Subtropical CyclonesDiabatic

Energy Sources

BaroclinicEnergy Sources

Adapted from Fig. 9 in Beven (2012)30th Conference on Hurricanes and Tropical Meteorology

TCs Subtropical cyclones

Frontal cyclones

• Davis (2010) methodology:– Based on Ertel potential vorticity (PV)– Formulated in terms of two PV metrics that quantify the relative

contributions of baroclinic processes and condensation heating to the evolution of individual cyclones

• Davis (2010) methodology is similar to Hart (2003) cyclone phase space diagrams

Adapted Davis (2010) Methodology

Adapted Davis (2010) Methodology

• Lower-troposphericbaroclinic processes:(near-surface potentialtemperature anomaly)

absolute vorticity

425 hPa

Potential temperature anomaly Length of 6° box centered on cyclone

Adapted Davis (2010) Methodology

PV1/PV2 : measure of the contribution of lower-troposphericbaroclinic processes relative to the contribution of condensation heating

• Lower-troposphericbaroclinic processes:(near-surface potentialtemperature anomaly)

• Midtroposphericlatent heat release:(interior PV anomaly)

425 hPa

Ertel PV anomaly

Potential temperature anomaly Length of 6° box centered on cyclone

absolute vorticity

Adapted Davis (2010) Methodology

200 hPa

925 hPa

Lower-tropospheric baroclinic processes (PV1)

200 hPa

925 hPa

Adapted Davis (2010) Methodology

• Lower-troposphericbaroclinic processes:(near-surface potentialtemperature anomaly)

Lower-tropospheric baroclinic processes (PV1)

200 hPa

925 hPa

Adapted Davis (2010) Methodology

• Lower-troposphericbaroclinic processes:(near-surface potentialtemperature anomaly)

• Midtroposphericlatent heat release:(interior PV anomaly)

500 hPa

Lower-tropospheric baroclinic processes (PV1)

200 hPa

925 hPa

Adapted Davis (2010) Methodology

Midtroposphericlatent heat release

(PV2)

• Lower-troposphericbaroclinic processes:(near-surface potentialtemperature anomaly)

• Midtroposphericlatent heat release:(interior PV anomaly)

PV1/PV2 : measure of the contribution of lower-tropospheric baroclinic processes relative to the contribution of condensation heating

Adapted Davis (2010) Methodology

• Additional metric introduced to diagnose upper-tropospheric dynamical processes

• Upper-troposphericdynamical processes:(upper-tropospheric PV anomaly)

Ertel PV anomaly

300 hPa

Length of 6° box centered on cyclone

500 hPa

Lower-tropospheric baroclinic processes (PV1)

200 hPa

925 hPa

Adapted Davis (2010) Methodology

Midtroposphericlatent heat release

(PV2)

• Lower-troposphericbaroclinic processes:(near-surface potentialtemperature anomaly)

• Midtroposphericlatent heat release:(interior PV anomaly)

PV1/PV2 : measure of the contribution of lower-troposphericbaroclinic processes relative to the contribution of condensation heating

500 hPa

Lower-tropospheric baroclinic processes (PV1)

200 hPa

925 hPa

Adapted Davis (2010) Methodology

Midtroposphericlatent heat release

(PV2)

Upper-troposphericdynamical processes

(PV3)

• Lower-troposphericbaroclinic processes:(near-surface potentialtemperature anomaly)

• Midtroposphericlatent heat release:(interior PV anomaly)

• Upper-troposphericdynamical processes:(upper-tropospheric PV anomaly)

PV1/PV2 : measure of the contribution of lower-troposphericbaroclinic processes relative to the contribution of condensation heating

500 hPa

Lower-tropospheric baroclinic processes (PV1)

200 hPa

925 hPa

Adapted Davis (2010) Methodology

Midtroposphericlatent heat release

(PV2)

Upper-troposphericdynamical processes

(PV3)

PV1/PV2 : measure of the contribution of lower-troposphericbaroclinic processes relative to the contribution of condensation heating

Calculated from the 0.5° Climate ForecastSystem Reanalysis

V2 dataset

Hurricane Sandy: 6° × 6° box, NHC Best Track

Pea

ks in

PV

3

PV

1/P

V2

22 O

ctob

er

23 O

ctob

er

24 O

ctob

er

25 O

ctob

er

26 O

ctob

er

27 O

ctob

er

28 O

ctob

er

29 O

ctob

er

30 O

ctob

er

31 O

ctob

er

PV

U

Hurricane Sandy: 10° × 10° box, NHC Best Track

Pea

ks in

PV

3

PV

1/P

V2 P

VU

22 O

ctob

er

23 O

ctob

er

24 O

ctob

er

25 O

ctob

er

26 O

ctob

er

27 O

ctob

er

28 O

ctob

er

29 O

ctob

er

30 O

ctob

er

31 O

ctob

er

Hurricane Sandy: 12° × 12° box, NHC Best Track

Pea

ks in

PV

3

PV

1/P

V2 P

VU

22 O

ctob

er

23 O

ctob

er

24 O

ctob

er

25 O

ctob

er

26 O

ctob

er

27 O

ctob

er

28 O

ctob

er

29 O

ctob

er

30 O

ctob

er

31 O

ctob

er

Hurricane Sandy: 14° × 14° box, NHC Best Track

PV

U

PV

1/P

V2

Pea

ks in

PV

3

22 O

ctob

er

23 O

ctob

er

24 O

ctob

er

25 O

ctob

er

26 O

ctob

er

27 O

ctob

er

28 O

ctob

er

29 O

ctob

er

30 O

ctob

er

31 O

ctob

er

Hurricane Sandy: 16° × 16° box, NHC Best Track

PV

U

PV

1/P

V2

Pea

ks in

PV

3

22 O

ctob

er

23 O

ctob

er

24 O

ctob

er

25 O

ctob

er

26 O

ctob

er

27 O

ctob

er

28 O

ctob

er

29 O

ctob

er

30 O

ctob

er

31 O

ctob

er

Hurricane Sandy: 18° × 18° box, NHC Best Track

PV

U

PV

1/P

V2

Pea

ks in

PV

3

22 O

ctob

er

23 O

ctob

er

24 O

ctob

er

25 O

ctob

er

26 O

ctob

er

27 O

ctob

er

28 O

ctob

er

29 O

ctob

er

30 O

ctob

er

31 O

ctob

er

Hurricane Sandy: 20° × 20° box, NHC Best Track

PV

U

PV

1/P

V2

Pea

ks in

PV

3

22 O

ctob

er

23 O

ctob

er

24 O

ctob

er

25 O

ctob

er

26 O

ctob

er

27 O

ctob

er

28 O

ctob

er

29 O

ctob

er

30 O

ctob

er

31 O

ctob

er

500 hPa

Lower-tropospheric baroclinic processes (PV1)

200 hPa

925 hPa

Adapted Davis (2010) Methodology

Midtroposphericlatent heat release

(PV2)

Upper-troposphericdynamical processes

(PV3)

• Lower-troposphericbaroclinic processes:(near-surface potentialtemperature anomaly)

• Midtroposphericlatent heat release:(interior PV anomaly)

• Upper-troposphericdynamical processes:(upper-tropospheric PV anomaly)

PV1/PV2 : measure of the contribution of lower-troposphericbaroclinic processes relative to the contribution of condensation heating

300 hPa

Lower-tropospheric baroclinic processes (PV1)

200 hPa

925 hPa

Adapted Davis (2010) Methodology

Midtroposphericlatent heat release

(PV2)

Upper-troposphericdynamical processes

(PV3)

• Lower-troposphericbaroclinic processes:(near-surface potentialtemperature anomaly)

• Midtroposphericlatent heat release:(interior PV anomaly)

• Upper-troposphericdynamical processes:(upper-tropospheric PV anomaly)

PV1/PV2 : measure of the contribution of lower-troposphericbaroclinic processes relative to the contribution of condensation heating

Hurricane Sandy: 6° × 6° box, 500 hPa, NHC Best Track

Pea

ks in

PV

3

22 O

ctob

er

23 O

ctob

er

24 O

ctob

er

25 O

ctob

er

26 O

ctob

er

27 O

ctob

er

28 O

ctob

er

29 O

ctob

er

30 O

ctob

er

31 O

ctob

er

PV

U

PV

1/P

V2

Pea

ks in

PV

3

22 O

ctob

er

23 O

ctob

er

24 O

ctob

er

25 O

ctob

er

26 O

ctob

er

27 O

ctob

er

28 O

ctob

er

29 O

ctob

er

30 O

ctob

er

31 O

ctob

er

Hurricane Sandy: 6° × 6° box, 300 hPa, NHC Best Track

PV

U

PV

1/P

V2

300 hPa

Lower-tropospheric baroclinic processes (PV1)

200 hPa

925 hPa

Adapted Davis (2010) Methodology

Midtroposphericlatent heat release

(PV2)

Upper-troposphericdynamical processes

(PV3)

• Lower-troposphericbaroclinic processes:(near-surface potentialtemperature anomaly)

• Midtroposphericlatent heat release:(interior PV anomaly)

• Upper-troposphericdynamical processes:(upper-tropospheric PV anomaly)

PV1/PV2 : measure of the contribution of lower-troposphericbaroclinic processes relative to the contribution of condensation heating

500 hPa

Lower-tropospheric baroclinic processes (PV1)

200 hPa

925 hPa

Adapted Davis (2010) Methodology

Midtroposphericlatent heat release

(PV2)

Upper-troposphericdynamical processes

(PV3)

PV1/PV2 : measure of the contribution of lower-troposphericbaroclinic processes relative to the contribution of condensation heating

Calculated from the 0.5° Climate ForecastSystem Reanalysis

V2 dataset