scholarly journals Polarimetric Radar Convective Cell Tracking Reveals Large Sensitivity of Cloud Precipitation and Electrification Properties to CCN

2019 ◽  
Vol 124 (22) ◽  
pp. 12194-12205
Author(s):  
Jiaxi Hu ◽  
Daniel Rosenfeld ◽  
Alexander Ryzhkov ◽  
Dusan Zrnic ◽  
Earle Williams ◽  
...  
Keyword(s):  
Cell Tracking ◽  
Convective Cell ◽  
Polarimetric Radar

scholarly journals Polarimetric Radar Observations from a Waterspout-Producing Thunderstorm

2015 ◽  
Vol 30 (2) ◽  
pp. 329-348 ◽  
Author(s):  
Matthew S. Van Den Broeke ◽  
Cynthia A. Van Den Broeke
Keyword(s):  
Lake Michigan ◽  
Convective Cell ◽  
Great Lakes Region ◽  
Polarimetric Radar ◽  
Air Mass ◽  
Radar Observations ◽  
Potential Source ◽  
Western Lake ◽  
Low Levels ◽  
Differential Reflectivity

Abstract A family of four waterspouts was produced by a convective cell over western Lake Michigan on 12 September 2013. This storm initiated along a boundary north of a mesolow in a low-level cold-air advection regime, and developed supercell characteristics once the second waterspout was in progress. Polarimetric characteristics of the storm, and of the development of supercell character, are presented. These observations represent the first documented polarimetric radar observations of waterspout-producing convection in the Great Lakes region. Unusually high differential reflectivity values accompanied this storm and its initiating boundary. The high values along the boundary are partially explained by a high density of dragonflies. High differential reflectivity values were present through much of the storm of interest despite very low aerosol concentration at low levels in the lake-influenced air mass. Finally, this case illustrates the importance of environmental awareness on waterspout-favorable days, especially when boundaries are nearby to serve as a potential source of enhanced environmental vertical vorticity.

scholarly journals Disdrometer, Polarimetric Radar, and Condensation Nuclei Observations of Supercell and Multicell Storms on 11 June 2018 in Eastern Nebraska

Atmosphere ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 770
Author(s):  
Matthew Van Den Broeke
Keyword(s):  
Particle Concentration ◽  
Rain Rate ◽  
Radar Data ◽  
Convective Cell ◽  
Observation Time ◽  
Precipitation Intensity ◽  
Polarimetric Radar ◽  
Condensation Nuclei ◽  
Supercell Storm ◽  
Differential Reflectivity

Disdrometer and condensation nuclei (CN) data are compared with operational polarimetric radar data for one multicell and one supercell storm in eastern Nebraska on 11 June 2018. The radar was located ~14.3 km from the instrumentation location and provided excellent observation time series with new low-level samples every 1–2 min. Reflectivity derived by the disdrometer and radar compared well, especially in regions with high number concentration of drops and reflectivity <45 dBZ. Differential reflectivity also compared well between the datasets, though it was most similar in the supercell storm. Rain rate calculated by the disdrometer closely matched values estimated by the radar when reflectivity and differential reflectivity were used to produce the estimate. Concentration of CN generally followed precipitation intensity for the leading convective cell, with evidence for higher particle concentration on the edges of the convective cell associated with outflow. The distribution of CN in the supercell was more complex and generally did not follow precipitation intensity.

scholarly journals Radar-based assessment of hail frequency in Europe

2020 ◽  
Author(s):  
Elody Fluck ◽  
Michael Kunz ◽  
Peter Geissbuehler ◽  
Stefan P. Ritz
Keyword(s):  
Cell Tracking ◽  
Radar Data ◽  
Convective Cell ◽  
Leeward Side ◽  
Convective Storm ◽  
Massif Central ◽  
Mountain Ranges ◽  
European Area ◽  
Time Period ◽  
Low Mountain Ranges

Abstract. In this study we present a unique 10-year climatology of severe convective storm tracks for a larger European area covering Germany, France, Belgium and Luxembourg. For the period 2005–2014, a high-resolution hail potential composite of 1 by 1 km2 is produced from two-dimensional reflectivity radar data and lightning data. Individual hailstorm tracks as well as their physical properties, such as radar reflectivity along the tracks were reconstructed for the entire time period using the Convective Cell Tracking Algorithm (CCTA2D). A sea-to-continent gradient in the number of hail days is present over the whole domain. In addition, the highest number of severe storms is found on the leeward side of low mountain ranges such as near the Massif Central in France and the Swabian Jura in southwest Germany. A latitude shift in the hail peak month is observed between the northern part of Germany where hail occurs most frequently in August, and southern France where the maximum of hail occurs two months earlier. The spatially most extended footprints with high reflectivity values occurred on 9 June 2014 and on 28 July 2013 with lengths reaching several hundreds of kilometers. Both events implied hailstones measuring up to 10 cm which caused damage in excess of 2 Billions Euros.

scholarly journals The interaction between cold fronts and convection in the mid-latitudes

2021 ◽  
Author(s):  
George Pacey ◽  
Stephan Pfahl ◽  
Lisa Schielicke
Keyword(s):  
Diurnal Cycle ◽  
Cell Tracking ◽  
Cold Front ◽  
Heavy Rain ◽  
Convective Cell ◽  
Detection Methods ◽  
Cold Fronts ◽  
Forcing Mechanisms ◽  
Convective Cells ◽  
Frontal Boundary

&lt;p&gt;Cold fronts provide an environment favourable for convective initiation in the mid-latitudes. Some studies also show the presence of a cold front can increase the chance of certain convective hazards, such as hail and heavy rain. Convection initiates in three locations in respect to cold fronts: &lt;em&gt;ahead&lt;/em&gt; of the cold front in the warm sector of the cyclone, directly &lt;em&gt;at&lt;/em&gt; the cold frontal boundary and also &lt;em&gt;behind&lt;/em&gt; the cold front. Previous literature has typically focused on each initiation location independently, thus a comprehensive study investigating the link between cold fronts and convection is currently lacking from literature. This study seeks to better understand the climatology, scale interactions and forcing mechanisms of convection at each initiation location relative to the front (i.e., behind, at, ahead).&lt;/p&gt;&lt;p&gt;Automatic front detection methods are applied to reanalysis data and a convective cell-tracking dataset from the German Weather Service is used to build a climatology of cold fronts and convection between April&amp;#8211;September. Convective cells are found to initiate most commonly 200&amp;#8211;300km ahead of the cold front during late afternoon. Cells behind the front primarily initiate in north-western Germany and exhibit a strong diurnal cycle. On the contrary, cells at and ahead of the front initiate most frequently in southern Germany and exhibit a less prominent diurnal cycle, especially for cells at the frontal boundary. Lightning probability decreases with closing proximity to the cold front and the average number of cell initiations per day is significantly higher on days with cold fronts opposed to days without. The next stages of research will investigate the relative importance of various forcing mechanisms on the development of convective cells at different cell-front positions.&lt;/p&gt;

scholarly journals Radar-based assessment of hail frequency in Europe

2021 ◽  
Vol 21 (2) ◽  
pp. 683-701
Author(s):  
Elody Fluck ◽  
Michael Kunz ◽  
Peter Geissbuehler ◽  
Stefan P. Ritz
Keyword(s):  
Cell Tracking ◽  
Convective Cell ◽  
Radar Reflectivity ◽  
Leeward Side ◽  
Convective Storm ◽  
Massif Central ◽  
Mountain Ranges ◽  
European Area ◽  
Time Period ◽  
Low Mountain Ranges

Abstract. In this study we present a unique 10 year climatology of severe convective storm tracks for a large European area covering Germany, France, Belgium and Luxembourg. For the period 2005–2014, a high-resolution hail potential composite of 1×1 km2 is produced from two-dimensional radar reflectivity and lightning data. Individual hailstorm tracks as well as their physical properties, such as radar reflectivity along the tracks, were reconstructed for the entire time period using the Convective Cell Tracking Algorithm (CCTA2D). A sea-to-continent gradient in the number of hail days per year is found to be present over the whole domain. In addition, the highest number of severe storms is found on the leeward side of low mountain ranges such as the Massif Central in France and the Swabian Jura in southwest Germany. A latitude shift in the hail peak month is observed between the northern part of Germany, where hail occurs most frequently in August, and southern France, where the maximum amount of hail is 2 months earlier. The longest footprints with high reflectivity values occurred on 9 June 2014 and on 28 July 2013 with lengths reaching up to 500 km. Both events were associated with hailstones measuring up to 10 cm diameter, which caused damage in excess of EUR 2 billion.

scholarly journals Investigating the sensitivity of high-resolution mesoscale models to microphysical parameters by the use of polarimetric radar observations

2010 ◽  
Vol 10 (8) ◽  
pp. 20461-20514
Author(s):  
R. Ferretti ◽  
K. De Sanctis ◽  
L. Molini ◽  
A. Parodi ◽  
M. Montopoli ◽  
...  
Keyword(s):  
Vertical Structure ◽  
Mesoscale Model ◽  
Deep Convection ◽  
Weather Prediction ◽  
Radar Data ◽  
Convective Cell ◽  
Polarimetric Radar ◽  
Horizontal Structure ◽  
Po Valley

Abstract. An improved methodology for investigating mesoscale model microphysics is presented and discussed for a case study. Polarimetric radar data are used to assess numerical weather prediction (NWP) model's skill in reproducing the microphysical features of severe rainfall. To this aim, an event of deep convection, developed on 20 May 2003 in the Po Valley (Italy), is analyzed. During the selected case study, two weather radars, sited in Gattatico and San Pietro Capofiume (near Bologna, Italy), detected a deep-convective and hail cell with a large inner graupel core which reached the ground, as was reported by local weather authorities and citizens. A hydrometeor classification algorithm, based on a Bayesian approach and a radar simulator model, are used to retrieve the vertical structure of the storm and characterize its ground effects. These products are used for evaluating the sensitivity of NWP models with respect to the graupel density, described in terms of the intercept parameter of the graupel size distribution and its depositional velocity. To this purpose two mesoscale NWP models, specifically COSMO-LAMI and MM5-V3, are used at high spatial resolution. Their ability in reproducing the vertical and the horizontal structure and the microphysical distribution of the major convective cell is evaluated. Both models show large sensitivity to different microphysical settings and a capability to reproduce fairly well the observed hail cell. Ground-radar reflectivity fields and the hydrometeor vertical structure are correctly simulated by both NWP models as opposed to a failure in reproducing the graupel distribution near the ground.

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