Analysis
I. Precipitation Form
To distinguish the precipitation types,
we used 1000-700hPa thickness map of January 4, 2010 and
analyzed 1000-500hPa thickness with 500hPa weather chart on January 12, 2021.
January 4,2010
(Left) January 4, 2010 1000-700hPa Thickness, (Right) January 4, 2010 Actual distribution of precipitation
Let’s take a look at the image on the left, 1000-700hPa thickness map on January 4, 2010. The red part, where the thickness is 2,760m to 2,820m, is a mixed area of rain and snow. The thickness of north side of the red area is less than 2,760m, we can estimate that it snowed there. The image on the right, the actual distribution of precipitation on January 4, 2010, shows that it was snowing in the north of the red line and raining in the south. Thus, it can be confirmed that it snowed in Seoul on January 4, 2010.
January 12, 2021
The green part of the image on the left, 700 hPa weather chart on January 12, 2021, is where the altitude of 700 hPa is 2,760m to 2,820m. Considering that the air pressure on that day is 1004.7 hPa, we can draw the red part (where the 1000-700 hPa thickness is 2,760m to 2,820m) like the image on the right, by lowering the green part to the south. However, since it is not exact thickness map, we are not sure that Seoul is actually in the red part. So we analyzed 1000-500 hPa thickness, too.
January 12, 2021 700 hPa weather chart
The picture on the left is a weather chart of 500 hPa on January 12, 2021. The light green line indicates an
altitude of 5,400m. Considering that the air pressure on that day is 1004.7 hPa, the 1000-500hPa thickness
of north of the green line is thinner than 5,400m.
And we can estimate that it snowed in Seoul,
on January 12, 2021.
January 12, 2021 500 hPa weather chart
Therefore, by analyzing the thickness, we can see that it snowed in Seoul both on January 4, 2010 and January 12, 2021.