WRF exercise 1

Kessler μ-physics schemevsThompson μ-physics scheme

Isaac HankesJoseph Ching

Difference between Kessler and Thompson schemes

• Kessler scheme: warm rain- no ice, idealized microphysics, time-split rainfall

• Thompson scheme: 6-class microphysics with graupel, ice and rain number conc. Predicted (double-moment ice), time-split fall terms

• Kessler takes about 2.5 hours, Thompson takes about 5+ hours computer time for a 180-mins simulation.

Comparison (2): vorticity tendency

• There are four terms in the vorticity tendency equation: tilting, divergence, solenoid and advection terms. Comparison is made among schemes, time, and height level.

Max. Vorticity Time Series (s-1)

Thompson

Kessler

3-D Max Vorticity Time Series

Thompson

Kessler

Vorticity Tendency Terms

Kessler

Thompson

Max Vorticity by Level

Thompson

Kessler

Vorticity Tendency: 1km (90min)

**Kessler on left, Thompson on right for all contour plots**

Vorticity Tendency: 2km (90min)

Vorticity Tendency: 5km (90min)

Vorticity Tendency: 10km (150min)

Vorticity TendencyAll Terms: 2km (30min)

Conclusions

• Max vorticity peaks earlier in Kessler• Max vorticity generally higher vertically in

Thompson• Advective term dominates for both, strongest

at 10km• Right cell much more dominant in Thompson

(more realistic)• Kessler storms move faster