Misc Flashcards
Members of an ensemble use slightly different…
Initial conditions
Two different ensemble methods
- Perturbed parameter ensembles
2. Multi-model ensembles
Deterministic forecasts always choose the most ____ outcome
Likely
Resolution of Met Office deterministic forecast
1.5 km
Resolution of Met Office ensemble forecast
2.2 km, 18 members
Postage stamp plots are used for…
Ensemble forecasts
How forecasts can be improved
- Better use of observational data
- Better model physics
- Increased resolution
- More ensembles
- Better communication
How is the knowledge of the atmosphere imperfect?
- Data voids
- Weather in between observing locations
- Instrument sensitivity/error
- No observation of important quantities
How is the computer model imperfect?
- Resolution
2. Physical understanding
How has use of initial conditions improved?
- More data
2. Better data assimilation
How has the model improved over time?
- Better resolution
2. Better preresentation of physical processes
How is chaos embraced?
- Stochastic parameterisations
2. Ensembles
Parameterisations deal with a lack of ____ and ___ of unresolved physical processes
Knowledge
Observations
What is parameterised at the scale of 10-100km?
- Cumulus
- Two stream radiation
- Planetary boundary layer
Sensible weather reflected by parameterised quantities
Clouds
Precipitation
Surface temperature
Near surface winds
Measurements available for convection
- Hydrometeors
2. Winds
Example of quanities needed to verify paramaterisations
- Turbulent kinetic energy
- Boundary layer depth
- Aerosol concentrations
- Convective heating profiles
Challenges of parameterisation
- Reductionist
- Observations needed
- Relationships assumed to be universal
- Act on a single profile
Most simple form of convection to parameterise
Dry convection