165871 dispersion conditions in complex terrain - a case study of the january 2010 air pollution...

165871

Dispersion conditions in complex terrain - a case study of the January 2010 air pollution

episode in Norway

Viel Ødegaard

Norwegian Meteorological Institute

Aftenposten

Viel Ødegaard, Norwegian Meteorological Institute met.no

Viel Ødegaard, Norwegian Meteorological Institute met.no

Viel Ødegaard, Norwegian Meteorological Institute met.no

Viel Ødegaard, Norwegian Meteorological Institute met.no

Viel Ødegaard, Norwegian Meteorological Institute met.no

Viel Ødegaard, Norwegian Meteorological Institute met.no

Viel Ødegaard, Norwegian Meteorological Institute met.no

Temperature at different elevations

Viel Ødegaard, Norwegian Meteorological Institute met.no

Near surface temperature gradient observations

Viel Ødegaard, Norwegian Meteorological Institute met.no

10 m wind, observed

Viel Ødegaard, Norwegian Meteorological Institute met.no

Operational air quality forecasting• UK Met Office Unified Model

– 1 km horizontal resolution

– 38 vertical levels, lowest level wind 10 m, T and q 20 m

– Non-hydrostatic

– 9 surface tiles, urban: rough concrete approach

– Convection and orographic roughness parameterizations turned off

– Experimental runs with 0.33 km horizontal resolution

• dispersion model and emission data base (AirQUIS)• Offline

– hourly data on 10 model levels: u,v,T,q

– Tsurf, clouds, precipitation, fluxes, BL height

• daily forecasts for day 2 during winter months

Viel Ødegaard, Norwegian Meteorological Institute met.no

Surface energy balance

Viel Ødegaard, Norwegian Meteorological Institute met.no

Viel Ødegaard, Norwegian Meteorological Institute met.no

Viel Ødegaard, Norwegian Meteorological Institute met.no

Viel Ødegaard, Norwegian Meteorological Institute met.no

Model temperature profiles (UM 1km)

Viel Ødegaard, Norwegian Meteorological Institute met.no

Oslo

Bergen

Comparing temperature in the free atmosphere with 2m temperature at same elevation

Viel Ødegaard, Norwegian Meteorological Institute met.no

Model near surface inversion

Viel Ødegaard, Norwegian Meteorological Institute met.no

2d trajectorieslowest level

Viel Ødegaard, Norwegian Meteorological Institute met.no

2d trajectorieslowest level

Viel Ødegaard, Norwegian Meteorological Institute met.no

2d trajectorieslowest level

Viel Ødegaard, Norwegian Meteorological Institute met.no

10 m wind

Viel Ødegaard, Norwegian Meteorological Institute met.no

Lowest level wind speed blue: > 2 m/s red: < 2 m/s

1 kmresolution

0.33 kmresolution

Viel Ødegaard, Norwegian Meteorological Institute met.no

Summary• Observing

– Large scale persistent ridge/high pressure

– Strong near surface inversion confined to level below 8 (10) m

– Large temperature increase from low to high elevated stations

– Low wind speed

– Significant local variations in wind speed and direction with the same large scale forcing

• Successfully modeling– Inversion evolution

– Drainage flow

– Recirculation

– Local wind variations provided high enough resolution

Viel Ødegaard, Norwegian Meteorological Institute met.no

Thank you for your attention

Acknowledgement to Leiv Håvard Slørdal at the Norwegian Institute for Air Research