| Type of case | anvil | ||||||
| Complexity | moderate | ||||||
| Convection | 1 of 2 cells | ||||||
| Electric field kV/m | Min Em_m = 0.009 Max Em_m = 2.740 Mean Em_m = 0.320 | ||||||
| Microphysics #/Liter |
| ||||||
| Location | (x,y) ~ (-100,-75) | ||||||
| Storm Motion | 2.2 m/s west, 2.2 m/s north gives: 3.1 m/s NW | ||||||
Brief Description | When the aircraft arrives at the anvil to cell 1 the cell itself is gone. The system is in decay and by 2140 the anvil is gone. |
| Type of case | anvil | ||||||
| Complexity | moderate | ||||||
| Convection | cell 2 of 2 cells | ||||||
| Electric field kV/m | Min Em_m = 0.070 Max Em_m = 0.337 Mean Em_m = 0.136 | ||||||
| Microphysics #/Liter |
| ||||||
| Location | (x,y) ~ (20,-20) | ||||||
| Storm Motion |
Initially: 5.5 m/s east, 1.1 m/s south, gives: 5.6 m/s SE by 2107: 1.7 m/s east, 1.7 m/s north, gives: 2.4 m/s NE | ||||||
Brief Description | The aircraft flew way below the anvil associated with the 2nd cell which developed after the first. |
There is no lightning data for this day.
The storm comes in at (-150,-150) the very edge of the grid at about 1750. It is not clear if there were 2 cells or if a single cell split. For the sake of this discussion I will treat it as 2 separate cells. By 1833 there are definately 2 cells and cell 1 (the northwestern most) shows a good anvil at the upper levels. By 1910 the 2 cells have increased the distance between them and cell 2 is either developing its own anvil or it is taking some of cell 1's anvil with it.
Due the to proximity to the grid edge the velocities are tenuous. In
the earlier stages the two cells seem to repel each other, then after
cell 1 dissipates cell 2 has a different velocity vector. A
difficulty in determining the velocity of cell 2 (once cell 1 in gone)
is that the storm appears to propogate by 'jumping' rather than a smooth
motion. In other words, a core will move slightly then dissipate, while
a new core grows just ahead of the first. The motion entered above in
Storm Motion is the motion of a single core. If you look at the
propagation that would be:
3.3 m/s east, 3.3 m/s north, gives: 4.7 m/s NE
Investigator: Eric Defer
[presented on Jan. 10, 2002]
Description: One single storm has been sampled that day. A
storm located over Tampa blew a huge anvil over Central Florida (>100 km,
GOES animation [8 Mb]).
Four passes were performed in the anvil (track).
The first pass started about 90
km away and 30 min after the last CG flash (all CGs were with negative
polarity). No LDAR data (total lightning activity) are available for that
day. The electric field did not exceed 3 kV/m for the entire flight. The
first pass shows an increase of the electric field when flying nearby a
15dBZ region (200550 UT). The same phenomena occured during the second pass
(north-east direction at about 2014 UT). The electric field was weaker for
the two other passes (overview).
For the entire flight, the time series of the concentration show:
- FSSP concentration for the entire flight between 100 and 2000
particles per liter.
- Total 2DC concentration between 1 and 150 paticles / liter.
- Concentration of particles > 1 mm is less than 1 particle/liter
for the entire flight.
- The south-west edge of the cloud has non monotoneous variation as
observed during the periods 2006-2010 , 2011-2014, 2032-2033 and
2037-2038. FSSP and 2DC show the same trends in the concentration
for different categories of particle sizes.
- No large particles measured at the south-west edge of the anvil.
- Where E field maximum (3 kV/m), no large or a very few large
particles measured by HVPS and 2DC.
Summary
|
Type of case
Complexity Convection Electric field Precipitation Location Focus issues
|
attached anvil then decaying anvil.
simple. no during the flight. weak. no. in early phase, core over Tampa; anvil over Central Florida.
|
Instruments
|
Airborne mills
Ground KSC mills Radar WSR74C Nexrad KMLB LDAR CGLSS FSSP 2-DC HVPS CPI GOES |
ok.
ok. ok. ok. NO DATA. ok. ok. ok. ok. ok. ok (AREA1). |
HTML page with regrouped plots: 25 June 2001
Detailed analysis of the measurements:
volume scan @ 194909 UT
MER
plot
- No particle observations because out of cloud.
- UND-Citation was heading to the storm after notification
- A self calibration of the mills was carried out during that period.
volume scan @ 195146 UT
MER
plot
- The aircraft was arriving in the area of the anvil (see the track
of the aircraft as
well the 74C and nexrad plots).
- First FSSP sensed small particles the cloud, then 2DC reported particles.
- MEz (from M-matrix) and KEz (from K-matrix) were similar.
volume scan @ 195423 UT
MER
plot
- Particle concentrations show that the aircraft was in cloud during
the volume scan.
Large particles were measured. Concentrations increased as a function
of time as well as the reflectivity at the flight level.
- For most of the scan period, the aircraft was flying in cloud region
with reflectivity
between 0 and 10 dBZ (temperature close to -30 deg. C).
- MEz and KEz show positive values but very low, with KEz > MEz.
volume scan @ 195660 UT (which should be 195700)
MER
plot
- The Citation was still in cloud according to the PMS probes and
the reflectivity curtain.
- Large particles measured.
- Reflectivity at flight level was varying between 10 and 15 dBZ.
- Reflectivity at flight level and concentration of particles > 1mm
show a similar trend in their time evolution (decrease then increase).
- MEz and KEz show an increasing difference, while MEz goes to 0 and
KEz goes
to 700 V/m at the end of the volume scan.
volume scan @ 195938 UT
MER
plot
- The citation still in cloud.
- Reflectivity at the flight level was varying roughly between 10 and
20 dBZ.
- The reflectivity curtain shows the strongest reflectivity was below
the Citation.
- MEz and KEz are showing a similar trend (decrease of the E field) but
with an offset between of about 700 V/m.
volume scan @ 200216 UT
MER
plot
- Large particle concentration dropped compared to the one on the previous
volume scan. Slight decrease of the FSSP concentration too.
- Reflectivity at the flight level mostly > 10 dBZ.
- Relectivity curtain show most the area with strong reflectivity were
below the aircraft.
- Both EZ show an increase but still with a offset of few hundreds
of V/m.
volume scan @ 200453 UT
MER
plot
- Mostly no large particle during this part.
- Reflectivity along the track mostly between 10 and 15 dBZ.
- Again most of the strong reflectivity along the curtain are below
the aircraft.
- the Ez is relatively constant during the first 30 s of the part (with
still an offset) then it increased then decreased. Observe that the slopes
of MEz and KEz changed when the aircraft was lightning above the 20-25
dBZ area. Observe also that after 200640, MEz and KEz are retrieved with
different sign. KEz and MEz reached their maximum of about 3 kV/m at
differnt times, probably due to offsets.
I created horizontal cross section associated with the present
volume scan at 6, 7, 8 and 9 km msl.
The track is plotted for the period 200240-200840
(6 min period; the beginning of the track is indicated by the square).
By looking the 6 km section, the period with an increase EZ (including
the previous and present scans) corresponds to the period when Citation
was flying 2km above 15 dBZ region. At 7km the same observation can be
made except the cloud was composed of pocket of 15dBZ. At 8km altitude,
roughly the altitude of the aircraft, the Citation was flying in 10-15
dBZ region. Note that between 200340 and 200700 UT the citation was at
the edge of a 15-20 dBZ region. [We need to look the Ey]. At 9km altitude,
the aircraft seems to be outside cloud, but I don’t think it is true. The
scan strategy and the interpolation of the radar data can explain the absence
of radar reconstruction and the different reconstructed rings.
volume scan @ 200731 UT
MER
plot
- particles concentrations are dropping. The citation was at the South-West
edge of the anvil and started to do a turn at about 201010 UT.
- reflectivity at the flight level is also dropping when the aricraft
is heading to the edge of the anvil.
- Both Ez show an negative variation, but KEz changed sign before MEz
(40s before) but the trends are the same for the two vertical components
of E. There is a 15-20 dBZ region below 7km altitude which may explain
the variation of Ez. Note that at the altitude of the aircraft no more
than 15dBZ was observed.
volume scan @ 201009 UT
MER
plot
- PMS probes do not agree with reflectivity at the flight level [must
check the PMS data]. It may also comes from the reflectivity interpolation.
- Both Ez seem consistent but still with an offset. At about 201055
the citation was flying in the area where Ez was relatively high in the
previous volume scan. The magnitude of Ez at that time is close to zero,
while the horizontal cross section at 5km shows the weaker reflectivity
in the same area (compare to the previous scan).
volume scan @ 201246 UT
MER
plot
- Large particles reappear during the second part of the scan period
in a location consistent with the one at 200453 where large particles were
measured.
- Reflectivity at flight level between 5 and 15 dBZ.
- Largest reflectivity below the aircraft.
- Ez increased when the citation was flying close to an area where
reflectivity above 15 dBZ was sensed at
6km and 8km. KEz is greater than MEz before reaching
a maximum, then the opposite is observed later. KEz changed sign before
MEz (delay of about 6-7s). Maximum Ez about 3 kV/m. At the end of the scan period, there is a difference
of about 700 V/m between the retrievals of Ez.
volume scan @ 201524 UT
MER
plot
- Large particles observed only at the end of the scan period. Relatively
less small particles.
- Reflectivity at flight level between 8 and 12 dBZ.
- Relative homogeneous reflectivity below the aircraft on 2km depth.
- Ez returned to lower values (compared to the previous scan). MEz
changed sign at about 201620 while KEz stayed positive and increased slightly
during the second part of the scan period.
volume scan @ 201801 UT
MER
plot
- Large particles were sensed during the entire scan period. All the
concentrations dropped during the study period.
- Reflectivity at flight level (7.5 km msl) between 5 and 12 dBZ.
- Reflectivity along the curtain less than 12dBZ.
- MEz and KEz have opposite signs, and in norm, KEz is about 4 time
greater than MEz.
volume scan @ 202038 UT
MER
plot
- Citation was making a loop.
- In cloud according to the PMS probes as well as the horizontal cross
section at the flight level.
- Reflectivity at the flight level between 5 and 12 dBZ.
- Ez retrievals are opposite in sign and with the same scale factor
of about 3.
volume scan @ 202316 UT
MER
plot
- All particle categories observed during the scan period.
- Reflectivity at the flight level between 5 and 10 dBZ.
- Reflectivity along the curtain less than 10 dBZ.
- Ez still opposite according to the two matrices. Note that after
202420, both Ez signals look the same except that there is an offset between
the two curves, but the variations are the same.
volume scan @ 202553 UT
MER
plot
- Large particles disappeared after the half part of the scan period.
- Reflectivity at flight level ranged from 5 to 10 dBZ.
- Ez retrievals still opposite in sign. Less difference between the
retrieval at the end of the sacn period.
volume scan @ 202830 UT
MER
plot
- Mostly no large particles
- Reflectivity at flight level between 0 and 5 dBZ.
- Gap between Ez retrievals smaller in the beginning of the scan period
than at the end.
volume scan @ 203108 UT
MER
plot
- Mostly no large particles. Concentrations dropped ate the end of
the scan period because outside cloud. Outside cloud at
- Altitude is dropping too, now at 6.5 km.
- Citation started turning at about 203350 UT.
- Variation of Ez different than before with a lot of sudden variations.
At 203300, roughly the time when the Citation was out of reflectivity.
KEz changed sign and came back positive in 10s. Again, both signals are
similar except that MEz is negative and there is scale factor in the variations
of Ez. It is like there is an offset plus a scale factor between the two
retrievals.
volume scan @ 203345 UT
MER
plot
- Citation was doing a loop.
- Particles sensed but no echo radar probably due to scan strategy
and reconstruction of gridded data.
- Ez retrievals has opposite signs and a very low (<100 V/m).
volume scan @ 203623 UT
MER
plot
- Citation back in track.
- Large particles only observed at the end of the scan period.
- Citation back in reflectivity at mid-period of the scan with a reflectivity
at flight level < 0 dBZ.
- Very small Ez. Some difference between the retrievals but still the
same evolution. Periods with missing data for E field.
volume scan @ 203903 UT
MER
plot
- Some large particles observed in a part of the cloud.
- Reflectivity at flight level < 5 dBZ.
- Ez retrievals same sign but scale factor.
volume scan @ 204141 UT
MER
plot
- Some large particles observed in the second part of the scan period.
Note also the decrease of the FSSP and total 2D concentrations.
- Reflectivity at flight level mostly < 0dBZ while curtain shows
some reflectivity above 0 dBZ.
- EZ retrievals have same sign until 204230 (with a scale factor) then
change sign with KEz negative.
volume scan @ 204418 UT
MER
plot
- Decrease of the time series of concentration suggesting that the
aircraft is flying tower the edge of the cloud.
- Reflectivity at flight level as well as curtain show some area with
no reflectivity at the flight level.
- Ez still very low and opposite sign.
volume scan @ 204656 UT
MER
plot
- Citation is leaving the storm. Went for calibration part of the flight.
- Ez retrievals have different signs, but the variation are the same.
volume scan @ 204933 UT
MER
plot
- No particle data measured.
- Self calibration of mills with opposite response from the M and K
methods.
volume scans @ 205211, 205448 and 205726 UT
MER
plot
MER
plot
MER
plot
- Self calibration of mills with opposite response, but same sign signals
in clear air.
Copyright © UCAR 1998 - Disclaimer - mmminfo@ncar.ucar.edu
Last Modified: 17 Jan 2002