Scale Issues Atmospheric Modelling Urban Scale

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Cliquez pour modifier le style du titre Cliquez pour modifier le style des sous-titres du masque © Copyright Météo-France 1 Scale issues for atmospheric modelling at urban scale Valéry MASSON Centre National de Recherches Météorologiques 15 November 2017 ECMWF Workshop

Transcript of Scale Issues Atmospheric Modelling Urban Scale

Page 1: Scale Issues Atmospheric Modelling Urban Scale

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© Copyright Météo-France 1

Scale issues for atmospheric

modelling at urban scale

Valéry MASSON

Centre National de

Recherches Météorologiques

15 November 2017

ECMWF Workshop

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Cities & Climate

1st december 2015

IPCC synthesis report (2014):

In urban areas climate change is projected to increase risks for people, assets,

economies and ecosystems, including risks from heat stress, storms and extreme

precipitation, inland and coastal flooding, landslides, air pollution, drought, water

scarcity, sea level rise and storm surges (very high confidence)

)

.

• 2.7% of land areas

• 55% of world population

• 80% of GDP

(gross domestic product)

• 70% of Green-House Gases

emissions

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Cities & Climate

1st december 2015

World Weather Research Programme has 4 objectives, 2 related to urban:

1. High Impact Weather and its socioeconomic effect in the context of global change

Urban floods,

Heat & Pollution

in megacities, …

2.Urbanization:

Research & services for megacities

and large urban complexes

Several actions at international scale

Source: https://public.wmo.int

Source: Baklanov, WMO, (2015)

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Cities & Climate

1st december 2015

World Weather Research Programme has 4 objectives, 2 related to urban:

1. High Impact Weather and its socioeconomic effect in the context of global change

Urban floods,

Heat & Pollution

in megacities, …

2.Urbanizarion:

Research & services for megacities

and large urban complexes

scientific issues: […]

high-resolution modelling,

Grey zone, […]

Several actions at international scale

Source: https://public.wmo.int

Source: Baklanov, WMO, (2015)

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Scale issues for modelling at urban scale

1) Mesoscale-impacts on thunderstorms

2) Local-scale impacts: the Urban Heat Island

3) Modelling

4) Description of the cities for models: the « LCZ »

5) Which scale for adaptation strategies ?

ECMWF Workshop

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Scale issues for modelling at urban scale

1) Mesoscale-impacts on thunderstorms

2) Local-scale impacts: the Urban Heat Island

3) Modelling

4) Description of the cities for models: the « LCZ »

5) Which scale for adaptation strategies ?

ECMWF Workshop

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Meso-scale Impacts on Thunderstorms

1st december 2015

Source: Bornstein and Leroy (1985)

2 mains urban effects

Analysis of 2 summers

of convection above NYC

& enhancement

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Meso-scale Impacts on Thunderstorms: splitting

1st december 2015

The splitting effect is mainly due to the increased roughness.

Such effects are mostly studied in USA and China

This may be because megacities are prominent obstacles in flat regions

Source: Niyogi et al, 2006

1st december 2015

Observed radar reflectivity (dBz) from OKC radar

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1st december 2015

Meso-scale Impacts on Thunderstorms: enhancement

Source: WMO website

1st december 2015

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Meso-scale Impacts on Thunderstorms: enhancement

Cas study of 26 August 2011 of flash flood on Tokyo (TOMACS campaign)

Canadian model

GEM at 250m

with

urban scheme

without

urban scheme

Source: Bélair et al,

2015

1st december 2015

Radar

observations

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Meso-scale Impacts on Thunderstorms: enhancement

1st december 2015

Cas study of 26 August 2011 of flash flood on Tokyo (TOMACS campaign)

Source: Bélair et al,

2015

1st december 2015

Canadian model

GEM at 250m

with

urban scheme

Radar

observations

GEM at 2.5km GEM at 1km

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Scale issues for modelling at urban scale

1) Mesoscale-impacts on thunderstorms

2) Local-scale impacts: the Urban Heat Island

3) Modelling

4) Description of the cities for models: the « LCZ »

5) Which scale for adaptation strategies ?

ECMWF Workshop

Page 13: Scale Issues Atmospheric Modelling Urban Scale

1st december 2015 © Copyright Météo-France

Urban Heat Island (UHI)

One summer night in Toulouse (using measurements from 20 met stations)

14°C

20°C17°C

Source: J. Hidalgo

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Modification of the Surface Energy Balance

Source: Nunez & Oke, 1976

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Modification of the Surface Energy Balance

1st december 2015

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1st december 2015 © Copyright Météo-France

Modification of the Surface Energy Balance

Surface Energy Balance, Singapore

Source: Roth et al, 20152015

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Scale issues for modelling at urban scale

1) Mesoscale-impacts on thunderstorms

2) Local-scale impacts: the Urban Heat Island

3) Modelling

4) Description of the cities for models: the « LCZ »

5) Which scale for adaptation strategies ?

ECMWF Workshop

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1st december 2015 © Copyright Météo-France

The old modelling way: rocks !

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The Urban Canopy Models (UCM)

1st december 2015

Oke et al (2017), Krayenoff (2017)

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The Urban Canopy Models (UCM)

1st december 2015

Oke et al (2017), Krayenoff (2017)

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Key physical processes of urban climate

3D surface (street canyon)

Radiative exchanges between walls & roads

Heat Fluxes, Water & Snow, Friction

Allows simulation of :

• Impact on Boundary Layer

• Street micro-climate

• Urban Heat Island

Coupled in many meteorological models

The Town Energy Balance (TEB) model

Modelling the Surface Energy Balance: TEB

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• Energy consumption of buildings

1) Building Energy Module

Wintertime building’s

energy consumption

in Toulouse, France

(Bueno et al 2012, Pigeon et al 2014, Schoetter et al 2017)

Modelling the Surface Energy Balance: TEB

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• Energy consumption of buildings

2) Surface Boundary Layer scheme

3) Three types of Urban vegetation

• Gardens, Street trees, green roofs

1) Building Energy Module

Modelling the Surface Energy Balance: TEB

Validation on Basel

(BUBBLE experiment)

Hamdi and Masson 2008

Lemonsu et al 2012, De Munck et al 2013,

Redon et al 2017

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CO2 fluxes in cities

Simulated Buildings + vegetation CO2 fluxes

4) Exemple of applications

(Goret et al 2018 in prep.)

(TEB)

wintertime, 2005

Modelling the Surface Energy Balance: TEB

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Modelling the Surface Energy Balance: TEB

1st december 2015

UHI simulation in Toulouse (France)

MesoNH model, 250m of resolution

average UHI on 2004 summer

Cloudy days Sunny days

Source: R. Schoetter

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Scale issues for modelling at urban scale

1) Mesoscale-impacts on thunderstorms

2) Local-scale impacts: the Urban Heat Island

3) Modelling

4) Description of the cities for models: the « LCZ »

5) Which scale for adaptation strategies ?

ECMWF Workshop

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Description of cities: the « Local Climate Zones »

Tombouctou,Mali

From: Steward and Oke (2012)

A typology :-recognized by the Urban Climate community

-10 urban classes

-Link with atmospheric models being developed

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World Urban Database initiative

Tombouctou,Mali

A methodology to map cities:-Using satellite images

-100m of resolution

-Produces LCZ maps by local experts

-Approx. 100 cities

www.wudapt.org

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From Buildings data, e.g. Open Street Map

Determination of model urban parameters from building’s databases

1st december 2015

Urban parameters from OSM

Source: Samsonov et al (2015)

LCZ from French Building’s Database

Source: Hidalgo et al (2017)

Moscow

Paris

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Architecture varies from one location to another

At world scale )

Architecture

for mid-rise

buildings

Seattle Copenhagen

Andalousia

Tombouctou,Mali

Quito, EquadorShanghai

Scale issues in

building’s description

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Architecture

for houses

Seattle

Copenhagen

Andalousia

Tombouctou,Mali

Quito, Equador

Shanghai

At world scale )

Architecture varies from one location to another

Scale issues in

building’s description

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Scale issues for modelling at urban scale

1) Mesoscale-impacts on thunderstorms

2) Local-scale impacts: the Urban Heat Island

3) Modelling

4) Description of the cities for models: the « LCZ »

5) Which scale for adaptation strategies ?

ECMWF Workshop

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What scale urban planners wish

• In order to do the link with urban planners and stake holders

– The pertinent spatial scale is …

City of Nantes

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What scale urban planners wish

• In order to do the link with urban planners and stake holders

– The pertinent spatial scale is … the urban block !!!

City of Nantes

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Adaptation of cities to climate change

In 2100, air-conditioning will probably be necessary

Air-conditioning

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1st december 2015

Adaptation of cities to climate change

In 2100, air-conditioning will probably be necessary

With projected air-conditioning(by 2030)

Without cooling

Source : de Munck et al 2013

+2°C

Temp

érature n

octu

rne (°C

)

33

32

31

30

29

28

27

26

25

Air conditioning increases heat outsideNeeds even more cooling !Impacts people without access to air-conditioning

Air-conditioning

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1st december 2015

Adaptation of cities to climate change

In 2100, air-conditioning will probably be necessary

But one can reduce its use !

Air-conditioning Heat waveEmergency practices

Buildings renovation

Urban Vegetation,

water ressources

Urban planning

• Levers that combine mitigation and adaptation

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1st december 2015

Adaptation of cities to climate change

In 2100, air-conditioning will probably be necessary

But one can reduce its use !

Air-conditioning Heat waveEmergency practices

Buildings renovation

Urban Vegetation,

water ressources

Urban planning

• Levers that combine mitigation and adaptation

Comportements et usages

• Evolution of behaviours : very efficient

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1st december 2015

Urban vegetation

Green roofs contribute to building insulation

Ground vegetation and trees are efficient to cool the air

Variation de température

Variation of temperature caused by an increase of 50%

of ground vegetation in available spaces (car parks, sidewalks, places,...)

Source : de Munck 2015

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Grand Paris (Groupe Descartes)

2008

~ 4°C

2030

~ 2°C

Scenario: Local vegetable farming around the city Short supply chains & food governance Cooling of 2 to 3°C

Source : Yves Lion et coll. 2009

The countryside can cool the city

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1st december 2015

Urban Climate Modelling … only starting

Kusaka et al 2012

August Tmin

2000s

August Tmin

2070s

1 month 3km-resolution simulation in

present and future climate in Japan

Need of downscalling methods

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1st december 2015

Urban Climate Modelling … only starting

Kusaka et al 2012

August Tmin

2000s

August Tmin

2070s

1 month 3km-resolution simulation in

present and future climate in Japan

Hamdi et al, 2014

Climate

simulation

at 4km

Downscalling

at 1km

Brussels

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Conclusions

1) Urban scale is meteorologically is at least in the greyzone

2) Specific processes and impacts

3) The city actors want very fine scale …

… even for weather forecast !

ECMWF Workshop

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Urban Weather Forecast

• Weather Forecast during the PAN-American games (Toronto 2015)

Simulations at 250m of resolution

Source: Leroyer et al 2015

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Urban Weather Forecast

•Forecast during the PAN-American games (Toronto 2015)

Source: Leroyer et al 2015

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ECMWF Workshop

Thank

You