Understanding the Impact an Artificial Cold Pool has on an Approaching Typhoon using The Nonhydrostatic Icosahedral Atmospheric Model (NICAM)

Tropical cyclones are highly destructive natural disasters that pose a grave threat to society. As a result, the Moonshot Project of the Typhoon Control Research Aiming for a Safe and Prosperous Society is working towards finding artificial means to reduce an approaching typhoon. Therefore, making it less destructive. To achieve this less destructive storm, we initiate a cold pool, a natural feature of convective storms, to suppress convection by cooling the sub-cloud layer of an approaching typhoon thereby reducing the amount of heat energy being fed to the storm. To test if this approach is feasible, we conduct a series of experiments using the stretched version of the non-hydrostatic icosahedral atmospheric model (NICAM) with a minimum grid spacing of 1.4km. The artificial cold pool is generated by simulated rain which we produce by pumping seawater continuously through 1km high cylindrical stacks and then ejecting it at the top. The stacks have a radius of 5km and 50km and are on a moving platform that is positioned at the centre of the Typhoon. Typhoon Jebi we use as our test case. Our generated cold pool has an intensity that is a constant cooling source of 1K/hr and 10K/hr each for each radius making a total of 4 experiments. The experiments run for 48 hours prior to landfall in Japan. Overall, the tracks of the four experiments are not affected, only minor shifts in the location of the centre. The time evolution of the sea level pressure (slp) shows that the presence of the cold pool affects the slp for all experiments where the experiment with an intensity of 10K/hr at a 50 km radius experiences the greatest increase in minimum slp, signaling a weakening of the cyclone. Snapshots at 6, 12, 24 and 48hr time intervals of the slp, 10m-windspeed, the 2m-temperature, and the total precipitation reveal that the presence of the cold pool varies in the degree it affects these parameters for each experiment. A pattern where areas of weakening and areas of strengthening encircle the cooling source emerged in the differences in the 10m-windspeed and slp snapshots. The experiment 10K/hr at 50km radius tends to show the only discernible cold pool in the 2m-temperature difference snapshot. However, this experiment was proven to be difficult to reproduce in reality so our focus is on the 10K/hr at 5km radius experiment. After zooming in on the 2m-temperature difference between the experiment and the control, we notice that the drop in temperature (evidence of the cold pool) for the 10K/hr at 5km radius, is very small therefore indicating that the cold pool is very weak. This initiated a new group of experiments where we are testing different locations to find the most suitable area in a tropical cyclone to position our moving platform with the cooling source. The preliminary results suggest that the best location lies somewhere in the inner eyewall region where the winds are no more than 20m/s. Further testing is being conducted.