Misc Flashcards

1
Q

Members of an ensemble use slightly different…

A

Initial conditions

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2
Q

Two different ensemble methods

A
  1. Perturbed parameter ensembles

2. Multi-model ensembles

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3
Q

Deterministic forecasts always choose the most ____ outcome

A

Likely

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4
Q

Resolution of Met Office deterministic forecast

A

1.5 km

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5
Q

Resolution of Met Office ensemble forecast

A

2.2 km, 18 members

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6
Q

Postage stamp plots are used for…

A

Ensemble forecasts

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7
Q

How forecasts can be improved

A
  1. Better use of observational data
  2. Better model physics
  3. Increased resolution
  4. More ensembles
  5. Better communication
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8
Q

How is the knowledge of the atmosphere imperfect?

A
  1. Data voids
  2. Weather in between observing locations
  3. Instrument sensitivity/error
  4. No observation of important quantities
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9
Q

How is the computer model imperfect?

A
  1. Resolution

2. Physical understanding

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10
Q

How has use of initial conditions improved?

A
  1. More data

2. Better data assimilation

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11
Q

How has the model improved over time?

A
  1. Better resolution

2. Better preresentation of physical processes

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12
Q

How is chaos embraced?

A
  1. Stochastic parameterisations

2. Ensembles

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13
Q

Parameterisations deal with a lack of ____ and ___ of unresolved physical processes

A

Knowledge

Observations

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14
Q

What is parameterised at the scale of 10-100km?

A
  1. Cumulus
  2. Two stream radiation
  3. Planetary boundary layer
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15
Q

Sensible weather reflected by parameterised quantities

A

Clouds
Precipitation
Surface temperature
Near surface winds

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16
Q

Measurements available for convection

A
  1. Hydrometeors

2. Winds

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17
Q

Example of quanities needed to verify paramaterisations

A
  1. Turbulent kinetic energy
  2. Boundary layer depth
  3. Aerosol concentrations
  4. Convective heating profiles
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18
Q

Challenges of parameterisation

A
  1. Reductionist
  2. Observations needed
  3. Relationships assumed to be universal
  4. Act on a single profile
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19
Q

Most simple form of convection to parameterise

A

Dry convection

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20
Q

Soundings with large CAPE tend to be ____ at low levels

A

Warm and moist

21
Q

Soundings with large CAPE tend to be ___ at upper levels

A

Cold and dry

22
Q

What is not redistributed in convection parameterisations?

A

Momentum

23
Q

Why may the cloud base be lower than predicted?

A

Dry air entrainment

24
Q

Why may the cloud base be higher than predicted?

A

The parcel still has momentum at the EL

25
Q

A critical issue for convective parameterisations

A

Timing and momentum

26
Q

How to address convective and stratiform areas

A
  1. Diagnose convective/explicit precipitation separately
  2. Interaction with microphysics
  3. Model grid spacing
27
Q

How to improve parameterisations

A
  1. Increase resolution

2. Explicitly represent convection

28
Q

Key problem with tropical rainfall forecasts

A

Convection parameterisation

29
Q

In the Atlantic & Eastern Pacific, instabilities form in the troughs of the…

A

African Easterly Jet

30
Q

Which direction do the monsoon winds flow?

A

Southwest

31
Q

Vertical wind shear has a ___ effect on tropical cyclone intensification

A

Negative

32
Q

Tropical cyclones decay with landfall due to

A
  1. Less latent & sensible heating

2. Increased friction

33
Q

Less latent and sensible heating leads to

A

Weaker convection

34
Q

Weaker convection leads to less intense ___ gradients

A

Pressure

35
Q

4 defining qualities of a tropical cyclone

A
  1. Non-frontal, synoptic-scale
  2. Originates over tropical waters
  3. Organised deep convection
  4. Closed circulation with well-defined centre
36
Q

Maximum vertical motion measures the strength of convection, related to the potential for…

A

Precipitation production

37
Q

In convection, too little moisture aloft will result in…

A

Evaporation of towering cumulus

38
Q

To produce a sustained convective system, you need

A

Mesoscale organisation

39
Q

In a mesoscale convective system, vertical wind shear

A

Separates the updrafts and downdrafts

40
Q

Separating the updrafts and downdrafts allows

A

Sustained convection

41
Q

Stratiform precipitation and systems are…

A

Frontal

42
Q

In a supercell, vertical wind shear is important for…

A

Vorticity and updraft/downdraft separation

43
Q

What makes the jet stream baroclinically unstable?

A

Strong temperature gradient

44
Q

Uneven heating and mountains can cause

A

Rossby waves

45
Q

Before ETC occlusion, rainband is

A

In front of the warm front

46
Q

After ETC occlusion, rainband is

A

Focused at the occlusion

47
Q

Occlusion of the cold front isn’t needed if the…

A

Isotherms wrap around the low

48
Q

Wind which is warmed and dried by descent on the lee side of a mountain

A

Foehn winds