atmospheric composition modelling · 2018-04-04 · composition change/climate change/radiative...

Day4 - L5 Atmospheric modelling 2 Hennie Kelder 1

DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING

Atmospheric Composition Modelling

Peter van Velthoven

Overview

• Chemistry-transport modelling with TM(Transport Model )version4/5

• Stratosphere-troposphere interactions

• Air pollution modelling

QuantityVolume

Emissions ( X sources)

Deposition (X sinks)

Chemical transformation ( X sources and/or sinks)

Horizontal transport

Vertical transport

Height of the ABL

= Mixing ratio trace gas x, time evolution of Cx ?

Chemistry Transport Modelling, CTM

The TM chemistry transport modelTM4: global model,TM5: zoom option

• Coupled to ECMWF meteorology

• Information on wind, temperature, humidity, clouds, precipitation, convection

• Tropospheric chemistry module

• Aerosol module

• Parametrisation of convection

• Integrated stratosphere-troposphere chemistrymodule with detailed PSC microphysics

TM5: high resolution in regions of interest (zoom)

Background stratospheric ozone chemistry Chapman mechanismOzone formation:

O2 + hν O + O (λ < 240 nm)O + O2 + M O3 + M

fastM stabilizes excited O3 by collision

Ozone destruction

O3+ hν + M O2 + O + M (λ < 320nm) fast

O3 + O 2O2

Chemical familyOx= O+O3 is conserved

Background stratospheric ozone chemistryChapman mechanism

The sink given by the Chapman theory is too smallLife time Reaction constants O3 distribution

Background stratospheric ozone chemistry Catalytic ozone loss cycles

X + O3 XO + O2

O + XO O2 + X

------------------

Net: O + O3 2O2

X = Ox, NO, HO, Cl, or Br

Stratosphere-troposphere chemistry

IPCC/ACCENT scenario calculations

Year 2000 2030 IIASA CLE

2030 IIASA MFR

2030 SRES A2

Nitrogen dioxide, NO2

IPCC/ACCENT scenario calculations

Surface ozone

Composition change/climate change/radiative forcing

How is radiative forcing calculated?

Emission inventories

Observations + future scenariosEmission time series

Atmospheric Chemistry ModelAtmospheric model (GCM)

Concentration time series

Radiative-Convective Model

Radiative forcing

Surface temperature time series

Example: Climate sensitivity of ozone changes

∆T ≈ λ ∆F

It matters where greenhouse gas concentrations change !

Impact of aviation, shipping road traffic emissions on composition and climate

Chemistry transport modelling: parametrisation of convectionCoupling between convection and chemistry

JJA ozone Diagnosed convection

Ozone difference (%) Diagnosed-Archived convection

Differences up to ~20% !

Ph.D. thesis Olivié

Stratosphere-troposphere exchange from ERA40 • Chemistry-transport

Tropospheric ozone formation Oxidation of hydrocarbons and CO

CO + OH CO2 + HH + O2 + M HO2 + MHO2 + NO OH + NO2NO2 + hν NO + O ( λ < 420 nm)O + O2 + M O3 + M------------------Net: CO + 2O2 + hν O3+ CO2

NOx = NO+NO2 catalyses ozone production

[OH] determines the oxidation capacity of the atmosphere

Tropospheric ozone Detailed chemical budget

10%other10%OH + O3

40%HO2 + O3

40%H2O + O(1D)

Ozone loss

10%RO2 + NO (higher hydrocarbons)

20%CH3O2 + NO (methane)70%HO2 + NOContributionOzone production

Tropospheric chemistry-climate coupling: changes in oxidation capacity

Chemical reanalysis of OH based on ERA15 (1979-1993)Dentener et al. (2003)

Polar stratospheric ozone by assimilation in TM3 model

Troposphere: Troposphere: Air pollution modellingAir pollution modelling

AAirir--qualityquality forecastsforecasts and and observationsobservationsover the over the NetherlandsNetherlands

Satellite

Surface network

Assimilation

Air qualityprediction

absorptionabsorption

Satellite measurements: GOME, SCIAMACHY, OMI

Combined retrieval - modelling - assimilation approach to SCIA NO2

Slant column retrievalby BIRA-IASB

Tropospheric column retrieval by KNMIAccounting for:• Clouds• Surface albedo• Profile shape• Stratosphere• T-dep cross sections

Satellite versus ground-based measurementsO

Chimère model

Developed in FranceR. Vautard, H. Schmidt, L. Menut, M. Beekman, N. Blond, ... )Operational air-quality forecasts: http://www.prevair.org/

Model ingredients (setup at KNMI):• MELCHIOR chemistry (82 species, 333 reactions) • EMEP emissions• ECMWF meteorological analyses• 15 vertical layers, surface - 200 hPa• Boundary conditions on concentrations trace gases from global CTMMOZART monthly-mean climatology

SCIAMACHY vs. Chimère: yearly mean

Yearly-mean bias = 0.2 1015 molec cm-2, RMS 2.9, correl.coeff. 0.73Cloud-free pixels

SCIAMACHY vs. Chimère: 27 Feb 2004

OMI vs. Chimère

Chimère vs surface observations RIVM: Jan-Jul 2003

- surfaceobservation

- Chimère

Netherlands:(rural stations)Bias 0.1 ppbRMS 7.2 ppbCorrel. 0.66

Synergy: Surface - Chimère - SCIAMACHY

Smog event in the Netherlands: 24 June

Prediction withChimère model

Summary

• Overview of chemistry-transport modelling

• Stratospheric and tropospheric chemistry

• Air pollution modelling

atmospheric composition modelling · 2018-04-04 · composition change/climate change/radiative...

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