摘要
湖冰物候事件是气候变化的敏感指示器。本文以西藏纳木错湖为研究对象,基于MODIS多光谱反射率产品数据监测了2000-2013年纳木错湖冰冻融日期,并结合多个气象站点的气象数据和实测湖面温度、湖面辐射亮温分析验证了湖冰变化的原因。纳木错湖冰变化较好地响应了区域气候变暖:开始冻结日期延迟和完全消融日期提前使湖冰存在期显著缩短(2.8 d/a)、湖冰冻结期增长、湖冰消融期缩短,其中消融期变化最为明显,平均每年缩短3.1 d。湖冰冻融日期的变化表明:2000年后纳木错湖冰冻结困难,消融加速,稳定性减弱。纳木错湖冰变化主要受湖面温度、湖面辐射亮温和气温变化的影响,它们可以作为气象因子来解释区域气候变化。
Lake ice is a sensitive proxy to climate variability as has been shown through observations and modeling. In this study, we used in-situ and satellite data to analyze lake ice change at the Nam Co Lake in Tibet in 2000-2013. The results from Moderate Resolution Imaging Spectrometer(MODIS) data showed that lake ice phenology changed significantly at the Nam Co Lake in the studied time period. The postponing freeze onset(FO) and advancing water clear of ice(WCI) dates were both obvious, resulting in the dramatic reduction of ice existence period(IEP)(2.8 days/year). Melt duration(MD), which stands for lake ice melting speed, was the most sensitive indicator of Nam Co Lake ice durations and MD was shortened by 3.1 days/year through the study period. Lake ice change at the Nam Co Lake was affected by regional climate variations, including air temperature and wind speed changes. In this study, daily air temperature from two automatic weather stations on the lakeshore showed highly consistent trend with lake ice phenology—both freeze onset(FO) and melt onset(MO) synchronized with air temperature variation. High wind speed in winter accelerates freezing. Lake ice tensile force rather than wind force can force the ice into pieces during the formation period. Lake ice phenology acts as a sensitive proxy of regional climate and can serve as an indicator of regional climate change. Further study on lake ice in the Tibetan Plateau is significant because of its sensitive response to climate change.
出处
《地理科学进展》
CSCD
北大核心
2015年第10期1241-1249,共9页
Progress in Geography
基金
国家自然科学基金项目(41071254)
国家自然科学基金重大国际合作研究项目(41120114001)
科技基础性工作专项项目(2013FY111400-2)
中国科学院资源环境科学与技术局青年人才类项目(KZCX2-EW-QN104)
关键词
湖冰
遥感
反射率阈值法
辐射亮温
青藏高原
lake ice
remote sensing
reflectivity threshold
brightness temperature
Tibetan Plateau
