Soot on Snow experiments Aki Virkkula Niku Kivekäs Onni Järvinen et al.

Transcription

1 Soot on Snow experiments Aki Virkkula Niku Kivekäs Onni Järvinen et al.

2 Outline Effects of soot on snow Idea of Soot on Snow (SoS) experiments SoS 2011 SoS 2012 SoS 2013 Summary Acknowledgements 9/17/2012 2

3 Effects of soot on snow Soot is transported in air to Arctic regions and mountain glaciers. When deposited on snow, soot decreases the snow albedo. This causes more energy to absorbe in the snow pack, enhancing melting. Lower albedo and shorter snow period lead to significant positive climate forcing. 9/17/2012 3

4 How much soot is needed to cause a measurable effect? 9/17/2012 4

5 Main idea: Soot on Snow (SoS) measurement campaigns 1. Deposit soot on natural snow pack in a controlled way. 2. Measure the snow albedo, snow depth and other snow properties through the entire melting period. 9/17/2012 5

6 SoS 2011 March Nurmijärvi, Finland 9/17/2012 6

7 SoS 2011, description On farming field at Nurmijärvi, Finland Soot was produced on site by burning rubber and other organic materials in a stove. Soot was led to deposit in a semi-open garage tent. One soot area and one reference area. 9/17/2012 7

8 Soot generator Smoke stack cooling Rubber pellets from used tyres + other material

9 Action, Friday, 4 March 2011

10 After soot production the tent was pulled away

11 SoS 2011, measurements When soot was being deposited: DMPS, CPC, nephelometer, snow samples Continuous or regular: Albedo, snow depth Later visit: Snow structure and temperature profile, spectral irradiance through snow 9/17/

12 Albedo measurements over dirty snow

13 Snowpits 1 April 2011 Dirty Clean

14 SoS 2011, results 9/17/

15 cm / day cm Albedo Clean alb Dirty alb /03 07/03 10/03 13/03 16/03 19/03 22/03 25/03 28/03 31/03 03/04 06/04 09/04 12/04 15/ Change of the snowbed level since the burning day Soot area, stick 3 Background, stick /03 07/03 10/03 13/03 16/03 19/03 22/03 25/03 28/03 31/03 03/04 06/04 09/04 12/04 15/ Rate of change of snowbed level Soot area, stick 3 Background, stick /03 07/03 10/03 13/03 16/03 19/03 22/03 25/03 28/03 31/03 03/04 06/04 09/04 12/04 15/04 Date

16

17 Irradiance at the depth of 20cm in the clean and dirty snow pit and the ratio ( (I Dirty / I Clean ) x 100 %)

18 Snow pit profiles Snow-type classication follows Snow crystal codes The International Classication for Seasonal Code Description Snow on the Ground (Fierz et al., 2009) RGlr Large rounded particles FCsf Faceted crystals in surface layer FCxr Rounding faceted particles MFpc Rounded polycrystals Red line indicates hardness Clean snow pit Dirty snow pit

19 SoS 2011, results Clear albedo effect even after snowfall Faster melting Different temperature profile and snow pack structure 9/17/

20 SoS 2012 February Jokioinen, Finland 9/17/

21 SoS 2012, description On farming field next to Jokioinen observatory, Finland Soot was collected earlier by chimney cleaners in Helsinki. Portable closed deposition chamber. Three soot spots and one reference spot. 9/17/

22 Soot blowing system in SoS 2012 excess air fine soot ambient air deposited soot Pump Cyclone raw soot coarse soot

23 Soot blowing system

24 Deposition chamber

25

26 SoS 2012, measurements When soot was being deposited: DMPS, CPC, nephelometer, PSAP, SP2, snow samples Continuous or regular: Albedo, snow depth Later visit: Snow temperature profile, snow samples 9/17/

27 Albedo and melting rate

28 SoS 2012, results 9/17/

29 Albedo There was a snow storm right after deposition, and the spots were covered unevenly with lots of new snow. No significant albedo effect could be retrieved.

30 Snow depth

31 EC in snow one month after deposition All spots had roughly the same amount of soot in respective depths. No added soot present anymore. Reference spot Most added soot (4900mg/l)

32 SoS 2012, results Albedo and melting effects were masked by new snow. Soot had melted through the snow (or been blown away). Weather phenomena can mask the effects of soot on snow pack. 9/17/

33 SoS 2013 March 2013 Sodankylä, Finland 9/17/

34 SoS 2013, description On an opening in forest at Sodankylä (FMI Arctic unit), Finnish Lapland Lots of snow Soot deposition system similar to SoS spots of soot and possibly volcanic ash and dust, one reference spot 9/17/

35 SoS 2013, measurements When soot is being deposited: DMPS, CPC, nephelometer, PSAP, SP2, snow samples Continuous or regular: Albedo, snow depth, snow profile and snow samples 9/17/

36 Summary We were able to cause a measurable effect when using very high soot concentrations in SoS Weather phenomena masked the soot effects in SoS The research is still going on. 9/17/

37 Participants Acknowledgements 1 Aki Virkkula 1,2, Niku Kivekäs 1, Onni Järvinen 2, Jonas Svensson 1,3, Heikki Lihavainen 1, Antti Hyvärinen 1, David Brus 1, Antti Aarva 1, Timo Mäkelä 1, Riikka Väänänen 2, John Backman 2, Outi Meinander 1, Anu Heikkilä 1, Ella-Maria Kyrö 2, Gerrit de Leeuw 1,2, 1 Finnish Meteorological Institute, Helsinki 2 University of Helsinki, Department of Physics, Helsinki 3 University of Stockholm, Department of Physics, Stockholm 9/17/

38 Materials and locations Consti Talotekniikka Oy, Oy Tikkurila Ab Anita Virkkula, Timo Vainio, MTT agricultural research center Funding Acknowledgements 2 EU Life+ project Mitigation of Arctic warming by controlling European black carbon emissions (MACEB) Academy of Finland, project A4 (Arctic Absorbing Aerosols and Albedo of Snow) Tor and Maj Nessling Foundation 9/17/

39 Thank you for your attention For more information visit posters 009 and 010

40 9/17/

41 Dirty snow just after new snowfall and a couple of days later Reference area

42 Snow temperature profiles on 1 April Air temperature was +1.8 C

43 Snow samples were melted and filtered through quartz filters EC/OC