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Convective-scale diagnostics
Rob Rogers
NOAA/AOML Hurricane Research Division
• Advances in forecasts of tropical cyclone (TC) intensity, and rapid
intensity change (RI) in particular, lag advances in TC track forecasts
• Multiscale nature of these processes major reason for this• environmental - O(1000 km) - troughs, shear
• vortex - O(1-100 km) - symmetric/asymmetric dynamics, VRWs
• convective – O(1 km) – convective bursts, vortical hot towers
• turbulent – O(1-100 m) - surface fluxes, entrainment/detrainment
• microscale – O(1mm) -- hydrometeor production, latent heat release
• Large-scale fields generally explain about 35% of skill in RI forecasts
(e.g., RI index). How much can smaller-scale processes explain?
• Numerical model forecasts of rapid intensity change (RI) should
improve as resolution increases
• For some cases it does, in others it does not – why?
• Robust diagnostic techniques for isolating impacts of physical
processes of various scales on RI important for improved physical
understanding, model evaluation and improvement
Motivation
Kaplan et al. 2009
35% of skill explained
by Rapid Intensification
Index (RII)
Motivation
Summary of diagnostics
Vortex-scale diagnostics• test of initial vortex structure, environment-vortex-convective
interactions, resolution
• symmetric structure of tangential, radial, vertical wind
• radial distribution
• vertical structure
• time evolution
Convective-scale diagnostics• test of physical parameterizations (microphysical, convective), resolution
• statistics of vertical motion, mass flux
• time-height vertical profiles
• vertical structure of distributions
• time evolution of distributions
• masking with 0.1 g/kg hydrometeor concentration used to approximate
Doppler sensitivity and facilitate comparison with observations
40
60
80
100
120
140
160
20
05
-08
-27
_0
0:0
0:0
0
20
05
-08
-27
_0
6:0
0:0
0
20
05
-08
-27
_1
2:0
0:0
0
20
05
-08
-27
_1
8:0
0:0
0
20
05
-08
-28
_0
0:0
0:0
0
20
05
-08
-28
_0
6:0
0:0
0
20
05
-08
-28
_1
2:0
0:0
0
20
05
-08
-28
_1
8:0
0:0
0
20
05
-08
-29
_0
0:0
0:0
0
20
05
-08
-29
_0
6:0
0:0
0
20
05
-08
-29
_1
2:0
0:0
0
Pe
ak
win
d (
kt)
27-9 km
9-3 km
BT
8/2
7 0
0Z
8/2
7 0
6Z
8/2
7 1
2Z
8/2
7 1
8Z
8/2
8 0
0Z
8/2
8 0
6Z
8/2
8 1
2Z
8/2
8 1
8Z
8/2
9 0
0Z
8/2
9 0
6Z
8/2
9 1
2Z40
60
80
100
120
140
160
Peak w
ind
(kt)
RI BTRI 9:3 km RI 27:9 km
• Hurricane Katrina (2005) • Underwent RI from Cat 3 to Cat 5 as it traversed Gulf of Mexico
• Both resolutions produced RI, but both delayed
• Good observational coverage (multiple P-3 flights with Doppler)
Example
00Z Aug 27
12Z Aug 27
00Z Aug 28
12Z Aug 28
00Z Aug 29
12Z Aug 29
50 100 150 200
00Z Aug 27
12Z Aug 27
00Z Aug 28
12Z Aug 28
00Z Aug 29
12Z Aug 29
50 100 150 20000Z Aug 27
12Z Aug 27
00Z Aug 28
12Z Aug 28
00Z Aug 29
12Z Aug 29
50 100 150 200
0
5
10
15
20
25
30
35
40
45
50
55
0
5
10
15
20
25
30
35
40
45
50
55
0
5
10
15
20
25
30
35
40
45
50
55
radius (km)
radius (km) radius (km)
RI
RI
RI
Time-radius Hovmoller of axisymmetric 10-m wind from H*Wind and HWRF-x
Vortex-scale diagnostics: Wind field size & structure
H*Wind
HWRF-x 27:9 km HWRF-x 9:3 km
IKE
0
20
40
60
80
100
120
140
8/2
7 0
0Z
8/2
7 0
3Z
8/2
7 0
6Z
8/2
7 0
9Z
8/2
7 1
2Z
8/2
7 1
5Z
8/2
7 1
8Z
8/2
7 2
1Z
8/2
8 0
0Z
8/2
8 0
3Z
8/2
8 0
6Z
8/2
8 0
9Z
8/2
8 1
2Z
8/2
8 1
5Z
8/2
8 1
8Z
8/2
8 2
1Z
8/2
9 0
0Z
8/2
9 0
3Z
8/2
9 0
6Z
8/2
9 0
9Z
8/2
9 1
2Z
IKE
(TJ)
IKE_H values for Hurricane Katrina
IKE_H 9:3km
IKE_H 27:9km
IKE_H H*Wind
0
50
100
150
200
250
8/2
7 0
0Z
8/2
7 0
3Z
8/2
7 0
6Z
8/2
7 0
9Z
8/2
7 1
2Z
8/2
7 1
5Z
8/2
7 1
8Z
8/2
7 2
1Z
8/2
8 0
0Z
8/2
8 0
3Z
8/2
8 0
6Z
8/2
8 0
9Z
8/2
8 1
2Z
8/2
8 1
5Z
8/2
8 1
8Z
8/2
8 2
1Z
8/2
9 0
0Z
8/2
9 0
3Z
8/2
9 0
6Z
8/2
9 0
9Z
8/2
9 1
2Z
IKE
(TJ)
IKE_TS values for Hurricane Katrina
IKE_TS 9:3km
IKE_TS 27:9km
IKE_TS H*Wind
8/2
7 0
0Z
8/2
7 0
6Z
8/2
7 1
2Z
8/2
7 1
8Z
8/2
8 0
0Z
8/2
8 0
6Z
8/2
8 1
2Z
8/2
8 1
8Z
8/2
9 0
0Z
8/2
9 0
6Z
8/2
9 1
2Z
8/2
7 0
0Z
8/2
7 0
6Z
8/2
7 1
2Z
8/2
7 1
8Z
8/2
8 0
0Z
8/2
8 0
6Z
8/2
8 1
2Z
8/2
8 1
8Z
8/2
9 0
0Z
8/2
9 0
6Z
8/2
9 1
2Z
0
50
100
150
200
250
0
20
40
60
80
100
120
140
IKE
(T
J)
IKE
(T
J)
obs 9:3 km obs 9:3 km27:9 km 27:9 km
Time series of integrated kinetic energy (IKE) for 10-m winds thresholded by
tropical storm and hurricane force winds from H*Wind and HWRF-x
Vortex-scale diagnostics: Wind field size & structure
IKE thresholded by tropical storm-force winds IKE thresholded by hurricane-force winds
25 50 75 100
2
4
6
8
10
12
14
16
he
igh
t (k
m)
2
4
6
8
10
12
14
16
2
4
6
8
10
12
14
16
25 50 75 100 25 50 75 100
25 50 75
2
4
6
8
10
12
14
16
he
igh
t (k
m)
2
4
6
8
10
12
14
16
2
4
6
8
10
12
14
16
25 50 75 100 25 50 75 100100
radius (km)
radius (km)
radius (km)
radius (km)
radius (km)
radius (km)
Axisymmetric tangential (shaded, m s-1) and radial wind (contour, m s-1) for Doppler
and HWRF-x
20:08Z 8/27
19:23Z 8/28
00Z 8/28
03Z 8/29
00Z 8/28
03Z 8/29
27:9 km 9:3 kmDoppler
27:9 km 9:3 kmDoppler
Vortex-scale diagnostics: Vertical structure of axisymmetric vortex
20
30
40
50
60
70
80
90
100
110
20
05
-08
-27
_0
0:0
0:0
0
20
05
-08
-27
_0
6:0
0:0
0
20
05
-08
-27
_1
2:0
0:0
0
20
05
-08
-27
_1
8:0
0:0
0
20
05
-08
-28
_0
0:0
0:0
0
20
05
-08
-28
_0
6:0
0:0
0
20
05
-08
-28
_1
2:0
0:0
0
20
05
-08
-28
_1
8:0
0:0
0
20
05
-08
-29
_0
0:0
0:0
0
20
05
-08
-29
_0
6:0
0:0
0
20
05
-08
-29
_1
2:0
0:0
0
2-km
RM
W (k
m)
RMW (27-9 km)
RMW (9-3 km)
RMW (Dop)
8/2
7 0
0Z
8/2
7 0
6Z
8/2
7 1
2Z
8/2
7 1
8Z
8/2
8 0
0Z
8/2
8 0
6Z
8/2
8 1
2Z
8/2
8 1
8Z
8/2
9 0
0Z
8/2
9 0
6Z
8/2
9 1
2Z
20
30
40
50
60
70
80
90
100
110
rad
ius (
km
)
obs 9:3 km 27:9 km
Time series of radius of peak axisymmetric tangential wind at 2 km altitude (km) from
Doppler and HWRF-x
Vortex-scale diagnostics: Time evolution of vortex size
50 100 150 200
radius (km)
25 75 125 17550 100 150 200
radius (km)
25 75 125 175
50 100 150 200
radius (km)
25 75 125 17550 100 150 200
radius (km)
25 75 125 175
00Z Aug 27
12Z Aug 27
00Z Aug 28
12Z Aug 28
00Z Aug 29
12Z Aug 29
00Z Aug 27
12Z Aug 27
00Z Aug 28
12Z Aug 28
00Z Aug 29
12Z Aug 29
00Z Aug 27
12Z Aug 27
00Z Aug 28
12Z Aug 28
00Z Aug 29
12Z Aug 29
00Z Aug 27
12Z Aug 27
00Z Aug 28
12Z Aug 28
00Z Aug 29
12Z Aug 29
RI RI
RI RI
Time-radius Hovmoller of axisymmetric tangential wind and vertical velocity at 5.1 km altitude
27:9 km
9:3 km
27:9 km
9:3 km
ut
ut
w
w
Vortex-scale diagnostics: Time evolution of axisymmetric vortex size
50 100 150 200
radius (km)
25 75 125 17550 100 150 200
radius (km)
25 75 125 175
50 100 150 200
radius (km)
25 75 125 17550 100 150 200
radius (km)
25 75 125 175
2
4
6
8
10
12
14
16
he
igh
t (k
m)
18
2
4
6
8
10
12
14
16
he
igh
t (k
m)
18
2
4
6
8
10
12
14
16
he
igh
t (k
m)
18
2
4
6
8
10
12
14
16
he
igh
t (k
m)
18
Axisymmetric tangential wind (shaded, m s-1) and vertical velocity (contour, m s-1)
27:9 km
27:9 km
9:3 km
9:3 km
00Z 8/28
03Z 8/29
00Z 8/28
03Z 8/29
Vortex-scale diagnostics: Vertical structure of axisymmetric vortex
-3
-2
-1
0
1
2
3
4
5
6
20
05
-08
-27
_0
0:0
0:0
0
20
05
-08
-27
_0
6:0
0:0
0
20
05
-08
-27
_1
2:0
0:0
0
20
05
-08
-27
_1
8:0
0:0
0
20
05
-08
-28
_0
0:0
0:0
0
20
05
-08
-28
_0
6:0
0:0
0
20
05
-08
-28
_1
2:0
0:0
0
20
05
-08
-28
_1
8:0
0:0
0
20
05
-08
-29
_0
0:0
0:0
0
20
05
-08
-29
_0
6:0
0:0
0
20
05
-08
-29
_1
2:0
0:0
0
eye
wal
l slo
pe
(km
/km
)2-8 km slope (27-9 km)
2-8 km slope (9-3 km)
2-8 km slope (Dop)8/2
7 0
0Z
8/2
7 0
6Z
8/2
7 1
2Z
8/2
7 1
8Z
8/2
8 0
0Z
8/2
8 0
6Z
8/2
8 1
2Z
8/2
8 1
8Z
8/2
9 0
0Z
8/2
9 0
6Z
8/2
9 1
2Z
-3
-2
-1
0
1
2
3
4
5
6
Eyew
all
slo
pe (
km
/km
)
obs 9:3 km 27:9 km
Time series of 2-8 km altitude eyewall slope (km km-1) from Doppler and HWRF-x
Vortex-scale diagnostics: Time evolution of vortex vertical structure
Outward slope with height
Inward slope with height
Wind speed (m/s) at
2-km altitude
Vorticity (shaded,
x 10-3 s-1) and w
(contour, m/s) at 4-
km altitude
Doppler 27:9 km HWRF-x 9:3 km HWRF-x
50 100 1500 50 100 1500 50 100 1500
50
100
150
0
50
100
150
0
50
100
150
0
50 100 1500 50 100 1500
50
100
150
0
50
100
150
0
500
50
0
0
-2
-1
1
3
5
7
2
4
6
35
30
40
50
60
70
45
55
65
distance (km)
dis
tan
ce (
km
)
distance (km)
dis
tan
ce (
km
)
distance (km)
dis
tan
ce (
km
)
distance (km)
dis
tan
ce (
km
)
distance (km)
dis
tan
ce (
km
)
distance (km)
dis
tan
ce (
km
)
2038-2231 UTC 8/28 0000 UTC 8/29 0000 UTC 8/29
Vortex- and convective-scale diagnostics: Wind speed, vertical motion, and vorticity
Time series of mean updraft/downdraft velocity (m s-1) profiles in 4° box with maskingh
eig
ht
(km
)
2
4
6
8
10
12
14 Updraft 27:9 kmRI
he
igh
t (k
m)
2
4
6
8
10
12
14 Updraft 9:3 kmRI
he
igh
t (k
m)
2
4
6
8
10
12
14 Downdraft 27:9 kmRI
he
igh
t (k
m)
2
4
6
8
10
12
14 Downdraft 9:3 kmRI
Convective-scale diagnostics: Time evolution of vertical profiles
Time series of aggregate updraft/downdraft vertical mass flux (x 1010 kg s-1) profiles
in 4° box with masking
he
igh
t (k
m)
2
4
6
8
10
12
14 Downdraft 9:3 km
he
igh
t (k
m)
2
4
6
8
10
12
14 Updraft 27:9 kmRI
he
igh
t (k
m)
2
4
6
8
10
12
14 Downdraft 27:9 kmRI
he
igh
t (k
m)
2
4
6
8
10
12
14 Updraft 9:3 kmRI
RI
Convective-scale diagnostics: Time evolution of vertical profiles
he
igh
t (k
m)
2
4
6
8
10
12
14
16
18
-6 -4 -2 0 2 4 6 8 10
vertical velocity (m/s)
12
1 km
-2 -1 0 1 2 3 4 5
vertical velocity (m/s)
6
10
20
30
40
50
60
70
80
90
100
0
pe
rcen
tag
e
14 km
-2 -1 0 1 2 3 4 5 6
vertical velocity (m/s)
5
10
15
20
25
30
35
40
0
pe
rcen
tag
e
vertical velocity
Convective-scale diagnostics: Contoured frequency by altitude diagram (CFAD)
he
igh
t (k
m)
he
igh
t (k
m)
12
2
4
6
8
10
12
14
16
18
-6 -4 -2 0 2 4 6 8 10 12
vertical velocity (m/s)
2
4
6
8
10
12
14
16
18
-6 -4 -2 0 2 4 6 8 10 12
vertical velocity (m/s)
2
4
6
8
10
12
14
16
18
-6 -4 -2 0 2 4 6 8 10 12
vertical velocity (m/s)
2
4
6
8
10
12
14
16
18
-6 -4 -2 0 2 4 6 8 10
vertical velocity (m/s)
2
4
6
8
10
12
14
16
18
-6 -4 -2 0 2 4 6 8 10 12
vertical velocity (m/s)
2
4
6
8
10
12
14
16
18
-6 -4 -2 0 2 4 6 8 10 12
vertical velocity (m/s)
Vertical velocity CFADs for Doppler radar and HWRF-x with masking
20:08Z 8/27
22:31Z 8/28
12Z 8/27
12Z 8/28
12Z 8/27
12Z 8/28
27:9 km
27:9 km
9:3 km
9:3 km
Doppler
Doppler
Convective-scale diagnostics: Contoured frequency by altitude diagram (CFAD)
00Z Aug 27
12Z Aug 27
00Z Aug 28
12Z Aug 28
00Z Aug 29
12Z Aug 29
00Z Aug 30
00Z Aug 27
12Z Aug 27
00Z Aug 28
12Z Aug 28
00Z Aug 29
12Z Aug 29
00Z Aug 30
00Z Aug 27
12Z Aug 27
00Z Aug 28
12Z Aug 28
00Z Aug 29
12Z Aug 29
00Z Aug 30
00Z Aug 27
12Z Aug 27
00Z Aug 28
12Z Aug 28
00Z Aug 29
12Z Aug 29
00Z Aug 30
-6 -4 -2 0 2 4 6 8 10 12 -6 -4 -2 0 2 4 6 8 10 12
-6 -4 -2 0 2 4 6 8 10 12 -6 -4 -2 0 2 4 6 8 10 12
vertical velocity (m/s) vertical velocity (m/s)
vertical velocity (m/s) vertical velocity (m/s)
14 km alt 27:9 km
5 km alt 27:9 km
14 km alt 9:3 km
5 km alt 9:3 km
Time series of vertical velocity distribution (%) at 5- and 14-km altitudes with masking
RI
RI
RI
RI
Convective-scale diagnostics: Time evolution of distributions
0
0.5
1
1.5
2
2.5
3
3.5
4
0
0.5
1
1.5
2
2.5
3
3.5
4
are
a (
x 1
04
km
2)
are
a (
x 1
04
km
2)
Time series of areal coverage (x 104 km2) of threshold values of
3-7 km vertical velocity in 4x4 deg box with masking
27:9 km 9:3 km1 m s-1
2 m s-1
3 m s-1
1 m s-1
2 m s-1
3 m s-1RI RI
Convective-scale diagnostics: Time evolution of convective coverage
Summary
•convective- and vortex-scale diagnostics can reveal much about inner-core
structure and evolution from model and observations• RMW, size of wind field at various thresholds, integrated kinetic energy
• secondary eyewall, outer rainband evolution, eyewall slope
• vertical velocity and mass flux profiles
• vertical structure of vertical velocity distributions
• time evolution of vertical velocity distributions
• differences between HWRF-x and observations for Katrina case• both resolutions produced RI, but both were delayed. 9:3 km was sooner, stronger
than 27:9 km
• vortex-scale
• RMW broader, outer wind field smaller in model compared to observations
• both resolutions produced outer updraft maxima, 9:3 km produced hint of
contracting secondary eyewall
• eyewall slope generally less for 9:3 km than 27:9 km, more time evolution
• convective-scale
• mean updraft profiles peaked at higher altitude, downdrafts stronger in 9:3 km
• stronger updraft and downdraft mass flux in 9:3 km
• stronger updraft/downdraft, vorticity cores in 9:3 km
•all these quantities readily calculated from HWRF-x, airborne Doppler, and
H*Wind analyses
Future work
• include azimuthal asymmetries
• partition into precipitation structure regimes
(eyewall/rainband/stratiform)
• finer-scale diagnostics (turbulent, microphysical) from model and
observations
• broaden to multi-case diagnostics – normalization issues?
• ensemble-based diagnostics