Observations of Kinematics and Thermodynamic Structure Surrounding a Convective Storm Cluster over a Low Mountain Range

Abstract

Measurements of a convective storm cluster in the northern Black Forest in southwest Germany have revealed the development of a warm and dry downdraft under its anvil cloud that had an inhibiting effect on the subsequent development of convection. These measurements were made on 12 July 2006 as part of the field campaign Prediction, Identification and Tracking of Convective Cells (PRINCE) during which a number of new measurement strategies were deployed. These included the collocation of a rotational Raman lidar and a Doppler lidar on the summit of the highest mountain in the region (1164 m MSL) as well as the deployment of teams carrying radiosondes to be released in the vicinity of convective storms. In addition, an aircraft equipped with sensors for meteorological variables and dropsondes was in operation and determined that the downdraft air was approximately 1.5 K warmer, 4 g kg 21 drier, and therefore 3 g m 23 less dense than the air at the same altitude in the storm's surroundings. The Raman lidar detected undulating aerosol-rich layers in the preconvective environment and a gradual warming trend of the lower troposphere as the nearby storm system evolved. The Doppler lidar both detected a pattern of convergent radial winds under a developing convective updraft and an outflow emerging under the storm's anvil cloud. The dryness of the downdraft air indicates that it had subsided from higher altitudes. Its low density reveals that its development was not caused by negative thermal buoyancy, but was rather due to the vertical mass flux balance accompanying the storm's updrafts.

The dependence of convection‐related parameters on surface and boundary‐layer conditions over complex terrain

“…Thus, a feedback between soil, surface and boundary-layer conditions and convective precipitation is likely and has already been observed for relatively flat terrain with sparse vegetation (Taylor and Lebel, 1998;Taylor and Ellis, 2006). South-western Germany and eastern France, meaning the upper Rhine valley, enclosed by the Black Forest and Vosges mountains, is well known as a favourable area for the triggering of convection (Bertram et al, 2004;Barthlott et al, 2006;Meißner et al, 2007;Groenemeijer et al, 2009). Additionally, considerable information about the spatial distribution of the energy balance (Kalthoff et al, 1999) as well as about the spatial and temporal variability of the CBL height is available (Kalthoff et al, , 2000Koßmann et al, 1998).…”

Profiles of second- to fourth-order moments of turbulent temperature fluctuations in the convective boundary layer: first measurements with rotational Raman lidar

“…In order to address the measurement needs, the University of Hohenheim (UHOH) RRL was optimized for high temperature measurement performance in daytime in the CBL (Radlach et al, 2008). The data of the UHOH RRL have already been used for studies on the characterization of transport and optical properties of aerosol particles near their sources (Behrendt et al, 2011b;Valdebenito et al, 2011), on the initiation of convection (Groenemeijer et al, 2009;Corsmeier et al, 2011), and on atmospheric stability indices Corsmeier et al, 2011). Here, the formalism introduced by Lenschow et al (2000) is applied for the first time to the data of an RRL to study the extension of the variable set of lidar turbulence studies within the CBL to temperature.…”

The water vapour intercomparison effort in the framework of the Convective and Orographically‐induced Precipitation Study: airborne‐to‐ground‐based and airborne‐to‐airborne lidar systems

“…COPS is the most recent in a series of field experiments dedicated to the improvement of quantitative precipitation forecasting (QPF) in different weather regimes, including the Mesoscale Alpine Programme (MAP: Rotunno and Houze, 2007), IHOP 2002 (Weckwerth et al, 2004), the Convective Storm Initiation Project (CSIP: Browning et al, 2007), and the COPS-pre-campaign Prediction, Identification and Tracking of Convective Cells (PRINCE: Groenemeijer et al, 2009).…”