rain cell tracking – Kai Lochbihler

The scaling of extreme rainfall events with surface moisture availability in Germany

Since the beginning of this project I was very curious about the relationship of extreme rainfall event intensity with temperature and the local moisture availability in Germany. And, even more about how this depends on the actual precipitation type. Now there has been previous work about this (Moseley et al. 2013) and I myself did an analysis for the Netherlands (Lochbihler et al. 2017). However, even though Moseley et al (2013) investigated the dependency on precipitation type, they only used two years of data. And, I completely neglected the precipitation type due to a lack of data for the Netherlands.

Here, I will do a scaling analysis for 15 years of data (March to October) and will see how this relates to the precipitation type. All code and data is freely available.

This post is part of the germanRADARanalysis project.

Trends of extreme rainfall events over 20 years in Germany

In the last post, I showed how to extract information about rainfall events from the output of a rain cell tracking of 20 years of rain radar data in Germany. The event data base is free to download, by the way. We have also looked at some basic statistics already. Here, I want to go one step further and have a closer look at the characteristics of extreme rainfall events and how they change over the time period from 2001 to 2020. More specifically, I will investigate changes in the intensity and size of events. Let’s see what we can find out.

This post is part of the germanRADARanalysis project.

A 20-year climatology of rainfall events in Germany

After downloading the German radar data set, preprocessing and applying a rain cell tracking to it, it is now finally time to have a look at the created rain event data set. Since the output of the rain cell tracking is quite elaborate, we will boil it down to a neat data base of the characteristics of rain events that I am interested in. We can then have a first look at some statistics. Follow me on this path.

This post is part of the germanRADARanalysis project.

Apply rain cell tracking to 20 years of rain radar data over Germany

So, I downloaded the 20-year radar data set (Mar to Nov) from the German meteorological service (DWD). It contains about 1.5 million individual radar-derived precipitation fields – one every 5 minutes. And, I was very excited to run a rain cell tracking on it. After handing in my PhD thesis, I was going for a short trip to visit family and friends in Germany. Fortunately, I have a home server and I decided to let it do the heavy work while I am on holidays. It took the full ten days of my absence plus two extra days for the 8-core Intel CPU machine to process all data. So, let’s see how I did it.

This post is part of the germanRADARanalysis project.