Added value to the investigation of Rossby wave-trains by

Added value to the investigation of
Rossby wave-trains
by using the wave activity flux diagnostic
Gabriel Wolf, Volkmar Wirth
Johannes Gutenberg-Universität Mainz
WWOSC 2014
Montreal, 18.8.2014
Basics about Rossby wavetrains (RWTs)
High PV-values
Rossby wave:
propagation mechanism
-
+
-
+
Low PV-values
Theory/Motivation
Wave activity flux diagnostic
Intense surface cyclone composite
Summary
01
Basics about Rossby wavetrains (RWTs)
High PV-values
Rossby wave:
propagation mechanism
-
+
-
+
Low PV-values
Theory/Motivation
Wave activity flux diagnostic
Intense surface cyclone composite
Summary
01
Basics about Rossby wavetrains (RWTs)
High PV-values
Rossby wave:
propagation mechanism
-
+
-
+
Low PV-values
Theory/Motivation
Wave activity flux diagnostic
Intense surface cyclone composite
Summary
01
Basics about Rossby wavetrains (RWTs)
High PV-values
-
Rossby wave:
propagation mechanism
+
-
+
Low PV-values
-
Rossby wavetrain:
propagation mechanism
&
downstream development
+
-
time
Theory/Motivation
Wave activity flux diagnostic
Intense surface cyclone composite
Summary
01
Basics about Rossby wavetrains (RWTs)
High PV-values
-
Rossby wave:
propagation mechanism
-
+
+
Low PV-values
-
Rossby wavetrain:
propagation mechanism
&
downstream development
time
Theory/Motivation
Wave activity flux diagnostic
-
+
+
-
+
Intense surface cyclone composite
Summary
01
Basics about Rossby wavetrains (RWTs)
High PV-values
-
Rossby wave:
propagation mechanism
-
+
+
Low PV-values
-
Rossby wavetrain:
propagation mechanism
&
downstream development
time
-
+
+
-
+
Wave breaking in
nonlinear RWT-stage
Theory/Motivation
Wave activity flux diagnostic
Intense surface cyclone composite
Summary
01
Connection of RWTs with extreme events
Wirth & Eichhorn (2013)
Composite:
5 % strongest surface cyclones
- at 50°N,10°E
- data: ERA40, winter season
meridional wind v'
v ' =v−v DJF
Theory/Motivation
Wave activity flux diagnostic
Intense surface cyclone composite
Summary
03
Overview
●
●
●
Wave activity flux (WAF) diagnostic
WAF applied to the intense-surface-cyclone
composite (motivation)
Summary
Wave activity flux diagnostic?!
Application to RWT investigations useful?
Basics of wave activity flux (WAF) diagnostic
Wave activity equation
WAF
∂A
+ ∇⋅⃗
F =D
∂t
⃗ =⃗c g A
F
Wave signal
Theory/Motivation
Wave activity flux diagnostic
Intense surface cyclone composite
Summary
04
Basics of wave activity flux (WAF) diagnostic
Wave activity equation
∂A
+ ∇⋅⃗
F =D
∂t
⃗ =⃗c g A
F
WAF
Background
flow
Wave signal
Wave breaking
∣∢( ⃗F , ⃗u bg )∣> 45 °
Theory/Motivation
Wave activity flux diagnostic
Intense surface cyclone composite
Summary
04
Basics of wave activity flux (WAF) diagnostic
Wave activity equation
∂A
+ ∇⋅⃗
F =D
∂t
⃗ =⃗c g A
F
WAF
Background
flow
Wave signal
Wave breaking
∣∢( ⃗F , ⃗u bg )∣> 45 °
Background
flow
Theory/Motivation
Wave activity flux diagnostic
Intense surface cyclone composite
Summary
04
Basics of wave activity flux (WAF) diagnostic
Wave activity equation
∂A
+ ∇⋅⃗
F =D
∂t
Background flow
WAF
⃗ =⃗c g A
F
Wave breaking
Wave signal
∣∢( ⃗F , ⃗u bg )∣> 45 °
Wave-mean flow
interaction
∂ uo /∂ t=∇⋅⃗
F+ D
Theory/Motivation
Wave activity flux diagnostic
Intense surface cyclone composite
Summary
04
Basics of wave activity flux (WAF) diagnostic
Wave activity equation
∂A
+ ∇⋅⃗
F =D
∂t
Background flow
WAF
⃗ =⃗c g A
F
Wave breaking
Wave signal
∣∢( ⃗F , ⃗u bg )∣> 45 °
Wave-mean flow
interaction
We choose WAF formulation of
Takaya & Nakamura (2001)
∂ uo /∂ t=∇⋅⃗
F+ D
Theory/Motivation
Wave activity flux diagnostic
Intense surface cyclone composite
Summary
04
Sharper image of RWT
meridional wind v
Geopotential
height
Modulus of WAF
WAF (direction)
Geopotential
height
Theory/Motivation
Wave activity flux diagnostic
Intense surface cyclone composite
Summary
05
Sharper image of RWT
meridional wind v
Geopotential
height
Modulus of WAF
WAF (direction)
Geopotential
height
Theory/Motivation
Wave activity flux diagnostic
Intense surface cyclone composite
Summary
05
Sharper image of RWT
meridional wind v
Geopotential
height
Modulus of WAF
WAF (direction)
Geopotential
height
Theory/Motivation
Wave activity flux diagnostic
Intense surface cyclone composite
Summary
05
Dynamical more useful information
meridional wind v
Geopotential
height
Modulus of WAF
WAF (direction)
Geopotential
height
Indication of
wavebreaking
Theory/Motivation
Wave activity flux diagnostic
Intense surface cyclone composite
Summary
06
Wave activity flux
Application to composite of RWTs connected
with strong surface cyclones
Connection of RWTs with extreme events
Composite:
5 % strongest surface cyclones
- at 50°N,10°E
- data: ERA40, winter season
meridional wind v'
v ' =v−v DJF
Theory/Motivation
Wave activity flux diagnostic
Intense surface cyclone composite
Summary
07
Connection of RWTs with extreme events
Wirth & Eichhorn (2013)
RWT-path
meridional wind v'
v ' =v−v DJF
Theory/Motivation
Wave activity flux diagnostic
Intense surface cyclone composite
Summary
07
Connection of RWTs with extreme events
Wirth & Eichhorn (2013)
northward jump
of RWT-path?
RWT-path
meridional wind v'
v ' =v−v DJF
Theory/Motivation
Wave activity flux diagnostic
Intense surface cyclone composite
Summary
07
Connection of RWTs with extreme events - WAF
Theory/Motivation
Wave activity flux diagnostic
Intense surface cyclone composite
Summary
08
Connection of RWTs with extreme events - WAF
meridional wind v'
v '=v−v DJF
x
F(x ) ' =F (x) −F(x ) DJF
⃗
F
⃗∣
stat.sign.test of ∣F
... of RWT-breaking
Theory/Motivation
Wave activity flux diagnostic
Intense surface cyclone composite
Summary
08
Connection of RWTs with extreme events - WAF
Interpretation from WAF-signal?
meridional wind v'
v '=v−v DJF
x
F(x ) ' =F (x) −F(x ) DJF
⃗
F
⃗∣
stat.sign.test of ∣F
... of RWT-breaking
Theory/Motivation
Wave activity flux diagnostic
Intense surface cyclone composite
Summary
08
Connection of RWTs with extreme events - WAF
meridional wind v'
v '=v−v DJF
x
F(x ) ' =F (x) −F(x ) DJF
⃗
F
⃗∣
stat.sign.test of ∣F
... of RWT-breaking
Theory/Motivation
Wave activity flux diagnostic
Intense surface cyclone composite
Summary
08
Connection of RWTs with extreme events - WAF
meridional wind v'
v '=v−v DJF
x
F(x ) ' =F (x) −F(x ) DJF
⃗
F
⃗∣
stat.sign.test of ∣F
... of RWT-breaking
Theory/Motivation
Wave activity flux diagnostic
Intense surface cyclone composite
Summary
08
Connection of RWTs with extreme events - WAF
Interpretation from WAF-signal?
meridional wind v'
v '=v−v DJF
x
F(x ) ' =F (x) −F(x ) DJF
⃗
F
⃗∣
stat.sign.test of ∣F
... of RWT-breaking
Theory/Motivation
Wave activity flux diagnostic
Intense surface cyclone composite
Summary
08
Connection of RWTs with extreme events - WAF
meridional wind v'
v '=v−v DJF
x
F(x ) ' =F (x) −F(x ) DJF
⃗
F
⃗∣
stat.sign.test of ∣F
... of RWT-breaking
Theory/Motivation
Wave activity flux diagnostic
Intense surface cyclone composite
Summary
08
Connection of RWTs with extreme events - WAF
meridional wind v'
v '=v−v DJF
x
F(x ) ' =F (x) −F(x ) DJF
⃗
F
⃗∣
stat.sign.test of ∣F
... of RWT-breaking
Theory/Motivation
Wave activity flux diagnostic
Intense surface cyclone composite
Summary
08
Connection of RWTs with extreme events - WAF
Interpretation from WAF-signal?
meridional wind v'
v '=v−v DJF
x
F(x ) ' =F (x) −F(x ) DJF
⃗
F
⃗∣
stat.sign.test of ∣F
... of RWT-breaking
Theory/Motivation
Wave activity flux diagnostic
Intense surface cyclone composite
Summary
08
Connection of RWTs with extreme events - WAF
meridional wind v'
v '=v−v DJF
x
F(x ) ' =F (x) −F(x ) DJF
⃗
F
⃗∣
stat.sign.test of ∣F
... of RWT-breaking
Theory/Motivation
Wave activity flux diagnostic
Intense surface cyclone composite
Summary
08
Interpretation of WAF composite-signal
There are at least two different processes relevant for intense cyclones (50°N,10°E):
1. Large-scale trough (downstream of blocking ridge - probably forced by RWT)
35 % *
2. Preceeding RWT (as proposed by initial v-composite)
45 % *
* based on visual inspection
Theory/Motivation
Wave activity flux diagnostic
Intense surface cyclone composite
Summary
10
Composite-seperation - WAF-signal
Composite with preceeding RWT (45 %)
Theory/Motivation
Wave activity flux diagnostic
Intense surface cyclone composite
Summary
11
Composite-seperation - WAF-signal
Composite with preceeding RWT (45 %)
Theory/Motivation
Wave activity flux diagnostic
Composite with blocking feature (35 %)
Intense surface cyclone composite
Summary
11
Summary
Summary
Wave activity flux diagnostic
→ Method to diagnose RWTs, based on conserved quantity
∂A
+∇ ⃗
F =D
∂t
→ sharper image of RWT
- propagation direction, wavebreaking,
wave-mean flow-interaction
→ extreme surface cyclone-composite: 2 different underlying processes
Theory/Motivation
Wave activity flux diagnostic
Intense surface cyclone composite
Summary
12
Appendix
Connection of RWTs with extreme events - WAF
meridional wind v'
v '=v−v DJF
x
F(x ) ' =F (x) −F(x ) DJF
⃗
F
⃗∣
stat.sign.test of ∣F
... of RWT-breaking
Theory/Motivation
RWT detection
Wave activity flux diagnostic
summary
11

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