WRF exercise 1 Kessler physics scheme vs Thompson

WRF exercise 1 Kessler μ-physics scheme vs Thompson μ-physics scheme Isaac Hankes Joseph 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: 1 km (90 min) **Kessler on left, Thompson on right for all contour plots**

Vorticity Tendency: 2 km (90 min)

Vorticity Tendency: 5 km (90 min)

Vorticity Tendency: 10 km (150 min)

Vorticity Tendency. All Terms: 2 km (30 min)

Conclusions • Max vorticity peaks earlier in Kessler • Max vorticity generally higher vertically in Thompson • Advective term dominates for both, strongest at 10 km • Right cell much more dominant in Thompson (more realistic) • Kessler storms move faster