17:15 〜 19:15
[ACG41-P13] Comparative verification of the rainfall intensity between GPM/DPR and POTEKA ground surface while the occurrence of a localized convective rainfall pattern
キーワード：GPM/DPR、POTEKA、局地型、対流性、校正、検証
POTEKA weather observation equipment which is originally developed by Meisei Electric and is certificated by Japan Meteorological Agency (hereinafter JMA) is installed with approximately 800 points in Japan and is continuing to observe 8 meteorological variables such as precipitation, temperature, sea-level pressure and forth. POTEKA network don’t have the uniformity of all over Japan such as the Automated Meteorological Data Acquisition System (AMeDAS) of JMA. However, there are not a few localized high-density meteorological observation networks with the resolution of approximately 1 to 10 km. Moreover, these networks include some mountains areas which have few AMeDAS points. I selected the four areas from the mountains areas and performed the comparative analysis between GSMaP_MVK and POTEKA about a yearly and a monthly precipitation. I confirmed that Nagano mountains area has the tendency of extreme overestimation different from the other mountains areas. Therefore, I confirmed the comparative analysis about a daily and an hourly precipitation in a detail in Nagano mountains area. As a result, I could assume that the direct reason of the extreme overestimation was that Nagano mountains area has many stratiform rainfalls which were easy to occur the GSMaP overestimation and few convective rainfalls which were easy to the GSMaP underestimation. Indeed, the comparison of total precipitation between GSMaP_MVK and POTEKA was different depending on the each mountains area. I decided that I would have to calibrate one by one for each a stratiform or a convective rainfall in any mountains areas, in order to realize the high accuracy of GSMaP satellite observation.
In the high-density observation network which had multiple POTEKA points in one grid of GSMaP as Nagano mountains area, I confirmed that the hourly precipitation values of the multiple POTEKA points were almost same, while the occurrence of the stratiform rainfall which was easy to occur the GSMaP overestimation. This indicates that if only one POTEKA point exists, we can calibrate GSMaP. Moreover, because of the high frequency of stratiform rainfalls, we have experienced many stratiform rainfall events and may be able to calibrate GSMaP. On the other hand, I confirmed that the hourly precipitation values of the multiple POTEKA points were very different, while the occurrence of the convective rainfall which was easy to occur the GSMaP overestimation. This indicates that it is not easy to calibrate GSMaP. Moreover, the low frequency of convective rainfalls may be able to link to the difficulty of GSMaP calibration empirically. Therefore, although there are few occurrences, I confirmed some convective rainfall events in Nagano mountains area in a detail. As a result, I confirmed that we had the two patterns such as the widely convective rainfall pattern (a cold front passing and forth) which had not so different POTEKA values in one GSMaP grid, and the localized convective pattern (an atmospheric instability and forth) which had very different POTEKA values in one GSNaP grid. In the former case of a widely convective pattern, even if there is only one POTEKA point, we will be able calibrate GSMaP same as a stratiform rainfall. Therefore, we decided to concentrate on the latter case of a localized convective rainfall pattern.
In order to confirm the precipitation situation in a detail, I searched the rare event which GPM/DPR was passing just above the POTEKA network while the occurrence of a localized convective rainfall in Nagano mountains areas, but I could not the event. However, if I expanded the research area to all over Japan, I could find the two events of Aug 27th, 2018 and Jul 12th, 2012 which GPM/DPR was passing just above the POTEKA network in the Kanto plain while the occurrence of a localized convective rainfall. I will report the investigated result for the two evens in my presentation.
In the high-density observation network which had multiple POTEKA points in one grid of GSMaP as Nagano mountains area, I confirmed that the hourly precipitation values of the multiple POTEKA points were almost same, while the occurrence of the stratiform rainfall which was easy to occur the GSMaP overestimation. This indicates that if only one POTEKA point exists, we can calibrate GSMaP. Moreover, because of the high frequency of stratiform rainfalls, we have experienced many stratiform rainfall events and may be able to calibrate GSMaP. On the other hand, I confirmed that the hourly precipitation values of the multiple POTEKA points were very different, while the occurrence of the convective rainfall which was easy to occur the GSMaP overestimation. This indicates that it is not easy to calibrate GSMaP. Moreover, the low frequency of convective rainfalls may be able to link to the difficulty of GSMaP calibration empirically. Therefore, although there are few occurrences, I confirmed some convective rainfall events in Nagano mountains area in a detail. As a result, I confirmed that we had the two patterns such as the widely convective rainfall pattern (a cold front passing and forth) which had not so different POTEKA values in one GSMaP grid, and the localized convective pattern (an atmospheric instability and forth) which had very different POTEKA values in one GSNaP grid. In the former case of a widely convective pattern, even if there is only one POTEKA point, we will be able calibrate GSMaP same as a stratiform rainfall. Therefore, we decided to concentrate on the latter case of a localized convective rainfall pattern.
In order to confirm the precipitation situation in a detail, I searched the rare event which GPM/DPR was passing just above the POTEKA network while the occurrence of a localized convective rainfall in Nagano mountains areas, but I could not the event. However, if I expanded the research area to all over Japan, I could find the two events of Aug 27th, 2018 and Jul 12th, 2012 which GPM/DPR was passing just above the POTEKA network in the Kanto plain while the occurrence of a localized convective rainfall. I will report the investigated result for the two evens in my presentation.