Winter school in Hyytälä 2025 - Seminar on the application of the Virga Sniffer

Introduction

The Virga-Sniffer is a tool to detect virga (precipitation which completely evaporates or sublimates before reaching the surface). Required input data are time-height fields of cloud radar reflectivity and time series of ceilometer cloud-base height. Optionally but highly recommended are the additional information of radar mean Doppler velocity, lifting condensation level and surface rain detection.

Virga sniffer documentation: https://virga-sniffer.readthedocs.io/en/latest/index.html

Virga sniffer code on github: https://github.com/remsens-lim/virga_sniffer/tree/main

Virga sniffer publication: https://amt.copernicus.org/articles/16/1683/2023/amt-16-1683-2023.html

Usage

Just go through the ipython notebook 'apply_virga-sniffer.ipynb' and follow the instructions

Agenda

Winter school working group 1:

Lead by Andreas Foth, Leipzig Institute for Meteorology, Leipzig University, Leipzig Germany

Title:

„Application of the Virga-Sniffer tool for the detection of virga based on ground-based remote sensing data”

Audience:

PhD students with an interest in ground-based remote sensing (5–8 participants). Basic python skills are required.

Focus:

The Virga-Sniffer is a tool for detecting virga from ground-based remote sensing measurements. In the simplest approach, it detects virga from time–height fields of cloud radar reflectivity and time series of ceilometer cloud base height. In addition, optional parameters like lifting condensation level, a surface rain flag, and time-height fields of cloud radar mean Doppler velocity can be added to refine virga event identifications. The Virga-Sniffer Python package is highly modular and configurable and can be applied to multilayer cloud situations. Due to the configurability of the virga sniffer, it is expected that different users will produce somewhat differing results of virga characteristics for the same provided input data set. In this work program, the variability of the results is to be estimated.

Goal:

The goal is for each participant to apply the virga sniffer tool to the same week of wintertime observations from Hyytiälä provided by the Cloudnet data portal, and produces statistical results about geometrical cloud and virga properties as well as statistics about classified targets from the Cloudnet target classification within detected virga. We will create a synopsis of the statistical results of each participant to determine the variability of the results produced by the participants and to finally estimate a quantification of uncertainty of the Virga-Sniffer output.

Preliminary schedule:

| | Mon | Tue | Wed | Thu | Fri | |:--------:|:-----------------:|:---------------:|:---------------:|:--------------:|:---------------:| | 12:00
-
13:00 | Introduction to Virga-Sniffer tool | Data analysis & processing | Data analysis & processing | Statistical analysis over single results | | | 15:30
-
16:30 | Installation of the Virga-Sniffer python package | Data analysis & processing | Data analysis & processing | Preparing presentations | Presentation of single results and discussion | | 18:00
-
EOD | Data familiarization & Q&A | Data analysis & processing | Discussing and interpreting the single results | Wrap up & feedback | |

(back to top)

License

Distributed under the MIT License. See LICENSE for more information.

(back to top)

Contact

Andreas Foth

(back to top)

Acknowledgments

Special thanks for templates and help during implementation.

• Readme Template
• remsens-lim

(back to top)