Alpine Summer School 25 June 2013 Angela Marinoni. Aerosol particles and mountain regions

Transcription

1 Alpine Summer School 25 June 2013 Angela Marinoni Aerosol particles and mountain regions

2 The mountain regions has gained growing attention due to its significant role in global atmospheric circulation and its sensitivity for providing a first indication of climate changes, and thus is vital for a better understanding of global climate and environmental changes and their impacts and interactions to human activities. MOUNTAINS: BAROMETERS OF CLIMATE CHANGE Mountains are barometers of climate change. As the world heats up, mountain glaciers the source of water for many of the world s river systems and people are melting at unprecedented rates, while rare plants and animals struggle to survive over ever diminishing areas. Mountain people, already among the world s most disadvantaged, face greater hardships. Understanding how climate change affects mountains, and learning how to manage and mitigate any negative effects, is vital for all of us, wherever we live. FAO focus on mountains by J Ross and T Hofer

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7 BC deposition on snow/ice surfaces Deposition of black carbon is a major driver of glacial retreat in the Hindu-Kush- Himalaya-Tibetan region (ABC Regional assessment, 2008). Ramanathan and Carmichael report that the impact of BC on melting snow and glaciers may equal the impact of increased atmospheric CO 2. Flanner et al (2007) estimated that BC-induced reduction of snow albedo is a major forcing term (about 20 W m-2) in the Tibetan side of the Himalayas. Starting from BC concentrations at NCO-P in pre-monsoon season we estimate: µg Kg -1 BC snow concentration % snow albedo reduction mm (we) runoff increase from a typical Tibetan glacier equal to 24 % of the seasonal runoff [Yasunari et al., ACP, 2010]

8 What is black carbon? Black carbon is a particulate aerosol resulting from the incomplete combustion of fossil fuels, biomass and biofuels. It is emitted from both anthropogenic and natural sources. It consists of pure carbon in several linked forms. Aerosols in the atmosphere scatter and/or absorb sunlight, cooling or warming the atmosphere accordingly. BC is the most efficient aerosol in warming the atmosphere Courtesy of Dennis Clare Radiative Forcing (W/m 2 )

9 How changed BC emissions? Source: Bond et al, 2007 Source: Ramanathan et al, 2008 In Asia (China, India) coal and biomass burning emit the majority of black carbon, with diesel vehicles contributing in a smaller proportion, while in USA and Europe diesel vehicles and use of fossil fuels are the most important source of black carbon.

10 BC can reduce the radiation at surface The aerosols in ABCs reduce the amount of solar radiation reaching the surface and such reduction can decrease crop productivity Estimated vertical temperature profile for the period due to greenhouse gases and sulphate aerosols (CO2+SO4 curve) and that due to the addition of ABCs to CO2+SO4 (ABC+CO2+SO4) (Source: Ramanathan and others 2007).

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12 Global Atmospheric Watch It is a program of the World Meteorological Organization Mondiale for evaluating the health conditions of the atmosphere with the aim to support correct environmental interventions.

13 The Global Atmosphere Watch (GAW) programme take place in 1989 with the aims: to monitor background conditions of the atmosphere, to evaluate pollution transport, to study pollutants trend, to study climate environemnt interactions High altitude stations

14 ountain ridges can represent a source of particles in the free troposphere Stratospheric intrusions, free troposphere transports Long-range transport Free Troposphere Planetary Boundary Layer Emissions (ABC) Local and regional scales

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16 Mt. Cimone O. Vittori Station 44.1N, 10.4E; 2165 m asl Mt. Everest NCO-Pyramid 27.9N, 86.7E; 5079 m asl 4/2009

17 Surface Ozone GreenHouse Gaese (CO 2, CH 4, N 2 O, SF 6 ) Black Carbon Measurements performed Aerosol size distribution (10nm to 20µm) Aerosol Mass (PM10) Halocarbons (CFC, HFC, HCFC,...) Natural Radioactivity (Be 7, Pb 210, Rn 222 ) Meteorological Parameters Aerosol Chemistry at Mt. Cimone Station Aerobiology (pollen and spores)

18 Khumbu Valley (Nepal), at 5079 m a.s.l. not far from the Italian Pyramid Observatory Lat. N 27 57' Lon. E 86 48' Altitude: 5079 m asl

19 Atmospheric background conditions and tropospheric composition can profitably be studied by means of continuous monitoring activities at High Mountain Stations that provide unique opportunities to detect and analyses global change processes Himalaya (Nepal) April 2009 Atmospheric Brown Clouds Po Valley (Italy) Black Summer 2006 Carbon Mt.Cimone NCO-P

20 ng m black carbon diurnal variations PRE-MONSOON MONSOON POST-MONSOON DRY Vy (m/s) Monsoon Pre-monsoon Post-monsoon Dry season [Bonasoni et al., 0 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 UTC + 4:45 [Marinoni et al., 2010]

21 NCO-P: Wildfires in South Asia (April 2009) High pollution can reach the high Himalayan region, in particular during pre-monsoon season carrying high concentrations of atmospheric pollutants Photo: Khumbu Valley, April /2009

22 Forest Fire Hot Spots April 24-25, 2009 Fire had spread to at least four high altitude protected areas, including Annapurna, Kanchanjunga, Langtang and Makalu Barun national parks for an unusually long period, (Department of National Parks and Wildlife Conservation) NCO-P, Khumbu Valley, April fire Incidents in Nepal on April 25

23 NCO-P: fires in South Asia (April 2010)

24 ng m -3 ACUTE POLLUTION EPISODE OF APRIL 2010 ng m L evoglucosan 0 22/03/10 23/03/10 24/03/10 25/03/10 26/03/10 27/03/10 28/03/10 29/03/10 30/03/10 31/03/10 01/04/10 02/04/10 03/04/10 04/04/10 05/04/10 06/04/10 07/04/10 08/04/10 09/04/10 10/04/10

25 APRIL, NCO-P webcam images 10:46 NST 16:46 NST

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27 Nucleation Event : 24 February 2006 Locally >5000 part. cm -3 Linked to windslope 4 h Takes place after decrease on condensational sink Not seen in Mass (BC or PM) Peak of nanoparticles takes place before accumulation mode - 4h delay- Not always «banana» shaped: spatial extention of nucleation event.

28 DIameter (nm) Daily variability of particle size distribution High CN conc. locally (over 5000 # cm -3 ) Dry season 25-50%RH Monsoon 84-98%RH Ultrafine particles appear with frequency 0.5 (up to 0.8 in July) Post-Monsoon 25-45%RH Pre-Monsoon 45-85%RH Local time (UTC + 4:45) Nucleation event control the free tropospheric background? Which are the precursor? [Sellegri et al., ACP, 2010] [Venzac et al., PNAS, 2009]

29 Evidence of high pollution event in the Himalaya during summer monsoon break Nepal Climate Observatory Pyramid, June 2006 Long-range transport of dust and pollution during Monsoon break Surface ozone, black carbon

30 NAINITAL Coarse, fine particles NCO-P Coarse, fine particles mg m chemical composition PM10 crustal matter Inorganic Cations Cl organic anions SO4 NO3 NH4 WSOM WINSOM night afternoon afternoon night afternoon Days of June

31 mm Northern - Southern Himalaya stations: DAILY RAINFALL June-July Xigaze Tingri Lhasa NCO-P /06/ /06/ /06/ /06/ /06/ /06/ /06/ /06/ /07/ /07/ /07/ /07/ /07/ /07/ /07/ /07/2006