Subjects: Geosciences >> Atmospheric Sciences submitted time 2023-08-25 Cooperative journals: 《干旱区研究》
Abstract： Using MOD10A2 snow product data from 2001 to 2020, along with digital elevation andmeteorological data, the spatiotemporal variation of snow cover in the Altai Mountains, Xinjiang, and theinfluence of topographic and meteorological factors over this period were analyzed. The results indicated thefollowing. (1) Snow cover percentage (SCP) in the Altai Mountains of Xinjiang exhibited a decreasing overalltrend from 2001 to 2020, with the lowest and highest values observed in 2007 and 2010, respectively, and avariation rate of − 5.69%·(10a) − 1. Troughs were observed throughout the year, with maximum and minimumtroughs in January and July, respectively. Seasonally, SCP increased in fall and decreased in the other threeseasons. The uneven distribution of climate conditions, including temperature and precipitation, causedfluctuations in the timing of maximum annual snow cover occurrence. The Altai annual SCP reached its peakbetween 96.45% and 99.92%, primarily observed in January and December. The lowest coverage range was0.84%-2.27%, which occurred in July and August. (2) SCP showed a positive correlation with altitude, withlower SCP values below 500 m (average of 8.11%) and higher values above 2000 m (average of 99.08% in anarea with stable snow cover all year round). SCP varied depending on the slope, with the northwest slopeexhibiting the highest values (28.45%) and the south slope showing the lowest values (18.36%). (3) Land surfacetemperature exhibited higher and lower distributions in the northeast and southwest, respectively, and wassignificantly positively correlated with altitude. Moreover, 67.65% of the Altai Mountain region showed adownward trend in snow cover frequency (SCF) from 2001 to 2020. High mountain areas experienced increasingSCF, whereas plain and river areas exhibited decreasing SCF. (4) Temperature was the main factor influencingsnow cover change, being negatively correlated with SCF over 9.08 × 103 km2 (80.52% of the total AltaiMountain area). Therefore, as altitude increases, the impact of temperature on snow cover gradually diminishes.Annual average precipitation in Altai decreased gradually from northwest to southeast, and precipitation waspositively correlated with 87.14% of regional SCF, with a weakened effect on SCF changes observed in highaltitudemountain areas and a more significant correlation observed in low-altitude areas.
Subjects: Geosciences >> Geography submitted time 2023-08-25 Cooperative journals: 《干旱区研究》
Abstract： To evaluate the ecological environment of Altay City in Xinjiang in a timely, objective, andquantitative manner, an improved remote sensing ecological index (MRSEI) was constructed based on multisourceremote sensing data. The spatial and temporal variation characteristics were then analyzed by combining astandard deviation ellipse and gravity center migration model. A geographical detector model was used to detectthe five indicators, which were greenness, dryness, humidity, temperature, and air quality. (1) From 2015 to 2021,the greenness and humidity indexes of Altay City showed a significant positive correlation with the ecologicalenvironment in the region. In contrast, the three indexes for temperature, dryness, and air quality showedsignificant negative correlations. (2) From 2015 to 2021, the average value of the MRSEI in Altay City increased.The spatial migration ability of ecological index areas I and II was strong, while III-V were relatively stable in thespatial structure. The center of gravity for ecological index areas I-IV moved north, while the center of gravity forarea V moved south, indicating that the distribution of the high ecological index in the south of Altay Cityincreased significantly. (3) The dominant factors causing the changes in the eco- environmental quality differedeach year. The spatial evolution of eco-environmental quality in Altay is the result of multiple factors. (4) Thedifferences in spatial distribution and the differences between the MRSEI and RSEI data are related to the spatialdistribution of AOD, indicating that even if Altay City had improved air quality, AOD would still have an impacton the ecological quality of the spatial distribution. From 2015 to 2021, the ecological environment of Altay Citywas thus found to be affected by many factors and tended to improve toward the south.
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