(sga / m&d / mpi-m) dewek 2008, bremen 26.11.2008 change of wind speed in europe in regional...

(SGA / M&D / MPI-M) DEWEK 2008, Bremen 26.11.2008

Change of Wind Speed in Europe in Regional Climate Model Scenario

Projections

B. Hennemuth, H.-D. Hollweg, M. Schubert

Service Group Adaption – SGA

Project hosted at Model & Data / MPI-M, Hamburg, Germany


Content

Introduction SGA, climate change

Regional model, data base

Methodology

Climatological averages

Statistics of wind speed and wind

speed change

Summary and outlook


Introduction SGA

Service Group Adaptation has been established by German Federal Ministry of Education and Research (BMBF) to assist projects which develop strategies for adaptation to climate trends and extreme weather.

SGA provides a common data base of regional climate model data.

SGA gives assistance with methods to analyse climate data.

SGA is hosted at the Max-Planck-Insitute for Meteorology in Hamburg, Germany, as project at the national data service group ‘Model and Data‘.

Introduction


Introduction

Global climate models

• Simulate all relevant processes in ocean, atmosphere, and (biosphere) on a global grid by physical equations.

• Small-scale processes (clouds, precipitation, radiation, soil, turbulence, etc. ) are described by large-scale parameters.


Introduction

Global climate models

• start with a pre-industrial long-term simulation with constant concentration of greenhouse gases.

• calculate present-day climate with realistic greenhouse gas concentration from 1860 to 2000.

• scenario projections of economic growth to assess corresponding future climates.

• do this for different starting points from pre-industrial equilibrium run different realizations Ensemble


Introduction

• demographic development

• socio-economic development

• technological change

• heterogeneity of world population

• global or regional solutions for challenges

IPCC (Intergovernmental Panel on Climate change) has defined scenarios depending on:

Implement these changes as emission scenarios for greenhouse gas concentration


global model:ECHAM5-MPIOM

Regionalmodell

CLM

CLM is embedded in global model ECHAM5/MPIOM, is initialized at 1960

Is forced by global model data throughout the simulation at the boundaries

CLM builds its own regional dynamical structures (= weather) within the model region


Regional model: CLM (Climate Local Model, based on weather forecast model of German Meteorological Service)


Model region Europe

Horizontal resolution ~20 km 33 vertical levels, lowest

levels: 33 m, 110 m, 220 m

‘Rotated grid’, NetCDF-format

Transient simulation 1960-2100

Climate of 20th century 1960 – 2000: C20 (3 runs)

Szenarios A1B (2 runs) 2001 – 2100: B1 (2 runs)

Orography


Model simulations:



• Output values must not be interpreted for single grid boxes.

• Time / date must not be taken as real time / date.

• Scenarios are assumptions of how the climate system may develop.

• Climate is variable (in model and in reality), decadal averages are still highly variable, therefore different realizations.

• Each model contains deficits, the global as well as the regional model.


Methodology

Statistical analysis is done by

• Calculation of climatological means of wind speed on model levels (time slices 1961-1990, 2021-2050, 2071-2100, all scenarios, all realizations).

• Scenario projections on mean wind speed comparedto present-day wind speed (‘climate change signal’).

• Histograms of 3 h wind speed over selected sub-regions (at least 20 grid boxes over rather homogeneous terrain) and 30-year time slices.

• Histograms of differences of 3 h wind speed.

• Caution: figures partly show 10 m wind speed on regular grid and for 2021-2050 and partly wind speed on model levels and for early 21. century time slice 2001-2030.


Methodology

For present-day and future climate data analysis we define sub-regions over Europe covering at least 20 model grid boxes:

North Sea area off the Frisian Islands Northern Germany near North Sea coast Middle German Low Mountains Southern Baltic Sea South-western highlands of Iberian peninsula Aegean Sea



3 realizations of present-day climate (10 m wind speed)

Similar structure

Regional wind systems visible: Mistral, storms in Northern Atlantic, Aegean Sea.

Large differences between sea and land (realistic over sea?), sharp transition.

Average annual mean of wind speed in Northern Germany: 4-5 m/s.

Comparison with data set for Germany (DWD) gives differences of up to ±1 m/s. (Walter et al., Meteorol.Z., 15, 2006)



Climate change signal for 10 m wind speed shows slight - increase for northern Europe (~0.1 m/s) - decrease for southern Europe (~0.1-0.2 m/s) - increase over Baltic Sea and Aegean Sea (~0.3 m/s)

2021-2050 – 1961-1990

A1B_1 – C20_1 (left)

A1B_2 – C20_2 (right)

2071-2100 – 1961-1990

A1B_1 – C20_1 (left)

A1B_2 – C20_2 (right)


Statistics of wind speed and wind speed change

Histograms show changes in different wind speed classes

Analyse 3 h wind speed data at 33 m, 110 m, 220 m

Consider all single values (statistics over n boxes)

Histograms have linear ordinate up from frequency of 1% (upper part) representing classes of most frequent wind speed and logarithmic ordinate (10-5 – 100) representing seldom events (like single storms, 10-5 = one event per region)

Green bars: present-dayOpen black bars: scenario


Statistics of windspeed and wind speed change

Wind speed at 110 mfor northern Germany (left) and German Bight (right), 1961-1990 (green) and Upper: 2001-2031 Bottom: 2071-2100

• very similar histograms in the ‘normal’ range

• increase in wind speed > 20 m/s at both

• Increase in low wind speed

• no large change between begin and end of century


Statistics of wind speed and wind speed change

Baltic Sea: decrease of low and moderate wind speed, increase of moderate to large wind speed

Aegean Sea: decrease of wind speed < 10 m/s and storms > 30 m/s, increase of large wind speed 10-20 m/s and ~30 m/s

Spain: increase of low wind speed, decrease of wind speed > 5 m/s

Present-day (green) and end of 21. century


Statistics of wind speed and wind speed changespring summer

autumn winter

Seasonal differences in 10 m wind speed over Germany: decrease in spring and summer, increase in autumn and winter, but in all seasons decrease over Alps and increase over sea


Summary and outlook

Average wind speed changes in Europe are expectedto be small under future scenario conditions.

Increase over northern Europe (Germany), decrease over southern Europe (Germany) except Aegean Sea.

Histograms of present-day show more details, e.g. increase of strong wind over northern Germany / German Bight,increase of low wind speed over Spain.

Seasonal differences of climate change signal for Germany: decrease of wind speed in summer, increase in winter.

Not yet all data processed, but tendency appears to be clear.Analysis continues …


Statistics of windspeed and wind speed change

German midlands:

Increase of low wind speed (< ~5 m/s)

Decrease of moderate to high wind speed (5 – 15 m/s)

Increase of strong winds > 15 m/si.e. more extreme values


M&D Technical Report about CLM-Simulationen: http://sga.wdc-climate.de/news

Service Gruppe Anpassung - SGA: Internet: http://sga.wdc-climate.de email: [email protected]

Climated data base WDCC: http://wdc-climate.de

CERA data base: http://cera.wdc-climate.de

Contact and Information


Rotierte Länge und Breite (blaue Linien) für ein sphärisches Koordinatensystem mit dem Nordpol am Punkt PN mit den geographischen Koordinaten

N=162°W und N=39,25°N.Orange Linien: Länge und Breite des unrotierten geographischen Systems.



Data are available from CERA database (Model & Data, MPI-M)

CERA-Portal

WDCC Experiments

Only data transformed to pressure levels or interpolated near-surface data (wind speed at 10 m, 2 m temperature, ..)

http://www.mad.zmaw.de/


Statistical Analysis, histograms

(sga / m&d / mpi-m) dewek 2008, bremen 26.11.2008 change of wind speed in europe in regional...

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