Tropical cyclone

• At the time of writing, tropical cyclone researchers were examining the so-called beta effect (latitudinal variation in Coriolis force matters)
• Definition: $e_w$ is zonal NCT, $w_e$ is vertical NCT

what experiments were run

• The experiment:

  • 25km grid spacing with two-way nest at 8km grid spacing
  • 20ºN
  • Pre-specified vortex in quiescent atmosphere ECMWF relative humidity was increased per-level.

• $f$ plane with/without $e_w$

• $\beta$ plane with/without $e_w$

• 72 hour integration

Results

• Control run shows 72 hour average of $w$ shows magnitudes of 0.5 m/s, resulting in a time-averaged $e_w$ that is almost 50% of the magnitude of the total acceleration magnitude.
• Figure 3: $f$ plane with $e_w$ shows rain structure is asymmetric, with differences northeast and southwest of the center. 20% of total rainfall.
• No obvious difference in TC intensity when $e_w$ is added.
• When $\beta$ plane is used without NCT, TC center moves northwestward. Westward deviation occurs when $e_w$ added.