Atmospheric composition at Princess Elisabeth: results of last seasons and outlook - by Alexander Mangold

Transcript

1. Atmospheric composition at Princess Elisabeth – results of last seasons and outlook Alexander Mangold ROYAL METEOROLOGICAL INSTITUTE of BELGIUM 17 September 2014
2. Overview  Background – Motivation  Instrumentation  Results  Summary + Outlook
3. atmospheric research in Antarctia – because … unique geographic situation particular meteorological and atmospheric conditions importance for the global atmospheric circulation circulation over Antarctica more stable than over the Arctic ozone hole Antarctica is a continent surrounded by oceans The Arctic is an ocean surrounded by continents
4. atmospheric research in Antarctia – because … the ozone hole  formation during spring: chemical reactions + sunlight  importance of the stability of the polar atmospheric circulation  less ozone  more UV-radiation  health risks amount of ozone depleting substances polar regions WMO ozone assessment 2010 year minimum of total ozone over Antarctica WMO ozone bulletin 2 / 2014 1 Aug 1 Sep 1 Oct 1 Nov 1 Dec
5. atmospheric research in Antarctia – because … sun radiation – attenuated, scattered, absorbed by atmospheric composition (gases, particles) radiation balance at the surface: temperature, energy-balance snow and ice  increased albedo  cooling effect more particles in the atmosphere  warming effect
6. atmospheric research in Antarctia – because … Aerosol–Cloud–Precipitation interaction  clouds form the link between water transport and precipitation  precipitation only source of mass to the ice sheet  future evolution of mass of ice sheet important – global sea level without particles no clouds composition important : sulfates, dust, … , number, size aerosol indirect effects on clouds change of cloud albedo, lifetime, ice crystal number, size
7. Aerosol • tiny, in air suspended particles • solid or liquid or mixture • in steady interaction with surrounding conditions Composition : • soot • dust • volcanic ash • metals • pollen • ammonia, sulfates, nitrates • other salts, water • organics • primary / secondary aerosol particle < 0.1 m  highest number particle < 1.0 m  highest surface particle > 1.0 m  highest mass particle 0.1 – 1.0 m  longest lifetime in atmosphere  if size, surface, or volume  different implications / radiation, health
8. search for Antarctic aerosol particles 60 km good visibility – pristine atmosphere
9. Instrumentation / Objectives ozone, sun radiation, UV amount particles total atmospheric column aerosol characterisation : number, size, mass, optical properties  influence of particles on climate  aerosol–cloud–precipitation interaction  climatology of UV-radiation  atmospheric ozone, ozone hole radiosonde balloon launches summer only and whole-year operation
10. Instruments in the shelter #1
11. Instruments in the shelter #2
12. Some Results
13. Gorodetskaya et al., 2013, JGR values from hourly means Temperature: minimum = –37.4 °C maximum = +4.0 °C mean = –18.2 °C mean relative humidiy: = 57 % (9 – 100 %) mean wind speed : = 5 m/s (0.1 to 26 m/s ) mean air pressure : = 827 hPa METEO multi-annual average Wind
14. total ozone and UV radiation example 14 December 2011  remainder of ozone hole above East-Antarctica  significant reduction of total ozone  Increase of UV-B radiation  UV index near 10  unprotected skin burned in minutes total ozone 14-Dec 2011 UV Index Utsteinen 14-Dec 2011 total ozone composite map 15-Sep 2014
15. aerosol total column properties total aerosol optical depth 2009 – 2014 data since Feb–2009 – only summer – Angström Exponent 440 – 870 nm all: 2.0 ± 0.7 intra-seasonal: 1.4 – 2.4 integrated water vapour / cm all : 0.14 ± 0.06 intra-seasonal: 0.12 – 0.18 Cimel sunphotometer CIMEL AOD Brewer AOD 340 nm
16. aerosol total mass and mass of light-absorbing aerosol seasonal total mass summer 1.5 ± 0.8 g/m3 ( 4 seasons ) autumn 1.4 ± 0.7 g/m3 ( 4 seasons ) winter 1.6 ± 0.8 g/m3 ( 1 season ) Seasonal soot/Black Carbon mass summer 9.2 ± 6.7 ng/m3 autumn 5.8 ± 4.6 ng/m3 winter 4.0 ± 3.9 ng/m3 Aethalometer TEOM-FDMS
17. aerosol optical properties – light absorption and scattering absorption coefficient increases exponentially from 370 – 880 nm Exponent: summer  1.5 ± 1.0 autumn  1.7 ± 1.3 winter  0.7 ± 0.8  not only pure soot as absorber ( soot would be ~1.0 ) combination absorption and scattering direct measurement of Single Scattering Albedo (SSA) SSA = Scattering / (Scattering + Absorption) 450 nm : 0.95 ± 0.7 525 nm : 0.96 ± 0.7 635 nm : 0.98 ± 0.8 nephelometer Aethalometer
18. aerosol total number concentration Ultrafine Condensation Particle Counter mean values particles/cm3 (Medians) November 469 ± 378 290 December 435 ± 448 271 January 365 ± 410 262 February 464 ± 386 370 March 439 ± 383 362 April 165 ± 103 121 May 92 ± 23 92 logarithmic scale ! season 2013/2014
19. example for detecting contamination – returning convoy from the coast 17 Dec 2012 spikes in number concentration
20. events with increased very small particles – new particle formation ? total aerosol number ( = CPC–number ) aerosol number > 90 nm ( = LAS–number ) aerosol number 3 – 90 nm ( = CPC – LAS)
21. critical diameter for cloud droplet activation combination aerosol number, size, CCN-conc  critical diameter for cloud droplet activation @ 0.5% SS  for time shown = 100–110 nm LAS CPC CCNc aerosol concentration 01 – 03 December 2013 mean concentration cloud nuclei water supersaturation %
22. Summary  in total 8 instruments installed at PE  5 aerosol instruments can operate during winter  however, only winter 2012 measured so far  aerosol instruments work well under Antarctic conditions  total ozone and UV observations for international databases  very low overall aerosol amount challenges instrumentation  particles << 1 μm dominate  derivation of optical parameters – careful QA needed  mass concentration light-absorbing aerosol differs by season  not only soot as absorbing aerosol  particle number shows seasonal cycle  several events with freshly formed particles – locally produced or entrained from upper troposphere
23. Outlook and additional instrumentation :  study events with new particle formation in more detail  aerosol type characterisation  study of aerosol cloud precip interaction  radiosonde balloon launches MoU between WSL (K. Steffen), RMI, IPF started season 2013/14  Cloud Condensation Nuclei counter summer only / from TROPOS Leipzig, Germany (Droplet Measurement Technol. Instrument) started season 2013/14, again 2014/15
24. Additional instrumentation / Plans :  Polarsondes experimental status / Prof. M. Hamilton, Univ. Adelaide, Australia / aim to distinguish liquid and ice phase of cloud first tests during 2014/15, together with radiosondes  feasibility study for filter sampling for aerosol chemistry  PANDORA multi-axis scattered sunlight measurements / lower tropospheric profiles of aerosol extinction coefficient, ozone, NO2 / total column ozone, NO2, AOD Partner Space Aeronomy Institute; probably from season 2015/16 on
25. Thank you very much