CBCM

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Conveyor Belt CM
Analysis & Diagnosis 1
The Conveyor Belt Conceptual Model
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Conveyor Belt CM
Analysis & Diagnosis 2
The Warm Conveyor Belt (notes pages information)
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Conveyor Belt CM
Analysis & Diagnosis 3
The Poleward view along the warm conveyor belt
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Conveyor Belt CM
Analysis & Diagnosis 4
The View perpendicular to the warm conveyor belt
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Conveyor Belt CM
Analysis & Diagnosis 5
Cold Conveyor Belt - CCB
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Conveyor Belt CM
Analysis & Diagnosis 6
Dry Conveyor Belt - DCB
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Conveyor Belt CM
Analysis & Diagnosis 7
Cold Frontal Cross-section along
Poleward Branch of the Dry Conveyor
Belt (DCB)
B
Common area for deep instability
A
DCB
CCB
Surface
Cold Front
WCB
B
A
Cold air in Cold Conveyor Belt (CCB) deep and moist
Warm Conveyor Belt (WCB) is deep, warm and moist
CCB backs with height consistent with cold advection
WCB just ahead of cold front also typically backs with height
Frontal slope is steeper than the typical 1:50
Backing winds above the frontal zone indicative of anabatic cold front
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Conveyor Belt CM
Analysis & Diagnosis 8
Preliminary Dry Conveyor Belt - PDCB
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Conveyor Belt CM
Analysis & Diagnosis 9
The Conveyor Belt Conceptual Model and
Vertical Stability
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Conveyor Belt CM
Analysis & Diagnosis 10
C
WCB
Vertical Deformation Zone Distribution and the CBM
Summary
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Conveyor Belt CM
Analysis & Diagnosis 11
The Conveyor Belt Conceptual Model and
Frontal Characteristics – Anabatic Katabatic
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Conveyor Belt CM
Analysis & Diagnosis 12
Anabatic and Katabatic Fronts Related to the CBCM
• Consider the winds in the warm air above the
frontal surface and apply the principle of
continuity
• If the winds back either above a warm or cold
frontal surface, convergence results above the
front and the air must rise
• If the winds veer either above a warm or cold
frontal surface, divergence results above the
front and the air must sink
• Anabatic and Katabatic fronts can be located
using the Deformation Zone CM applied to the
Conveyor Belt CM.
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Conveyor Belt CM
Analysis & Diagnosis 13
Active or Anabatic Warm Front
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Conveyor Belt CM
Inactive or Katabatic Warm Front
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Conveyor Belt CM
Active or Anabatic Cold front
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Conveyor Belt CM
Cross Section of Active Cold Front
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Conveyor Belt CM
Inactive or Katabatic Cold Front
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Conveyor Belt CM
Cross Section of Inactive
Cold Front
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Conveyor Belt CM
Conveyor Belt Conceptual Model and
Conveyor Belt Characteristics
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Conveyor Belt CM
Analysis & Diagnosis 20
Vertical Deformation Zone Distribution and the CBM
Simplified Summary
C
WCB
The WCB overrides the warm front
The CCB undercuts the warm front
The frontal surface overlies the
mixing layer
Wind shear in the CCB is variable
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Looking along the flow:
•In WCB to the right of the Col
expect veering winds with height –
Katabatic warm front
•In WCB approach to the right of
the Col expect maximum
divergence – the eagle pattern
with ascent and increasing pcpn
•In WCB to the left of the Col
expect backing winds with height –
Anabatic warm front
Conveyor Belt CM
Analysis & Diagnosis 21
The Precipitation Area Conceptual Model and the CBCM
• The virga trick is a subset of the precipitation area
conceptual model
• The precipitation area (reaching the ground) increases
with:
• Increasing relative humidity of the CCB
– CCB relative humidity is related to:
• CCB characteristics given the source region
• CCB moistening by precipitation (and/or surface characteristics)
• Increasing vertical dynamics and isentropic lift along the
frontal surface.
– Vertical dynamics is related to:
• Warm frontal slope
• WCB component perpendicular to the frontal surface
• Katabatic versus anabatic frontal diagnosis
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Conveyor Belt CM
Analysis & Diagnosis 22
B
Warm Frontal Cross-section along
Leading Branch of the Warm Conveyor
Belt (WCB)
Common location for virga
A
WCB
Increasing CCB
Moistening
Surface
Warm Front
CCB
B
A
Cold air in Cold Conveyor Belt (CCB) deep and dry
Moist portion of Warm Conveyor Belt (WCB) is high and veered from frontal perpendicular – katabatic tendency
Dry lower levels of WCB originate from ahead of the system and backed from frontal perpendicular
WCB typically veers with height (it is after all, a warm front)
Frontal slope is more shallow than the typical 1:200
Precipitation extends equidistant into the unmodified CCB
Precipitation extends further into the moistened, modified CCB
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Conveyor Belt CM
Analysis & Diagnosis 23
B
Warm Frontal Cross-section along
Central Branch of the Warm Conveyor
Belt (WCB)
A
Virga likely only on leading edge of WCB
WCB
Increasing CCB
Moistening
Surface
Warm Front
Precipitation
At Surface
CCB
B
A
Cold air in Cold Conveyor Belt (CCB) more shallow and moist
Moist portion of Warm Conveyor Belt (WCB) is thicker, higher and perpendicular to front
Lower levels of WCB have the same origin as the upper level of the WCB - frontal perpendicular
WCB shows little directional shift with height. A greater WCB depth is frontal perpendicular
Frontal slope is near the typical 1:200
Precipitation extends further into the moistened, modified CCB.
Horizontal rain area begins to expand as CCB moistens.
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Conveyor Belt CM
Analysis & Diagnosis 24
B
Warm Frontal Cross-section along
Trailing Branch of the Warm Conveyor
Belt (WCB)
Virga unlikely except along the leading edge of the WCB
A
WCB
Increasing CCB
Moistening
Surface
Warm Front
Precipitation
At Surface
CCB
B
A
Cold air in Cold Conveyor Belt (CCB) even more shallow and more moist
Moist portion of Warm Conveyor Belt (WCB) is thicker, higher and backed from frontal perpendicular – anabatic tendency
Lower levels of WCB have the same origin as the upper level of the WCB
WCB probably backs slightly with height in spite of the warm air advection. A greater WCB depth is frontal perpendicular
Frontal slope likely steeper than the typical 1:200
Precipitation extends further into the moistened, modified CCB.
Horizontal rain area expands rapidly as CCB moistened.
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Conveyor Belt CM
Analysis & Diagnosis 25
The Precipitation Phase CM and the CBCM
• The precipitation area (reaching the ground) increases
with:
• Increasing relative humidity of the CCB
– CCB relative humidity is related to:
• CCB characteristics given the source region
• CCB moistening by precipitation (and/or surface characteristics)
• Increasing vertical dynamics and isentropic lift along the
frontal surface.
– Vertical dynamics is related to:
• Warm frontal slope
• WCB component perpendicular to the frontal surface
• Katabatic versus anabatic frontal diagnosis
• Add in a temperature parameter to deduce this.
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Conveyor Belt CM
Analysis & Diagnosis 26
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