influence of cloud-radiative processes on tropical cyclone storm structure and intensity
DESCRIPTION
HSRP meeting 9 May 2013, NASA Ames. Influence of cloud-radiative processes on tropical cyclone storm structure and intensity. Robert Fovell and Yizhe Peggy Bu University of California, Los Angeles [email protected]. Collaborators : - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/1.jpg)
Influence of cloud-radiative processes on tropical cyclone storm structure and intensityRobert Fovell and Yizhe Peggy BuUniversity of California, Los [email protected]
Collaborators: Hui Su and Longtao Wu, JPL; Greg Thompson, NCAR/DTC; Ligia Bernardet and Mrinal Biswas, DTC; Brad Ferrier, NCEP
1
HSRP meeting 9 May 2013, NASA Ames
![Page 2: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/2.jpg)
2
Near environment(200-400 km)
Relative humidity anomalies in TC front-right quadrant
Far environment(600-800 km)
Wu et al. (2012, GRL)
W: Weakening; N: Neutral; I: Intensifying; RI: Rapidly Intensifying
![Page 3: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/3.jpg)
Relevant science questions
• How does the outflow layer interact with the environment?• How do intrusions of dry air impact
intensity change?
3
![Page 4: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/4.jpg)
Background
4
![Page 5: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/5.jpg)
• Real-data WRF-ARW @ 3 or 4 km• 72 h• Uniform SST• No initial flow• NO LAND• 7 microphysics (MP)
schemes• One initial condition
Semi-idealized experiment
Fovell et al. (2009)Fovell et al. (2010)
very small part of domain shown
5
![Page 6: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/6.jpg)
• These MP schemes yielded different…• …amounts of various
hydrometeors• …diabatic heating
patterns• …symmetric wind
structures• …asymmetry patterns• …motions• …intensities
Semi-idealized experiment
Fovell et al. (2009)Fovell et al. (2010)
very small part of domain shown
6
![Page 7: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/7.jpg)
Influence of cloud-radiative feedback (CRF)
Fovell et al. (2010)
CRF offCRF on
7
CRF-on CRF-off
![Page 8: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/8.jpg)
Troposphere-averaged vertical velocity
8
Top row: CRF onBottom row: CRF off
150 km CRF caused storms to be wider, less asymmetric, weaker
Fovell et al. (2010)with ARW, curved Earth
![Page 9: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/9.jpg)
Hypotheses• CRF amplifies differences among MP schemes• CRF actively leads to wider anvils• Anvil self-spreading mechanism
• CRF indirectly enhances outer core convective activity• Moistening of outer core region
• CRF leads to weaker inner core intensity• Competition between eyewall and outer core convection
• CRF results in wider eyes• Possible direct (CRF diabatic forcing) and indirect (via enhanced
convection) influences• Lack of CRF in HWRF may explain eye size and intensity biases• HWRF eyes tend to be too small, too annular• HWRF storms tend to be too intense
9
![Page 10: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/10.jpg)
More semi-idealized WRF-ARW simulationsf-plane & curved Earth
10
![Page 11: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/11.jpg)
Experimental design
• WRF 3.4.1 “real-data” version• f-plane 20˚N or fully curved Earth• 4 km resolution• No land, uniform SST• Modified Jordan sounding• No initial wind or shear• Bubble initialization• Thompson microphysics (among others)• RRTMG LW and SW radiation (among others)• 96 h simulations with and without CRF
11
![Page 12: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/12.jpg)
Radial (colored) and tangential (contoured) winds
Top: CRF-onBottom: CRF-off
12
CRF-off storm is narrower, stronger
CRF-on storm has more extensive radial outflow
400 km
f-planeTemporally & azimuthally averaged – last 24 h
![Page 13: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/13.jpg)
Condensate (colored) and net radiative forcing (contoured)
Top: CRF-onBottom: CRF-off
13
CRF-on storm has more extensive anvil
400 km
f-plane-0.9 K/h
only clear sky
C
W
![Page 14: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/14.jpg)
Condensate (colored) and radiative forcing (contoured)
Top: LW componentBottom: SW component
14
Substantial cancellation between LW & SW… during the day
400 km
f-plane-1.6 K/h
0.8 K/h
LW
SWOver 24 h
![Page 15: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/15.jpg)
Condensate (colored) and radiative forcing (contoured)
Top: LW ONLYBottom: SW ONLY
15
Substantial cancellation between LW & SW… during the day
400 km
f-plane-1.6 K/h
0.8 K/h
LW
SW
CloudSat obs Wu and Su,
JPL
![Page 16: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/16.jpg)
Diabatic heating from microphysics (colored) and net radiative forcing (contoured)
Top: CRF-onBottom: CRF-off
16
CRF-on storm has more upper-level heating, less lower-level cooling
400 km
f-plane
![Page 17: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/17.jpg)
Difference fields fordiabatic heating from microphysics (colored) and net radiative forcing (contoured)
Top: CRF-onBottom: CRF-off
17400 km
f-plane
CRF-on storm has more extensive heating, concentrated in upper troposphere
Eye widthdifference
Extra heating
![Page 18: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/18.jpg)
Tangential wind at lowest model level: CRF-on vs. CRF-off
10 m/s or 20 kt
18
CRF-on is:
weakerwider
broader
CRF-on
CRF-off
![Page 19: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/19.jpg)
Tangential wind at lowest model level: f-plane vs. curved Earth
10 m/s or 20 kt
19
Curved EarthCRF-on now
more intense;outer winds still
stronger
CRF-on
CRF-off
curved Earth
![Page 20: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/20.jpg)
Radial (colored) and tangential (contoured) winds
Top: CRF-onBottom: CRF-off
20
CRF-off storm is slightly narrower, but weaker
CRF-on storm has more extensive radial outflow
400 km
Curved Earth
![Page 21: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/21.jpg)
Diabatic heating from microphysics (colored) and net radiative forcing (contoured)
Top: CRF-onBottom: CRF-off
21
400 km
Curved Earth
CRF-on storm has more outer core heating;little net cooling seen
![Page 22: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/22.jpg)
22
f-plane curved EarthDiabatic forcing
ON
OFF
![Page 23: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/23.jpg)
Difference fields fordiabatic heating from microphysics (colored) and net radiative forcing (contoured)
Top: f-planeBottom: curved Earth
23
Heating difference patterns are different
400 km
![Page 24: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/24.jpg)
Impacts of CRF• Strengthens radial outflow• Enhances outer region convection• Broadens wind field• Widens storm eye• No systematic influence on intensity• Sensitivity to microphysics scheme• Large in schemes rich in cloud ice and snow• Small in “graupel-happy” parameterizations
• Operational HWRF (still) has no CRF• May help explain some model size, structure biases
24
Red text = not shown here
![Page 25: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/25.jpg)
The physics of CRF: how and whyAxisymmeric simulations with CM1Moist and dry versions
25
![Page 26: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/26.jpg)
CM1 experimental design
• Axisymmetric framework (f-plane 20˚N)• 5 km resolution• 16 day simulations• Rotunno-Emanuel moist-neutral sounding• Goddard radiation (modified)• Thompson microphysics• Averaging period: last 4 days
26
![Page 27: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/27.jpg)
Tangential wind at lowest model level
10 m/s or 20 kt
27
CRF-on stronger than
CRF-off;Both much
stronger than 3D versions
CRF-on
CRF-off
10 m/s
![Page 28: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/28.jpg)
Condensate (colored) and total radiative forcing (contoured)
Top: CRF-onBottom: CRF-off
28
CRF-on storm has wider anvil, and is also deeper
400 km
![Page 29: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/29.jpg)
Radial (colored) and tangential (contoured) winds
Top: CRF-onBottom: CRF-off
29
CRF-on storm again wider with stronger outflow but also higher intensity
400 km
![Page 30: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/30.jpg)
Radial wind (colored) and CRF forcing (contoured)
Top: CRF differences
30
By itself, CRF forcing encourages stronger radial outflow
Eye widthdifference
Deeper, stronger, more extensive outflow
![Page 31: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/31.jpg)
Radial wind (colored) and CRF forcing (contoured)
Top: CRF differencesBottom: dry model
31
By itself, CRF forcing encourages stronger radial outflow
![Page 32: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/32.jpg)
Direct response to CRF forcing
32• CRF induces stronger radial outflow
• Outflow advects hydrometeors that carry the CRF forcing• Anvil expansion (positive feedback)
![Page 33: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/33.jpg)
Condensate (colored) and total radiative forcing (contoured)
Top: CRF-onBottom: CRF-off
33
Is the cloud-radiative forcing active or passive?
400 km
![Page 34: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/34.jpg)
Condensate (colored) and total radiative forcing (contoured)
Top: CRF-onBottom: CRF-fixed
34
CRF is active.
400 km
CRF forcing averaged overlast 3 days, applied &held fixed. BackgroundLW cooling removed.
![Page 35: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/35.jpg)
A diabatic heating difference field (CRF-on – CRF-off)
35Eye widthdifference
Extra heating owing to CRF
![Page 36: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/36.jpg)
Dry model response
Diabatic forcing from moist modelCRF-on
36
400 km
500 km
![Page 37: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/37.jpg)
Dry model response
widens, broadens
37
Diabatic forcing from moist modelCRF-on
400 km
500 km
![Page 38: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/38.jpg)
Dry model response 38
Diabatic forcing from moist modelCRF-on
400 km
500 km
![Page 39: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/39.jpg)
Cartoon
39
![Page 40: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/40.jpg)
Cartoon
40
CRF
![Page 41: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/41.jpg)
Cartoon
41
![Page 42: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/42.jpg)
Cartoon
42
![Page 43: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/43.jpg)
Cartoon
43
![Page 44: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/44.jpg)
Conclusions• CRF (directly) encourages stronger radial outflow, and
(indirectly) establishes stronger cyclonic winds• Influence on intensity … adds to uncertainty• Significant diurnal cycle also results (not shown)• Dependent on particle sizes (microphysics assumptions)• May explain some model structural biases• Need better understanding (observations) of LW & SW forcing
magnitudes
44
![Page 45: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/45.jpg)
[end]
45
![Page 46: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/46.jpg)
46
![Page 47: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/47.jpg)
47
![Page 48: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/48.jpg)
Radial (colored) and tangential (contoured) winds
Top: RRTMG standardBottom: RRTMG connect
48
Passing particle size information from microphysics to radiation has little impact
400 km
ARW with Thompson MP: RRTMG vs. “connected RRTMG”f-plane
![Page 49: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/49.jpg)
Radial (colored) and tangential (contoured) winds
Top: RRTMG LW/SWBottom: FLG LW/SW
49
Radiation scheme makeslittle difference
400 km
ARW with Thompson MP: RRTMG vs. Fu-Liou-Gu radiationf-plane
![Page 50: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/50.jpg)
How does dry air impact TC storm development and/or intensity?
• Possible negative influences• Promote downdrafts, lowering inflow CAPE and/or blocking
inflow• Ventilation above surface layer• Encourage asymmetric convection
• Possible positive influences• Suppress outer core convective activity
50
![Page 51: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/51.jpg)
• Close proximity of dry air delays TC development,primarily by encouraging asymmetric convection• Eventually, TC moistens its local environment
Braun et al. (2011)
51
![Page 52: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/52.jpg)
Bu (2012)
Axisymmetric model experiments
52
![Page 53: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/53.jpg)
Bu (2012)
53
Axisymmetric model experiments
![Page 54: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/54.jpg)
54
Bu (2012)
![Page 55: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/55.jpg)
55
Near environment(200-400 km)
Relative humidity in TC front-right quadrant
Far environment(600-800 km)
Wu et al. (2012)
W: Weakening; N: Neutral; I: Intensifying; RI: Rapidly Intensifying
![Page 56: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/56.jpg)
56
Near environment(200-400 km)
Relative humidity in TC front-right quadrant
Far environment(600-800 km)
Wu et al. (2012)
Near-Far RH gradient
![Page 57: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/57.jpg)
“Bubble” initialization
57
Small portion of domain shown
![Page 58: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/58.jpg)
Condensate (colored) and net radiative forcing (contoured)
Top: CRF-onBottom: CRF-off
58
400 km
Curved Earth
CRF-on storm has more extensive anvil
![Page 59: Influence of cloud-radiative processes on tropical cyclone storm structure and intensity](https://reader035.vdocuments.us/reader035/viewer/2022070422/56816581550346895dd81d9b/html5/thumbnails/59.jpg)
ARW simulation strategy
59All plots are temporally averaged in a vortex-centered reference frame
between 72 and 96 h.Vertical cross-sections are also averaged azimuthally.