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Wolf, V. (2019). Analysis of Arctic ice cloud properties using in-situ and remote sensing measurements. (Doctoral dissertation). Luleå: Luleå University of Technology
Open this publication in new window or tab >>Analysis of Arctic ice cloud properties using in-situ and remote sensing measurements
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Analys av egenskaper av arktiska ismoln med hjälp av in situ och fjärrananlysmätningar
Abstract [en]

Cirrus clouds play an important role in the radiation balance of the atmosphere as theycan have a warming and cooling effect. The resulting net radiation effect depends ontheir micro- and macrophysical properties such as particle size, shape, and numberconcentration. The net warming or cooling effect of clouds is still one of the biggest uncertainties, for example in climate models. For weather and climate models and remotesensing retrievals, precise knowledge of micro- and macrophysical cloud propertiesis therefore necessary. This is true in particular for Arctic cirrus clouds, where we still lack data and need better understanding. Yet, climate change affects high latitudes stronger than other regions. Thus, more knowledge about micro- and macrophysicalproperties of Arctic cirrus clouds is needed urgently.

The focus of this thesis is on the retrieval of physical particle properties of Arcticice clouds. Balloon-borne in-situ measurements with concurrent lidar measurementshave been performedinKiruna in winter. The Balloon-borne IceCloud Particle Imager(B-ICI) takes images of ice particles directly inside the cloud. After recovery, the imagesare analysed to gain information about particle shape, size, area, and number concentrationand to determine the extinction coefficient.

Whenever possible, concurrent lidar measurements have supplemented the balloonbornemeasurements. Due to balloon drift, there is a spatial and temporal distance betweenB-ICI and lidar. Hence, both instruments do not sample a cloud at the same timeand place. Taking into account the wind speed, it is possible to determine the time of lidarobservation at which the cloud segment probed by balloon was closest to the lidar. However, cloud homogeneity has to be assumed. The results from B-ICI are comparedto extinction coefficients and depolarization ratios obtained fromlidar measurements. Measurement results from B-ICI and lidar measurements are, despite the spatial andtemporal distance, very similar and thus comparable. Clouds consisting of small andcompact particles have a smaller extinction coefficient and depolarization ratio thanclouds which consist of large, complex-shaped particles.

For each cloud that has been measured, the cloud origin, i.e. its formation processis determined with the help of back-trajectory modelling. With that, it can be studiedif particle properties depend on cloud origin. This analysis reveals that particle sizeand shape exhibit strong differences with respect to the formation process. If ice particleshave been formed via the liquid droplet phase, they can grow to large sizes andinto complex shapes. If, however, they have been formed directly from vapour or supercooledsolutions, they are smaller and most often compact in shape. Hence, it ispossible to predict the formation process if size distribution and predominant particleiiishapes are known. Or inversely, size distribution and shapes can be predicted by knowingthe formation process. To account for these differences, a new parametrization forparticle size distribution is given that depends on the formation process.

While the cloud formation process is depending on temperature, supersaturation,and updraught speed, it should not depend on latitude. In fact, comparing results fromArctic measurements with measurements from other latitudes similarities are recognizable. For example, the new parametrization for particle size distributions of Arcticcirrus clouds depending on formation processes and an established parametrizationfor midlatitude cirrus depending on particle size are very similar. Thus, this thesis andthe attached papers will not just provide better information about the particle propertiesof Arctic ice clouds, it can also be used to improve weather and climate models forall latitudes.

Abstract [sv]

Cirrusmoln spelar en viktig roll i atmosfärens strålningsbalans eftersom de kan ha en värmande eller kylande effekt. Den resulterande nettostrålningseffekten beror på deras mikro- och makrofysikaliska egenskaper, såsom partiklarnas storlek, form och koncentration.Till vilken grad molnen totalt skulle ha en uppvärmande eller nedkylandeeffekt är emellertid fortfarande en av de största osäkerheterna i klimatmodellerna. För väder- och klimatmodeller och fjärranalysretrieval är det nödvändigt med exakt kunskap om dessa egenskaper. Detta gäller i synnerhet för arktiska cirrusmoln, där vi fortfarandehar mindre data och kunskaper. Klimatförändringen är också starkare i högabreddgrader än i andra regioner. Således krävs mer kunskap om mikro- och makrofysikaliska egenskaper av arktiska cirrusmoln.

Denna avhandling fokuserar på partikelegenskaper av arktiska ismoln. Ballongburnain-situ mätningar med samtidiga lidarmätningar har utförts i Kiruna under vintern.Den ballongburna Ice Cloud partikelavbildaren (Balloon-borne Ice Cloud ParticleImager B-ICI) tar bilder av ispartiklar direkt i molnet. Efter bärgning av instrumentetanalyseras bilderna för att få information om partikelform, storlek, area ochkoncentration samt för att bestämma extinktionskoefficienten.

När det är möjligt har samtidiga lidarmätningar kompletterat de ballongburna mätningarna.Eftersomballongexperimentet driver med vinden finns det ett rumsligt ochtemporärt avstånd mellan B-ICI och lidar. Därför kan inte båda instrument studeraett moln på samma tid och plats. Med hänsyn till vindhastigheten är det möjligt attbestämma tidpunkten för lidarobservation då molnsegmentet som undersökts medballongen var närmast lidarn. Detta under antagendet att molnsegmentet vid dennatidpunkt hade en homogen sammasättning. Resultaten från B-ICI jämförsmedextinktionskoefficientenoch depolarisationsförhållandet som erhållits från lidarmätningar.B-ICI och lidarmätningar ger, trots det rumsliga och tidsmässiga avståndet, likartaderesultat och är sålunda jämförbara. Små och kompakta partiklar har en mindre extinktionskoefficientoch ett mindre depolarisationsförmåga än stora komplexformadepartiklar.

För varje molnsomhar uppmätts bestäms molnets ursprung, d.v.s. dess bildningsprocessmedhjälpav ’back-trajectory’ modellering, och dessentomompartikelegenskapernaberor på molnets ursprung. Denna analys avslöjar att partikelstorlek och form uppvisarstora skillnader beroende på bildningsprocessen. Om ispartiklar har bildatsvia underkylda vattendroppar kan de växa sig stora och till komplexa former. Om de emellertid har bildats direkt från vattenånga eller superkylda lösningar, är de mindreoch oftast av kompakt form. Därmed är det möjligt att bestämma bildningsprocessenvom storleksfördelning och dominerande partikelformer är kända. Eller omvänt kanstorleksfördelning och former förutspås i fall bildningsprocessen är känd. För att redovisadessa skillnader ges en ny parametrisering för fördelningen av partikelstorlekberoende på bildningsprocessen.

Även om molnbildningsprocessen beror på temperatur, mängd av vattenånga ochvertikal vind, bör det inte bero på latitud. Resultat från arktiska mätningar och mätningar från andra breddgrader kan därför jämföras. Till exempel är den nya parametriseringen för fördelningar av partikelstorlek i arktiska cirrusmoln som beror på bildningsprocesser, mycket likt en i litteraturen etablerad parametrisering för midlatitudecirrus där parametrisiering beror på partikelstorlek. Således kommer denna avhandlingoch de bifogade artiklarna inte bara att ge bättre information om partikelegenskaperna hos arktiska ismoln, utan dessa kan också användas för att förbättra väder och klimatmodeller för alla breddgrader.

Place, publisher, year, edition, pages
Luleå: Luleå University of Technology, 2019
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
Keywords
Arctic cirrus clouds, ice particle properties, in-situ measurements, in-situ and lidar comparison
National Category
Meteorology and Atmospheric Sciences
Research subject
Atmospheric science
Identifiers
urn:nbn:se:ltu:diva-73710 (URN)978-91-7790-368-0 (ISBN)978-91-7790-369-7 (ISBN)
Public defence
2019-06-14, Rymdcampus 1, Aula (IRF), Kiruna, 09:30 (English)
Opponent
Supervisors
Available from: 2019-04-23 Created: 2019-04-19 Last updated: 2019-08-14Bibliographically approved
Wolf, V., Völger, P., Kuhn, T. & Gumbel, J. (2019). ANALYSIS OF PARTICLE SHAPE, DEPOLARIZATION AND LIDAR RATIO IN ARCTIC CIRRUS CLOUDS: A CASE STUDY. In: : . Paper presented at The 29th International Laser Radar Conference (ILRC29).
Open this publication in new window or tab >>ANALYSIS OF PARTICLE SHAPE, DEPOLARIZATION AND LIDAR RATIO IN ARCTIC CIRRUS CLOUDS: A CASE STUDY
2019 (English)Conference paper, Published paper (Refereed)
National Category
Natural Sciences Meteorology and Atmospheric Sciences
Identifiers
urn:nbn:se:ltu:diva-73537 (URN)
Conference
The 29th International Laser Radar Conference (ILRC29)
Available from: 2019-04-09 Created: 2019-04-09 Last updated: 2019-05-03
Wolf, V., Kuhn, T., Milz, M., Völger, P., Krämer, M. & Rolf, C. (2018). Arctic ice clouds over northern Sweden: microphysical properties studied with the Balloon-borne Ice Cloud particle Imager B-ICI. Atmospheric Chemistry And Physics, 18(23), 17371-17386
Open this publication in new window or tab >>Arctic ice clouds over northern Sweden: microphysical properties studied with the Balloon-borne Ice Cloud particle Imager B-ICI
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2018 (English)In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 18, no 23, p. 17371-17386Article in journal (Refereed) Published
Abstract [en]

Ice particle and cloud properties such as particle size, particle shape and number concentration influence the net radiation effect of cirrus clouds. Measurements of these features are of great interest for the improvement of weather and climate models, especially for the Arctic region. In this study, balloon-borne in situ measurements of Arctic cirrus clouds have been analysed for the first time with respect to their origin. Eight cirrus cloud measurements have been carried out in Kiruna (68 N), Sweden, using the Balloon-borne Ice Cloud particle Imager (B-ICI). Ice particle diameters between 10 and 1200 µm have been found and the shape could be recognized from 20 µm upwards. Great variability in particle size and shape is observed. This cannot simply be explained by local environmental conditions. However, if sorted by cirrus origin, wind and weather conditions, the observed differences can be assessed. Number concentrations between 3 and 400 L−1 have been measured, but the number concentration has reached values above 100 L−1 only for two cases. These two cirrus clouds are of in situ origin and have been associated with waves. For all other measurements, the maximum ice particle concentration is below 50 L−1 and for one in situ origin cirrus case only 3 L−1. In the case of in situ origin clouds, the particles are all smaller than 350 µm diameter. The PSDs for liquid origin clouds are much broader with particle sizes between 10 and 1200 µm. Furthermore, it is striking that in the case of in situ origin clouds almost all particles are compact (61 %) or irregular (25 %) when examining the particle shape. In liquid origin clouds, on the other hand, most particles are irregular (48 %), rosettes (25 %) or columnar (14 %). There are hardly any plates in cirrus regardless of their origin. It is also noticeable that in the case of liquid origin clouds the rosettes and columnar particles are almost all hollow.

Place, publisher, year, edition, pages
Copernicus Publications, 2018
National Category
Aerospace Engineering
Research subject
Atmospheric science
Identifiers
urn:nbn:se:ltu:diva-72316 (URN)10.5194/acp-18-17371-2018 (DOI)000452384100002 ()2-s2.0-85058149311 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-01-08 (johcin)

Available from: 2018-12-18 Created: 2018-12-18 Last updated: 2019-04-19Bibliographically approved
Kuhn, T., Wolf, V., Völger, P., Stanev, M. & Gumbel, J. (2017). Comparison of In-Situ Balloon-Borne and Lidar Measurement of Cirrus Clouds. In: Proceedings of the 23rd ESA Symposium on European Rocket and Balloon Programmes and Related Research: . Paper presented at 23rd ESA Symposium on European Rocket and Balloon Programmes and Related Research, Visby, 11-15 June 2017. Noordwijk, The Netherlands, Article ID A-091kuhn.
Open this publication in new window or tab >>Comparison of In-Situ Balloon-Borne and Lidar Measurement of Cirrus Clouds
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2017 (English)In: Proceedings of the 23rd ESA Symposium on European Rocket and Balloon Programmes and Related Research, Noordwijk, The Netherlands, 2017, article id A-091kuhnConference paper, Published paper (Other academic)
Abstract [en]

A series of in-situ balloon-borne experiments con- ducted at Kiruna, Sweden (68°N), is studying upper- tropospheric, cold ice clouds in arctic latitudes. Ex- periments are launched from Esrange Space Center and collect ice particles with an in-situ imaging instrument. One of the aims with these measurements is to improve satellite remote sensing of cold ice clouds. Such clouds can be observed by lidar. Therefore, when possible, concurrent ground-based lidar measurements have been carried out with two available lidar systems to accom- pany the balloon-borne measurements. The Esrange lidar is located at Esrange Space Center, approximately 500 m from the in-situ launch site on the balloon pad; the IRF lidar is located about 29 km to the west of Esrange Space Center (operated by the Swedish Institute of Space Physics, IRF). Here we present results from these lidar measurements and compare them to ice particle proper- ties determined during the in-situ measurements. 

Place, publisher, year, edition, pages
Noordwijk, The Netherlands: , 2017
Keywords
Cirrus; ice clouds; lidar; ice particles; in-situ; balloon-borne; Arctic; high latitude measurements
National Category
Natural Sciences Earth and Related Environmental Sciences Aerospace Engineering
Research subject
Atmospheric science
Identifiers
urn:nbn:se:ltu:diva-66461 (URN)
Conference
23rd ESA Symposium on European Rocket and Balloon Programmes and Related Research, Visby, 11-15 June 2017
Funder
Swedish National Space Board
Available from: 2017-11-08 Created: 2017-11-08 Last updated: 2019-04-19Bibliographically approved
Ekman, J., Antti, M.-L., Martin-Torres, J., Emami, R., Törlind, P., Kuhn, T., . . . Fakhardji, W. (2015). Projekt: Rymdforskarskolan. Paper presented at .
Open this publication in new window or tab >>Projekt: Rymdforskarskolan
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2015 (English)Other (Other (popular science, discussion, etc.))
Abstract [en]

The Graduate School of Space Technology

National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering Other Materials Engineering Aerospace Engineering Other Engineering and Technologies not elsewhere specified Tribology (Interacting Surfaces including Friction, Lubrication and Wear) Chemical Process Engineering
Research subject
Industrial Electronics; Engineering Materials; Atmospheric science; Onboard space systems; Product Innovation; Machine Elements; Chemical Technology; Entrepreneurship and Innovation
Identifiers
urn:nbn:se:ltu:diva-36154 (URN)8c1c49e5-8fd1-4b50-992e-abd48bc5619c (Local ID)8c1c49e5-8fd1-4b50-992e-abd48bc5619c (Archive number)8c1c49e5-8fd1-4b50-992e-abd48bc5619c (OAI)
Note

Publikationer: Opportunities and Challenges for Additive Manufacturing in Space Applications; Status: Ongoing; Period: 01/01/2015 → …; End date: 31/12/2018

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2019-05-03Bibliographically approved
Wolf, V., Kuhn, T. & Krämer, M.On the dependence of Arctic cirrus parametrizations on the cloud origin.
Open this publication in new window or tab >>On the dependence of Arctic cirrus parametrizations on the cloud origin
(English)Manuscript (preprint) (Other academic)
National Category
Meteorology and Atmospheric Sciences
Identifiers
urn:nbn:se:ltu:diva-73538 (URN)
Available from: 2019-04-09 Created: 2019-04-09 Last updated: 2019-05-03
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-0071-5415

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