Presentation on theme: "Applications of meteorology and climatology to volcanic ash disruption Julian Hunt University College, London University of Cambridge TU Delft House of."— Presentation transcript:
Applications of meteorology and climatology to volcanic ash disruption Julian Hunt University College, London University of Cambridge TU Delft House of Lords Met. Background ; warnings ; institutional arrangements ; future concerns/possibilities /proposals
Volcanic plumes Height depends on speed, size, temp of eruption ie Fb(but not v sensitive) and background stability of atmos N (H~F\(1/4). N\(-3/4) ~ 10km +/-) -also verified by nuclear explosions (ie Fb can be unsteady). Depth of plume much less than H –contains most of the eruption.; plume moves with wind U(z), z=H. But if Fb varies -> variation of H-> plume spread over wider area, and greater depth since U varies with (z). Plume physics; lightning induced in plume cloud-detected remotely (Met office atd-on web) ; Plume cloud spreads by mean flow gradients dU/dz and turbulence cloud affects radiation, temp, turbulence, precip. (regional effects on crops -1780s;Pinatubo reduces global temp by 0.2 deg for about 2 years -1992)
Zones in the atmosphere Upper atmosphere –above 10km Ionosphere, mesosphere- electrical signals ; waves ( as induced by convection in some equakes/volcanoes – Russian research-Maths Today june 2010) Stratosphere (10-100km)-stable, weak turbulence, thin clouds-particles carried around the world-long range aircraft -high vol. plumes (ozone hole dynamics and chemistry) Troposphere –below tropopause at 10km Mixture of stable /convective/cloud motions 10km- 1000km -particles carried over continental scale,-typical volc plumes – short range aircraft -in relation to height of volcanic plumes
Long range dispersion –depending on synoptic conditions (Maryon/Buckland studies 1995) Particles carried by wind at different heights leads to spreading, but v slow dry deposition. -in usual westerly winds volc.(also chimneys/fires) plumes are as deep as the initial plume and carried within weather patterns- (1000km) ->deposition at fronts( if plume is in troposphere). -in blocked flows (easterly winds over europe ) plumes travel slowly and recirculate (eg Chernobyl; Iceland )-can thicken with convection -can preclude aircraft paths around/under plume.
Cloud patterns related to synoptic weather structures Note that dust moves through similar structures –mixing and deposition near fronts –where clouds swirl.
Forecasts of dispersion Overall plume forecast -Requires accuracy at all levels of plume; * accuracy needed where flow patterns change –esp from/to deep blocking. (note 5-10 days possible – but timing may be in error) * cloud/dispersion processes have to be modelled ( note detailed simulations on Jap earth sim.)
Typical storm event for NW Europe – plus NS pressure gradient (NAO <0)
Images from the Houze Cloud Atlas http://www.atmos.washington.edu/gcg/Atlas/ Clouds and Climate Low clouds reflect sunlight trap little infra-red radiation High thin clouds reflect less sunlight trap more infra-red radiation High deep clouds.reflect and trap infra red connections between particles, clouds, rain are critical for climate V small particles can cause v small droplets & clouds, but no rain -observed in urban areas; may be significant for cosmic ray(XT) particles Note low sun spots -> less XT particles ; variable rain (1600 -1750)
Small scale structure (1-10mm) of turb eddies –now revealed on Jap Earth Simulator. Tiny Vortices within thin shear layers -> possibility of modelling cloud droplets and effects of dust particles etc (collab europe- japan)
1. Emission Agencies (IAVCE for volcanoes; IAEA for nuclear ; regional/national for pollutants/ forest fires) 2. Atmospheric agencies for dispersion, deposition, chemical transformation (WMO + ICSU(?), national met services) 3. Agencies for impacts (ICAO for air traffic; WHO –health, FAO ag/forestry etc IAEA for radio active ) International warning systems for effects of large emissions into the atmosphere.
Operation of warning systems 1. agreement between emissions/atm/impacts agencies ;(eg Iavce, wmo, icao; wmo, iaea in 1990s) 2. Regular testing of communications and operation of systems (eg nat met serv comparing test cases)- the volcanic ash incidents since 1990s had been handled ; and air traffic adjusted to warnings. 3. Also testing needed to include systems and Interests affected by large emissions- this situation –For the 2010 Iceland volcano this had not been done (Note operational and risk analyses of such a complex system - needs to be done in future GSDP) 4. Note that with bigger impact events greater interest in higher risk operations, eg aircraft moving around ash clouds-is the forecasting good enough?
SCHEMATIC DIAGRAM OF CLIMATE CHANGE PROCESSES Less snow/ice -> more volcanoes?
Conclusions and recommendations Development in volcano warning and monitoring world wide (new/open multi-disciplinary technology –satellites/sferics/elec fields) -+Russia-Jap Forecasts improving-but better physics needed esp in cloud processes (+jap es) More effective use of data and forecasts for operations and for risks –complex system methods needed.(GSDP project –needs to be part of international control/planning system)- Note some scientific and operational similarities for different large atmospheric emission problems. Governments and research agencies should collaborate more closely with the UN agencies –often ignored-> duplication (EU/EC needs new mechanisms for its projects to integrate with UN operations /programs).