2024-2 Numerical Weather Prediction
SUPERCELL
Data & Method
The simulation of idealized supercells with the WRF model focused on analyzing the impact of supercell size on key meteorological factors.
We analyzed intensity, precipitation, and instability changes across different supercell sizes.
Analysis Variables & Plots
Precipitation Analysis
Variables
: QCLOUD (cloud water mixing ratio), QRAIN (rain water mixing ratio), RAINC (convective rainfall),
RAINNC (non-convective rainfall)
Analysis Focus
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Accumulated precipitation patterns
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Precipitation rate changes
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Comparison of precipitation intensity across different sizes
Expectation
: Larger supercells may produce more precipitation due to stronger vertical motions
Instability
Intensity Analysis
Variables
: U (x-wind), V (y-wind), W (z-wind)
Analysis Focus
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Wind components variation with height
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1000-925 hPa: wind shear in lower atmosphere
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925-850 hPa: vorticity and updraft support
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850-700 hPa: mesocyclone dynamics
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700-500 hPa: stability and atmospheric instability
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Wind shear patterns between layers
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Vorticity evolution
Expectation
: Larger supercells may show stronger updrafts and intensity
Instability Analysis
Variables
: CAPE(Convective Available Potential Energy), SI(Showalter Index), TT(Total Total Index),
T-Td(Temperature-dewpoint differences)
Analysis Focus
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Evaluate extent and strength of instability by size
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CAPE: measures available energy for convection
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Time series of area with intense instability (greater than 1800 J/kg)
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SI: instability evaluation at 500 hPa
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Time series of area with values below 2
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TT: convection estimation
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Time series of area with values above 54
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T-Td
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Time series of area with values below 4
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Expectation
: Larger initial sizes may show more stronger convection, more moisture, increased precipitation
Visualization Approach
Plot Types
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Horizontal cross-sections at different pressure levels
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Vertical cross-sections through storm center
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Time series of key variables
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Comparative plots between different supercell sizes
Key Visualization Heights
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Lower atmosphere (1000-925 hPa)
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Middle layers (850-700 hPa)
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Upper levels (700-500 hPa)
Method
1. Simulation Model and Setup
Model
The Weather Research and Forecasting (WRF) model was used to simulate idealized supercells.
Domain Setup
A 100x100 domain size was configured, with a simulation duration of 6 hours and an output interval set at 10-minute increments.
Time Configuration
Simulations were set from 15:00 to 21:00 on June 1 of Year 0001, totaling 6 hours of data.
2. Supercell Size Variation
Six simulations were conducted with varying supercell sizes, adjusting the horizontal radius from 5 km to 30 km.
Radius Configurations
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5km: zrad center at 750m
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10km: zrad center at 1500m
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15km: zrad center at 2250m
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20km: zrad center at 3000m
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25km: zrad center at 3750m
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30km: zrad center at 4500m
3. Data Collection and Variables
Key meteorological variables, including precipitation, intensity, and stability indices, were collected at 10-minute intervals for each supercell size. Details on specific variables are provided in the Data section.
4. Analysis Procedure
Precipitation Analysis
Analyzed cumulative precipitation patterns and intensity variations across supercell sizes to understand the relationship between size and precipitation rate.
Intensity Analysis
Examined vertical wind shear and vorticity changes at multiple atmospheric layers to assess how supercell size influences storm intensity.
Stability Analysis
Compared instability indices across supercell sizes to evaluate potential for stronger convective activity and storm development.