Formation, Lifetime, Properties and Radiative Impact of Mid–Latitude Cirrus Clouds

Mission status: Completed

Persons in Charge


Christiane Voigt (DLR-IPA)

Contact point at DLR-FX for this mission:

HALO Project Management: Martina Hierle

Postal address:
DLR Oberpfaffenhofen
Flugexperimente (FX)
Münchener Str. 20
82234 Weßling

Office phone:
+49 (0)8153 28-1792

HALO Deployment Base

Project Description

Cirrus clouds, which often occur in the upper troposphere, are very important for the weather, atmospheric chemistry and the climate. Air traffic may form artificial cirrus clouds via condensation trails, which quickly develop into widespread cirrus clouds in ice supersaturated air. However, the detailed mechanism through which ice crystals form is still largely unknown. During the ML-CIRRUS mission (Formation, Lifetime, Properties and Radiative/Chemical Impact of Mid-Latitude Cirrus Clouds), comprehensive instrumentation were used to measure the properties of cirrus clouds.

To do this, HALO was fitted with equipment such as a lidar, a measuring instrument that emits laser pulses and receives the signals backscattered from molecules and particles in the atmosphere. This enables to measure, among other things, the concentration profiles of water vapour, aerosol and cirrus particles below the flight altitude to be surveyed. In order to characterise ice particles in terms of size, number concentration and shape, special measurement probes will be fitted under the wings.

During the mission, the scientists aimed to investigate both the formation processes of natural cirrus clouds and the formation of ice clouds induced by air traffic. Some of the measurement flights took place in the North Atlantic flight corridor, including about 1000 flights per day.

Time Period

Feb – Apr 2014


    • German Aerospace Center, Institute of Atmospheric Physics (DLR-IPA)
    • Karlsruhe Institute of Technology (KIT)
    • Forschungszentrum Jülich (FZ Jülich)
    • Goethe University Frankfurt
    • Heidelberg University
    • Johannes Gutenberg University Mainz
    • University of Wuppertal

Scientific instruments and payload configuration

  • List of scientific instruments for the mission:

DescriptionPrincipal investigatorInstitution
WALESWater Vapour Differential Absorption LidarAndreas Fix, Martin WirthDLR-IPA
FISHFast In-situ Stratospheric Hygrometer Martina KrämerFZ Jülich
HAIHygrometer for Atmospheric InvestigationsVolker Ebert, Bernhard BuchholzPTB (National Metrology Institute)
FAIROFast Ozone MeasurementAndreas ZahnKIT
AENEASNOY MeasurementHelmut ZiereisDLR-IPA
AIMSAtmospheric Chemical Ionization Mass Spectrometer Christiane Voigt, Tina JurkatDLR-IPA
Dropsonde systemMeteorological DropsondesStefan KaufmannDLR-IPA
miniDOASDifferential Optical Absorption SpectroscopyKlaus PfeilstickerUniv. Heidelberg
BAHAMASHALO Basic Data Acquisition SystemAndreas GiezDLR-FX

Cabin and exterior configuration of HALO for the mission

HALO cabin layout for ML-CIRRUS

Schematic HALO PMS wing carrier configuration for ML-CIRRUS

Halo flights for this mission

Aircraft registrationDateTake off - Landing / UTTotal flight time / hFrom - ToMission #
D-ADLR2014-02-0710:50:00 - 12:45:001.917EDMO - EDMOFlight test
D-ADLR2014-02-1007:30:00 - 08:00:000.500EDMO - EDMOFlight test
D-ADLR2014-02-1010:50:00 - 12:30:001.667EDMO - EDMOFlight test
D-ADLR2014-02-1110:30:00 - 11:25:000.917EDMO - EDMOFlight test
D-ADLR2014-03-1910:20:00 - 12:25:002.083EDMO - EDMOFlight test
D-ADLR2014-03-2111:55:00 - 14:10:002.250EDMO - EDMOMission flight
D-ADLR2014-03-2208:55:00 - 10:55:002.000EDMO - EDMOMission flight
D-ADLR2014-03-2211:30:00 - 13:45:002.250EDMO - EDMOMission flight
D-ADLR2014-03-2605:50:00 - 14:05:008.250EDMO - EDMOMission flight
D-ADLR2014-03-2711:00:00 - 15:30:004.500EDMO - EDMOMission flight
D-ADLR2014-03-2912:35:00 - 19:50:007.250EDMO - EDMOMission flight
D-ADLR2014-04-0109:35:00 - 15:55:006.333EDMO - EDMOMission flight
D-ADLR2014-04-0313:15:00 - 18:15:005.000EDMO - EDMOMission flight
D-ADLR2014-04-0409:05:00 - 15:55:006.833EDMO - EDMOMission flight
D-ADLR2014-04-0417:05:00 - 19:40:002.583EDMO - EDMOMission flight
D-ADLR2014-04-0707:00:00 - 12:20:005.333EDMO - EDMOMission flight
D-ADLR2014-04-1013:30:00 - 16:30:003.000EDMO - EDMOMission flight
D-ADLR2014-04-1107:25:00 - 12:20:004.917EDMO - EDMOMission flight
D-ADLR2014-04-1113:25:00 - 17:40:004.250EDMO - EDMOMission flight
D-ADLR2014-04-1310:30:00 - 17:45:007.250EDMO - EDMOMission flight
D-ADLR2014-04-1507:50:00 - 10:35:002.750EDMO - EDMOMission flight

More information

Press releases, media etc

Press release DLR (24-Mar-2014):
Klimafaktor Eiswolke: Forschungsflugzeug HALO untersucht Zirren und Kondensstreifen

Press release TROPOS (24-Mar-2014):
Klimafaktor Eiswolke: Forschungsflugzeug HALO untersucht Zirren und Kondensstreifen. [..] Mit an Bord bei der HALO-Mission ML-CIRRUS ist auch ein Einlass-System des TROPOS zur Sammlung von Eispartikeln (Gegenstrom-Impaktor, engl. Counterflow Virtual Impactor, kurz CVI. [Read more..]

DIE WELT (24-Mar-2014):
Wie Eiswolken den Klimawandel beeinflussen. Wissenschaftler des Deutschen Zentrums für Luft- und Raumfahrt und des Forschungszentrums Jülich wollen den Einfluss von Wolken auf den Treibhauseffekt mithilfe des Forschungsflugzeugs „Halo“ erkunden. [Read more..]

DLR Luftfahrt News-Archiv (24-Mar-2014)
Ice clouds as a climate factor – research aircraft HALO examines cirrus clouds and vapour trails.   Unanswered questions about the formation of clouds and their impact on the climate are currently setting limitations on the validity of global climate forecasts. To make a detailed analysis of the climate effects of natural ice clouds and the vapour trails created by air traffic, the HALO (High Altitude and LOng Range) research aircraft embarked on the first of a total of 12 measurement flights on 24 March 2014. For four weeks, as part of the ML-CIRRUS (Mid-Latitude Cirrus) mission, ice clouds (also known as ‚cirrus‘) will be measured at altitudes of between eight and 14 kilometres above Europe and the North Atlantic.
Read more.. (in English)   |   Weiterlesen.. (auf deutsch)


Schumann, U., Baumann, R., Baumgardner, D., Bedka, S. T., Duda, D. P., Freudenthaler, V., Gayet, J.-F., Heymsfield, A. J., Minnis, P., Quante, M., Raschke, E., Schlager, H., Vázquez-Navarro, M., Voigt, C., and Wang, Z.: Properties of individual contrails: a compilation of observations and some comparisons, Atmos. Chem. Phys., 17, 403-438, doi:10.5194/acp-17-403-2017, 2017. http://www.atmos-chem-phys.net/17/403/2017/

Voigt, C., Minikin, A., Schumann, U., Abdelmonem, A., Afchine, A., Borrmann, S., Boettcher, M., Buchholz, B., Bugliaro, L., Costa, A., Curtius, J., Dollner, M., Dörnbrack, A., Dreiling, V., Ebert, V., Ehrlich, A., Fix, A., Forster, L., Frank, F., Fütterer, D., Giez, A., Graf, K., Grooß, J.-U., Groß, S., Heimerl, K., Heinold, B., Hüneke, T., Järvinen, E., Jurkat, T., Kaufmann, S., Kenntner, M., Klingebiel, M., Klimach, T., Kohl, R., Krämer, M., Krisna, T. C., Luebke, A., Mayer, B., Mertes, S., Molleker, S., Petzold, A., Pfeilsticker, K., Port, M., Rapp, M., Reutter, P., Rolf, C., Rose, D., Sauer, D., Schäfler, A., Schlage, R., Schnaiter, M., Schneider, J., Spelten, N., Spichtinger, P., Stock, P., Walser, A., Weigel, R., Weinzierl, B., Wendisch, M., Werner, F., Wernli, H., Wirth, M., Zahn, A., Ziereis, H., and Zöger, M.: ML-CIRRUS – The airborne experiment on natural cirrus and contrail cirrus with the high-altitude long-range research aircraft HALO, Bull. Amer. Meteorol. Soc., online, doi: 10.1175/BAMS-D-15-00213.1, 2016.

Wolf, K., Ehrlich, A., Hüneke, T., Pfeilsticker, K., Werner, F., Wirth, M., and Wendisch, M.: Potential of remote sensing of cirrus optical thickness by airborne spectral radiance measurements in different viewing angles and nadir geometry, Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2016-970, in review, 2016.

Urbanek, B., Groß, S., Schäfler, A., and Wirth, M.: Determining stages of cirrus life-cycle evolution: A cloud classification scheme, Atmos. Meas. Tech. Discuss., doi:10.5194/amt-2016-332, in review, 2016.