2002-2012年青藏高原积雪物候变化及其对气候的响应
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摘要
积雪是地表最活跃的自然要素之一,其动态变化对气候、环境以及人类生活都产生了重要影响。本文利用MODIS积雪产品和IMS雪冰产品,首先通过Terra、Aqua双星合成和临近日合成去除MODIS积雪产品中的部分云像元,再与IMS融合,获取了青藏高原2002-2012年逐日无云积雪覆盖产品,并逐像元计算每个水文年的积雪覆盖日数(SCD)、积雪开始期(SCS)和积雪结束期(SCE),分析了不同生态分区积雪的时空变化特征,以及积雪开始期和结束期与温度、降水的关系。结果表明:青藏高原积雪分布存在明显的空间差异,南部喜马拉雅山脉和念青唐古拉山地区以及西部帕米尔高原和喀喇昆仑山脉为SCD的2个高值区,年均积雪日数在200 d以上。18.1%的区域SCS表现出明显的提前趋势,主要集中在青藏高原中东部;羌塘高原南部、念青唐古拉山西段以及川西地区有显著推迟趋势,占高原面积的8.5%。23.2%的区域SCE显著推迟,主要集中在果洛那曲高寒区、昆仑山区和念青唐古拉山地区;而仅有6.9%的区域表现出提前趋势,主要分布在高原西南部。总体上,不同生态单元内积雪开始与结束期受温度、降水的影响差异很大,表现出不同的空间格局与演变趋势。
Snow cover is one of the most active natural components on Earth's surface. The variability of snow phenology has a major impact on water cycle, climate change, environment and human activities. The Qinghai-Tibetan Plateau has a wide range of seasonal snow cover, and its accumulation and rapid meltdown can affect the regional and global climate change. Studying the snow variability in the Qinghai-Tibetan Plateau is therefore important. In this study, the MODIS snow product and IMS snow-ice product were used. Firstly, the Terra and Aqua satellite images were combined to reduce the proportion of cloud pixels. Secondly,the temporal combinations were employed to further reduce the cloud pixels. Finally, the processed MODIS snow product and IMS were fused to produce the daily cloud-free snow product of the Qinghai-Tibetan Plateau from 2002 to 2012. Then, the snow-covered days(SCD), snow cover start(SCS) and snow cover end(SCE) dates were calculated for each hydrological year, and their spatial and temporal variations in different eco-geographical regions were analyzed. The correlations among the SCS, SCE and climate factors were also investigated. The results show that the distribution of snow cover over the Qinghai-Tibetan Plateau was very uneven.The longest SCD, totalized to be more than 200 days, occurred in the Himalayas, Karakoram, Nyainqentanglha Mountains and the Pamirs Plateau. Up to 18.1% of the area of SCS showed a significantly advanced trend, which mainly occurred in the Golog-Nagqu high-cold region and the southern Qinghai high-cold region; while 8.5% of the area showed a slightly delayed trend. Up to 23.2%of the area of SCE was delayed, occurring mainly in the central and eastern Tibetan Plateau; while only 6.9% of the area showed an advanced trend. The SCS and SCE were greatly affected by temperature and precipitation, but showed different spatial patterns and evolution trends in different ecological zones. Generally, the higher temperature delayed the SCS and advanced the SCE, but more precipitation led to the earlier SCS and the later SCE.
Snow cover is one of the most active natural components on Earth's surface. The variability of snow phenology has a major impact on water cycle, climate change, environment and human activities. The Qinghai-Tibetan Plateau has a wide range of seasonal snow cover, and its accumulation and rapid meltdown can affect the regional and global climate change. Studying the snow variability in the Qinghai-Tibetan Plateau is therefore important. In this study, the MODIS snow product and IMS snow-ice product were used. Firstly, the Terra and Aqua satellite images were combined to reduce the proportion of cloud pixels. Secondly,the temporal combinations were employed to further reduce the cloud pixels. Finally, the processed MODIS snow product and IMS were fused to produce the daily cloud-free snow product of the Qinghai-Tibetan Plateau from 2002 to 2012. Then, the snow-covered days(SCD), snow cover start(SCS) and snow cover end(SCE) dates were calculated for each hydrological year, and their spatial and temporal variations in different eco-geographical regions were analyzed. The correlations among the SCS, SCE and climate factors were also investigated. The results show that the distribution of snow cover over the Qinghai-Tibetan Plateau was very uneven.The longest SCD, totalized to be more than 200 days, occurred in the Himalayas, Karakoram, Nyainqentanglha Mountains and the Pamirs Plateau. Up to 18.1% of the area of SCS showed a significantly advanced trend, which mainly occurred in the Golog-Nagqu high-cold region and the southern Qinghai high-cold region; while 8.5% of the area showed a slightly delayed trend. Up to 23.2%of the area of SCE was delayed, occurring mainly in the central and eastern Tibetan Plateau; while only 6.9% of the area showed an advanced trend. The SCS and SCE were greatly affected by temperature and precipitation, but showed different spatial patterns and evolution trends in different ecological zones. Generally, the higher temperature delayed the SCS and advanced the SCE, but more precipitation led to the earlier SCS and the later SCE.
引文
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[9]Wang K,Zhang L,Qiu Y B,et al.Snow effects on alpine vegetation in the Qinghai-Tibetan Plateau[J].International Journal of Digital Earth,2015,8(1):56-73.
[10]Paudel K P,Adersen P.Response of rangeland vegetation to snow cover dynamics in Nepal Trans Himalaya[J].Climatic Change,2013,117(1-2):149-162.
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[13]马丽娟,秦大河,卞林根,等.青藏高原积雪的脆弱性评估[J].气候变化研究进展,2010,6(5):325-331.[Ma L J,Qin D H,Bian L G,et al.Assessment of snow cover vulnerability on the Qinghai-Tibetan Plateau[J].Advances in Climate Change Research,2010,6(5):325-331.]
[14]Ault T W,Czajkowski K P,Benko T,et al.Validation of the MODIS snow product and cloud mask using student and NWS cooperative station observations in the Lower Great Lakes Region[J].Remote Sensing of Environment,2006,105(4):341-353.
[15]刘洵,金鑫,柯长青.中国稳定积雪区IMS雪冰产品精度评价[J].冰川冻土,2014,36(3):500-507.[Liu X,Jin X,Ke C Q.Accuracy evaluation of the IMS snow and ice products in stable snow covers regions in China[J].Journal of Glaciology and Geocryology,2014,36(3):500-507.]
[16]Mazari N,Tekeli A E,Xie H J,et al.Assessment of ice mapping system and moderate resolution imaging spectroradiometer snow cover maps over Colorado Plateau[J].Journal of Applied Remote Sensing,2013,7(1):073540.
[17]Yang J,Jiang L,Menard C B,et al.Evaluation of snow products over the Tibetan Plateau[J].Hydrological Processes,2015,29(15):3247-3260.
[18]黄晓东,郝晓华,王玮,等.MODIS逐日积雪产品去云算法研究[J].冰川冻土,2012,34(5):1118-1126.[Huang X D,Hao X H,Wang W,et al.Algorithms for cloud removal in MODIS daily snow products[J].Journal of Glaciology and Geocryology,2012,34(5):1118-1126.]
[19]Wang X,Xie H.New methods for studying the spatiotemporal variation of snow cover based on combination products of MODIS Terra and Aqua[J].Journal of Hydrology,2009,371(1):192-200.
[20]李培基,米德生.中国积雪的分布[J].冰川冻土,1983,5(4):9-18.[Li P J,Mi D S.Distribution of snow cover in China[J].Journal of Glaciology and Geocryology,1983,5(4):9-18.]
[21]伯玥,李小兰,王澄海.青藏高原地区积雪年际变化异常中心的季节变化特征[J].冰川冻土,2014,36(6):1353-1362.[Bo Y,Li X L,Wang C H.Seasonal characteristics of the interannual variations centre of the Tibetan Plateau snow cover[J].Journal of Glaciology and Geocryology,2014,36(6):1353-1362.]
[22]田柳茜,李卫忠,张尧,等.青藏高原1979-2007年间的积雪变化[J].生态学报,2014,34(20):5974-5983.[Tian L X,Li W Z,Zhang Y,et al.The analysis of snow information from 1979 to 2007 in Qinghai-Tibetan Plateau[J].Acta Ecologica Sinica,2014,34(20):5974-5983.]
[23]王春学,李栋梁.中国近50 a积雪日数与最大积雪深度的时空变化规律[J].冰川冻土,2012,34(2):247-256.[Wang C X,Li D L.Spatial-temporal variations of snow cover days and the maximum depth of snow cover in China during recent 50 years[J].Journal of Glaciology and Geocryology,2012,34(2):247-256.]
[2]林金堂,冯学智,肖鹏峰,等.基于MODIS数据的玛纳斯河山区雪盖年内变化特征研究[J].遥感信息,2012(2):20-24,80.[Lin J T,Feng X Z,Xiao P F,et al.Inner-annual variation of snow cover in mountainous area of Manas river basion based on MODIS[J].Remote Sensing Information,2012,2:20-24,80.]
[3]白淑英,史建桥,高吉喜,等.1979-2010年青藏高原积雪深度时空变化遥感分析[J].地球信息科学学报,2014,16(4):628-637.[Bai S Y,Shi J Q,Gao J X,et al.Analysis of spatial-temporal variations of snow depth over the Qinghai-Tibetan Plateau during 1979-2010[J].Journal of Geo-information Science,2014,16(4):628-637.]
[4]Brown R D,Robinson D A.Northern Hemisphere spring snow cover variability and change over 1922-2010 including an assessment of uncertainty[J].The Cryosphere,2011,5(1):219-229.
[5]Peng S,Piao S,Ciais P,et al.Change in snow phenology and its potential feedback to temperature in the northern hemisphere over the last three decades[J].Environmental Research Letters,2013,8(014008):1-8.
[6]Dietz A J,Kuenzer C,Conrad C.Snow-cover variability in central Asia between 2000 and 2011 derived from improved MODIS daily snow-cover products[J].International Journal of Remote Sensing,2013,34(11):3879-3902.
[7]王叶堂,何勇,侯书贵.2000-2005年青藏高原积雪时空变化分析[J].冰川冻土,2007,29(6):855-861.[Wang Y T,He Y,Hou S G.Analysis of the temporal and spatial variations of snow cover over the Tibetan Plateau based on MODIS[J].Journal of Glaciology and Geocryology,2007,29(6):855-861.]
[8]Chen X N,Liang S L,Cao Y F,et al.Observed contrast changes in snow cover phenology in northern middle and high latitudes from 2001-2014[J].Scientific Reports,2015,5:16820
[9]Wang K,Zhang L,Qiu Y B,et al.Snow effects on alpine vegetation in the Qinghai-Tibetan Plateau[J].International Journal of Digital Earth,2015,8(1):56-73.
[10]Paudel K P,Adersen P.Response of rangeland vegetation to snow cover dynamics in Nepal Trans Himalaya[J].Climatic Change,2013,117(1-2):149-162.
[11]刘章文,陈仁升,宋耀选.寒区灌丛与积雪关系研究进展[J].冰川冻土,2014,36(6):1582-1590.[Liu Z W,Chen RS,Song Y X.Advance in study of the relationship between shrub and snow cover in cold regions[J].Journal of Glaciology and Geocryology,2014,36(6):1582-1590.]
[12]张镱锂,李炳元,郑度.论青藏高原范围与面积[J].地理研究,2002,21(1):1-8.[Zhang Y L,Li B Y,Zheng D.A discussion on the boundary and area of the Tibetan Plateau in China[J].Geographical Research,2002,21(1):1-8.]
[13]马丽娟,秦大河,卞林根,等.青藏高原积雪的脆弱性评估[J].气候变化研究进展,2010,6(5):325-331.[Ma L J,Qin D H,Bian L G,et al.Assessment of snow cover vulnerability on the Qinghai-Tibetan Plateau[J].Advances in Climate Change Research,2010,6(5):325-331.]
[14]Ault T W,Czajkowski K P,Benko T,et al.Validation of the MODIS snow product and cloud mask using student and NWS cooperative station observations in the Lower Great Lakes Region[J].Remote Sensing of Environment,2006,105(4):341-353.
[15]刘洵,金鑫,柯长青.中国稳定积雪区IMS雪冰产品精度评价[J].冰川冻土,2014,36(3):500-507.[Liu X,Jin X,Ke C Q.Accuracy evaluation of the IMS snow and ice products in stable snow covers regions in China[J].Journal of Glaciology and Geocryology,2014,36(3):500-507.]
[16]Mazari N,Tekeli A E,Xie H J,et al.Assessment of ice mapping system and moderate resolution imaging spectroradiometer snow cover maps over Colorado Plateau[J].Journal of Applied Remote Sensing,2013,7(1):073540.
[17]Yang J,Jiang L,Menard C B,et al.Evaluation of snow products over the Tibetan Plateau[J].Hydrological Processes,2015,29(15):3247-3260.
[18]黄晓东,郝晓华,王玮,等.MODIS逐日积雪产品去云算法研究[J].冰川冻土,2012,34(5):1118-1126.[Huang X D,Hao X H,Wang W,et al.Algorithms for cloud removal in MODIS daily snow products[J].Journal of Glaciology and Geocryology,2012,34(5):1118-1126.]
[19]Wang X,Xie H.New methods for studying the spatiotemporal variation of snow cover based on combination products of MODIS Terra and Aqua[J].Journal of Hydrology,2009,371(1):192-200.
[20]李培基,米德生.中国积雪的分布[J].冰川冻土,1983,5(4):9-18.[Li P J,Mi D S.Distribution of snow cover in China[J].Journal of Glaciology and Geocryology,1983,5(4):9-18.]
[21]伯玥,李小兰,王澄海.青藏高原地区积雪年际变化异常中心的季节变化特征[J].冰川冻土,2014,36(6):1353-1362.[Bo Y,Li X L,Wang C H.Seasonal characteristics of the interannual variations centre of the Tibetan Plateau snow cover[J].Journal of Glaciology and Geocryology,2014,36(6):1353-1362.]
[22]田柳茜,李卫忠,张尧,等.青藏高原1979-2007年间的积雪变化[J].生态学报,2014,34(20):5974-5983.[Tian L X,Li W Z,Zhang Y,et al.The analysis of snow information from 1979 to 2007 in Qinghai-Tibetan Plateau[J].Acta Ecologica Sinica,2014,34(20):5974-5983.]
[23]王春学,李栋梁.中国近50 a积雪日数与最大积雪深度的时空变化规律[J].冰川冻土,2012,34(2):247-256.[Wang C X,Li D L.Spatial-temporal variations of snow cover days and the maximum depth of snow cover in China during recent 50 years[J].Journal of Glaciology and Geocryology,2012,34(2):247-256.]