Clouds and precipitation are important components of the climate system, but their key processes are not sufficiently understood. In our research group, we develop innovative measurement techniques to characterize cloud and precipitation properties.

Research profile

The clouD and pRecipitation Observations for Process Studies (drOPS) research group is working on innovative methods to better measure precipitation and cloud properties using ground-based remote sensing and in-situ techniques.

The goal is to better understand and analyze the processes within clouds that are responsible for the formation of precipitation using improved measurements. Furthermore, it is investigated how clouds interact with external factors such as aerosols. Innovative measurement techniques are being developed that use machine learning methods to combine information from different measurement devices in order to characterize cloud and precipitation properties. For snowfall, remote sensing observations are combined with the specially developed Video In Situ Snowfall (VISSS) camera.

Nina Maherndl and Dr Maximlian Maahn monitoring a measuring device on the roof of the Leipzig Institute of Meteorology. Photo: Christian Hüller
Nina Maherndl and Dr Maximlian Maahn monitoring a measuring device on the roof of the Leipzig Institute of Meteorology. Photo: Christian Hüller

RESEARCH PRIORITIES

Current research priorities are:

  • The characterization of the spatial variability of Arctic mixed-phase clouds; and
  • A better understanding of the riming process.
View form the airplane on arctic mixed phase clouds during the HALO-AC3 campaign west of Spitsbergen. Photo: Maximilian Maahn / Universität Leipzig
Arctic mixed phase clouds during the HALO-AC3 campaign west of Spitsbergen. Photo: Maximilian Maahn / Universität Leipzig

Research Projects

Arctic Amplification: Climate Relevant Atmospheric and Surface Processes, And Feedback Mechanisms

Period: 01.01.2020 – 31.12.2023

Funding: German Research Foundation

Planet earth has warmed on average by 0.87 K over the past 150 years. In the Arctic, the warming is much larger, which became most prominent over the last decades. Currently, the Arctic warming exceeds the increase of near-surface air temperature in the mid-latitudes by about 2 K. This phenomenon is commonly referred to as Arctic amplification.

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 Contour plot of winter temperature change as a function of latitude for the years 1950 to 2020. The Arctic shows the largest increase in temperature of about 3 K over the reference period 1951- 1980. Graph: Manfred Wendisch
Plot of zonally median global temperature change in the period 1950 - 2020 compared to the reference period 1950 - 1980. Graph: Manfred Wendisch

Fusion of Radar Polarimetry and Numerical Atmospheric Modelling Towards an Improved Understanding of Cloud and Precipitation Processes

Funding: German Research Foundation

Wolken- und Niederschlagsprozesse sind seit Jahrzehnten die Hauptquelle von Unsicherheiten in der Wettervorhersage und in Projektionen zum Klimawandel. Ein Großteil dieser Unsicherheiten kann auf fehlende Beobachtungen zurückgeführt werden, die geeignet sind, die Darstellung von Wolken- und Niederschlagsprozessen in atmosphärischen Modellen zu hinterfragen. Die gesamte Atmosphäre über Deutschland wird seit kurzem von 17 hochmodernen polarimetrischen Doppler-Wetterradaren überwacht, die alle fünf Minuten 3D-Informationen über die flüssigen und gefrorenen Niederschlagsteilchen und deren Bewegungen mit einer Sub-Kilometer-Auflösung liefern, die auch von den Atmosphärenmodellen für Wettervorhersagen und Klimastudien herangezogen wird. Die Datenassimilation führt Beobachtungen und Modelle zur Zustandsschätzung als Voraussetzung für die Vorhersage zusammen und kann als intelligente Interpolation zwischen Beobachtungen betrachtet werden, wobei die physikalische Konsistenz der atmosphärischen Modelle als mathematische Randbedingung genutzt wird. Es bestehen jedoch erhebliche Wissenslücken sowohl in der Radarpolarimetrie als auch in den atmosphärischen Modellen, die die volle Ausnutzung des Dreiecks Radarpolarimetrie - atmosphärische Modelle - Datenassimilation behindern und eine koordinierte interdisziplinäre Anstrengung erfordern. Das Schwerpunktprogramm wird die Synergie der neuen Beobachtungen und modernster atmosphärischer Modelle nutzen, um feuchte Prozesse in der Atmosphäre besser zu verstehen und ihre Darstellung in Klima- und Wettervorhersagemodellen zu verbessern. Das Programm wird unser wissenschaftliches Verständnis an den Grenzen der drei Disziplinen für bessere Vorhersagen von niederschlagbringenden Wolkensystemen erweitern, indem es die folgenden Ziele anspricht.

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Subproject: Characterisation of orographically influenced riming and secondary ice production and their effects on precipitation rates by radar polarimetry and Doppler spectra (CORSIPP)

Period: 01.01.2022 – 30.06.2025

Team: Dr. Isabelle Steinke, Dr. Maximilian Maahn

The goal of the project "CORSIPP" in cooperation with the research group of Jun-Prof. Dr. Heike Kalesse-Los is to better understand the interaction of ice crystals and liquid supercooled cloud droplets. A special focus is put on the riming process and on secondary ice crystals, which can break off e.g. during the riming process.

Planned measurement setup for the SAIL experiment. Illustration: Teresa Vogl / University of Leipzig
Planned measurement setup for the SAIL experiment. Illustration: Teresa Vogl / University of Leipzig

To obtain the necessary data, a 94 GHz cloud radar and a VISSS snowfall camera will be sent to Colorado in the winter of 2022/23 to participate in the international SAIL campaign.

Polar P5 (front) and Polar P6 (back) were used in the HALO-(AC)3 campaign to make combined remote sensing and in situ measurements of Arctic mixed-phase clouds around Spitsbergen. Photo: Maximilian Maahn / Universität Leipzig
Polar P5 (front) and Polar P6 (back) were used in the HALO-(AC)3 campaign to make combined remote sensing and in situ measurements of Arctic mixed-phase clouds around Spitsbergen. Photo: Maximilian Maahn / Universität…

Instrumentation

The Video In Situ Snowfall Sensor during the MOSAiC campaign on sea ice. Photo: Matthew Shupe
The Video In Situ Snowfall Sensor during the MOSAiC campaign on sea ice. Photo: Matthew Shupe

The Video In Situ SNowfall Sensor (VISSS) is an optical instrument developed in the drOPS group that can be used to determine the size, shape and fall speed of snowflakes.

The VISSS has a fairly large, free-standing observation volume, allowing a large number of snowflakes to be measured at high optical and temporal resolution without disturbing the wind field. The first VISSS was built specifically for MOSAiC, and an improved version was deployed in Ny-Ålesund in 2021.

Campaigns:

CORSIPP contribution zu SAIL (Surface Atmosphere Integrated Field Laboratory) Gothic, Colorado, 2022/2023
(AC)3 SYNCLOUD (Synergistic long-term observations of vertically resolved cloud properties using a novel microwave radiometer/radar for Arctic) Ny-Ålesund Norway since 2021
CRIOS (Combining Radar and Imagining Observations for Snowfall measurements) Hyytiälä Finnland, since 2021

MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate)
Daten

Arctic sea 2019/20
Ground-based observations: LIMRAD 94 on the roof of our institute. Photo: Katrin Schandert / Universität Leipzig
Ground-based observations: LIMRAD 94 on the roof of our institute. Photo: Katrin Schandert / Universität Leipzig

Manufacturer: Radiometer Physics GmbH
Centre Frequency: 94 GHz (λ=3.19 mm) ± 100 MHz typical
IF range:  0.35 to 4.5 MHz

This radar was developed for atmospheric research. It operates at 3.2 millimeter wavelength which allows for reaching high sensitivity with small sizes of the instrument. The radar provides range profiles of parameters that contain information about scatterers in the atmosphere such as cloud particles, raindrops, snowflakes and insects. The radar utilizes frequency modulated continuous wave (FMCW) signals and therefore has high range resolution down to 1 m. Doppler and polarimetric (optional) capabilities of the radar make a good basis for a classification of particles and a quantitative characterization of hydrometeors.

Areas of Applications

  • Calibration of precipitation and cloud radars including satellite-based systems
  • Estimation of propagation effects for satellite links
  • Precipitation and fog nowcast
  • Hydrometeor classification
  • Quantitative precipitation estimation
  • Wind direction and speed retrieval
  • Profiling of liquid water
  • Microphysical analysis of clouds and precipitation

Campaigns:

CORSIPP contribution zu SAIL (Surface Atmosphere Integrated Field Laboratory) Gothic, Colorado, 2022/2023
HALO-(AC)3 Svalbard, Norway Spring 2022

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Publications

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Research at the institute

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