| As the highest pole of the earth,the Tibetan Plateau and the north pole climate interact with each other,which has a significant impact on the climate,vegetation and biogeochemical cycle of the northern hemisphere and even the world.The analysis and comparison of vegetation and climate change between the Arctic and the high pole than it is helpful to understand the internal difference in the effects of bipolar climate change on the surface vegetation community and the adaptability of the polar vegetation to adapt to global warming.the study selected MODIS EVI and ERA5 meteorological data(temperature,precipitation and radiation)from 2001 to 2018,and the traditional statistical method,the maximum value synthesis method,the trend analysis method and the correlation analysis method respectively were used to carry out comparative study on vegetation and climate change in the high pole and the north pole.In addition,based on the EVI data and the method of curvature extremum of logistic fitting curve,the phenology of vegetation at the two poles is retrieved,then the time differences of stant and end of growth season are compared and analyzed.The results are as follows:(1)The distribution frequency of EVI mean is very high in 0-0.2 non-vegetation interval in the high pole and the north pole,but the distribution frequency of Arctic in vegetation interval greater than 0.2 is significantly lower than that of high pole,and there is no distribution frequency in the interval greater than 0.6 in 2001-2018.The distribution frequency of Arctic EVI mean in the interval 1-2 is much higher than that in the high pole,but in other intervals it is lower than the high pole.It is difference in the appearance time of the maximum value of the two poles EVI.The maximum value of EVI in high polar year mainly occurs in 161-257 days,and the maximum value is almost all distributed in the range of0.2-0.6.However,the maximum value of the annual EVI in the Arctic is almost all distributed in the range of 0.2-0.5,and the maximum value appears mainly in 193-225 days.(2)The inter-annual variability of the high pole and Arctic EVI were more frequently distributed in a positive growth interval greater than 0,and the distribution of the Arctic EVI increased year by year in 2001-2018,but The annual average temperature and accumulated precipitation in the Arctic are increasing year by year,while the annual average radiation is decreasing year by year.The annual average temperature and radiation in the high-pole region are increasing year by year as a whole,and the annual precipitation is decreasing year by year.(3)The return time of high-polar vegetation is in the 120-180 days,the decay time is in the 240-300 days,and the length of the growing season lasts approximately 90-150 days.The time for the Arctic vegetation to return to green is in the 120 th to 180 th days,and the decay time is in the 240 th to 270 th days.The length of the growing season lasts approximately 90-120 days.(4)The annual average temperature of the high pole and the Arctic is relatively low,and the annual accumulated precipitation is relatively small,but the annual average temperature and annual accumulated precipitation of the high pole area are much higher than the North Pole.The annual average radiation of the two poles is quite different,and the annual average radiation of the North Pole is much less than that of the high pole.From 2001 to 2018,the correlation coefficients between high pole and North Pole EVI and temperature were concentrated in the 0.8-1 interval,and the correlation coefficients between the two pole EVI and precipitation were mainly concentrated in the 0.4-1 interval,but the high poles were distributed in the 0.8-1 interval Higher frequency.There is a large difference in the correlation between vegetation and radiation at the poles.Among them,the correlation coefficient between high-pole EVI and radiation is mainly distributed in the-0.4-0.4 interval,while the Arctic is mainly concentrated in the 0-0.8 interval. |
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