Test 2 Flashcards
Under which of the following circumstances do errors in model physics have the highest impact?
A. When dynamic forcing is strong
B. When physical processes are strong
C. When dynamic forcing is weak
D. When physical processes are weak
B and C
Which of the following elements help forecasters add value over NWP?
A. Continuous MetWatch
B. Use of MOS for rare events
C. Regular use of verification
D. Forecaster experince
A, C, and D
Which of the following tools help forecasters perform the continuous meteorological watch (MetWatch)?
A. Radar reflectivity and velocity
B. Medium-range NWP forecasts
C. Satellite depictions
D. Surface analyses
A, C, and D
True or False.
Model analysis and forecaster experience have a direct impact on the final forecast issued by meteorologists.
True.
The following statement is about MOS guidance.
True or False.
Data sets are seasonally stratified.
True.
The following statement is about MOS guidance.
True or False.
Model guidance will lead to a good forecast if environmental conditions are typical for the event.
True.
The following statement is about MOS guidance.
True or False.
Model guidance is skillful in forecasting atypical events.
False.
The following statement is about MOS guidance.
True or False.
Regional parametrization affects MOS guidance.
False.
The following statement is about MOS guidance.
True or False.
Model guidance corrects for the systematic errors in the NWP models.
True.
A major snowstorm is to occur on the 10th of October at a station in Nebraska. Snow is rarely observed in early October at this location, and the air mass accompanying and following the storm is unusually cold. Forecast 850-mb temperatures are expected to be at least 3 standard deviations below normal, which is statistically present only 1% of the time. Based on this, how would you adjust the temperatures for October 12 (day 4)?
A. I would use them as presented because MOS removes statistical bias.
B. I would use them as presented because MOS predicts extreme events well.
C. I would lower them because of the unusual snow cover and the cold air mass.
D. I would raise them because of the unusual snow cover and the cold air mass.
C.
Which of the following situations present opportunities to improve on the NWP forecast?
A. Forecasting temperature in the medium range when your area is in a stable block
B. Forecasting severe weather in the short range when convection is initiating.
C. Forecasting temperatures is areas of rugged terrain.
D. Forecasting precipitation for a landfalling hurricane
B, C, and D
Limited area models (LAMs) have ___________ and _________ boundaries.
lateral (horizontal)
vertical
Global models have only __________ boundaries.
vertical
Where do limited area models get their boundary information?
Three sources
From global models they are nested in.
Data assimilation.
Some type of climatological or fixed value.
What are some key issues related to model domain to consider when using model guidance, specifically in limited area models (LAMs)?
- proximity of local forecast area to model boundaries
- the quality and resolution of the forecast of the larger-domain model used to supply boundary conditions for the limited-area model
- the accuracy in which the physical processes are depicted
Errors in the larger-domain model are (amplified/subdued) when incorporated in the limited-area model.
Why?
Amplified
LAMs are generally higher-resolution than their global counterparts.
Lateral boundary conditions on LAMs affect the position and evolution of features within the domain. What can be accurately represented regardless of boundary location? What suffers?
Jet streaks and fronts (especially those downwind of a boundary)
Wave pattern – almost entirely determined by boundary conditions
The influence of boundary conditions spreads (toward/away from) and particularly (upstream/downstream) of the boundaries.
away from
downstream
Where is the area of primary forecast concern in a LAM?
as far away from the boundaries as possible, especially the upstream boundary
True or False.
As the area between the nest model boundary and the LAM boundary increases, the space “wasted” to prevent boundary-condition errors decreases.
True.
What is one-way interaction in LAMs?
Information flows in one direction from the previously integrated nest model.
Name the 3 models in which the LAMs are nested within larger versions of the same model.
UW-NMS, ARPS, MM5
Why is model nesting necessary?
Computer speed and memory limitations prohibit fine-resolution
What is two-way resolution in LAMs?
When the finer scale model is overlain with the coarser version and they interact with each other
What are the advantages of two-way resolution?
- it allows fine scale processes to affect the larger scale processes
- allows the boundary to be moved to reduce error and keeps the fine model small enough to run in real time
- reduces the conflict in different equations with different models
What are sources of error for horizontal nesting?
- accuracy errors in the forecast supplying the boundary conditions
- differences in forecasting from the larger scale model to the smaller scale model
In horizontal nesting, a well-resolved wave will move at a (slower/correct/faster) speed and a poorly-resolved wave will move at a (slower/correct/faster) speed.
correct
slower
What is the worst error that can occur when dealing with wave propagation and horizontal nesting?
wave refraction
What kind of waves is the wave refraction error prominent in?
On what meteorological scale do wave refraction errors occur?
waves poorly resolved on the coarser mesh feeding the model
mesoscale
What meteorological features can be affected by refraction or redirection of waves at model’s lateral boundaries?
precipitation fields temperature fields jet streak structure vertical motion field intensity and placement of surface lows
Where are model tops placed?
well above the tropopause
True or False.
Vertical motion is allowed to pass through the model top.
False.
What is the main forecast concern with a rigid model top?
Gravity wave refraction
How is the gravity motion problem with rigid model tops dealt with?
The numerical implementation of an “absorbing” or “dampening” layer.
Of the model components listed below, which five have the greatest impact on the accuracy of boundary conditions input to the surface layer of a model’s vertical domain?
A. Horizontal resolution B. Vertical resolution C. Vertical coordinate D. Forecast precipitation accuracy E. Radiation and surface physics F. Convective parametrization G. Model top location
A, B, C, D, E
Which of the following low-level parameters of model output are directly affected by the accuracy of the boundary conditions input to the model surface layer?
A. Temperature gradient B. Moisture C. Winds D. Turbulence E. Stability
All dat shit.
What approaches can both modelers and forecasters take to alleviate some of the errors introduced by boundary conditions?
Modelers - improve the physics parameterizations of the model
Forecasters - check boundary areas against real-time data
Match each domain element with its characteristic or impact.
A. Model top boundary B. Limited area models C. Lateral boundary condition source D. Global (continuous grid) E. Grid interaction F. Surface layer boundary condition
i. Data interpolation required at the boundaries
ii. Wave reflection
iii. No lateral boundaries
iv. One- or two-way information exchange
v. Quality of boundary data inputs
vi. Accuracy and depiction of physical processes and characteristics
A. - ii. B. - i. C. - v. D. - iii. E. - iv. F. - vi.
Choose all of the domain elements that apply to global models.
A. Model top boundary
B. Lateral boundary conditions
C. Grid interaction with a larger domain model
D. Boundary conditions at the surface layer
E. Multiple grid interactions
A and D
Choose all of the domain elements that apply to limited area models.
A. Model top boundary
B. Lateral boundary conditions
C. Grid interaction with a larger domain model
D. Boundary conditions at the surface layer
E. Multiple grid interactions
ALLA DEEZ
Which four of the following initial lower boundary variables have the most sensitivity to a lack of observational data?
A. Sea surface temperature B. Snow mass C. Soil moisture D. Land surface temperature E. Snow cover F. Sea ice
B, C, D, E
