Aerosols and their relevance

to forecasts by the Hungarian Meteorological Service

Tamás Tóth

Hungarian Meteorological Service

Phone: +36 62/624-042

E-mail: toth.t@met.hu

Aerosols

Def. : dispersion of the solid and liquid particles suspended in gas.

source: http://my.opera.com/nielsol/blog/2008/11/11/atmospheric-dust-aerosols

Incidence: everywhere in the atmosphere

- Three types on basis of diameter:• Nuclei mode: particle size < 0.1 μm• Accumulation mode: 0.1 μm < p.s.< 2.5 μm• Coarse-particle mode: particle size > 2.5 μm

-Natural and antropogenic sources

-Most important effect: direct and indirect influences for the Earth’s radiation budget

Aerosols: natural sources

Source: http://climatechange.wikispaces.com/5.+Aerosols

Primary: continuously emit

- Soil dust - Sea salt - volcanic ash - botanical debris

Secondary particles are formed by chemical reaction in the air:-Volatile Organic Compounds such as monoterpenes

Antropogenic aerosols

Concentrate in industrial areas (mainly in the Northern Hemisphere)

Most important: sulphates originating from the burning of coal and oil

Nitrogen-oxides from transportation

CFCs originating from sprays, fridges

source: http://climatechange.wikispaces.com/5.+Aerosols http://climatechange.wikispaces.com/5.+Aerosols

Health effects

The atmospheric aerosol has significant influences on our health. They can cause reduced lung functions, increased respiratory symptoms, cardiovascular diseases, irritants for eyes, etc.Small particles can enter in the deeper parts of the lung (alveoli), where the transfer of O2 and CO2 take place.

Climatological effects

Source: http://suzaku.eorc.jaxa.jp/GCOM_C/w_gcomc/temp_f1.html

Climatological effects 2

http://wattsupwiththat.com/2010/12/29/prediction-is-hard-especially-of-the-future/

Sources: http://benvironment.org.uk/post/8217302379/pinatubo

Mt. Pinatubo: major eruption in 1991

Droplets of sulfuric acid are spread in the stratosphere by the wind.

They reflect sunlight, reducing solar energy.

At least 0.2-0.3 degrees cooling for years.

How can the Hungarian Meteorological Service use aerosol forecasts?

Hungarian „speciality”

• Hungary : problem with air pollution in winter, especially PM10 (aerial dust)

• Cold air pad situation: foggy and misty weather with low level clouds (stratus)

• Forecast: weather prediction models usually indicate clear conditions

• Reality: may be totally different – fog and durable low level clouds

First day

After a cold front: cold air settles

Very low temperature at night with strong ground radiation up to space

Developing low-level

inversion

Lack of upstreams

Thickness of boundary layer is absolutely 0!

Later

Stratiform clouds gradually cover the whole Carpathian Basin.

The top of this cloudmass is usually at 600-1000 metres, sometimes at 1500 metres.

Highest peaks tower above the stratus

The inversion layer is slowly lifting; coldest place near the cloud top

Experiences above the clouds

Low-polluted air

Sunny and at least 5-8 degrees warmer conditions

Very dry air (relative humidity 10-20%), high visibility

Spectacular landscape with ”sea of clouds”

Suffering in the plains

Source: http://owww.met.hu/pages/20111120_szmoghelyzet_november/

• High concentrations of polluting materials • Foggy or misty air

• The sky is overcast

• Low temperature

• Little diurnal temperature variation

• Increasing number of asthma and lung diseases

Is it forecastable?

Although weather prediction models are usually unable to forecast the amount of low level clouds, the inversion layer will usually indicate it. Forecasters’ experiences can help recognizing similar synoptic situations in time, and the developing cold air pad is usually predicted successfully. We usually measure the highest concentration of air pollution in the beginning of similar periods.

CHIMERE model

• Time step: 1-hour

• Prediction system for CO2, NOx, O3, PM10 conc. variability

• The concentration values are strongly influenced by weather

• The weather parameters come from WRF limited area model

• On the other hand, we know the emission sources, (power plants, factories, transportation)

• The model calculates estimated emission data (based on early measured average data), and average daily transportation conditions.