Efeitos das partículas de aerossóis no sistema climático Paulo Artaxo Instituto de Física, Universidade de São Paulo

Transcrição

1 Programa FAPESP de mudanças globais 28/Agosto/2008 Efeitos das partículas de aerossóis no sistema climático Paulo Artaxo Instituto de Física, Universidade de São Paulo

2 Processos físicos e químicos que regulam a composição da atmosfera

3 Efeitos climáticos de partículas de aerossóis I) Efeitos diretos (i.e., não envolvendo nuvens) a) Reflexão de radiação solar ao espaço aumenta o albedo resfriamento II) Efeitos indiretos dos aerossóis Cada gota de nuvem precisa de um núcleo de condensação (CCN) para ser formada Para uma dada nuvem, mais CCN mais gotículas de nuvens Como a quantidade de água é limitada, isso significa menores gotas de nuvens IIc) Efeito dos aerossóis na termodinâmica atmosférica e na dinâmica da convecção. Nuvens rasas com gotículas líquidas trocadas por nuvens altas com gelo.

4 Nuvens e Chuva são feitos de 3 ingredientes básicos: vapor de água Partícula de aerossol que age como núcleo de condensação de nuvens Condições termodinâmicas da atmosfera Processos altamente não lineares e complexos

5 Forçantes radiativas do sistema climático global

6 Estimates of the aerosol direct radiative forcing by 20 models at 4AR IPCC 2007 Best estimate: -0.5 W/m 2 Range: -0.9 to -0.1 W/m 2

7 Estimates of the Cloud Albedo radiative forcing due to aerosols from different models Best estimate: -0.7 W/m 2 Range: -1.8 to -0.3 W/m 2

8 Forçante radiativa da combinação de todos os efeitos antropogênicos O que será feito a esta componente é critico à forçante final IPCC 2007

9 Temperature change simulated by a climate model for the period with strong or weak aerosol effect Andreae et al., Nature (2005)

10 Balanço de radiação terrestre

11 Aerosol global distribution Aerosol optical depth (0.44 m) AERONET and Hadley model Winter Summer

12 The Large Scale Biosphere Atmosphere Experiment in Amazonia - LBA Water (in clouds and biosphere) Aerosols (and trace gases) Anthropogenic activities Nutrients (P, N, K, others) Carbon Nitrogen (Vegetation and soil)

13 Natural biogenic aerosol particles EPMA photos from Gunther Helas, MPIC

14 Produção natural de CCN na Amazônia Isoprene 2-methilthertiol (From Clayes et al., Science 2004) Fungal hyphae 1) 2) 3) 4) Primary biogenic particles acting as Giant CCN Secondary organic aerosol from terpenes, isoprene, and others Soil dust (very little) Sulfates and nitrates (low contribution)

15 Amazonia in the aerosol world Andreae et al., 2008

16 Medidas de longo prazo de aerossóis na Amazônia Melina Paixao

17 Fogo e queimadas

18 Razões para o desmatamento

19 77/88* 88/89 89/90 90/91 91/92 92/94 94/95 95/96 96/97 97/98 98/99 99/00 00/01 01/02 02/03 03/04 04/05 05/06 06/07 07/08 Deforestation (km² per year) Deforestation in Amazonia in km² per year * média annual da década Dados do INPE, 2008

20 The most important air pollution issue in South America is associated to the continental scale biomass burning during the dry season. With several hundred of thousands of fires each year Severe health effects on the population Climate effects Weather effects Large scale aerosol distribution: strong effects on the direct radiation balance and cloud formation

21 Regional haze problem is increasing around the globe Haze over Ganges - Brahmaputra plain

22 Beijing China

23 Absorção e espalhamento de radiação por aerossóis de queimadas Scattering (Cooling) Absorption (Atmospheric Warming) Absorption (Column Warming) Cloud Evaporation (Warming) Cloud Seeding (Cooling) Dimming of Surface Surface Cooling Suppression of Rain; increase of life time. Cooling; Vertical redistribution of latent and radiative heating

24 Radiative forcing (W/m 2 ) aot (500 nm) Aerosol surface forcing in Rondonia AEROSOL SURFACE FORCING - Rondonia AEROSOL FORCING AOT Jan Apr Jul Oct-99 5-Feb May Aug-00 1-Dec Mar Jun Sep-01 5-Jan Apr Jul-02 1-Nov Aline Procópio, GRL 2006

25 Amazonia Average aerosol forcing clear sky Top: - 10 w/m² INDOEX average aerosol forcing clear sky Top: w/m² Atmosphere: + 28 w/m² Atmosphere: w/m² Surface: - 38 w/m² Conditions: surface: forest vegetation AOT ( =0.95 at 500nm); 24 hour average 7 years (93-95, dry season Aug-Oct) Surface: w/m² Conditions: surface: ocean AOT ( =0.3 at 630 nm); 24 hour average Jan-Mar 99 Procópio et al. (2005)

26 Aerosol Optical Thickness 550 nm Solar Radiation at surface (W m -2 ) Continental scale effects Karla Longo and Saulo Freitas (INPE)

27 Aerosol effects on the Net Plant Productivity CO 2 Concentration + + Photosynthesis + Temperature +? Aerosol Concentration BVOC emissions Kulmala et al., 2004

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29 NEE (µmolm -2 s -1 ) Efeitos significativos de aerossóis na produtividade primária da floresta amazônica Forest site, year: Solar zenith angle:10-30 degrees Dry Season - NEE increase: 46 % -10 Wet Season - NEE increase: 24 % Aumento de aerossóis Relative Irradiance

30 Potential annual forest Net Ecosystem Exchange (NEE) in the Amazon region Malhi & Kruijt

31 Aerosol-cloud-precipitation feedbacks AEROSOLS CCN Activation Ice Nuclei Activation Cloud/Aerosol Radiative Transfer Cloud Microphysics Cloud Dynamics PRECIPITATION Aerosol Wet Removal

32 Crystal shattering * Crystal collection * * * * * Evaporation Aerosol particles, cloud condensation nuclei and precipitation Coalescence Diffusion SO 4 - Collection SO 2 Nucleation Aerosols Soluble: Nitrates, DON, NH 3, NH 4+, etc

33 Hydrological cycle critical for Amazonia. Variety of cloud structure caused by different CCN amounts and other cloud dynamic issues Pyrocumulus Clouds Green Ocean Clouds

34 Addition of pyrogenic CCN has pronounced impact on cloud droplet size spectra Four aerosol regimes of: (A) Blue Ocean,(B) Green Ocean, (C) Smoky clouds, (D) Pyro-clouds Note that the narrowing of CDSD and the slowing of its rate of broadening with height for the progressively more aerosol rich regimes from A to D. Andreae et al., 2005

35 Large scale low cloud suppression by biomass burning aerosols Terra and Aqua satellite images of the east Amazon basin, 11 August (A) The clouds (Terra, 10:00 local time) are beginning to form. (B) The clouds (Aqua, 13:00 local time) are fully developed and cover the whole Amazon forest except for the smoke area. The boundary between forest and Cerrado region is marked in white on both images, and the seashore is marked in green. (From Ilan et al., Science March 2004)

36 Suppression of low cloud formation by aerosols in Amazonia. (from Koren and Kaufman, 2003) Cloud fraction as function of aerosol optical depth (OD). The cloud fraction decreases almost linearly with increasing OD. The red and blue curves denote the average of east and west areas, respectively. On average, the cloud fraction decreases to less than 1/8 of the cloud fraction in clean conditions when OD = 1. The shaded area represents the relative area covered by the respective OD, with the integral of this curve equal to one, representing the total Amazon basin

37 Relationships between cloud properties and aerosol loading in Amazonia Left cloud top pressure (P) vs. AOD. Lower P may indicate taller convective clouds that reach to higher levels of the atmosphere. Right cloud fraction vs. AOD. The upper row is for all data and the lower row is for data restricted to cloud fraction less than half. Cloud fraction <50% Microphysics absorption effects Ilan Koren et al., Science 2008

38 Dependence of CCN activation on organic mass fraction Sulfur at a level of ng/m³) AMAZE data from Artaxo, Sachin Gunthe, Scot Martin and Qi Chen

39 Deforestation increase or decrease precipitation? It depends on the scale.

40 Precipitation formation The effect of aerosol particles in the vertical profile of cloud droplets size, phase, and precipitation High aerosol Low aerosol

41 Nature, 2008 Predicted change in the probability of a 2005-like drought in Amazonia, based on results from the HadCM3LC GCM run with aerosols. a, probability versus year; b, probability versus simulated CO2 concentration. Simulations for the twenty-first century show a strong tendency for the SST conditions associated with the 2005 drought to become much more common, owing to continuing reductions in reflective aerosol pollution in the northern hemisphere.

42 São Paulo 06 de setembro de 2004

43 Campo Grande 15 de setembro de 2004

44 São Paulo 15 de setembro de 2004

45 Efeitos radiativos dos aerossóis em São Paulo

46 Obrigado pela atenção!!!

47 Relationships between cloud properties and aerosol loading in Amazonia Conceptual model of microphysics (MP) and absorption effects on cloud fraction for 3 saturation/initial cloud fractions Cf 0. Ilan Koren et al., Science 2008