EGU General Assembly 2011 1

C. Cassardo1, M. Galli1, N. Vela1 and S. K. Park2,3

1Department of General Physics, University of Torino, Italy

2Department of Environmental Science and Engineering, Ewha Womans University, Seoul, Korea

3Severe Storm Research Center & Center for Climate/Environment Change Prediction Research, Ewha Womans University, Seoul, Korea

Heat and cold spells over the Alpine region in the future

climate

Ewha Womans University

이 화 여 자 대 학 교

2EGU General Assembly 2011

Outline :: The aim of the project The experiment setup The models used

◦ The Regional Climate Model

◦ The Land Surface scheme

A rapid sketch of the main results◦ The change of the hydrologic balance in summer

◦ The anticipation of the snow melting season

The analyses carried out◦ The cold spells

◦ The hot spells

◦ The arid days

◦ The wet days

Conclusions

3EGU General Assembly 2011

Introduction :: The global aim of the project

◦ To understand the effects of climate change on the Soil-Atmosphere Interface (energy and hydrological budgets)

◦ Highlight on mesoscale: Alps, Po Valley

◦ Occurrence of dry and wet periods

◦ Correct partitioning of energy balance components

◦ Better description of surface layer evolution: Convective phenomena

Cloud formation

Precipitation

4EGU General Assembly 2011

The method: a simulation chain General Climate Model simulation

◦ HadAM3H/HadRM3H global climate model (Hadley Centre) Grid: 1.25° (latitude) x 1.875° (longitude) [high

resolution version]

Details from Jones et al. (2001)

Regional Climate Model simulation◦ Model: RegCM3 (also used in PRUDENCE)

Grid size: 20 km

Details from Giorgi et al. (2003) [Climate Dynamics]

5EGU General Assembly 2011

The data extraction Data extraction

◦ Domain: rectangle 6°E-15°E and 43°N-47°N

◦ 720 grid points including Alps and the Po river basin (grid size: 20 km)

◦ All 3-hours RegCM3 outputs (but precipitation) were interpolated every hour using cubic splines, while precipitation was simply redistributed assuming a constant rate

◦ 10 soil layers were considered, with thicknesses progressively doubling from surface 5 cm to deepest 25 m (boundary relaxation zone)

Run of the land surface scheme UTOPIA for each grid point

6EGU General Assembly 2011

The simulation domain

7EGU General Assembly 2011

The land surface scheme UTOPIA

University of TOrino model of land Process Interaction with Atmosphere 1-D, multilayer, diagnostic

model of energy, momentum and water exchanges between soil and atmosphere

Describes the surface processes in terms of physical fluxes and hydrological state of soil

Represents the interactions of soil and vegetation with the atmosphere (big-leaf)

Driven by commonly measured meteorological parameters or by atmospheric models

8EGU General Assembly 2011

The UTOPIA run Data needed:

◦ surface air temperature, humidity, pressure, wind, precipitation, short- and long-wave radiation

For each grid point:

◦ Soil type assigned using ECOCLIMAP (Masson et al., 2003)

◦ Vegetation type imposed equal to short grass

Run of UTOPIA

Extraction of the following variables:

◦ Soil temperature, soil moisture, sensible and latent heat flux, surface runoff, bottom drainage, evapotranspiration

9EGU General Assembly 2011

The periods simulated Present climate (1960 - 1990)

◦ useful for comparisons

Future climate (2070 - 2100)◦ A2 and B2 scenarios

10EGU General Assembly 2011

The analysis of the data

The analysis was carried out considering the soil temperature and the soil moisture

◦ Soil temperature exhibits less noise than air temperature (at any level in the surface layer)

◦ Soil moisture depends more specifically on hydrological budget than relative or specific humidity

Definitions:

◦ Cold days: when T1<0°C

◦ Warm days: when T1>30°C

◦ Dry days: when QI<0

◦ Wet days: when QI>0.8 WIFC

WII qq

qqQ

1

T1: soil temperature in the uppest 10 cm

q1: soil moisture in the uppest 10 cm

qFC: field capacityqWI: wilting point

11EGU General Assembly 2011

The number of hot days

The number of hot days increases in the plain by 30 in B2 and by 40 in A2 with respect to control, and few hot days appear in lower elevations

12EGU General Assembly 2011

The number of cold days

The number of cold days is null in the plains in A2 and B2, and reduces by 40 to 80 days in the mountains

13EGU General Assembly 2011

The number of dry days

The number of dry days increases by about 20-30 in B2 and by about 30-40 in A2 mainly in the plains and hills

14EGU General Assembly 2011

The number of wet days

The number of wet days increases slightly by about 5-10 days in some areas in proximity of the mountains, while in few other areas there is a light decrease

15EGU General Assembly 2011

The wet and dry days interannual variability (soil moisture)

No changes for the wet days interannual variability Decrease of the interannual variability of dry days in Italy and over the

Alps, increase in Switzerland

16EGU General Assembly 2011

The warm and cold days interannual variability (soil temperature)

Increase of the interannual variability for warm days Decrease of the interannual variability for cold days

17EGU General Assembly 2011

Conclusions :: Aim: to evidence the climate change consequences on

Alpine area

Analysis performed on soil temperature/moisture need to use a model simulation chain: GCMRCMLSM

Selected periods: A2, B2 scenarios (2071-2100) vs present climate (1961-1990)

Number of dry days increases, with less variability future climate is drier

Number of wet days increases sligthly, but variability does not frequency of floods may increase

Number of hot days increases, as well as their variability

Number of cold days decreases, as well as their variability (but less)

18EGU General Assembly 2011

AcknowledgmentsThis research is partly supported by the Ministry of

Environment, Korea, under the National Comprehensive Measures against Climate Change Program (No. 1700-1737-322-210-13)

N. Vela 3-month stay in Seoul has been supported by the Korean Ministry of Environment

Input data (RegCM3) have been provided by the Earth System Physics Section of the ICTP, Italy

The collaboration between C. Cassardo and S.K. Park has been partly supported by the government of Italy and Korea, respectively, for visiting each institution