An analysis of simulated and observed storm An analysis of simulated and observed storm An analysis of simulated and observed storm An analysis of simulated and observed storm An analysis of simulated and observed storm An analysis of simulated and observed storm An analysis of simulated and observed storm An analysis of simulated and observed storm

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-------- Can we expect a change in the future?Can we expect a change in the future?Can we expect a change in the future?Can we expect a change in the future?Can we expect a change in the future?Can we expect a change in the future?Can we expect a change in the future?Can we expect a change in the future?

R.E. Benestad, CES, June 01 2010

Number of cyclones:

RCM

analysisCCI

(Benestad & Chen, 2006) �

No change in storm frequency?No change in storm frequency?

RCM:

N corresponds

|v| too high

...or simulated wind speeds?...or simulated wind speeds?

•CCI

•triangulation

Method: storm characteristicsMethod: storm characteristics

RCM: storms too small

too strong.

Gradient wind

Obs=ERAINT (reanalysis) �

Storm statisticsStorm statistics

Domain:

12°W-38°E/48-66°N

(Same as RCM)

Historical reanalysis

ERAINT

Little trend!

Historical analysis: NHistorical analysis: N

CCI on small domain:

restricted

RCM domainRCM domain

Domain:

80°W-40°E/20-

75°N

Different story!

Geographical

distribution?

Storm statistics: Whole North AtlanticStorm statistics: Whole North Atlantic

Homogeneous?

Historical analysis: |v|Historical analysis: |v|

Southern Norway

SLP 'triangulation'

historical

ERAINT

RCM

Geostrophic windGeostrophic wind

Meteorologisk institutt met.no

A change in storminess?

• Storms: baroclinic instability, available energy• Ambient conditions:

– dT/dy, moisture, flow.

• Energy flow:

– evaporation, motion, condensation, radiation, advection.

• Aspects:

– Clouds, winds, pressure & precipitation.

• Data difficult.

• High uncertainty!