Ground-based and airborne measurement techniques are applied to study the interaction of atmospheric radiation with clouds and the Earth‘s surface. For that purpose, imaging and non-imaging spectrometers are used for remote sensing applications and to quantify the radiation energy budget. Radiative transfer models represent our major tool to interprete our measurements and to improve retrievals of cloud and surface parameters.

Current research projects

The following projects are sub-projects in joint projects of the German Research Foundation (DFG) and the Federal Ministry of Education (BMBF).

The first picture shows a measuring aircraft after landing. The second picture shows a measuring tower in the Brazilian rainforest. In the third picture, a tethered balloon is released in front of the research vessel Polarstern. Photos: Andre Ehrlich, Kátia Mendes de Barros, Michael Lonardi
Impressions of the measurement campaigns HALO, ATTO, MOSAiC (top left, bottom left, right). Photos: André Ehrlich, Kátia Mendes de Barros, Michael Lonardi

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

Funding: German Research Foundation

Period: 01.01.2020 – 31.12.2023

Planet Earth has warmed on average by 0.87 K over the past 150 years. In the Arctic, the warming is much stronger, 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

Atmospheric and Earth System Research with the "High Altitude and longe Range Aircraft (HALO)"

Funding: German Research Foundation

Period: 09.05.2016 – 31.12.2027

Team: Prof. Dr. Manfred Wendisch, Dr. Jörg Schmidt, Dr. Anja Schwarz

Our group is coordinating the DFG Priority Program: HALO-SPP 1294 on "Atmospheric and Earth System Research with HALO". The HALO-SPP supports research of atmospheric and Earth system related processes. HALO is a Gulfstream G-550 aircraft specifically equipped with numerous in situ and remote sensing instruments. It brings scientists together who work in a wide range of disciplines including physics, chemistry, meteorology, geosciences, mathematics, informatics, engineering and others to maximize the scientific output and to carry out multi-disciplinary research.
Details on the HALO-SPP are provided on the HALO-SPP-web pages

Aims

Our scientific aim using HALO is to investigate the radiative effects of different clouds regimes. We operate spectral solar remote sensing instruments including the SMART-Albedometer, which allows to measure solar spectral up- und downward irradiances to quantify for example cloud radiative effects. More recently, we deployed a new thermal-infrared imager in cooperation with the MPI Hamburg. This imager enables investigations on the spatial distribution of liquid water and ice in clouds, but also on the spatial variability of Arctic surface properties during the upcoming HALO-(AC)3 campaign in 2022.

All flight tracks of the NAWDEX campaign are marked on a map covering the North Atlantic. The flights starting from Iceland extend to North America or Scandinavia, among other places, and document the wide range of HALO. Grafic: Kevin Wolf
Flight tracks of the 2016 NAWDEX campaign starting from Iceland illustrate the wide reach of HALO. Graphic: Kevin Wolf

Project: Remote sensing and radiative forcing of inhomogeneous trade wind cumuli

Period: 01.09.2019 – 30.04.2023

Team: Prof. Dr. Manfred Wendisch, Dr. André Ehrlich, Dr. Anna Lübke, Dr. Michael Schäfer

The main focus of the project is the quantification of the large scale radiative effect of trade wind cumuli as a function of the macro- and microphysical cloud properties, the spatial distribution of these clouds, and the mesos-scale vertical motion. The measurements were conducted during the EUREC4A (ElUcidating the Role of Cloud-Circulation Coupling in ClimAte) campaign east of Barbados in February 2020. They include first observations with the new multi-channel thermal-infrared imager and a new set of solar and thermal broadband radiation sensors.

VELOX measurements at 9 km altitude during EUREC4A show (a) the distribution of the uncorrected brightness temperature of cumuli tops with a minimum of 6°C and a sea surface with a maximum of about 20°C and (b) the derived cloud top height. Graph: Michael Schäfer / University of Leipzig
VELOX measurements at 9 km altitude during EUREC4A show (a) the distribution of the uncorrected brightness temperature of cumuli tops and the sea surface, and (b) the derived cloud top height. Graph: Michael Schäfer /…

Project: Influence of ice crystal shape on the radiation effect of Arctic cirrus: measurements and representation in numerical weather prediction models

Periond 01.02.2021  – 31.01.2024
Team: Prof. Dr. Manfred Wendisch, Dr. André Ehrlich, Johannes Röttenbacher

The parametrization of radiative properties of ice cloud particles affects the output of the radiation scheme in the output of the radiation scheme ecRad, which is applied in the ECMWF Integrated Forecast System (IFS). The analysis of the radiation budget for Arctic cirrus needs to be extended to the thermal-infrared spectral range, since its fraction is enhanced compared to the solar contribution.  The project is connected to the upcoming HALO missions Cirrus-HL (High Latitude) und HALO-(AC)3. Measurements by the new broadband radiation system, a new thermal-infrared imager, and the SMART-albedometer will be used to characterize the radiation budget above and below the high latitude cirrus. It will be analyzed, how the high reflecting sea ice and the persistent low-level clouds influence the radiative effect of Arctic cirrus. Further, it will be investigated by means of a systematic comparison with measurements, how the radiative effects are represented in numerical weather forecast models.

MOSAiC - ALIBABA: Application of airborne ice surface and radiation data based on MOSAiC observations for surface albedo parameterizations of the central Arctic (ALIBABA)

Funding: Federal Ministry of Education and Research

The impact of climate change is most significant in the Arctic. Here, drastic changes in the climate and ecosystem have taken place in recent decades.  To understand this new climate state and its future development, a large international measurement campaign was initiated by the Atmosphere Working Group of the International Arctic Science Committee (IASC) in 2011. The initiative has been expanded across several disciplines and is being run under the title "Multidisciplinary drifting Observatory for the Study of Arctic Climate" (MOSAiC). The core of MOSAiC was an intensive one-year observation and measurement programme based on the research icebreaker Polarstern as a drifting station, which was successfully completed in October 2020.

The photo shows the helicopter-borne sonde HELiPOD standing on the snow-covered sea ice. The research vessel Polarstern is in the background. Photo: Falk Pätzold / TU Braunschweig
Helicopter-borne sonde HELiPOD in front of the research vessel Polarstern during the MOSAiC expedition. Photo: Falk Pätzold / TU Braunschweig

Project: Parametrization of the Arctic surface albedo for climate models

Period: 01.11.2020 – 31.10.2023

Team: Prof. Dr. Manfred Wendisch, Dr. Evelyn Jäkel, Tim Sperzel, Dr. Khalil Karami

Within the frame of the MOSAiC - Expedition the the helicopter-borne meteorological sonde HELiPOD, operated by TU Braunschweig, delivered data of the spatial variablity of atmospheric parameters, sea ice surface properties, as well as solar and thermal radiation measurements. The ALIBABA project aims to use these versatile measurements to improve the albedo parametrization of Arctic surfaces in climate models depending on the ice properties and atmospheric conditions. So far, the complex interactions between clouds and the highly variable Arctic surface types are not well considered in the current models.

Typical spatial scales of regional climate models and satellite observations, ranging between 250 m and 10 km, are taken into account. The surface reflections properties for these spatial scales mostly represent a mixture of different surface types. For this reason three-dimensional (3D) radiative transfer simulations are combined with measurements of these complex surface reflection properties to estimate the contribution of  the individual parameters.

Previous research projects

The following projects were funded by the German Research Foundation (DFG) and the European Union (EU).

Logos of our finished projects NAWDEX, ACRIDCON-CHUVA, NAWDEX und ANT-LAND. Grafics: University of Leipzig
Logos of our finished projects NAWDEX, ACRIDCON-CHUVA, NAWDEX und ANT-LAND. Grafics: University of Leipzig

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

Funding: German Research Foundation

Period: 01.01.2016 – 31.12.2019

Planet Earth has warmed on average by 0.87 K over the past 150 years. In the Arctic, the warming is much stronger, 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.

Read more

 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

Project: C02 – Interactions of snow on sea ice with atmospheric constituents including black carbon

Team: Dr. André Ehrlich, Tobias Donth, Dr. Evelyn Jäkel

Results of the study on the solar radiative effects of black carbon
Donth, T., Jäkel, E., Ehrlich, A., Heinold, B., Schacht, J., Herber, A., Zanatta, M., and Wendisch, M., 2020: Combining atmospheric and snow radiative transfer models to assess the solar radiative effects of black carbon in the Arctic, Atmos. Chem. Phys., 20, 8139–8156, doi:10.5194/acp-20-8139-2020.

A measuring system with radiation sensors stands in the snow-covered, flat landscape in North Greenland. Photo: Tobias Donth
Ground-based radiation measurements in Greenland during PAMARMiP 2018. Photo: Tobias Donth

Atmospheric and Earth System Research with the "High Altitude and longe Range Aircraft (HALO)"

Funding: German Research Foundation

Our group is coordinating the DFG Priority Program: HALO-SPP 1294 on "Atmospheric and Earth System Research with HALO". The HALO-SPP supports research of atmospheric and Earth system related processes. HALO is a Gulfstream G-550 aircraft specifically equipped with numerous in situ and remote sensing instruments. It brings scientists together who work in a wide range of disciplines including physics, chemistry, meteorology, geosciences, mathematics, informatics, engineering and others to maximize the scientific output and to carry out multi-disciplinary research.
Details on the HALO-SPP are provided on the HALO-SPP-web page.

Project: A contribution to HALO campaigns NARVAL-II and NAWDEX

Period: 2016 – 2020

Team: Dr. Kevin Wolf, Prof. Dr. Manfred Wendisch

Results of the project:

  • Wolf, K., A. Ehrlich, M. Mech, R. J. Hogan, and M. Wendisch, 2020: Evaluation of ECMWF Radiation Scheme Using Aircraft Observations of Spectral Irradiance above Clouds, J. Atmos. Sci., 77 (8) , 2665–2685 , DOI:10.1175/JAS-D-19-0333.1
  • Wolf, K., A. Ehrlich, M. Jakob, S. Crewell, M. Wirth, and M. Wendisch, 2019: Improvement of Airborne Retrievals of Cloud Droplet Number Concentration of Trade Wind Cumulus Using a Synergetic Approach, Atmos. Meas. Tech., 12 , 1635-1658 , DOI:10.5194/amt-12-1635-2019
Comparison of the normalised distribution density function of the measured and simulated solar broadband radiation over midlatitude cirrus for different ice particle parameterisations (Wolf et al., 2020)
Comparison of the normalised distribution density function of the measured and simulated solar broadband radiation over midlatitude cirrus for different ice particle parameterisations. Graph: Kevin Wolf

Project: ACRDICON - Aerosol, Cloud, Precipitation, and Radiation Interactions and Dynamics of Convective Cloud Systems

Period: 2010 – 2017

Team: Prof. Dr. Manfred Wendisch, Dr. André Ehrlich, Dr. Evelyn Jäkel, Dr. Trismono C. Krisna

An extensive airborne/ground-based measurement campaign to study tropical convective clouds was performed in the Amazon rainforest in 2014. The project combined the joint German-Brazilian ACRIDICON (Aerosol, Cloud, Precipitation, and Radiation Interactions and Dynamics of Convective Cloud Systems) and CHUVA projects. ACRIDICON aimed at the quantification of aerosol-cloud-precipitation interactions and their thermodynamic, dynamic and radiative effects in convective cloud systems by in-situ aircraft observations and indirect measurements (aircraft, satellite, and ground-based).

The HALO aircraft was equipped with remote sensing and in-situ instrumentation for meteorological, trace gas, aerosol, cloud, and precipitation measurements. Five mission objectives were pursued: (1) cloud vertical evolution (cloud profiling), (2) aerosol processing (inflow and outflow), (3) satellite validation, (4) vertical transport and mixing (tracer experiment), and (5) clouds over forested and deforested areas. The five cloud missions collected data in clean atmospheric conditions and in contrasting polluted (urban and biomass burning) environments.

  • A campaign overview is given in BAMS:
    Wendisch, M.,  et al.: The ACRIDICON-CHUVA campaign: Studying tropical deep convective clouds and precipitation over Amazonia using the new German research aircraft HALO, B. Am. Meteorol. Soc., 97, 1885–1908, 2016.:
  • Further results of the project are published in the AMT/ACP Special Issue
View from the HALO aircraft showing deep convection. Photo: Manfred Wendisch / Universität Leipzig
Typical deep convective clouds over the Amazon rainforest during ACRIDICON-CHUVA 2014. Photo: Manfred Wendisch / Universität Leipzig

Antarctic research with comparative studies in Arctic ice regions

Funding: German Research Foundation

The priority program uses a multidisciplinary approach to study the complex interactions in the Earth system, to contribute significant insights to understanding the changes in the past, present and future. This is achieved by focusing on four interdisciplinary major research topics: “Linkages with Lower Latitudes", "Dynamics of Climate System Components", "Response to Environmental Change“ and “Improved Understanding of Polar Processes and Mechanisms”. The logo, showing a puzzle shaped like the Antarctic continent and the adjacent ocean, symbolizes the multidisciplinary approach, where all pieces fit together.

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The logo of SPP 1158 shows the shape of Antarctica made of light puzzle pieces on a dark background. University of Rostock
Logo of SPP 1158. Logo University of Rostock

Project: Coupling of airborne and in situ-graound base measurementsof surface albedo, BRDF and snow properties in Antarctica to improve prognostic snow models

Period: 2014 – 2017

Team: Prof. Dr. Manfred Wendisch, Dr. Tim Carlsen, Dr. André Ehrlich, Dr. Michael Schäfer

Surface albedo is one of the most important factors determining near-surface energy fluxes. Snow and ice represent the surfaces with the highest albedo on Earth. This multiplies their impact on the radiative energy budget. All the same, changes in snow grain size, surface roughness or atmospheric parameters such as cloud cover cause high spatial and temporal variability in snow surface albedo and therefore lead to local changes of the radiative energy budget. Consequently, it is of great interest to incorporate a reliable measurement-based surface albedo scheme into numerical climate models. However, past measurements were either limited to short timescales or single observation sites.

We therefore dedicated a field campaign to snow surface properties during the austral summer 2013/14 at Kohnen Station (75°00'S, 00°04'E) on the East Antarctic Plateau.

Results are published:

  • Validation study on the snow grain size
    Carlsen, T., Birnbaum, G., Ehrlich, A., Freitag, J., Heygster, G., Istomina, L., Kipfstuhl, S., Orsi, A., Schäfer, M., and Wendisch, M.: Comparison of different methods to retrieve optical-equivalent snow grain size in central Antarctica, The Cryosphere, 14, 3959–3978, 2020, doi:10.5194/tc-14-3959-2020
  • Parametrization of the snow reflectance anisotropy :
    Carlsen, T., Birnbaum, G., Ehrlich, A., Helm, V., Jäkel, E., Schäfer, M., and Wendisch, M., Parameterizing anisotropic reflectance of snow surfaces from airborne digital camera observations in Antarctica, The Cryosphere, 14, 3959 – 3978, 2020. doi:10.5194/tc-14-3959-2020.
 A scientist takes a snow sample to measure the snow grain size, next to it the radiation rack is shown, which is overflown by a research aircraft and a satellite. Graphic: Tim Carlsen
Illustration of the different measurement methods to derive the snow grain size. Graphic: Tim Carlsen

Development of tropical high-level convection derived from ground-based imaging spectroradiometer measurements

Funding: German Research Foundation

Period: 01.02.2017 – 31.01.2021

Team: Kátia Mendes de Barros, Dr. Evelyn Jäkel, Prof. Dr. Manfred Wendisch

In this project, the temporal evolution of tropical convective clouds was investigated with respect to the impact of aerosol particles and the thermodynamic conditions. ATTO (Amazonian Tall Tower Observatory) in the middle of the Brazilian rainforest provides ideal conditions to observe convective clouds in pristine and polluted aerosol conditions.
Field measurements of cloud sides were conducted in 2018 using a thermal imager and a fully radiometrically calibrated digital camera equipped with a fisheye-lens. Specifically, the infrared images, radio soundings, and ERA5 are combined with radiative transfer simulations for cloud reconstruction of the cloud’s macroscopic properties. These clouds serve as input for cloud microphysical estimates based on 3D simulations, such thsuch that the cloud evolution of macroscopic and microphysical parameters can be documented depending on the external conditions.
 

Left: Photo of convective clouds over the rainforest. Right: Reconstructed cloud height from thermal imager measurements. Graphic: Kátia Mendes de Barros. Photo/Graphic: Kátia Mendes de Barros
Convective clouds over the rainforest and reconstructed cloud height from thermal imager measurements. Photo/Graphic: Kátia Mendes de Barros

ACORES - Azores stratoCumulus measurements Of Radiation, turbulEnce and aeroSols

Funding: German Research Foundation (DFG)

Period: 2015 – 2019

To improve the understanding of the impact of boundary layer clouds on the Earth's climate system, helicopter measuring flights over the Azores (39°N, 28°W) were performed in July 2017. Over this area extended fields of stratocumulus clouds frequently occur, especially in June/July and October/November. The homogeneous water surface allows studying the processes in stratocumulus clouds without the impact of an inhomogeneous surface.

The photo shows typical marine stratocumulus clouds over the Azores. Photo: Felix Lauermann
Typical marine strato-cumulus over the Azores. Photo: Felix Lauermann

The objectives of the ACORES – Kampagne (Azores stratoCumulus measurements Of Radiation, turbulEnce and aeroSols)) were

  • to improve the understanding of the fine-scale structure of the EIL (entrainment interfacial layer),
  • to quantify the influence of the EIL on the entrainment in stratocumulus clouds, and
  • to quantify the role of radiative heating and cooling rates in cloud entrainment and convection processes.

The helicopter carried two measuring platforms on an overall 170 m long cable. SMART-HELIOS (HELIcopter-borne Observations of Spectral Radiation), located 20 m below the helicopter, and ACTOS (Airborne Cloud Turbulence Observation System) fixed at the end of the cable. SMART-HELIOS flew over the cloud and measured radiative quantities. ACTOS, operated by TROPOS, was located within the cloud layer for measuring cloud microphysical, dynamic, thermodynamic and radiative quantities within the cloud.

Results of the project:

Siebert, S. et al.: Observations of aerosol, cloud, turbulence, and radiation properties at the top of the marine boundary layer over the Eastern North Atlantic Ocean: The ACORES campaign, Bull. Am. Meteorol. Soc., 1–59, doi:10.1175/BAMS-D-19-0191.1, early online release.

 The picture shows the measuring platform SMART-HELIOS with the shape of a torpedo standing on the ground and hanging from the helicopter during the measurement. Photo: Felix Lauermann
The measurement platform SMART-HELIOS, which is equipped with various radiation sensors. Photo: Felix Lauermann

Stratospheric and upper tropospheric processes for better climate predictions (StratoClim)

Funding: European Union (Grant agreement ID: 603557)

Period: 2016 – 2018

Team: Prof. Dr. Manfred Wendisch, Dr. Tim Carlsen

You can find further information on the STRATOCLIM-Webpage.

 

Previous Campaigns

The positions of numerous measurement campaigns are shown on a world map. The focus is on the polar regions as well as the tropical and subtropical areas. Graphic: Evi Jäkel / University of Leipzig
Sites of measurement campaigns conducted since 2010. Graphic: Evi Jäkel / University of Leipzig

Campaign

Year

Region

Platform

HALO-(AC)3 2022 Arctic Aircraft

MOSAiC-ACA

2020

Arctic (Svalbard)

Aircraft

MOSAiC

2020

Arctic

Balloon

EUREC4A

2020

Barbados

Aircraft

AFLUX

2019

Arctic (Svalbard)

Aircraft

ATTO

2018

Tropics

Tower

PAMARCMiP

2018

Arctic (Greenland)

Aircraft,Ground-based

ACORES

2017

Azores

Helicopter

PASCAL

2017

Arctic

Balloon

ACLOUD

2017

Arctic (Svalbard)

Aircraft

NARVAL

2016

Barbados

Aircraft

NAWDEX

2016

North Atlantic

Aircraft

ACRIDICON

2014

Tropics

Aircraft

ML-Cirrus

2014

Mid-latitudes

Aircraft

ANT-Land

2013/2014

Antarctica

Aircraft,Ground-based

RACEPAC

2014

Arctic (Inuvik)

Aircraft

ANT-XXVII/4

2012

Atlantic

Ship

VERDI

2012

Arctic (Inuvik)

Aircraft

SORPIC

2010

Arctic (Svalbard)

Aircraft

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