Search Results

You are looking at 1 - 9 of 9 items for :

  • Cloud forcing x
  • RELAMPAGO-CACTI: High Impact Weather in Subtropical South America x
  • All content x
Clear All
T. Connor Nelson, James Marquis, Adam Varble, and Katja Friedrich

environments supporting it with adequate spatial and temporal resolution, as well as an incomplete understanding of environment–cloud interactions supporting growing congestus (e.g., Crook 1996 ; Weckwerth and Parsons 2006 ; Houston and Niyogi 2007 ; Lock and Houston 2014 ; Rousseau-Rizzi et al. 2017 ; Weckwerth et al. 2019 ). For CI to occur, the atmosphere requires three fundamental ingredients: static instability, moisture, and a triggering mechanism (e.g., surface airmass boundaries, orographic

Restricted access
Timothy J. Lang, Eldo E. Ávila, Richard J. Blakeslee, Jeff Burchfield, Matthew Wingo, Phillip M. Bitzer, Lawrence D. Carey, Wiebke Deierling, Steven J. Goodman, Bruno Lisboa Medina, Gregory Melo, and Rodolfo G. Pereyra

), which is physically separate from the much larger Andes range located to its west ( Fig. 1 ). The SDC interacts with the warm and moist air from the South American low-level jet (SALLJ), mechanical subsidence in the lee of the Andes, and other meteorological features to provide orographic forcing of deep, intense convection that often back builds along the terrain ( Rasmussen and Houze 2011 , 2016 ; Rasmussen et al. 2014 ; Bruick et al. 2019 ). This creates a relatively geographically confined

Restricted access
Robert J. Trapp, Karen A. Kosiba, James N. Marquis, Matthew R. Kumjian, Stephen W. Nesbitt, Joshua Wurman, Paola Salio, Maxwell A. Grover, Paul Robinson, and Deanna A. Hence

Electrification, Lightning, And Mesoscale/microscale Processes with Adaptive Ground Observations (RELAMPAGO) field program, funded primarily by the National Science Foundation ( Nesbitt et al. 2016 ), and the complementary Clouds, Aerosols, and Complex Terrain Interactions (CACTI) field program funded by the Department of Energy Atmospheric Radiation Measurement (DOE-ARM) program ( ). The detailed justification for RELAMPAGO-CACTI, as well as

Restricted access
Jake P. Mulholland, Stephen W. Nesbitt, Robert J. Trapp, and John M. Peters

design is provided in section 2 . Section 3 contains the results from the idealized numerical modeling simulations and related discussion, and conclusions are located in section 4 . 2. Experimental design Numerical modeling setup A series of idealized numerical model simulations were conducted using Cloud Model 1 (CM1; Bryan and Fritsch 2002 ), version 19.7. CM1 is a compressible, nonhydrostatic numerical model. The CM1 simulations were conducted with a uniform horizontal grid spacing of 500 m

Restricted access
Sujan Pal, Francina Dominguez, María Eugenia Dillon, Javier Alvarez, Carlos Marcelo Garcia, Stephen W. Nesbitt, and David Gochis

environments; 2) characterize thermodynamic and microphysical properties of clouds and precipitation, convective outflow, lightning, and hail events; and 3) observe hydrometeorological interactions with convective systems ( Nesbitt 2016 ). The occurrence of convective events in this region is linked to the strengthening of topographically guided South American low-level jet (SALLJ), which brings moist air poleward, and strong convection is formed at the exit region controlled primarily by diabatic effects

Restricted access
Zachary S. Bruick, Kristen L. Rasmussen, and Daniel J. Cecil

November–18 December 2018; ) and the Cloud, Aerosol, and Complex Terrain Interactions (CACTI) field campaign (1 October 2018–30 April 2019; ). This study will contribute to a better global understanding of hailstorms to help to improve forecasting and diagnosis of hailstorms in subtropical South America. 2. Method Because of the lack of a hail-report database in subtropical South America, satellite

Free access
Jake P. Mulholland, Stephen W. Nesbitt, and Robert J. Trapp

(LLJ), and upper-level negative geostrophic potential vorticity (weak ambient inertial instability) all favored the most rapid transition of discrete convective cells into an MCS. Furthermore, Dial et al. (2010) found that for cases of convection initiation (CI) along a frontal or similar boundary, the potential for UCG increased when the cloud-layer wind and deep-layer vertical wind shear vectors were nearly parallel to the initiating boundary. Additionally, as the magnitude of low-level forcing

Free access
Matthew R. Kumjian, Rachel Gutierrez, Joshua S. Soderholm, Stephen W. Nesbitt, Paula Maldonado, Lorena Medina Luna, James Marquis, Kevin A. Bowley, Milagros Alvarez Imaz, and Paola Salio

force, as it had penetrated 2–3 cm into the ground when she found it. The photographs from shortly after it was retrieved ( Figs. 8a,b ) show a rather round stone with scalloped lobes (e.g., Knight and Knight 1970 ) covering much of the surface, and no large icicle lobes. This implies no preferred orientation direction in its final growth layer, presumably owing to random tumbling during its descent. She recounted that many of the stones had similar roundish shapes, with clear outsides and milky

Full access
Hernán Bechis, Paola Salio, and Juan José Ruiz

moist tropical air mass to the north of the line and dry, warm air, which moves leeward of the Andes slopes in a zone of prevailing westerly flow. The regional circulation that leads to this airmass contrast is linked to the characteristics of the topography. North of 35°S the Andes block the low-level flow, forcing a mainly meridional displacement of air masses. In particular, the channeling of warm, moist air masses from low latitudes leads to the formation of the South American low-level jet

Free access