11th EMS, Berlin, 12-16 September 2011

The 'FluxSAP 2010' hydroclimatological

experimental campaign

over an heterogeneous urban area

presented by Yves Brunet

EPHYSE, INRA, Bordeaux, France

The FluxSAP team

P. Mestayer1,3, I. Bagga3, I. Calmet3, G. Fontanilles3, D. Gaudin3, J. H. Lee3, T. Piquet3,

J.-M. Rosant3, K. Chancibault2, L. Lebouc2, L. Letellier2, M.-L. Mosini2, F. Rodriguez2,

J.-M. Rouaud2, M. Sabre4, Y. Tétard4, A. Brut5, J.-L. Selves5, P.-A. Solignac5, Y. Brunet6,

S. Dayau6, M. Irvine6, J.-P. Lagouarde6, Z. Kassouk7, P. Launeau7, O. Connan8,

P. Defenouillère8, M. Goriaux8, D. Hébert8, B. Letellier8, D. Maro8, G. Najjar9, F. Nerry9,

C. Quentin9, R. Biron10, J.-M. Cohard10, J. Galvez11, P. Klein11

• 1Institut de recherche en sciences et techniques de la ville (IRSTV), FR CNRS 2488, BP 92101, Nantes,

France

• 2Département géotechnique, eau et risques (GER), IFSTTAR, Bouguenais, France

• 3Laboratoire de mécanique des fluides (LMF), UMR CNRS 6598, École Centrale de Nantes, France

• 4Département climatologie, aérodynamique, pollution et épuration (CAPE), CSTB, Nantes, France

• 5Centre d'études spatiales de la biosphère (CESBIO), UMR CNRS 5126, Toulouse, France

• 6Ecologie fonctionnelle et physique de l’environnement, UR1263 EPHYSE, INRA, Villenave d'Ornon,

France

• 7Laboratoire de planétologie et géodynamique de Nantes (LPGN), UMR CNRS 6112, Nantes, France

• 8Laboratoire de radioécologie de Cherbourg-Octeville (LRC), IRSN, Cherbourg, France

• 9Laboratoire des sciences de l'image de l'informatique et de la télédétection (LSIIT), UMR CNRS 7005,

Strasbourg, France

• 10Laboratoire d'étude des transferts en hydrologie et environnement (LTHE), UMR CNRS 5564,

Grenoble, France

• 11School of Meteorology, University of Oklahoma, Norman, OK 73072 USA

The context

VegDUD: the role of vegetation in sustainable urban development

Funded by the French National Research Agency (2010-2013)

Understanding and quantitatively assessing the impact of vegetation

in present and future urban development projects

Mixed urban areas (built, unbuilt, green surfaces)

Climatology, hydrology, energy control, environment

Location: city of Nantes, around the permanent observation site of

IRSTV ('Pin Sec' district)

Two ground and airborne measurement 'FluxSAP' campaigns:

2010, 2012

The objectives

FluxSAP objective: obtain reference data

for evaluating urban hydrology and microclimate models

for assessing quantitatively the role of vegetation on urban

climate

FluxSAP 2010 objective: test the methods allowing

to measure sensible heat and water vapour fluxes over a

heterogeneous urban district

to spatialize the measurements, taking into account landuse

heterogeneity

to test footprint models over an urban area

Loire river

Erdre river

Nantes region

'Pin Sec' measurement area

10 eddy covariance sensor systems

S

M

B

C

G E

W

D

5 LAS, 1 SAS

14 T-RH sensors at z = 2-3 m

10 piezometers, 8 T- profiles

Set-up summary

● T-RH (2 m)

⇑ EC mast

–– Scintillo

☐ GIS limits

Ground-based measurements

Airborne (13 flights) and handheld (140 refs) TIR

TIR measurements

20 flight lines

Hyspex sensor and inertial plateform

Hyperspectral airborne measurements

VNIR (400-1000 nm)

160 bands (4 nm)

0.6 m resolution

SWIR (1000-2500 nm)

256 bands (6 nm)

1.2 m resolution

95 ground measts

portable spectrometer

Meteo mast Tethered balloon

Emission sites

30 passive tracer dispersion experiments

Balloon DIAPEG

The meteorology (26 April – 7 june)

Temperature and humidity gradients

from T-RH and surface sensors

0

10

20

30

40

50

60

70

80

90

100

21-mai 22-mai 23-mai 24-mai 25-mai

hum

idité a

ir

(%)

10 11 12

13 14 15

16 17 18

19 Dunant

10

15

20

25

30

35

21-mai 22-mai 23-mai 24-mai 25-mai

tem

péra

ture

s a

ir

(°C

)

10 11 12

13 14 15

16 17 18

19 Dunant

Taupe 3

0

5

10

15

20

25

30

35

40

45

21-mai 22-mai 23-mai 24-mai 25-mai

Te

mp

éra

ture

s (

°C

)

Temp. air

surface

- 5 cm

- 35 cm

- 1 m

4 K 18 %

150 Wm-2

Heat flux measurements

with EC turbulent sensors

-100

0

100

200

300

400

500

1-May 6-May 11-May 16-May 21-May 26-May 31-May

date

se

nsib

le h

ea

t flu

x (

W m

-2)

G site_26 m G site_21 m E site_20 m M site_10m S site_32 m rain

Heat flux measurements

with LAS scintillometers

300 Wm-2

Preliminary conclusions

• Differences between measurement techniques but good

coherence between sites

• Differences between sites linked with different

distributions of land cover (buildings, pavement, bare

soil, high and low vegetation)

• Footprint analysis should allow us to identify the various

flux contributions and quantify the influence of

vegetation

Mestayer et al. (2011). Urban Climate News, 40:22-30 (www.urban-climate.org)

Mestayer et al. (2011). La Météorologie, 73:33-43 (www.smf.asso.fr)

Further analysis : the footprint issue

turbulent flux sensor

source area or footprint

wind U

Further analysis : the footprint issue

turbulent flux sensor

wind U L and D = f(z, z0, U, z/L…)

D L

Preparation for May-June 2012 campaign

More variable land cover within footprint

More EC masts over vegetated urban areas

More H2O turbulent sensors (Li-Cor)

More differentiated LAS paths (mineral, vegetal, mixed)

1 or 2 water vapour scintillometers?

Measure PTUV profile (0-150 m) with tethered balloon

Monitor water table (soil moisture profile)

11th EMS, Berlin, 12-16 September 2011

Thank you