paper review by zhibo zhang
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Evolution of a Florida Thunderstorm during the Convection and Precipitation/Electrification Experiment: The Case of 9 August 1991. Paper Review By Zhibo Zhang. Paper Overview. Motivation - PowerPoint PPT PresentationTRANSCRIPT
Evolution of a Florida Thunderstorm during the Convection and
Precipitation/Electrification Experiment:
The Case of 9 August 1991
Evolution of a Florida Thunderstorm during the Convection and
Precipitation/Electrification Experiment:
The Case of 9 August 1991 Paper Review
By
Zhibo Zhang
Paper Review
By
Zhibo Zhang
Paper OverviewPaper Overview
Motivation Presents an analytical, detailed and vivid description of the evolution of a
multicell thunderstorm , with particular focus on the relationships among kinematic, microphysical and electric field.
Event A multicell thunderstorm,9 August 1991, in Florida
Characteristics Various observation platforms involved Good overlapping coverage in radar and aircraft data
(three Doppler radars, four aircrafts, a surface electric field net work, etc…) Main Results ……
Motivation Presents an analytical, detailed and vivid description of the evolution of a
multicell thunderstorm , with particular focus on the relationships among kinematic, microphysical and electric field.
Event A multicell thunderstorm,9 August 1991, in Florida
Characteristics Various observation platforms involved Good overlapping coverage in radar and aircraft data
(three Doppler radars, four aircrafts, a surface electric field net work, etc…) Main Results ……
Our Questions Our Questions
Motivation Did the authors success to give the us a clear and convincing analysis about
the relationships between kinematic, microphysical and electric field properties?
Event What’s going on in that storm according to the authors and why did they think
so?
Characteristics How did the data coming from different facilities work together? Is this more
supportive or causing more troubles?
Main Results Which one is most exciting? Which one may not be common in other cases?
Motivation Did the authors success to give the us a clear and convincing analysis about
the relationships between kinematic, microphysical and electric field properties?
Event What’s going on in that storm according to the authors and why did they think
so?
Characteristics How did the data coming from different facilities work together? Is this more
supportive or causing more troubles?
Main Results Which one is most exciting? Which one may not be common in other cases?
Background Knowledge Background Knowledge
CaPE project (Convective and Precipitation/Electrification, East Central Florida, 8 July -18 August, 1991)
Objective: Identify the relationships among the coevolving wind,
water, and electric fields within convective clouds. Observation facilities
CaPE project (Convective and Precipitation/Electrification, East Central Florida, 8 July -18 August, 1991)
Objective: Identify the relationships among the coevolving wind,
water, and electric fields within convective clouds. Observation facilities
Particle images, electric field, IWC, LWC,w,Zh,Zdr, LDR, A3
CP-2,CP-3,Cp-4 P-3, T28, WKA, NKA
Evolution of The Strom Evolution of The Strom
Time:1758: cell B vigorous growth Zh~40dBZ, w~14m/s Zdr column up to 6.5km
Time:1803:A number of new cells formedTime:1808:Strongest updraft in cell A (16m/s) Zdr column up to 6.0 km with values exceeding 3dB from 2-5km
Time:1810:Cell A in vigorous growth P-3 penetrates cell a along X” from SE to NW, at 180937-181027
Time:1814:A new updraft core,cell A’, developed to the SE of cell A. Time:1821:Cell A remains dominant, but Zdr column down to 4-km, with maximum value down to 2dB
Time:1827:Cell A’ in mature stage, with a young developing cell, A”, at SE. T-28 penetrates cell A’ and A” along X”’, from SE to NW, at 182645-182845
Vigorous Growth Period--Cell AVigorous Growth Period--Cell A
Cell A: radar evolution Cell A: radar evolution
First updraft pulse
Enhanced LDR cap
•First updraft around 1810(360s) carries raindrops to low temperature and they freeze•LDR cap•IWC grows between 5-7km at beginning, leads to max rain flux 600s later at 2-km level
IWC grows between
5-7km
Max rain flux at 2-km level 600s after first
updraft
Cell A: Snapshot at 1810 UTCCell A: Snapshot at 1810 UTC
180937181027
SENW
Cell A: Mixed phase domainCell A: Mixed phase domain
Radar signals
Zh contour Zdr gray scaleZdr contour LDRr gray scale Zdr contour A3 gray scale
Zh>40dB Zdr>1dB LDR>-21dB A3~0.5-1.5dB
Microphysics Mixed phase domainSuper cooled drop, frozen and partially frozen drops
Cell A: Particle imagesCell A: Particle images
Smooth edge+elliptical cross section~liquid drops (distortion of airflow)
Circular cross section~Frozen drops (unlikely to be distorted))
Particle image suggests
The mixed phase domain
Cell A: Theoretical calculationCell A: Theoretical calculation
•Size distribution model (in situ observation)•Particle model: super-cooled oblate water drops with concentric oblate ice shell •Orientation (distortion angles): Gaussian distribution
Proper set up of size distribution,Particle and distortion model can give rise to measured radar signals,without invoking wet growth.
Cell D: Radar evolution & Aircraft
penetration Cell D: Radar evolution & Aircraft
penetration 1,WKA 4km,1804
2a,WKA,5.5km 18082b,NKA,4.5km 1808
3a,WKA,5.5km 18113b,NKA,4.0km 1811
Cell D: Snapshot at1808UTC Cell D: Snapshot at1808UTC
Relative Low Zh~35dBZ,High Zdr~2.5dB
Warm rain process: Large drops Low concentrationActive coalescence process
Cell D VS Cell A Cell D VS Cell A Cell A: W~12m/s Zh~45-50dBZ Zdr~1.5dB LDR~-21dB
Cell D: W~12m/s Zh~30-35dBZ Zdr~2.5dB LDR N/A
Penetration height: 6.5kmTemperature :-11oCMax w height: 6.0kmIWC~1.5g/m3 LWC<0.5g/m3
Penetration height: 5.5/4.0 kmTemperature :-6oC/3oCMax w height: 5.0kmIWC<0.4g/m3 LWC>0.4g/m3
Mature structure at 1827UTC Cell A’
Mature structure at 1827UTC Cell A’
1828.45 1826.45
SENW
A”A’
Cell A’:Particle imagesCell A’:Particle imagesCenter of A” Young developing cell
Center of A’ Mature cell
Liquid drops
Rough-edged graupel
Conclusions & Summary By Authors
Conclusions & Summary By Authors
A typical thunderstorm in CaPE study Typical radar structure in all developing cell: Zdr
column exceeding above freezing level, with LDR “cap” above the maximum altitude that Zdr can reach.
High Zdr low Zh region associated with low concentration of millimeter-size drops; enhanced LDR(A3) region indicates mixed phase condition
Highest cloud water concentration in updrafts accompanied by low concentration of large drops
A typical thunderstorm in CaPE study Typical radar structure in all developing cell: Zdr
column exceeding above freezing level, with LDR “cap” above the maximum altitude that Zdr can reach.
High Zdr low Zh region associated with low concentration of millimeter-size drops; enhanced LDR(A3) region indicates mixed phase condition
Highest cloud water concentration in updrafts accompanied by low concentration of large drops
Comments?!Comments?!
Most valuable thing--in situ observation, quantitative data, especially the co-overlapping region covered by both radar and aircraft
Excellent description of the structure and development of each cell in this thunderstorm
Good analysis about the mixed phase domain in cell A
In situ observation of the high Zdr low Zh region associated with low concentration of large drops
More work could be done…
Most valuable thing--in situ observation, quantitative data, especially the co-overlapping region covered by both radar and aircraft
Excellent description of the structure and development of each cell in this thunderstorm
Good analysis about the mixed phase domain in cell A
In situ observation of the high Zdr low Zh region associated with low concentration of large drops
More work could be done…
Thank YouThank You