关键词：
water storage;spatiotemporal change;driving factors;cryosphere;Three-River Headwaters Region
摘要：
Water storage (WS) is a crucial terrestrial ecosystems service function. In cold alpine regions (CAR), the cryosphere elements are important solid water resources, but the existing methods for quantitatively assessing WS usually ignore cryosphere elements. In this study, a revised Seasonal Water Yield model (SWY) in the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST), which considers the effects of frozen ground (FG) and snow cover (SC) on WS, was employed to estimate the spatiotemporal distribution and changes in WS in the Three-Rivers Headwaters region (TRHR) from 1981 to 2020. Sensitivity analyses were conducted to understand the overall effects of multiple factors on WS, as well as the dominant driving factors of WS change at the grid scale in the TRHR. The results show that (1) the WS in the TRHR generally increased from 1981 to 2020 (0.56 mm/year), but the spatial distribution of WS change varied greatly, with a significant increasing trend in the northwest part and a significant decreasing trend in the southeast part. (2) In the last 40 years, increased precipitation (Pre) positively affected WS, while increased potential evapotranspiration (ET0) reduced it. Increased permeability caused by degradation of frozen ground increased WS, while snow cover and LULC changes reduced it. (3) In the TRHR, Pre primarily affected the WS with the largest area ratio (32.62%), followed by land use/land cover (LULC) (19.69%) and ET0 (18.49%), with FG being fourth (17.05%) and SC being the least (6.64%). (4) The highly important and extremely important zones generally showed a decreasing trend in WS and should be treated as key and priority conservation regions. It is expected that this research could provide a scientific reference for water management in the TRHR.
关键词：
western North Pacific summer monsoon;tropical central-western Pacific;SST;interdecadal change
摘要：
This study reveals the strengthened interdecadal relationship between the western North Pacific summer monsoon (WNPSM) and tropical central-western Pacific sea surface temperature anomaly (SSTA) in summer after the early 1990s. In the first period (1979-91, P1), the WNPSM-related precipitation anomaly and horizontal wind anomaly present themselves as an analogous Pacific-Japan (PJ)-like pattern, generally considered to be related to the Nino-3 index in the preceding winter. During the subsequent period (1994-2019, P2), the WNPSM-related precipitation anomaly presents a zonal dipole pattern, correlated significantly with the concurrent SSTA in the Nino-4 and tropical western Pacific regions. The negative (positive) SSTA in the tropical western Pacific and positive (negative) SSTA in the Nino-4 region, could work together to influence the WNPSM, noting that the two types of anomalous SSTA configurations enhance (weaken) the WNPSM by the positive (negative) phase PJ-like wave and Gill response, respectively, with an anomalous cyclone (anticyclone) located in the WNPSM, which shows obvious symmetry about the anomalous circulation. Specifically, the SSTA in Nino-4 impacts the WNPSM by an atmospheric Gill response, with a stronger (weaker) WNPSM along with a positive (negative) SSTA in the Nino-4 region. Furthermore, the SSTA in the tropical western Pacific exerts an influence on the WNPSM by a PJ-like wave, with a stronger (weaker) WNPSM along with a negative (positive) SSTA in the tropical western Pacific. In general, SSTAs in the tropical western Pacific and Nino-4 areas could work together to exert influence on the WNPSM, with the effect most likely to occur in the El Nino (La Nina) developing year in P2. However, the SSTAs in the tropical western Pacific worked alone to exert an influence on the WNPSM mainly in 2013, 2014, 2016, and 2017, and the SSTAs in the Nino-4 region worked alone to exert an influence on the WNPSM mainly in Central Pacific (CP) La Nina developing years. The sensitivity experiments also can reproduce the PJ-like wave/Gill response associated with SSTA in the tropical western Pacific/Nino-4 regions. Therefore, the respective and synergistic impacts from the Nino-4 region and the tropical western Pacific on the WNPSM have been revealed, which helps us to acquire a better understanding of the interdecadal variations of the WNPSM and its associated climate influences.
作者机构：
[Deng, Zhiwei; Quan, Bin] Hengyang Normal Univ, Coll Geog & Tourism, Hengyang 421002, Peoples R China.;[Quan, Bin] Hengyang Base Int Ctr Space Technol Nat & Cultural, Hengyang 421002, Peoples R China.
通讯机构：
[Quan, B ] H;Hengyang Normal Univ, Coll Geog & Tourism, Hengyang 421002, Peoples R China.;Hengyang Base Int Ctr Space Technol Nat & Cultural, Hengyang 421002, Peoples R China.
关键词：
land use and land cover change;Intensity Analysis;change detection;Chang-Zhu-Tan Metropolitan Region
摘要：
Abstract: Quantifying the change in land use and land cover (LULC) is critical for revealing the impact of human activities on the environment of the Earth’s surface. Although some studies were conducted on the change in LULC in rapidly urbanizing areas, conventional methods could not provide a systematic understanding of the changes and their underlying causes. This study adopted an enhanced Intensity Analysis and landscape matrices to deeply explore the change information and expansion modes of LULC in the Chang-Zhu-Tan Metropolitan Region (CZTMR). This exploration was based on remote sensing images from the past 40 years and GIS tools. The results show that the overall change in the LULC accelerated during the period 1980–2020, with its intensity expanding by 16 times. The Built gain and the Crop loss were steadily active. The Built gain was derived mainly from Crop and Forest, and its mode was dominated by edge expansion. It was detected that the Built gain steadily targeted Crop but avoided Forest despite Built gaining a large area from Forest. The reason for this is because Forest initially had the largest area. The measurement results contribute to the formulation of urban plans and land policies for sustainable development in the CZTMR. Our study explained the evolution of Intensity Analysis and its analytical thought, which could be employed in other regions for the detection of land change to help decision makers develop more targeted and sustainable land management strategies. Keywords: land use and land cover change; Intensity Analysis; change detection; Chang-Zhu-Tan Metropolitan Region
作者机构：
[Li, Suxun] Changan Univ, Sch Earth Sci & Resources, Xian 710054, Peoples R China.;[Feng, Chang; Yang, Liu; Li, Suxun] Hengyang Normal Univ, Coll Geog & Tourism, Hengyang 421002, Peoples R China.;[Feng, C] Hengyang Normal Univ, Coll Geog & Tourism, Hengyang 421002, Peoples R China.
通讯机构：
[Feng, C ] ;Hengyang Normal Univ, Coll Geog & Tourism, Hengyang 421002, Peoples R China.
关键词：
driving factors;evapotranspiration;MODIS;spatiotemporal patterns;standard deviation ellipse;Xiangjiang River Basin
摘要：
Evapotranspiration (ET) is a crucial parameter in the process of the hydrological cycle. It is of great significance for water resource management and the improvement of ecological systems in the Xiangjiang River Basin (XRB) to explore the spatial and temporal dynamic characteristics of ET. Based on MOD16, this study revealed the characteristics of spatial and temporal patterns of ET in the XRB from 2000 to 2020. We first applied land use data and change rate for overall trend analysis on ET. Then, we obtained spatiotemporal migration routes of ET through standard deviation ellipse (SDE). Furthermore, we demonstrated the effects of monsoon and urban expansion on ET change. Accordingly, we observed the following novel spatiotemporal patterns of ET: (1) while the ET of artificial surfaces decreased from 2000 to 2020, the change rate in most regions of the XRB was 8.83%, indicating that the overall trend of ET in the XRB was increasing. (2) At 10-year intervals, the SDE center of ET all migrated in a clockwise direction. (3) The correlation between precipitation and ET is more obvious than that between temperature and ET. (4) With the direct effects of monsoon on precipitation in East Asia, we found that the changes in precipitation are consistent with the ET change.
