17:15 〜 18:45
[ACG36-P20] Effect confirmation to GSMaP MVK value change between before and after the GPM/DPR satellite passing over Nagano mountains areas which have a strong overestimation tendency
キーワード：GSMaP、GPM/DPR、POTEKA、衛星、高密度、地上
POTEKA weather observation equipment originally which is developed by Meisei Electric and is certificated by Japan Meteorological Agency (hereinafter JMA) can observe the 8 meteorological variables of not only precipitation but also temperature, relative humidity, and sea-level pressure. Meisei Electric has approximately 800 POTEKA points in Japan as of January 2024. These observation points do not have the uniformity same as the Automated Meteorological Data Acquisition System (AMeDAS) of JMA. However, these points compose many localized high-density ground surface meteorological observation networks (hereinafter POTEKA networks) with the resolution of approximately 1 to 10 km in not only plains but also mountains depending on the area in Japan.
We selected the 4 areas of Nagano, Iwate, Shimane and Kochi/Ehime prefectures from the POTEKA mountains networks and performed the comparative validation between GSMaP_MVK (Ver.7) and POTEKA for the yearly total precipitation of 2020. As the results, the GSMaP values were almost same as POTEKA values in the 3 areas other than Nagano (Iwate:1.01 times, Shimane:1.04 times, Kochi/Ehime:0.89 times). On the other hand, the GSMaP value had the extremely big overestimation for the POTEKA value in Nagano (Nagano:2.25 times). Considering these observation results, in order to realize the high accuracy of the satellite precipitation observation, we judged that we had to perform the comparative validation between GSMaP and POTEKA in details in Nagano mountains areas.
The POTEKA mountains network in Nagano prefecture concentrated on Ikeda town and Chikuhoku village in only the northern area until 2021, but the new POTEKA network was composed in Minowa town in the southern area from 2022. We compared between GSMaP_MVK (the latest Ver.8) and POTEKA for each monthly total precipitation of FY2022 (from April 2022 of March 2023) in both the northern and the southern areas of Nagano prefecture. GSMaP values of May and June in particular had the high overestimation in the northern area and in the southern area respectively. Moreover, we compared for each daily total precipitation of these months and confirmed that there were the very big overestimation days and the small underestimation days of GSMaP in both the northern and the southern areas. Confirming the daily precipitation of each POTEKA point in details, we had the small deviation of the POTEKA observation values and the occurrence tendency of a stratiform rainfall about the overestimation days. An extratropical low and a warm front were passing on the weather charts of these overestimation days, which became the evidence of a stratiform rainfall occurrence. On the other hand, we had the big deviation of the POTEKA observation values and the occurrence tendency of a convective rainfall about the underestimation days. An atmosphere was unstable on the weather charts of these underestimation days, which became the evidence of a convective rainfall occurrence.
I hear that GSMaP_MVK values have the 2 patterns which is based on the observation value directly by the satellite radar and is based on the extrapolation estimation value utilizing the cloud movement vector calculated by the Himawari satellite. In the cases of GPM/DPR passing just over the mountains of Nagano prefecture on the days of both the stratiform and the convective rainfalls, we will report the effect to the change of GSMaP_MVK values between before and after the passing of GPM/DPR in this presentation.
We selected the 4 areas of Nagano, Iwate, Shimane and Kochi/Ehime prefectures from the POTEKA mountains networks and performed the comparative validation between GSMaP_MVK (Ver.7) and POTEKA for the yearly total precipitation of 2020. As the results, the GSMaP values were almost same as POTEKA values in the 3 areas other than Nagano (Iwate:1.01 times, Shimane:1.04 times, Kochi/Ehime:0.89 times). On the other hand, the GSMaP value had the extremely big overestimation for the POTEKA value in Nagano (Nagano:2.25 times). Considering these observation results, in order to realize the high accuracy of the satellite precipitation observation, we judged that we had to perform the comparative validation between GSMaP and POTEKA in details in Nagano mountains areas.
The POTEKA mountains network in Nagano prefecture concentrated on Ikeda town and Chikuhoku village in only the northern area until 2021, but the new POTEKA network was composed in Minowa town in the southern area from 2022. We compared between GSMaP_MVK (the latest Ver.8) and POTEKA for each monthly total precipitation of FY2022 (from April 2022 of March 2023) in both the northern and the southern areas of Nagano prefecture. GSMaP values of May and June in particular had the high overestimation in the northern area and in the southern area respectively. Moreover, we compared for each daily total precipitation of these months and confirmed that there were the very big overestimation days and the small underestimation days of GSMaP in both the northern and the southern areas. Confirming the daily precipitation of each POTEKA point in details, we had the small deviation of the POTEKA observation values and the occurrence tendency of a stratiform rainfall about the overestimation days. An extratropical low and a warm front were passing on the weather charts of these overestimation days, which became the evidence of a stratiform rainfall occurrence. On the other hand, we had the big deviation of the POTEKA observation values and the occurrence tendency of a convective rainfall about the underestimation days. An atmosphere was unstable on the weather charts of these underestimation days, which became the evidence of a convective rainfall occurrence.
I hear that GSMaP_MVK values have the 2 patterns which is based on the observation value directly by the satellite radar and is based on the extrapolation estimation value utilizing the cloud movement vector calculated by the Himawari satellite. In the cases of GPM/DPR passing just over the mountains of Nagano prefecture on the days of both the stratiform and the convective rainfalls, we will report the effect to the change of GSMaP_MVK values between before and after the passing of GPM/DPR in this presentation.