid nested inside a 3-km domain and starts from an assimilated initial condition at...

  • Convective Plume Paths from a Line Source. REES, D. A.; STORESLETTEN, L. // Quarterly Journal of Mechanics & Applied Mathematics;Aug2002, Vol. 55 Issue 3, p443 

    We consider the flow induced by a line source placed at the intersection of two semi‐infinite plane surfaces, and our main aim is to determine the influence of these bounding surfaces on the direction the plume takes. To this end a two‐term boundary layer theory is presented from...

  • Convective Structures in a Cold Air Outbreak over Lake Michigan during Lake-ICE. Zurn-Birkhimer, Suzanne M.; Agee, Ernest M.; Sorbjan, Zbigniew // Journal of the Atmospheric Sciences;7/1/2005, Vol. 62 Issue 7, p2414 

    The Lake-Induced Convection Experiment provided special field data during a westerly flow cold air outbreak (CAO) on 13 January 1998, which has afforded the opportunity to examine in detail an evolving convective boundary layer. Vertical cross sections prepared from these data, extending from...

  • Deep Convection Triggering by Boundary Layer Thermals. Part II: Stochastic Triggering Parameterization for the LMDZ GCM. Rochetin, Nicolas; Grandpeix, Jean-Yves; Rio, Catherine; Couvreux, Fleur // Journal of the Atmospheric Sciences;Feb2014, Vol. 71 Issue 2, p515 

    This paper presents a stochastic triggering parameterization for deep convection and its implementation in the latest standard version of the Laboratoire de Météorologie Dynamique-Zoom (LMDZ) general circulation model: LMDZ5B. The derivation of the formulation of this parameterization and...

  • Deep Convection Triggering by Boundary Layer Thermals. Part I: LES Analysis and Stochastic Triggering Formulation. Rochetin, Nicolas; Couvreux, Fleur; Grandpeix, Jean-Yves; Rio, Catherine // Journal of the Atmospheric Sciences;Feb2014, Vol. 71 Issue 2, p496 

    This paper proposes a new formulation of the deep convection triggering for general circulation model convective parameterizations. This triggering is driven by evolving properties of the strongest boundary layer thermals. To investigate this, a statistical analysis of large-eddy simulation...

  • The Dryline on 22 May 2002 during IHOP_2002: Convective-Scale Measurements at the Profiling Site. Demoz, Belay; Flamant, Cyrille; Weckwerth, Tammy; Whiteman, David; Evans, Keith; Fabry, Frédéric; Di Girolamo, Paolo; Miller, David; Geerts, Bart; Brown, William; Schwemmer, Geary; Gentry, Bruce; Feltz, Wayne; Wang, Zhien // Monthly Weather Review;Jan2006, Vol. 134 Issue 1, p294 

    A detailed analysis of the structure of a double dryline observed over the Oklahoma panhandle during the first International H2O Project (IHOP_2002) convective initiation (CI) mission on 22 May 2002 is presented. A unique and unprecedented set of high temporal and spatial resolution measurements...

Share

Read the Article

Courtesy of THE LIBRARY OF VIRGINIA

Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics