scholarly journals A Two-Stage Fusion Framework to Generate a Spatio–Temporally Continuous MODIS NDSI Product over the Tibetan Plateau

2019 ◽  
Vol 11 (19) ◽  
pp. 2261 ◽  
Author(s):  
Jing ◽  
Shen ◽  
Li ◽  
Guan

The Tibetan Plateau (TP) is an important component of the global environmental system, on which the snow cover greatly affects the regional climate and ecology. Moderate resolution imaging spectroradiometer (MODIS) snow cover products have been demonstrated to be appropriate for investigating the snow cover over the TP. However, they are subject to cloud obscuration, and the TP’s extremely complex terrain makes the snow monitoring difficult. Therefore, in this paper, we propose a two-stage spatio–temporal fusion framework for the cloud removal of MODIS C6 snow products, including an adjusted Terra and Aqua combination (TAC) and a spatio–temporal fusion based on Gaussian kernel function and error correction (STF-GKF-EC). To the best of our knowledge, this is the first time that a spatio–temporally continuous daily 500-m MODIS normalized difference snow index (NDSI) product has been generated for the TP, which greatly improves the spatial and temporal resolutions of the current snow cover products. The main stage, STF-GKF-EC, adaptively weights the spatial and temporal correlations by the Gaussian kernel function, and further takes the rapid changes of snow cover into consideration through the error correction. The experiments indicated that STF-GKF-EC removes clouds completely, achieving an overall accuracy (OA) and mean absolute error (MAE) of 91.48% and 3.88, respectively. Based on the cloud-removed results, during 2001–2017, as far as the intra-annual variation is concerned, a large proportion of the snow cover appears between October and May, with a peak in February/March, and the variation is mainly controlled by temperature. For the inter-annual variation, an obvious increasing trend of 0.68/year for NDSI is observed before 2005, followed by a slight decreasing trend of 0.16/year, in which precipitation is a better explanation factor than temperature.

Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 307
Author(s):  
Chi Zhang ◽  
Naixia Mou ◽  
Jiqiang Niu ◽  
Lingxian Zhang ◽  
Feng Liu

Changes in snow cover over the Tibetan Plateau (TP) have a significant impact on agriculture, hydrology, and ecological environment of surrounding areas. This study investigates the spatio-temporal pattern of snow depth (SD) and snow cover days (SCD), as well as the impact of temperature and precipitation on snow cover over TP from 1979 to 2018 by using the ERA5 reanalysis dataset, and uses the Mann–Kendall test for significance. The results indicate that (1) the average annual SD and SCD in the southern and western edge areas of TP are relatively high, reaching 10 cm and 120 d or more, respectively. (2) In the past 40 years, SD (s = 0.04 cm decade−1, p = 0.81) and SCD (s = −2.3 d decade−1, p = 0.10) over TP did not change significantly. (3) The positive feedback effect of precipitation is the main factor affecting SD, while the negative feedback effect of temperature is the main factor affecting SCD. This study improves the understanding of snow cover change and is conducive to the further study of climate change on TP.


2014 ◽  
Vol 7 (1) ◽  
pp. 169-194 ◽  
Author(s):  
Wei Wang ◽  
Xiaodong Huang ◽  
Jie Deng ◽  
Hongjie Xie ◽  
Tiangang Liang

Author(s):  
Leilei Xu ◽  
Peng Liu ◽  
Bingji Zhao ◽  
Qingjun Zhang ◽  
Yaqiu Jin

Author(s):  
Shirui Hao ◽  
Lingmei Jiang ◽  
Jiancheng Shi ◽  
Gongxue Wang ◽  
Xiaojing Liu

IEEE Access ◽  
2018 ◽  
Vol 6 ◽  
pp. 55599-55613 ◽  
Author(s):  
Yongjun Zhang ◽  
Xunwei Xie ◽  
Xiang Wang ◽  
Yansheng Li ◽  
Xiao Ling

Author(s):  
Y. Ha ◽  
Y. M. Zhu ◽  
Y. J. Hu ◽  
Z. Zhong

Abstract. Abrupt interdecadal changes in summer precipitation (May – September) over the Indochina Peninsula in the past 40 years have been investigated based on the NCEP-NCAR reanalysis product over 1979–2013 and multiple precipitation datasets. The mechanism for the abrupt change is explored. Results indicate that an abrupt interdecadal change in summer precipitation over the Indochina Peninsula occurred in the middle 1990s, and the annual mean summer precipitation during 1994–2002 increased by about 10% compared to that during 1982–1993. The most significant precipitation change occurred in the central and northern peninsula. Further analysis reveals that the interdecadal decrease in snow cover over the Tibetan Plateau in the winter and spring contributed to the summer precipitation increase over the Indochina Peninsula. The decrease in snow cover over the Tibetan Plateau actually increased the thermal contrast between the Tibetan Plateau and the tropical Indian Ocean-northwestern Pacific, leading to intensified summer monsoon over the northwestern Pacific and the South China Sea. As a result, westerly anomalies occurred from the Bay of Bengal to the northwestern Pacific, while anomalous cyclonic circulation prevailed in the upper levels above East Asia. Correspondingly, the western Pacific subtropical high weakened and shifted eastward. Under the joint effects of the above circulation patterns, the atmosphere became wetter in the Indochina Peninsula and summer precipitation increased. Results of the present study provide a theoretical basis for the prediction of long-term summer precipitation change in the Indochina Peninsula.


2017 ◽  
Vol 9 (12) ◽  
pp. 1332 ◽  
Author(s):  
Hui Liang ◽  
Xiaodong Huang ◽  
Yanhua Sun ◽  
Yunlong Wang ◽  
Tiangang Liang

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