I am quite sure that most people have the experience of being surprised by a sudden downpour in the middle of a sunny day. Due to the advancement of technology, the predictability of the rapid changes in weather phenomena has improved significantly, but is still not perfect.

Why are weather forecasts not always accurate, even in the modern era? Weather predictions do not seem that difficult considering the fact that we can predict solar or lunar eclipse with a great deal of accuracy.

Believe or not, the reason lies in mathematical equations. Human beings can predict solar and lunar eclipses because the orbital equations of Moon, Sun and Earth are known and they can be exactly solved.

What about the weather? Do we have equations that explain weather changes? We have them in the form of fluid dynamics equations, but these weather controlling equations do not have mathematical solutions, unlike those used to predict solar eclipses. Therefore, meteorologists use approximations in order to solve these equations, called numerical weather prediction (NWP).

Approximated solutions produced by NWP are the reason for the imperfect weather forecasts. Although the concept of NWP was born in the early 19th century, this method was not applicable to real life weather prediction until high performance computers were invented in the 1960s, due to the huge amount of computations needed by NWP.

With advent of the NWP era, the perspective of weather forecasts changed from a subjective, empirical approach to an objective, scientific method. It is like the evolution from oral to written history. In a modern weather forecast, the accuracy is directly proportional to the performance of the NWP model. Because of the difficulty of developing an NWP system and the need for a supercomputer, only eight countries in the world possess a global NWP system (USA, UK, France, Germany, Canada. Russia, Japan and China). After a nine-year government funded project, Korea successfully developed the global NWP system (KIM, Korean Integrated Model) and became the ninth country to own a global model. The KIM has been operational since April 2020.

Before operating the KIM, Korea borrowed foreign models for everyday weather forecasts over the Korean Peninsula, so it was impossible to update the model to accommodate forecaster’s demands and to improve the predictability of unique weather patterns over Korea.

Using the self-developed model, Korea now has the flexibility to play with KIM without any restrictions, which may lead to better weather forecasts for the Korean public.

Like Hyundai’s first car, the Pony, the initial output of KIM might be weak, but the future should be prosperous. In order to achieve this, the people at Korea Meteorological Administration will work hard, so I hope the domestic and international meteorological communities encourage the KMA’s first steps in operating its first self-developed global model.

By Park Kwang-suk, administrator of the Korea Meteorological Administration