Mizuno Yuki, Tachikawa Hina, Sasagawa Taiga, Kobayashi Toshiyuki, Nasahara Kenlo Nishida
Graduate School of Science and Technology, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, 305-8572, Ibaraki, Japan.
Institute of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, 305-8572, Ibaraki, Japan.
Sci Rep. 2025 Apr 16;15(1):12920. doi: 10.1038/s41598-025-94623-9.
In Japan, the exceptionally high temperatures in 2023 and 2024 may have impacted vegetation phenology. We investigated the timing of the spring leaf flush (SOS) of non-evergreen plants using satellite remote sensing. We utilized data from the SGLI sensor on JAXA's GCOM-C satellite. Compared to NASA's MODIS sensors, which are widely used for phenology studies, GCOM-C/SGLI offers two advantages: more stable orbital control in recent years and a higher spatial resolution (250 m) in the green channel which allows to calculate the Chlorophyll Carotenoid Index (CCI), a more robust index than NDVI against snowmelt. We defined the onset of SOS as the point where CCI exceeds zero during spring, and estimated SOS over seven years (2018-2024) in Japan, validated with ground-based time-lapse camera data. On average (2018-2022), SOS tended to occur later in northern or inland mountainous areas. Compared to the average, SOS in 2023 and 2024 occurred earlier in most of northern Japan. Specifically, an earlier SOS by 3 to 7 days occurred in the southern Tohoku, Kanto, and Chubu in 2023, and across the entire Tohoku and Hokuriku in 2024. These responses of SOS to temperature anomalies align with previous studies on future phenology in Japan.
在日本，2023年和2024年异常高温可能影响了植被物候。我们利用卫星遥感调查了非常绿植物的春季展叶始期（SOS）。我们使用了日本宇宙航空研究开发机构（JAXA）的全球变化观测卫星 - 气候（GCOM - C）上的第二代全球成像仪（SGLI）传感器的数据。与广泛用于物候研究的美国国家航空航天局（NASA）的中分辨率成像光谱仪（MODIS）传感器相比，GCOM - C/SGLI有两个优势：近年来轨道控制更稳定，以及绿色通道的空间分辨率更高（250米），这使得能够计算叶绿素类胡萝卜素指数（CCI），该指数比归一化植被指数（NDVI）在应对融雪时更稳健。我们将春季展叶始期定义为春季CCI超过零的点，并估计了日本七年（2018 - 2024年）的春季展叶始期，并用地面延时相机数据进行了验证。平均而言（2018 - 2022年），春季展叶始期在日本北部或内陆山区往往出现得更晚。与平均情况相比，2023年和2024年日本大部分地区的春季展叶始期出现得更早。具体而言，2023年在东北南部、关东和中部地区春季展叶始期提前了3至7天，2024年在整个东北地区和北陆地区都出现了提前。春季展叶始期对温度异常的这些响应与此前关于日本未来物候的研究结果一致。
