Day-to-day meteorological variability in northern Chile: impacts and

Day-to-day meteorological variability in northern Chile:
impacts and predictability
René D. Garreaud
Department of Geophysics
Universidad de Chile
• General circulation and climate context
• Regional circulation
• Mid-latitude systems
• Central Andes Convection
• Weather forecasting: Basis – Methods - Applications
Circulación media de gran escala
ZCIT
ecuador
B
A
B
33S
B
In the context of weather and climate phenomena
atmosphere ≈ continuum fluid
Basic equations
r
v
v
dV
1
+ fkˆ × V = − ∇p − FR + gv
dt
ρ
∂ v
( + V ⋅ ∇)T − S ω = Q
∂t
P
RAD
v ∂ω
∇ ⋅V +
=0
∂p
∂ ( gz )
RT
=−
∂p
p
+Q
Conv
+Q
Sfc
But ...
• Previous system is highly non-linear and implicit; no analytic
solution can be obtained
• Some physical processes are difficult to model (cloud
formation, radioactive transfer, surface exchange, etc.)
.... Numerical modeling
•Use regular grids (vertical coordinate)
•Finite differences in space and time (vs. Spectral models)
•Parameterization of sub-grid processes
• Regional versus Global modeling
Horizontal domain
Horizontal grid spacing
Horizontal grid type
Vertical resolution below 800 hPa
Integration times
Spin-up time
Lead applications
Physical parametrizations
Initialization (IC)
Regional
Global
1000 × 1000 km2
108 km2
5-50 km
200-500 km
Regular grid point
Spectral (T45 / R63)
10-15
4-9 (5 in CCM3)
Days to weeks (year?)
Season to decades
Few hours
Few years
NWP –
Diagnosis of weather events
Climate studies, seasonal
prediction
Several options
Single option
Analysis
Cold start
Lateral Boundary Conditions (LBC)
Analysis, Forecast
Bottom Boundary Conditions (BBC)
Fixed / Coupled
Coupled with ocean
or land
Regional atmospheric modeling: Current status
Regional atmospheric modeling is currently being performed
in many groups at Universities, State Agencies and Private
companies, in part because:
• Availability of modestly priced single and multiprocessor
workstations that provide "supercomputer" processing
capabilities
• Availability of regional (synoptic-mesoscale) models that
run efficiently on workstations, sometimes as a black box
(MM5, RAMS)
• Real-time accessibility of analysis and forecast grids from
operational, global models (MRF-NCEP, ETA-CPTEC, etc.)
a. Met. variable (Taire, R, etc.)
b.Seeing (T≈1 día)
Nowcast
Weather forecast
c. River runoff (T≈1 semana)
Weather forecast
Extended forecast
Initial conditions
d. Tomato growth (T≈2 mes)
Climate prediction
Initial conditions
Time (2 months)
3 days
Vis
Vapor de Agua
IR(lejano)
IR (cercano)
D1
MM5-DGF (2002)
D2
D3
met.dfg.uchile.cl/tiempo/MM5
Detalles de la corrida
D1: 135 x 135 (km) - 34 x 40 x 30 puntos
D2: 45x45 (km) - 55 x 55 x 30 puntos
D3: 15 x 15 (km) - 73 x 73 x 30 puntos
Inicialización: Un ciclo 0000 UTC (2000 HL) cada día
Periodo de simulación: 72 horas
Intervalo de salida: 1 hora
Condiciones de borde e iniciales: NCEP-NOAA (USA)
Mapas
sinópticos
Series
de Tiempo
Cortes
tiempo-altura