f. gheusi, j.-p. cammas, j.-p. chaboureau, j. duron, c. mari, p. mascart and j.-p. pinty
DESCRIPTION
A regional-model « climatology » of vertical mass and water-vapour transport for the Hibiscus-Troccinox-Troccibras campaign 2004. F. Gheusi, J.-P. Cammas, J.-P. Chaboureau, J. Duron, C. Mari, P. Mascart and J.-P. Pinty Laboratoire d’Aérologie Toulouse (France). - PowerPoint PPT PresentationTRANSCRIPT
A regional-model « climatology » of vertical mass and water-
vapour transport for the Hibiscus-Troccinox-Troccibras
campaign 2004
F. Gheusi, J.-P. Cammas, J.-P. Chaboureau, J. Duron, C. Mari, P. Mascart
and J.-P. Pinty
Laboratoire d’Aérologie
Toulouse (France)
Meso-NH forecast support during the campaign (1)
Resolution = 30 kmDomain 3000 km x 3000 km
« Radar » rectangle
Mass budget (arbitrarily) restricted
to this area
Meso-NH forecast support during the campaign (2)
Daily time-period considered for• vertical air-displacement• integration of mass budgets
06 UTC06 UTC 24 UTC24 UTC
Set of 30 simulations from 05 Feb to 05 Mar
Makes possible some statistics !
Wind-strength @ z = 1500 m
Some climatological features
(30-day averaged fields)P + wind @ z = 3000 m
Temp. °C (colorscale)-2 PVU tropopause (dashed)Zonal wind (dotted)
SACZ
verticalcross-section
Mean daily vertical motion (06-24 UTC)
S-N cross-section: z = z – z0 (km) z0 (m) @ z = 6000 m
SACZ
Mass budget computation: a post-processing method
z
Surface = air-parcels with common initial altitude z0
x
z0
Upward mass flux through z0
between t0 and t:
Air-parcels that • were initially below z0
• are finally above z0
Mass flux between t0 and t
=Mass of the colored
volume
Model run: transport of a passive tracerinitialized with the altitude, then …
Mass budget computation: what was performed
3000 m
6000 m
9000 m
12000 m
15000 m
18000 m
21000 m
= flux 06-24 UTC (up / down)
Net flux = up - down
For each day (simulation Day 1)
Computation for 30 days: few seconds on a Linux PC !
Mass flux = dry air or water-vapour
Qualitative comparison against rain satellite-retrievals (TRMM,
125x125 km²)Net Flux (Up - Down)
-100
0
100
200
300
400
500
600
700
01-m
ars-
04
02-m
ars-
04
03-m
ars-
04
04-m
ars-
04
05-m
ars-
04
Day
-25
0
25
50
75
100
125
150
175
24h precip (mm/day)
6000m
9000m
12000m
OBS RAIN
Mixed results, better with sub-grid cloud fraction ? To be tested…
06 Februaryheavy-rainover Bauru,
good forecast !
14 Februaryactive front,forecasted too late…
28 Februarygood !
diurnal convection period,
not good…
3-4 Marchnot so bad
Dry-air mass budget30-day averaged mass fluxes (Day 1)
0
3000
6000
9000
12000
15000
18000
21000
24000
-300 -200 -100 0 100 200 300 400 500 600
Net Flux
Alt
itu
de
Net Flux
Vert div
Dry-air mass budgetMost convective 10 days, avg mass fluxes (Day 1)
0
3000
6000
9000
12000
15000
18000
21000
24000
-300 -200 -100 0 100 200 300 400 500 600
Net Flux
Alt
itu
de
Net Flux
Vert div
Criterion: Max( flux(9000m) + flux (12000m) )
Dry-air mass budgetLeast convective 10 days, avg mass fluxes (Day 1)
0
3000
6000
9000
12000
15000
18000
21000
24000
-300 -200 -100 0 100 200 300 400 500 600
Net Flux
Alt
itu
de
Net Flux
Vert div
Criterion: Min( flux(9000m) + flux (12000m) )
Water-vapor flux:qualitative comparison against rain
satellite retrievals (TRMM, 125x125 km²)
Better correlation with the « observed » precipitation
Net Flux (Up - Down)
-200
0
200
400
600
800
1000
1200
1400
01-m
ars-
04
02-m
ars-
04
03-m
ars-
04
04-m
ars-
04
05-m
ars-
04
Day
-25
0
25
50
75
100
125
150
175
24h precip (mm/day)
6000m
9000m
12000m
OBS RAIN
Water-vapour mass budget
30-day averaged mass fluxes (Day 1)
0
3000
6000
9000
12000
15000
18000
21000
24000
-300 -200 -100 0 100 200 300 400 500 600 700 800
Net Flux
Alt
itu
de Net Flux
Vert div
Net Source
ConclusionsNumerical aspects• 30 MesoNH runs in forecast mode: statistical approach
over the period 05 Feb – 05 Mar 2004.• Flux computation based on
– On-line passive transport of initial-coordinate tracers– Low-cost and highly adaptable post-processing (PC)
Vertical motion « model climatology »• Subsidence in the lower troposphere, S of the SACZ• Largest ascent just below the tropopause, N of the SACZ• Slight but significant subsidence above the tropopause convergence in the TTL, no export in the stratosphereVertical mass budget• Downward flux in the lower stratosphere• Upward flux maximum at 9000m (6000m for WV)• Mass and humidity convergence in the TTL
Future work
• Work with better simulation sets
• Compare findings and observations
• Investigate the diurnal evolution of the vertical
transport