11:30 AM - 11:45 AM
[AAS05-08] Reducing the Intensity of an Approaching Typhoon Forced by an Artificial Cold Pool Using the Stretched Version of a Non-hydrostatic Icosahedral Atmospheric Model (NICAM)
Keywords:Tropical cyclones, Typhoon, Artificial cold pool, Temperature forcing, Evaporative rainwater forcing
Tropical cyclones are highly destructive natural disasters that can be very costly, and therefore, is of grave concern to any society. As a part of the Moonshot project of the Typhoon Control Research Aiming For a Safe and Prosperous Society, a series of experiments were conducted using the stretched version of the non-hydrostatic icosahedral atmospheric model (NICAM) with a minimum grid spacing of 1.4km to see the impact an artificial cold pool will have on an approaching typhoon. The cold pool was generated in two ways. The first being by reducing the temperature below 1km at a constant rate of 1K/hr and 10K/hr where each intensity has a radius of 5km and 10km. The second was by evaporative rain, where the same height, intensity and radii were maintained. The artificial cold pool for each experiment was located at 27 degrees North Latitude and 135 degrees East longitude in the pathway of typhoon Hagibi, two days (48 hours) prior to landfall in Japan.
The cold pool, in both experiments, has a life cycle where at certain times it was at its strongest, however, the cold pool generated by the temperature forcing provided a stronger and more noticeable cold pool. The cold pool in the evaporative rain experiments is very weak and in some cases almost non-existent. In both experiments the cold pool that was generated with an intensity of 10K/hr with a radius of 50km was the most visible one. From 21 to 24 hours the cold pool was positioned in the eye where it was at its strongest. The temperature forcing experiment with the intensity of 10K/hr with the 50km radius impacted the typhoon such that a reduction as great as 6K for temperature, 15m/s for 10m-wind speed and 6hPa for sea level pressure (slp) was observed. We observed a clear response to the forcing in the inner region of the typhoon. The effects of the impact by the evaporative rainwater forcing experiments are less than the temperature forcing experiments. Similar to the temperature experiments the 10K/hr with a radius of 50km showed weakening in the eye region. Although the cold pool may have caused a reduction in slp, wind speed and temperature in certain regions, there were other regions where increases for the same parameters were noted. This increase may be due to a shift in where the low is located due to the cold pool. These results are promising since we are able to see an impact even if it is localised in certain regions. The intense winds affected the cold pool from fully developing, and the surface fluxes also hindered the development of the cold pool. These two factors are being taken into account when making improvements to the experiments.
This research was supported by JST Moonshot R&D Grant Number JPMJMS2282.
The cold pool, in both experiments, has a life cycle where at certain times it was at its strongest, however, the cold pool generated by the temperature forcing provided a stronger and more noticeable cold pool. The cold pool in the evaporative rain experiments is very weak and in some cases almost non-existent. In both experiments the cold pool that was generated with an intensity of 10K/hr with a radius of 50km was the most visible one. From 21 to 24 hours the cold pool was positioned in the eye where it was at its strongest. The temperature forcing experiment with the intensity of 10K/hr with the 50km radius impacted the typhoon such that a reduction as great as 6K for temperature, 15m/s for 10m-wind speed and 6hPa for sea level pressure (slp) was observed. We observed a clear response to the forcing in the inner region of the typhoon. The effects of the impact by the evaporative rainwater forcing experiments are less than the temperature forcing experiments. Similar to the temperature experiments the 10K/hr with a radius of 50km showed weakening in the eye region. Although the cold pool may have caused a reduction in slp, wind speed and temperature in certain regions, there were other regions where increases for the same parameters were noted. This increase may be due to a shift in where the low is located due to the cold pool. These results are promising since we are able to see an impact even if it is localised in certain regions. The intense winds affected the cold pool from fully developing, and the surface fluxes also hindered the development of the cold pool. These two factors are being taken into account when making improvements to the experiments.
This research was supported by JST Moonshot R&D Grant Number JPMJMS2282.