Dual-Doppler processing of weather radars for the analysis of storm dynamics in association with polarimetric analysis of microphysics.
Final Report Abstract
In this project wind fields were retrieved using a multi-Doppler technique (open source code: Pythonic Direct Data Assimilation PyDDA) for a few convective events that occurred in the Bonn region. The vertical component of the wind was validated using an approach developed in this project. It consists in using the Doppler velocity obtained from vertical scan of the BoXPol, correct it for the terminal fall velocity of hydrometeors and compare it to the retrieved wind field from PyDDA. Results showed a good match between the two methods at low and mid levels but an underestimation of the retrieved updraft at higher levels, which is in agreement with previous studies that assessed the errors of multi-Doppler techniques. The output was used to study the interactions between dynamics of convective cells and other parameters related to convection. Much effort was dedicated to the relationship between updrafts and Zdr columns (narrow vertical columns of enhanced differential reflectivity (Zdr) associated with convection). Up to now there hasn’t been much observational evidence connecting these two fields. The results showed a systematic spatial overlap between Zdr columns and updrafts, as well as with lightning strikes, which are another indicator of convection. It was found a tendency for stronger and larger updrafts to be associated with taller and larger Zdr columns, as expected. However much variability was observed from cell to cell and a universal relationship could not be derived. Sources of error in the wind retrievals and in the Zdr column height may be influencing this result, but those are due to the nature of the radar observations and cannot be circumvented with the current setup and instruments. It is also possible that the complexity of kinematics and microphysics depend on unique and specific characteristics that differ among cells (as hinted at by modeling studies with different CCN concentrations). As for the effects of convection at the surface, it was found that the intensity of the precipitation is related to the height and volume of the Zdr columns but no lead time was found for this relation. However, for one specific event that caused flooding in Cologne there was a lead time of 20 minutes between the peak in Zdr column size (volume and area) and surface intensification (gates exceeding 50 dBZ in reflectivity). Lastly, analysis were conducted to link Zdr columns and updrafts with lightning activity. Comparisons were performed between cells with and without a lightning jump (LJ) in their lifecycle. LJs are defined as a sudden increase in lightning rate and have been previously linked to severe weather. The results confirmed that parameters linked to the cell intensity and severity are stronger for cells that present a LJ, namely that these have larger and wider Zdr columns, longer lifetimes, more intense updrafts, higher reflectivity values and larger reflectivity cores.
Publications
-
Characteristics of updrafts and relationship to the development of hail and Zdr columns, 3rd European Hail Workshop, 15-18 March 2021, online workshop.
Evaristo, R., Simmer, C., Trömel, S. & Muehlbauer, K.
-
Validation of Wind Fields Retrieved by Dual-Doppler Techniques Using a Vertically Pointing Radar, International Radar Symposium, 21-22 June 2021, online.
Evaristo, R., Reinoso-Rondinel, R., Trömel, S. & Simmer,C.
-
Validation of Wind Fields Retrieved by Dual-Doppler Techniques Using a Vertically Pointing Radar. 2021 21st International Radar Symposium (IRS), 1-7. IEEE.
Evaristo, Raquel; Reinoso-Rondinel, Ricardo; Tromel, Silke & Simmer, Clemens
-
A synergetic approach to study Differential Reflectivity Columns for precipitation, 11th European Conference on Radar in Meteorology and Hydrology, 29 August-2nd September 2022, Locarno, Switzerland.
Evaristo, R., Reinoso-Rondinel, R., Chen, J.Y. & Trömel, S.
-
Evaluation of modelled summertime convective storms using polarimetric radar observations. Atmospheric Chemistry and Physics, 22(11), 7593-7618.
Shrestha, Prabhakar; Trömel, Silke; Evaristo, Raquel & Simmer, Clemens
-
Evolution of Lightning Activity, Zdr Column Properties, and Updrafts, AMS General Meeting , 23-27 Jan 2022 Houston, Texas, USA.
Evaristo, R., Reinoso-Rondinel, R. & Trömel, S.
-
Information content of differential reflectivity columns for precipitation nowcasting, EGU General Assembly, 23-27 May 2022, Vienna, Austria.
Evaristo, R., Reinoso-Rondinel, R., Crijnen, F., Chen, J.Y. & Trömel, S.
-
Link between Lightning activity and Properties of Zdr columns, 30th Conference on Severe Local Storms, 24-28 October 2022, Santa Fe, NM, USA.
Evaristo, R., Reinoso-Rondinel, R. & Trömel, S.
-
Comparing Dynamics and Microphysics of Modeled and Observed Convective Events Using a Polarimetric Forward Operator, 40th AMS Conference on Radar Meteorology, 28 August–01 September 2023, Minneapolis, MN, USA.
Evaristo, R., Shrestha, P. & Trömel, S.
-
Fusion of radar polarimetry and atmospheric modeling. Advances in Weather Radar. Volume 2: Precipitation science, scattering and processing algorithms, 293-344. Institution of Engineering and Technology.
Trömel, Silke; Blahak, Ulrich; Evaristo, Raquel; Mendrok, Jana; Neef, Lisa; Pejcic, Velibor; Scharbach, Tobias; Shrestha, Prabhakar & Simmer, Clemens
