From Tallbloke’s Talkshop

June 25, 2023 by oldbrew 

Pardon the scepticism, but welcome to another visit to climate cloud cuckoo land. This week we’re going to figure out with climate models (of course) how to turn the tables on those nasty floods, hurricanes, mega-heatwaves or any other undesirable weather events you might like to tame. Bring on the small tweaks…
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RIKEN scientists have demonstrated a way to make small tweaks in weather systems as a means to prevent, or at least reduce, the severity of extreme weather events such as torrential rain, says Phys.org.

They did this by taking advantage of the chaos that is inherent to such systems.

Through this work they hope to develop ways to prevent extreme weather events, which have become more common in recent years.

According to Takemasa Miyoshi, the leader of the research group, “It is generally accepted that we need to learn how to predict severe weather events so that we can prepare for them, but it would also be desirable to be able to mitigate the events themselves. That’s what we are interested in achieving.”

His group took on this challenge as part of the Japanese government’s moonshot-millennia program, and in previously published work, they described the possibility of controlling weather by initiating small changes in it as it forms.

At that time, they used the simple Lorenz 63 weather model, which only has a few variables, and showed that it would be possible to induce small perturbations in the system to keep it on one side of a so-called “butterfly pattern.”

Their new study published in Nonlinear Processes in Geophysics goes beyond the simple model. In it, the team adopted the Lorenz 96 model. Essentially, it sets a weather variable for 40 points along a line of latitude around the Earth, and looks at how each of these points changes as it interacts with neighboring points throughout the year.

Approximately once or twice a year, the points show large variations, which correspond to extreme weather events. As part of a control simulation experiment, the members of the team were able to eliminate the extreme events by making small tweaks in a 100-year run of the model.

Full article here.

CSE description: when a T d forecast from t_m shows extreme values, perturbations are applied to the nature run between t_m and t_m+0.05. At time t_m+0.05,previous forecast and observation based on the controlled nature run are available, and a new analysis ensemble is created. Credit: Nonlinear Processes in Geophysics (2023). DOI: 10.5194/npg-30-117-2023