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[HGG01-P02] The actual situation of "Hakusan-Oroshi" blowing in Hakusan City and the residents' perception for this wind
Keywords:Hakusan-Oroshi, Down slope wind, Foehn phenomenon, Mountain breeze, Meteorological observation, Questionnaire survey
Introduction
It is known that a down slope wind called "Hakusan-Oroshi" is blowing in Hakusan City, Ishikawa Prefecture. It is known as a strong wind that blows in spring and autumn in the Shiramine area, and as a cool summer wind around the Tsurugi and Torigoe areas. In other words, the wind of the same name "Hakusan-Oroshi", which has different properties depending on the region, is blowing. Therefore, the authors done the both of meteorological observation for considering the physical properties and a questionnaire survey to investigate the recognition of residents, about "Hakusan-Oroshi".
Meteorological observation
An AWS (Vantage Pro2, DAVIS) was installed in the Shiramine area from March to November 2020, and data was obtained every minute. Winds with an instantaneous wind speed of 15.0 m / s or more were extracted as the date and time of strong wind occurrence, and the causes of this strong wind were investigated using data from AWS, AMeDAS, and surface weather charts. From the AMeDAS data, it was confirmed that precipitation was confirmed in the windward area when strong winds occurred, and that the southeastern wind was blowing in the northwestern part of Gifu prefecture. We also created values for the temperature every 10 minutes and the average wind speed for 10 minutes using the data from the AWS installed at Shiramine, and analyzed the changes before and after the occurrence of strong winds. Around 6:00 on April 20 and 8:00 on September 7, when strong winds occurred, the temperature increased as the average wind speed increased.
These facts indicate that the strong winds observed in the Shiramine area are due to the foehn phenomenon. From this, the authors speculated that "Hakusan-Oroshi" in the Shiramine area is the strong wind of foehn.
An AWS (Vantage Pro2) was installed in the Tsurugi area from August to November, and data was obtained every minute. From the reported characteristics, the "Hakusan-Oroshi" in Tsurugi area was expected to be a mountain breeze. For the analysis, we used the data of the temperature every 10 minutes, the average wind speed for 10 minutes, the maximum wind direction, the data of the surrounding AMeDAS, and the data from the AWS.
According to AWS data, it was confirmed that a wind of about 4 m, which indicates a certain direction in the southeast and southeast, was blowing at night. This wind direction is different from the wind observed at the surrounding AMeDAS. The nighttime temperature in Hakusan-Kawachi AMeDAS during the same period is lower than that of other observation points. From this, it is inferred that cold air was accumulated in the valley bottom due to radiative cooling at night. It is thought that the "Hakusan-Oroshi" in the Tsurugi area is mountain breeze generated when this cold air mass flows out from the exit of the valley.
Residents' perception of "Hakusan-Oroshi"
A questionnaire survey was conducted among residents of Hakusan City in order to clarify the perception of "Hakusan-Oroshi" and the actual state of wind utilization. The questionnaire paper was distributed to areas where the wind was blowing from a preliminary survey. The area from valley mouth to the plains of the Tedori River alluvial fan including Tsurugi area is classified as Area A, the Torigoe area located in valley bottom is classified as Area B, and the Fukase, Kuwashima, and Shiramine areas located in the upstream are classified as Area C.
More than 50% of the residents in areas A and B answered "I know" or "I have heard but do not know the details" of "Hakusan-Oroshi". On the other hand, in Area C, he was only about 20% aware. We also confirmed the use, benefits, damage, and countermeasures of "Hakusan-Oroshi". In area A, a cool mountain breeze was used for agriculture. In Area B, it is also used for agriculture, and there were many answers about damage to agricultural houses and countermeasures due to strong winds in Spring. On the other hand, in Area C, there were few responses regarding use / damage and countermeasures. From these facts, if there are any factors in the use, damage, and countermeasures of "Hakusan-Oroshi", the residents may be able to recognize the wind of "Hakusan-Oroshi" in each area.
It is known that a down slope wind called "Hakusan-Oroshi" is blowing in Hakusan City, Ishikawa Prefecture. It is known as a strong wind that blows in spring and autumn in the Shiramine area, and as a cool summer wind around the Tsurugi and Torigoe areas. In other words, the wind of the same name "Hakusan-Oroshi", which has different properties depending on the region, is blowing. Therefore, the authors done the both of meteorological observation for considering the physical properties and a questionnaire survey to investigate the recognition of residents, about "Hakusan-Oroshi".
Meteorological observation
An AWS (Vantage Pro2, DAVIS) was installed in the Shiramine area from March to November 2020, and data was obtained every minute. Winds with an instantaneous wind speed of 15.0 m / s or more were extracted as the date and time of strong wind occurrence, and the causes of this strong wind were investigated using data from AWS, AMeDAS, and surface weather charts. From the AMeDAS data, it was confirmed that precipitation was confirmed in the windward area when strong winds occurred, and that the southeastern wind was blowing in the northwestern part of Gifu prefecture. We also created values for the temperature every 10 minutes and the average wind speed for 10 minutes using the data from the AWS installed at Shiramine, and analyzed the changes before and after the occurrence of strong winds. Around 6:00 on April 20 and 8:00 on September 7, when strong winds occurred, the temperature increased as the average wind speed increased.
These facts indicate that the strong winds observed in the Shiramine area are due to the foehn phenomenon. From this, the authors speculated that "Hakusan-Oroshi" in the Shiramine area is the strong wind of foehn.
An AWS (Vantage Pro2) was installed in the Tsurugi area from August to November, and data was obtained every minute. From the reported characteristics, the "Hakusan-Oroshi" in Tsurugi area was expected to be a mountain breeze. For the analysis, we used the data of the temperature every 10 minutes, the average wind speed for 10 minutes, the maximum wind direction, the data of the surrounding AMeDAS, and the data from the AWS.
According to AWS data, it was confirmed that a wind of about 4 m, which indicates a certain direction in the southeast and southeast, was blowing at night. This wind direction is different from the wind observed at the surrounding AMeDAS. The nighttime temperature in Hakusan-Kawachi AMeDAS during the same period is lower than that of other observation points. From this, it is inferred that cold air was accumulated in the valley bottom due to radiative cooling at night. It is thought that the "Hakusan-Oroshi" in the Tsurugi area is mountain breeze generated when this cold air mass flows out from the exit of the valley.
Residents' perception of "Hakusan-Oroshi"
A questionnaire survey was conducted among residents of Hakusan City in order to clarify the perception of "Hakusan-Oroshi" and the actual state of wind utilization. The questionnaire paper was distributed to areas where the wind was blowing from a preliminary survey. The area from valley mouth to the plains of the Tedori River alluvial fan including Tsurugi area is classified as Area A, the Torigoe area located in valley bottom is classified as Area B, and the Fukase, Kuwashima, and Shiramine areas located in the upstream are classified as Area C.
More than 50% of the residents in areas A and B answered "I know" or "I have heard but do not know the details" of "Hakusan-Oroshi". On the other hand, in Area C, he was only about 20% aware. We also confirmed the use, benefits, damage, and countermeasures of "Hakusan-Oroshi". In area A, a cool mountain breeze was used for agriculture. In Area B, it is also used for agriculture, and there were many answers about damage to agricultural houses and countermeasures due to strong winds in Spring. On the other hand, in Area C, there were few responses regarding use / damage and countermeasures. From these facts, if there are any factors in the use, damage, and countermeasures of "Hakusan-Oroshi", the residents may be able to recognize the wind of "Hakusan-Oroshi" in each area.