1 of 8

^{Results of DCMIP 2025 Test Cases with Gungho}

Thomas Bendall

Dynamics Research, Met Office

www.metoffice.gov.uk

2 of 8

Test Case 1: Breaking Gravity Wave

thomas.bendall@metoffice.gov.uk

2

3 of 8

Test Case 1: Breaking Gravity Wave

thomas.bendall@metoffice.gov.uk

3

4 of 8

Test Case 2a: Mountain Gap

thomas.bendall@metoffice.gov.uk

4

5 of 8

Test Case 2a: Mountain Gap

This test showed up two issues!

Monotonicity on potential temperature transport is necessary for stability (I haven’t seen a test demonstrating this before)

2) Conservative transport of potential temperature exposed a grid-scale computational mode, resulting in model failure (so mountain results use advective form). Something we need to go and fix!

Plot shows divergence just below the top of the model, with conservative potential temperature transport

thomas.bendall@metoffice.gov.uk

5

6 of 8

Test Case 2b: Vortex Shedding

thomas.bendall@metoffice.gov.uk

6

7 of 8

Test Case 3: Squall Line

Cloud and radar reflectivity,

at 5km and 10km

This looks very different from other dycores…

thomas.bendall@metoffice.gov.uk

7

8 of 8

Test Case 3: Squall Line

I’m currently blaming different initial conditions in Gungho, likely:

(a) bugs in my initialisation procedure and/or (b) my confusions about moist variables

FV3 Initial T

Gungho Initial T

thomas.bendall@metoffice.gov.uk

8