Selected Presentation from the INSTAAR Monday Noon Seminar Series.

Transcription

1 Selected Presentation from the INSTAAR Monday Noon Seminar Series. Institute of Arctic and Alpine Research, University of Colorado at Boulder. This seminar presentation has been posted to the internet to foster communication with the science community and the public. Most of the INSTAAR presentations were originally given in PowerPoint format; they were converted to Adobe PDF for posting. You may need to install the free Adobe Acrobat Reader to view these files. These presentations are "works in progress". They are not peer reviewed. They should not be referenced for any kind of publication. Contact the author for proper references and additional information before any use, even for unpublished works such as your own presentations. LICENSING AGREEMENT. Free use of these presentations is limited to a nonprofit educational or private non-commercial context and requires that you contact the author, give credit to the author, and display the copyright notice. All rights to reproduce these presentations are retained by the copyright owner. Images remain the property of the copyright holder. By accessing these presentations, you are consenting to our licensing agreement. 03 Feb Detlev Helmig, INSTAAR and Program in Atmospheric and Oceanic Sciences (PAOS) Detlev@instaar.Colorado.Edu "New insights into snow-photochemical processes and snow-atmosphere gas exchange (if you ever wonder what may happen in your freezer if the light stays on)." Seminar given at INSTAAR, University of Colorado. Copyright 2003 Detlev Helmig. All Rights Reserved. Helmig presentation (2.2 Mb PDF).

2 Selected Presentation from the INSTAAR Monday Noon Seminar Series. Institute of Arctic and Alpine Research, University of Colorado at Boulder Feb Detlev Helmig, INSTAAR and Program in Atmospheric and Oceanic Sciences (PAOS) "New insights into snow-photochemical processes and snow-atmosphere gas exchange (if you ever wonder what may happen in your freezer if the light stays on)." Seminar given at INSTAAR, University of Colorado. Copyright 2003 Detlev Helmig. All Rights Reserved. Helmig presentation (2.2 Mb PDF). Abstract Snowpack has been considered a rather inert substrate that undergoes little chemical interaction with the atmosphere. The conservation of gases in interstitial air and ice cores has been used to decipher records of past atmospheric composition and climate. Over the past decade an increasing number of previously unknown snow-photochemical reactions have been discovered. These processes have been shown to affect the surface-atmosphere exchange of many trace gases and may have implications on the interpretation of ice core records.

3 Inert??? No next day hangover Deficient in active properties; especially lacking a usual or anticipated chemical or biological action Having no or little activity to react Having no effect

4 Detlev Helmig "New Insights into Snow-Photochemical Processes and Snow-Atmosphere Gas Exchange (if you ever wondered what may happen in your freezer in case the light stays on)

5 Carina in the freezer

6 Ice Core Measurements CO 2 Methane Nitrous Oxide (N 2 O) CO Hydrogen Peroxide (H 2 O 2 ) Formaldehyde (H 2 CO) Methyl Bromide (CH 3 Br) Chlorofluorocarbons (CFC) Methanesulfonate (MSA) Oxygen Nitrogen Argon Anions: Cl -, NO - 3, SO 2-4, Cations: Ca 2+, K +, Mg 2+, Na +, NH + 4 Others: Fe, S, Al, Si, Ti, Mg Primary Aerosol Electrical Conductivity (balance of acids and bases) Minerals (Silicates, Clay, Mirca, Feldspars, etc.) Microparticles, Dust 18 O in H 2 O 14 C in CO 14 C in CO 2 15 N in N 2 36 Cl 10 Be

7 Pristine Arctic?

8 Pollution in the Arctic Lead Records in Greenland Ice Cores Heavy Metals (Lead, Hg) in Fish, Mammals Pesticides (DDT, Lindan) in Birds, Mammals Environmental Pollutants (PCB, PCP) in Wildlife Antarctic (Arctic) Ozone Hole Hg in Arctic Environment Polar Sunrise Ozone Depletion??? Nitrogen Photochemistry???

9 Front Cover AE

10 Polar Springtime Ozone Depletion (Alert) Bottenheim et al., Atmos Environ. 36, 2535 (2002)

11 X Barrow

12 Polar Ozone Depletion Chemistry 1. Formation of Br 2 (HOBr) g -> (HOBr) aq (HOBr) aq + H + aq + Br - aq -> (Br 2 ) aq + H 2 O (Br 2 ) - aq > (Br 2 ) g 2. Ozone Destruction Br 2 + hn -> 2 Br 2 Br + 2 O 3 -> 2 BrO + 2 O 2 3. Recycling of BrO a) BrO + BrO -> 2 Br + O 2 b) OH + CO (or VOC) -> HO 2 + CO 2 (or VOC products) BrO + HO 2 -> HOBr + O 2 HOBr + hn -> Br + OH

13 BrO/Ozone Honninger and Platt, Atmos. Environ. 36, 2481 (2002)

14 Ozone Depletion in Arctic Snowpack Diurnal Ozone and NOx at 30 cm depth Ozone in Firn Air NOx in Firn Air Solar Actinic Flux NOx in Ambient Air Peterson and Honrath, GRL 28, 511, 2001

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16 Sun/Shading Experiments

17 Actinic Flux into Snowpack

18 CH 3 CO-O-O-NO 2 Shepson et al., AGU, 2000

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21 CO production in snow

22 Chemical Fluxes out of the Snow at Summit

23 NO at South Pole

24 Photochemical Cycles

25 Photochemical Ozone Production

26 Photochemical Ozone Production Summit Diurnal Photochemical Ozone Production: ppb/day South Pole Diurnal Photochemical Ozone Production: 3-5 ppb/day (Crawford et al., GRL 28, 3641 (2001)

27 OH at South Pole

28 Photochemical Ozone Production

29 Ambient Ozone at South Pole

30 Ozone Depletion in Arctic Snowpack Ozone in Firn Air NOx in Firn Air Solar Actinic Flux NOx in Ambient Air Peterson and Honrath, GRL 28, 511, 2001

31 Ozone Fluxes out of Seasonal Snow Zeller, 2000

32 Table 1 Literature with ozone deposition measurements over snow-covered surfaces. Reference Location Landscape Measurement Dep. Velo- Comments Technique city (cm s-1) Aldaz, 1969 New Mexico BE 0.02 Galbally & Allison, Mt Buller, 1.3 m Snow TG Ozone release from snow 1972 Australia Depth observed. Galbally and Roy, 1980a,b Australia TG, BE 0.06 Deposition velocity increased with snow age. Wesely et al., Illinois Plowed Field ECM*, CL 0.03 (mean) 1981 Colbeck & Harrison, 1985 Lancaster/E ngland Grass Field TG, CL 0.08 Padro et al Canada Deciduous ECM 0.3 Forest Stocker et al., 1995 Colorado Grassland ECM, CL Deposition velocity decreased with snow age. Zeller & Hehn, 1996 Wyoming Coniferous Forest ECM, CL Consistent upwards ozone fluxes observed. Gong et al., 1997 Camp Ice Camp TB Data for ozone depletion events Narwahl Zeller, 2000 Wyoming Coniferous Forest ECM, CL (Polar Sunrise) Upwards ozone fluxes from surface (mean 0.2 mg m -2 s -1 ) *BE: Box Enclosure; ECM :Eddy Correl. Method; CL: Chemiluminescence; TG: Tower Gradient; TB: Teth. Balloon

33 Ozone in the Arctic Boundary Layer at Summit, Greenland

34 Instrumentation for Tethered Balloon Vertical Profiling

35 Summit Surface Ozone Measurements

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38 Ozone Diurnal Trends at Summit Diurnal Mean Ozone (ppb) :00 3:00 6:00 9:00 12:00 15:00 18:00 21:00 0:00 Time (hrs) Stand. Dev. of Diural Means (ppb) :00 3:00 6:00 9:00 12:00 15:00 18:00 21:00 0:00 Time (hrs)

39 Summit June 10, 2000 Profiling Data

40 Summit Potential Temperature Profile June 10, Up, 16:14 Down, 16:38 Height (m) Potential Temperature (K)

41 Boundary Layer Height

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43 Summit Ozone/RH Profile June 18, 2000 Flight #43up TS Temperature Flight #43up TS Potential Temperature Flight #43up TS Wind Speed Flight # 43up - ECC Ozone Profile Mixing Temp Temp WS WS ozone Ozone Richardson Stability Ozone Ozone Layer Height 2/3 MLH 1/3 MLH 2/3 MLH 1/3 MLH 2/3 MLH 1/3 MLH Number Function Flux Dep. Vel. m K K m/s m/s ppb ppb kg/(s m2) cm/s 8up E up E up E

44 Surface Data/Balloon Sonde Comparison

45 Summit 3D Potential Temperature

46 Summit 3D Wind Speed

47 Summary Aerosols NO 3-, Organics Ozone??? NO HONO Cl, F CO Alkenes HCHO H 2 O 2 PAN? NO 2 HNO 2 H 3 CCHO HNO 3 Mechanisms? Seasonality? Magnitude of Fluxes? Seasonal Snow <-> Year-Round Snow?

48 Niwot Ridge Summit Future Flux Research Coastal Greenland? Summit 2000

49 ANTCI Future Balloon Research Antarctic Tropospheric Chemistry Investigation South Pole 2003/2004

50 Contributors Don David Doug Hultstrand Jim Boulter Florence Bocquet Nancy Rivera Garymar Rivera Scott Peckham

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