Frozen ground degradation plays an important role in vegetation growth and activity in high-altitude cold regions.This study estimated the spatiotemporal variations in the active layer thickness(ALT)of the permafrost ...Frozen ground degradation plays an important role in vegetation growth and activity in high-altitude cold regions.This study estimated the spatiotemporal variations in the active layer thickness(ALT)of the permafrost region and the soil freeze depth(SFD)in the seasonally frozen ground region across the Three Rivers Source Region(TRSR)from 1980 to 2014 using the Stefan equation,and differentiated the effects of these variations on alpine vegetation in these two regions.The results showed that the average ALT from 1980 to 2014 increased by23.01 cm/10 a,while the average SFD decreased by 3.41 cm/10 a,and both changed intensively in the transitional zone between the seasonally frozen ground and permafrost.From 1982-2014,the increase in the normalized difference vegetation index(NDVI)and the advancement of the start of the vegetation growing season(SOS)in the seasonally frozen ground region(0.0078/10 a,1.83 d/10 a)were greater than those in the permafrost region(0.0057/10 a,0.39 d/10 a).The results of the correlation analysis indicated that increases in the ALT and decreases in the SFD in the TRSR could lead to increases in the NDVI and advancement of the SOS.Surface soil moisture played a critical role in vegetation growth in association with the increasing ALT and decreasing SFD.The NDVI for all vegetation types in the TRSR except for alpine vegetation showed an increasing trend that was significantly related to the SFD and ALT.During the study period,the general frozen ground conditions were favorable to vegetation growth,while the average contributions of ALT and SFD to the interannual variation in the NDVI were greater than that of precipitation but less than that of temperature.展开更多
多年冻土的活动层具有周期性的变化规律,使用传统测量方法监测冻土形变不能满足高精度、低成本连续观测的需求.GNSS定位技术可以很好解决这些问题,但使用传统大地测量型接收机的监测系统成本较高,限制了该技术的普及.为提高冻土监测的...多年冻土的活动层具有周期性的变化规律,使用传统测量方法监测冻土形变不能满足高精度、低成本连续观测的需求.GNSS定位技术可以很好解决这些问题,但使用传统大地测量型接收机的监测系统成本较高,限制了该技术的普及.为提高冻土监测的普适性,本文提出使用监测专用的北斗/GNSS接收机结合供电系统以及物联网技术组成一套冻土综合监测系统.通过精密单点定位(precise point positioning,PPP)技术获取冻土地面形变并反演大气可降水量(precipitable water vapor,PWV),并利用全球导航卫星系统干涉反射(Global Navigation Satellite System Interferometric Reflectometry,GNSS-IR)技术反演冻土区域地表环境参数,实现冻土区域多参数的综合监测,为保证GNSS数据的质量,使用Anubis软件对观测文件的数据质量进行了综合分析.结果显示在正常情况下观测数据的信噪比(signal-to-noise ratio,SNR)和多路径误差满足要求,数据完整率较低,部分观测数据的周跳比较高,利用四系统融合解算得到的冻土形变在精度和稳定性上相较于单北斗和单GPS系统都更好,多系统融合获得的PWV和雪深序列能够较好的反映测站环境的变化,土壤湿度反演结果与ERA5土壤湿度产品能够较好的匹配.该北斗/GNSS监测系统为监测冻土地区地面形变和环境参数提供了一种高效且经济的方案,为冻土灾害预警、冻土退化评估等提供数据支持的同时,拓展了北斗/GNSS在冻土地区监测的应用价值.展开更多
基金funded by the National Natural Science Foundation of China (41807061)Postdoctoral Science Foundation of China (2018M633454)+2 种基金Fundamental Research Funds for the Central Universities of China (GK201803046)National Science Foundation of China (41930641)National Key Research and Development Plan of China (2017YFC0504702)
文摘Frozen ground degradation plays an important role in vegetation growth and activity in high-altitude cold regions.This study estimated the spatiotemporal variations in the active layer thickness(ALT)of the permafrost region and the soil freeze depth(SFD)in the seasonally frozen ground region across the Three Rivers Source Region(TRSR)from 1980 to 2014 using the Stefan equation,and differentiated the effects of these variations on alpine vegetation in these two regions.The results showed that the average ALT from 1980 to 2014 increased by23.01 cm/10 a,while the average SFD decreased by 3.41 cm/10 a,and both changed intensively in the transitional zone between the seasonally frozen ground and permafrost.From 1982-2014,the increase in the normalized difference vegetation index(NDVI)and the advancement of the start of the vegetation growing season(SOS)in the seasonally frozen ground region(0.0078/10 a,1.83 d/10 a)were greater than those in the permafrost region(0.0057/10 a,0.39 d/10 a).The results of the correlation analysis indicated that increases in the ALT and decreases in the SFD in the TRSR could lead to increases in the NDVI and advancement of the SOS.Surface soil moisture played a critical role in vegetation growth in association with the increasing ALT and decreasing SFD.The NDVI for all vegetation types in the TRSR except for alpine vegetation showed an increasing trend that was significantly related to the SFD and ALT.During the study period,the general frozen ground conditions were favorable to vegetation growth,while the average contributions of ALT and SFD to the interannual variation in the NDVI were greater than that of precipitation but less than that of temperature.
文摘多年冻土的活动层具有周期性的变化规律,使用传统测量方法监测冻土形变不能满足高精度、低成本连续观测的需求.GNSS定位技术可以很好解决这些问题,但使用传统大地测量型接收机的监测系统成本较高,限制了该技术的普及.为提高冻土监测的普适性,本文提出使用监测专用的北斗/GNSS接收机结合供电系统以及物联网技术组成一套冻土综合监测系统.通过精密单点定位(precise point positioning,PPP)技术获取冻土地面形变并反演大气可降水量(precipitable water vapor,PWV),并利用全球导航卫星系统干涉反射(Global Navigation Satellite System Interferometric Reflectometry,GNSS-IR)技术反演冻土区域地表环境参数,实现冻土区域多参数的综合监测,为保证GNSS数据的质量,使用Anubis软件对观测文件的数据质量进行了综合分析.结果显示在正常情况下观测数据的信噪比(signal-to-noise ratio,SNR)和多路径误差满足要求,数据完整率较低,部分观测数据的周跳比较高,利用四系统融合解算得到的冻土形变在精度和稳定性上相较于单北斗和单GPS系统都更好,多系统融合获得的PWV和雪深序列能够较好的反映测站环境的变化,土壤湿度反演结果与ERA5土壤湿度产品能够较好的匹配.该北斗/GNSS监测系统为监测冻土地区地面形变和环境参数提供了一种高效且经济的方案,为冻土灾害预警、冻土退化评估等提供数据支持的同时,拓展了北斗/GNSS在冻土地区监测的应用价值.
