Wisdom of 'Cheugugi' in weather forecasting

By Yoo Hee-dong

Korea has long been an advanced country in meteorology, taking changes in weather seriously and making efforts to understand weather scientifically. A prime example is the rain gauge called the "Cheugugi," which was invented in Korea in 1441.

The Cheugugi deserves recognition as the world's greatest invention in meteorology for three reasons. First, despite being created about 600 years ago, the Cheugugi is remarkably similar to modern rain gauges that use cutting-edge technology, in terms of how they measure rainfall scientifically.

Second, the Chegugi was actually installed nationwide and connected to create a network, establishing a rainfall monitoring system for each province and being directly utilized in agriculture, the main industry of the time.

Lastly, it was invented a whopping 150 years before the world's second meteorological invention, the Galileo thermometer, showcasing Korea's pioneering spirit and capability in meteorological science unmatched by any other country.

Nowadays, weather observation is carried out using automatic weather observation instruments that can automatically measure not only rainfall but also temperature, humidity, wind, atmospheric pressure, snowfall and other meteorological parameters.

The Korea Meteorological Administration (KMA), a state weather agency in Korea, has installed 600 automatic weather stations across Korea an average of 12 km apart from each other to observe and collect meteorological data.

The KMA uses the collected data as crucial input for identifying current weather conditions and predicting future weather. One significant tool for predicting future weather is the numerical weather prediction (NWP) model.

An NWP model is software that represents the atmosphere as a set of physical equations and performs calculations on a supercomputer to generate numerical weather predictions for future times. What is crucial in increasing the prediction accuracy of NWP models is accurate analysis of the current state of the atmosphere using various observations.

The butterfly effect, where the flapping of a butterfly's wings can cause a typhoon, implies that a tiny change in initial conditions can have an enormous impact on the whole. This idea was first suggested by the meteorologist Edward Lorenz. If explained simply in the context of weather forecasting, it indicates that small errors in observations of the current weather can snowball into dramatic effects, leading to a dramatic drop in the accuracy of future weather predictions.

Observations should not only be accurate but also sufficiently abundant in quantity. This is because the more observations we have, the more accurately we can identify current weather conditions and understand what is happening with the weather.

This is similar to how a television with higher resolution can provide a clearer picture. While most observations are conducted by the KMA, other organizations such as the Korea Forest Service, Rural Development Administration and local governments across Korea carry out their own meteorological observations.

The KMA closely collaborates with these organizations to help them produce higher-quality meteorological observations. Additionally, the KMA has established a system that utilizes observations from other organizations as initial input data to improve the performance of NWP models.

Since last August, observations collected from 1,700 weather stations operated by other organizations have been incorporated into the Korean Integrated Model, which is Korea's own NWP model. As a result, the performance of precipitation prediction of the model has been enhanced.

As we are faced with the climate crisis, which extends beyond mere climate change, countries around the world including Korea have been witnessing frequent and unprecedented weather events. Last year, Korea experienced record-breaking rainfall, the heaviest in 115 years, and in January this year, the cities of Gangneung and Sokcho recorded a daily low temperature of 7.2 degrees Celsius, unusually high for the middle of winter.

China grappled with extreme drought, resulting in plummeting water levels that revealed Buddhist statues believed to be 600 years old. Moreover, after suffering extreme heat waves last summer, Europe experienced a warm winter this year, with temperatures reaching as high as 20 degrees Celsius.

In this era of rapidly changing weather, accurate weather forecasting has become a top priority.

To achieve this, in addition to efforts to improve the performance of NWP models and supercomputers, we need to strive for more accurate, diverse and abundant observations. In particular, establishing denser observation networks by leveraging observations from different organizations can significantly enhance the forecasting accuracy for severe weather events that develop strongly in narrow areas. This would be of great assistance in preparing for weather-related disasters.

The wisdom of Koreans in the past, who installed the Cheugugi in each province to comprehensively and accurately understand the weather, has influenced the current efforts to install weather instruments all over the country and utilize their observations for precise weather forecasts. The KMA will carry on the scientific spirit of our ancestors and strive to ensure the safety of Koreans with accurate forecasts in the face of ever-changing weather conditions.

Yoo Hee-dong is administrator of Korea Meteorological Administration.