1:45 PM - 3:15 PM
[O08-P108] Exploring the winds that blow across the Shiranui Sea 2
Keywords:Sea Land Wind, Seasonal Wind, Shiranui Sea, Eino, Shiranui Phenomenon
1 Objective
Through the study of Shiranui, I learned that wind is one of the conditions for its occurrence. We wanted to know about the wind that actually blows at Eino, which is an observation station for Shiranui. However, there is no meteorological observatory in the vicinity of Eino, so there is no wind data. Therefore, we decided to estimate the winds blowing at Eino by grasping the trend of winds in the Shiranui Sea as a whole.
2Wind Direction and Speed in the Northern Shiranui Sea
(1) Daily winds
We focused on wind direction and wind speed at Matsushima, a point on the northern coast of the Shiranui Sea, using data from the Japan Meteorological Agency under the following conditions.
(1) Weather: zero precipitation day (2) Season: winter (January, February)
(3) Time: hourly (4) Period:2011-2020
The wind direction was northeasterly during the day and southwesterly during the night, and the wind speed was stronger during the day and weaker during the night. The fact that wind direction and speed change in a daily cycle led us to believe that these winds may be land and sea winds.
(2) Winds throughout the year
We focused on wind direction and speed in Triangle, Matsushima, and Yatsushiro, where JMA stations are located along the Shiranui Sea coast, and examined them based on JMA data.
Conditions
Weather: days with zero precipitation
Time: every month
Period: 2011-2020
(4) Wind speed: Median value at each location, classified as strong and weak (5) Wind direction: 16 directions classified into 4 categories by ±45° from each direction
At night, winds are weak regardless of the season and are considered to be land breezes of the sea-land winds. During the day, the wind direction changes with the season, so this wind is considered to be a monsoon. Therefore, the sea-land wind blows in both summer and winter. At night, land breezes are more pronounced. However, daytime is greatly influenced by the monsoon.
3 Sea-Land Winds
The following is a discussion of where land and sea winds are generated under the influence of land and sea.
(1) East-west direction
Hypothesis 1: "Ocean" is the East China Sea and "land" is Kyushu.
Hypothesis 2: The "sea" is the Shiranui Sea, and the "land" is Kyushu and the Amakusa Islands.
Proof of Hypothesis 2
The wind directions at Matsushima and Yatsushiro are opposite at the same time of day. Therefore, Hypothesis 2 is considered correct.
(2) North-South direction
Hypothesis 1: "Land" is the Udo Peninsula and "sea" is the Shiranui Sea.
Hypothesis 2: There is no "land," and the "sea" is the Shiranui Sea and the Ariake Sea.
Proof of Hypothesis 2
Wind direction is measured at night and day at two points on the northern (Mikoshirai Coast) and southern (Eino Coast) sides of the Udo Peninsula.
It was observed that winds were blowing in opposite directions on the north and south sides of the Udo Peninsula. Therefore, we know that the Udo Peninsula is "land" and that Hypothesis 1 is correct.
4 Seasonal winds
Seasonal winds are winds that blow over a wider area than sea and land winds. Therefore, wind direction is analyzed monthly at five stations including the Ariake Sea coastal area located north of the Shiranui Sea.
During the daytime, the wind direction was the same over a wide area, with southerly winds blowing strongly in summer and northerly winds in winter, and the wind direction changed with the season. Therefore, it was found that daytime was strongly influenced by the monsoon.
5 Wind at Eino
(1) Hypothesis
Weak land breezes blow toward the inner Shiranui Sea at night, and the monsoon has a stronger influence during the daytime.
(2) Proof of hypothesis (actual observation)
The wind direction and speed were measured at night and during the day at two locations on the north (Mikoshirai Coast) and south (Eino) sides of the Udo Peninsula, and the results from September to December showed that the wind blew only in the opposite direction at night at Eino and Mikoshirai Coast, and that the north wind sometimes blew during the day in both locations, and sometimes in the opposite direction.
(3) Consideration
Eight of the ten times the wind direction was the same as the land wind at night and the monsoon at daytime, and in two cases the wind direction was the same as the sea-land wind both at daytime and at night. This indicates that the tendency of winds blowing at Eino is the same as that of sites located along the Shiranui Sea coast.
6 Conclusion
The winds at Eino blow northerly at night, southerly in summer, and northerly in winter.
The trend along the Shiranui Sea coast is marked by land breezes at night, while daytime winds are more influenced by monsoons.
The same tendency is observed at Eino, where there is no meteorological observatory, as at the other sites.
Through the study of Shiranui, I learned that wind is one of the conditions for its occurrence. We wanted to know about the wind that actually blows at Eino, which is an observation station for Shiranui. However, there is no meteorological observatory in the vicinity of Eino, so there is no wind data. Therefore, we decided to estimate the winds blowing at Eino by grasping the trend of winds in the Shiranui Sea as a whole.
2Wind Direction and Speed in the Northern Shiranui Sea
(1) Daily winds
We focused on wind direction and wind speed at Matsushima, a point on the northern coast of the Shiranui Sea, using data from the Japan Meteorological Agency under the following conditions.
(1) Weather: zero precipitation day (2) Season: winter (January, February)
(3) Time: hourly (4) Period:2011-2020
The wind direction was northeasterly during the day and southwesterly during the night, and the wind speed was stronger during the day and weaker during the night. The fact that wind direction and speed change in a daily cycle led us to believe that these winds may be land and sea winds.
(2) Winds throughout the year
We focused on wind direction and speed in Triangle, Matsushima, and Yatsushiro, where JMA stations are located along the Shiranui Sea coast, and examined them based on JMA data.
Conditions
Weather: days with zero precipitation
Time: every month
Period: 2011-2020
(4) Wind speed: Median value at each location, classified as strong and weak (5) Wind direction: 16 directions classified into 4 categories by ±45° from each direction
At night, winds are weak regardless of the season and are considered to be land breezes of the sea-land winds. During the day, the wind direction changes with the season, so this wind is considered to be a monsoon. Therefore, the sea-land wind blows in both summer and winter. At night, land breezes are more pronounced. However, daytime is greatly influenced by the monsoon.
3 Sea-Land Winds
The following is a discussion of where land and sea winds are generated under the influence of land and sea.
(1) East-west direction
Hypothesis 1: "Ocean" is the East China Sea and "land" is Kyushu.
Hypothesis 2: The "sea" is the Shiranui Sea, and the "land" is Kyushu and the Amakusa Islands.
Proof of Hypothesis 2
The wind directions at Matsushima and Yatsushiro are opposite at the same time of day. Therefore, Hypothesis 2 is considered correct.
(2) North-South direction
Hypothesis 1: "Land" is the Udo Peninsula and "sea" is the Shiranui Sea.
Hypothesis 2: There is no "land," and the "sea" is the Shiranui Sea and the Ariake Sea.
Proof of Hypothesis 2
Wind direction is measured at night and day at two points on the northern (Mikoshirai Coast) and southern (Eino Coast) sides of the Udo Peninsula.
It was observed that winds were blowing in opposite directions on the north and south sides of the Udo Peninsula. Therefore, we know that the Udo Peninsula is "land" and that Hypothesis 1 is correct.
4 Seasonal winds
Seasonal winds are winds that blow over a wider area than sea and land winds. Therefore, wind direction is analyzed monthly at five stations including the Ariake Sea coastal area located north of the Shiranui Sea.
During the daytime, the wind direction was the same over a wide area, with southerly winds blowing strongly in summer and northerly winds in winter, and the wind direction changed with the season. Therefore, it was found that daytime was strongly influenced by the monsoon.
5 Wind at Eino
(1) Hypothesis
Weak land breezes blow toward the inner Shiranui Sea at night, and the monsoon has a stronger influence during the daytime.
(2) Proof of hypothesis (actual observation)
The wind direction and speed were measured at night and during the day at two locations on the north (Mikoshirai Coast) and south (Eino) sides of the Udo Peninsula, and the results from September to December showed that the wind blew only in the opposite direction at night at Eino and Mikoshirai Coast, and that the north wind sometimes blew during the day in both locations, and sometimes in the opposite direction.
(3) Consideration
Eight of the ten times the wind direction was the same as the land wind at night and the monsoon at daytime, and in two cases the wind direction was the same as the sea-land wind both at daytime and at night. This indicates that the tendency of winds blowing at Eino is the same as that of sites located along the Shiranui Sea coast.
6 Conclusion
The winds at Eino blow northerly at night, southerly in summer, and northerly in winter.
The trend along the Shiranui Sea coast is marked by land breezes at night, while daytime winds are more influenced by monsoons.
The same tendency is observed at Eino, where there is no meteorological observatory, as at the other sites.