|
<br />-r-r--
<br />
<br />u "<:
<br />
<br />Updraft calculations are then performed
<br />in a one-dimensional Lagrangian parcel model
<br />which includes the process of lateral entrain-
<br />ment, microphysical-dynamic interactions and
<br />
<br />and mass continuity between the cloud and its
<br />environment. Next, the effects of environmental
<br />subsidence are evaluated. Then, precipitation,
<br />collection and subcloud evaporation are com-
<br />puted. Horizontal mixing of mature cloud and
<br />subsided environment parcels is then performed
<br />uSing a height-dependent ratio of cloud mass to
<br />environment mass. Next, the sounding which has
<br />been changed by cloud-environment interactions
<br />is exami ned to determi ne whether there is
<br />sufficient ABE to develop more clouds. If
<br />sufficient instability exists, up to three
<br />additional clouds may be developed. Then
<br />mesosynoptic-scale lifting is applied to the
<br />sounding. The lifting analyses in the previous
<br />study (Matthews and Si lverman, 1980) assumed a
<br />lifting rate considered to be reasonable to
<br />examine model sensitivity. However, in this
<br />study, objectively analyzed vertical profiles of
<br />lifting derived from the kinematic analyses are
<br />used in MESOCU calculations. After lifting is
<br />applied, surface eddy mixing, solar heating and
<br />the search for a convect i ve base and cyc 1 e of
<br />cloud-environment interaction repeats until the
<br />final time is reached. Once this time (selected
<br />at 3 h based on the frequency of soundi ng
<br />observations) is reached, model computations
<br />stop and a summary of convective development is
<br />produced.
<br />
<br />4. Digital Radar Processing
<br />
<br />The radar ana lys is software package used
<br />to generate the qualitative and quantitative
<br />radar information permits the discretization of
<br />the slant-range radar data into a field of
<br />three-dimensional reflectivity. A transforma-
<br />tion is initially made from the slant-range,
<br />azimuth, and elevation angle domain into a
<br />three-dimensional Cartesian field. Surfaces of
<br />reflectivity are obtained by projecting the
<br />reflectivity values onto selected constant
<br />heights. The final gridded field for each
<br />surface is determined using bi-linear inter-
<br />polation of the reflectivity values surrounding
<br />each gri d poi nt produci ng an average ref] ec-
<br />tivity field.
<br />
<br />To produce the qualitative analysis prod-
<br />ucts discussed in previous sections, the regions
<br />of interest are removed from the total refl ec-
<br />tivity field and held for analysis. This data
<br />subset is passed through a 16-point interpola-
<br />t i on scheme to generate a fi ne-mesh ana lys is
<br />grid. At this time, the data can be fed to
<br />a number of horizontal or vertical contour
<br />analysis routines.
<br />
<br />5.0 Case Study:
<br />
<br />Mesoscale Lines: June 8, 1979
<br />
<br />A very well defi ned jet entrance zone
<br />remained over the network throughout the day,
<br />resu It i ng in a narrow 1 i ne of deep convect ion
<br />that was triggered by strong divergence .at
<br />200 to 300 mb 1 eve 1 s and convergence at 900 to
<br />
<br />::~"~#4~ _
<br />-.. ~~..;::::::.:::~~
<br />~'l ~~~...::::2'~
<br />...,,~~~~..::=::::::?
<br />Ilg~llgOIOI~~~
<br />:::k =~-~"'" " .-
<br />..' ~~~~~
<br />Dt ::::::::-~~~~~~~~
<br />-I ~~~~~~~~
<br />llg~ 1=0 lOll ;:-:--~~.:=:::=:::~
<br />::~ ___" . ICI.1 tlll~ 10lC liXll IlIlt
<br />_.. -====- ;::::: .E-~ ~ ~ __
<br />-. ~ -===- -===- ..::::=: ~ ;:::: ~ .;:::=: ~
<br />-.. - - -:.==- ~ _::::::- ;=:: ;:::::::'" ~ ~
<br />:-k .~..:-..~~~!"&.
<br />-. .~~. ~ ~'~ ~ , ,
<br />-. ,'""",,'............,'
<br />-. ~ ..' " " " " , "
<br />... ... :.... ~" " ......,""" ,,,'
<br />UIo,. .., ., .... ...
<br />
<br />:';RlootO PH\..TSIS rOR -. 79OCo09O:J
<br />
<br />
<br />Ill() nCUI
<br />IlACROSCIU r ICUlS
<br />1"51
<br />
<br />700 Ire!
<br />
<br />goo Ire!
<br />
<br />b
<br />::~ ./ --::-
<br />~"I -7..:::.
<br />IlID." : ..-
<br />It.. -.:-
<br />
<br />...~ 'r"'.: .".. ~- "... ,,~, .' - -
<br />:: / .... .... ..... .... .' 01.0 111'.1
<br />
<br />~: ..' .:" :. ." .. ..-. ;/
<br />11ll.~ IIQ.O . .. :!' 5'
<br />::l. -- "~ . "... .,,~, "... ."'.. ....::'
<br />
<br />~ '--.:'.---.-- ..:=-.. .-' r;
<br />~ .. .. ...- ;- :r~
<br />.'k ~ .... &.. .... . ~
<br />:: I" .... .,' 77Z!iJ.' ~. &.. ..
<br />
<br />- ..,'.'...:... "(i:'
<br />- .' ..' ..' ... .' ..' ..... ....
<br />~...." ~.
<br />-. -,- _.. ... ..:. ~ .?
<br />
<br />-=-
<br />
<br />
<br />MIte) FltLD '''51
<br />I(:SOSCIU rJCUlS
<br />.300 11131
<br />
<br />500 IPIlI
<br />
<br />700 ltel
<br />
<br />900 ltel
<br />
<br />c
<br />:::] ~ E
<br />.....~~ .% =-
<br />171,., Ilg.~ ===--~~
<br />
<br />::::~ ff~~~~
<br />
<br />_.~ ::::=-~~~~~~
<br />-.'1 -...:.----:~-=====-~...::;.--~~
<br />
<br />IC.l 1Cll.~ 101.' ..:.----=-..::::::=-~~
<br />
<br />::~ _ 101.. 101., 101.~ 101.11 1--
<br />-- .....
<br />..... ~ -=:=:- ~~
<br />.... - -------..:.-- ~ ~
<br />.... "-==-..:=::- _ _-=:=-.:;:::::- ~ .f:f' .:f?
<br />
<br />::'k~ :~-~.~.!.. ..-
<br />
<br />:: '".' ..... ..' "...' ", " " :\: w:
<br />. ~" .,,' ,,' ", ~' ~ ~
<br />~~,,',,:0 ..-
<br />.............,. ...., .... ~
<br />
<br />
<br />IQ.DS IKTSI
<br />f\. rJCUlS
<br />PIlI
<br />
<br />100 ftel
<br />
<br />900 llel
<br />
<br />Figul'e3: Macroscale-low pass filter (a),
<br />mesoscale-high pass fi lter (b),
<br />and total field analysis (c) of
<br />wind field at 0000 GMT, June 9,
<br />1979. Vector 1 engths represent .5h
<br />displacements.
<br />
<br />700 rnb. This was a classical jet streak evolu-
<br />tion with numerous narrow thin lines of convec-
<br />tive activity that developed over Texas, shown
<br />in satellite imagery from 1900 to 0200 GMT. A
<br />synopt i c cold fronta 1 zone from LUB to ABQ pro-
<br />duced widespread stratus, altocumulus and cirrus
<br />over the area at 1200 GMT. These clouds dissi-
<br />pated from 1200 to 1800 GMT over the network.
<br />
<br />33
<br />
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