Bauru November 2004

Modelling interpretation of in situ H2O, CH4 and CO2 measured by

SDLA balloon borne instrument (SF2 and SF4 flights).

N. Huret(1),G. Durry (2),S. Freitas(3),M.Pirre(1) , A. Hauchcorne(2)

(1) LPCE/CNRS,France(2)IPSL, Service d’Aéronomie du CNRS,France

(3)CPTEC, Brazil

Bauru November 2004

OBJECTIVES

• To understand how the convection can modify the Upper Troposphere (UT) and the Tropical Transition Layer (TTL) ?

• What type of model we have to use to investigate the tropical UT and TTL ?

• Previously in polar region and at mid-latitude we used insentropic trajectories from ECMWF

Bauru November 2004

Mesoscale interpretation• RAMS/CPTEC model outputsOperational mesoscale model (40 km x 40

km)

• 3D trajectory code (Freitas et al. 2000)

– 4 days backward trajectories – 10-20 km every km– Temperature, pressure, water vapor,

liquid water content, solid water content, vertical velocity

Bauru November 2004

• SF2 flight, 13 February 2004

•Upper troposphere : Air mass ascent from 8 to 10.5 km, 20h before the measurements

•Tropical Transition Layer : nothing special

Bauru November 2004

• SF4 flight, 24 February 2004

•Tropical Transition Layer : very strong uplifting from the ground to 17 km 80h before the measurements

Bauru November 2004

Is SF4 17km trajectory realistic ?

• Very strong uplifting from the ground to 17 km, 80h before the measurements

• Does a strong convective system exist ?

•Accumulated precipitation map from RAMS and TRMM satellite data

•GOES-E satellite cloud MAP • Does RAMS mesocale model predict this

convective system at the good location ?

Bauru November 2004

3 days before the SF4 measurements

A strong convective system exists at the location of the uplifting

SF4 RAMS Validation

Bauru November 2004

• RAMS validation : accumulated precipitation• RAMS outputs / TRMM satellite data

•This case was very convective because of the South Atlantic Convergence Zone activity• RAMS predictions are validated

Bauru November 2004

SDLA water vapor measurementsSF2/ SF4 comparison

• a water vapor bubble from SDLA (17 km) for SF4

• can be due to a deep convective system seen on GOES satellite maps and simulated using RAMS mesocale model

• The convection affects the TTL

Bauru November 2004

RAMS(40 km) grid close to BauruProfiles extracted at each grid point in this region

Bauru

Bauru November 2004

RAMS water vapor profiles

Water vapor excess in the TTL

Very dry layerIn the UT :

SF4

Good agreement between RAMS simulation and measurementsExcept : between 14 and 16 km but not critical

between 8-10km in the UT

Bauru November 2004

SDLA-RAMS temperature profiles comparisons

Bauru November 2004

Mixing ratio RAMS fields

Bauru

Strong water vapor gradient south of Bauru The dry layer is predicted by the RAMS model

Bauru

Bauru November 2004

MIMOSA PV contour advection model

Hauchecorne et al. 2001• On isentropic surfaces MIMOSA

calculates the Potential vorticity evolution from ECMWF wind fields.

• Global scale transport

340 K isentropic surface

Bauru November 2004

MIMOSA Outputs

PV filament coming from low stratopshere mid-latitude with PVU > 2Large scale isentropic transport

Bauru November 2004

SF4 : CH4 , CO2 , H2O and O3 (sonde)

Bauru November 2004

CONCLUSIONS SF4 flightStrong uplifting from the ground to the TTL (17 km) due to convectionMesoscale transport process

Isentropic transport from mid- latitude to the tropical UT (8-10 km)Large scale transport

SF4 profiles

Bauru November 2004

Many thanks• TROCCIBRAS partners• team from USP and CPTEC

– S. Freitas – P. Leite da Silva Dias