C. Flamant(1), C. Champollion(1,2), S. Bastin(1) and E. Richard(3)

(1)Institut Pierre-Simon Laplace, UPMC/CNRS/UVSQ (2)Géosciences Montpellier UM2/CNRS,(3)Laboratoire d'Aérologie OMP/CNRS

Water vapour variability in the Rhine Valley and its role on

convective initiation:first results from LEANDRE 2

COPS workshop 27-29 February 2008, University of Hohenheim

Objectives

• understand the role of mesoscale dynamics processes on the water vapour variability in the Rhine Valley, and particularly on the formation of dry layers and lids above the Atmospheric Boundary Layer (ABL),

LEANDRE 2 01/08/08 around 0810 UTC

Objectives

• understand the role of mesoscale dynamics processes on the water vapour variability in the Rhine Valley, and particularly on the formation of dry layers and lids above the Atmospheric Boundary Layer (ABL),

• comprehend the relative importance soil moisture, surface heterogeneities, and orography on the ABL water vapour variability,

• assess the impact of mesoscale water vapour variability on convection initiation (CI), and the role of dry layers & lids on CI or convection inhibition,

• demonstrate the potential of airborne lidar-derived water vapor measurements for improving CI in mesoscale models through 4D assimilation,

• contribute to the water vapour profiling instruments intercomparison.

Tools & strategy

• Systematic sampling of water vapour in the Rhine Valley (incl. the Vosges and the Black Forest) using the airborne DIAL LEANDRE 2, prior to CI events,

• implementation of supersites with dedicated profiling systems,• Mesoscale simulations (control and sensitivity analyses),

• lidar-derived water vapour mixing ratio profiles assimilation experiments (using AROME).

LEANDRE 2 IOP 8b (15/07)High-pressure convection2 flights: 0630 - 0950 UTC

1141 – 1457 UTC

LEANDRE 2 IOP 9c (20/07) Forced convection1 flight: 0657 – 0918 UTC

LEANDRE 2 IOP 13a (01/08)High-pressure convection2 flights: 0808 – 1106 UTC

1344 – 1643 UTC

Systematic sampling of water vapour in the Rhine Valley using the airborne DIAL LEANDRE 2, prior to CI events:

Data

Water vapour mixing ratioHorizontal resolution ~3 kmVertical resolution ~300 m

Atmospheric reflectivityHorizontal resolution ~3 kmVertical resolution ~300 m

IOP 8b (15/07) High-pressure convection

Meso-NH

1000 m

Winds & wvmr

IOP 8b (15/07) High-pressure convection

Meso-NH

1000 m

Winds & wvmr

D1D5B1B5Tim

eC1C5

CI

West of Vosges Vosges Rhine Valley

Lati

tud

eTime

B4D4G4North / Supersite R

B3D3G3 Supersite V

B1D1G1South / Burnhaupt

G4B4: 0657-0708 UTC

IOP 9c (20/07) Forced convection

B3G3: 0712-0724 UTC

G2B2: 0732-0744 UTC

IOP 9c (20/07) Forced convection

G1D1: 0806-0814 UTC

Meso-NH

2000 m

Winds & wvmr

Meso-NH

1000 m

Winds & wvmr

IOP 13a (01/08) High-pressure convection

Meso-NH

2000 m

Winds & wvmr

IOP 13a (01/08) High-pressure convection

Meso-NH

1000 m

Winds & wvmr

Time

B4G4North / Supersite R

B3G3 Supersite V

B2G2

Lati

tud

e

dust

E1E5Tim

eC1C5Vosges Black Forest

D1D5Rhine Valley

Saharan air mass

Conclusions and perspectives

• great LEANDRE 2 dataset, we should be able to complete our initial objectives !!

• LEANDRE 2 dataset quality currently being assessed by Paolo’s group (bias & RMS deviation, see Rohini’s talk),

• data available right now!!! cyf@aero.jussieu.fr

• 15 July & 1 August day long evolution,

• 15 & 20 July pre-CI observations in the Rhine Valley.

• design mesoscale simulations 15 & 20 July, 1 August cases and sensitivity experiments,

• liaise with other experimental groups,

• conduct 4D-VAR assimilation experiments of airborne lidar-derived water vapour measurements,

• contribute to the IASI water vapour profiling validation.

Data from:

IOP 8b (15/07): LEANDRE 2, RDS in Hornisgrinde & IASI

IOP 13a (01/08): LEANDRE 2, dropsondes, RDS in Hornisgrinde & IASI

First comparison of IASI water vapor mixing ratio profiles with airborne DIAL LEANDRE

2, dropsondes and radiosondes observations over the Black Forest region

during COPSC. Flamant, H. Herbin, C. Champollion

LEANDRE 2 IOP 8b (15/07) G4B4: 0630-0643 UTC Intercomparison region:

Hornisgrinde (Black Forest)

HornisgrindeDIAL LEANDRE 2

Profil IASI: 0905 UTC

RDS: 0800 UTC