东北地区湖冰生消过程遥感反演研究

Lake ice phonology is a sensitive indicator for climate changes and the monitoring using remote sensing has great scientific influence on regional lacustrine environment and water resources. Taken lake areas in Northeast China as study objects, the physical changes and temporal change of freeze/thaw cycle by the method of field measurement, transect analysis, lake comparison, climate abrupt detection and so on. The project plan to carry out ice investigation and spectra collection to study lake ice reflectance feature of different types and to find the sensitive band ranges. Based on the time series of satellite information, grid based and lake-based lake ice phenology are extracted automatically, which are validated by field measurement and mid and high resolution images. The objective of this projected is to improve the knowledge of the remote sensing mechanics and regional lake ice phenology changes, to study the regional coherence of lake ice phenology, to study the influence of geographic location, lake morphometry and climate factors on lake ice phenology, to provide data source for monitoring and assessing the lake environment changes, and to provide the mechanical study and technical support for global change monitoring.

湖冰物候变化是全球气候变化敏感指示器，监测湖冰物候变化对区域湖泊环境、水资源管理具有重要的科学意义。选择东北典型湖区作为研究对象，通过野外观测、样带分析、湖泊比较学、气候突变检测等方法，研究湖泊生消过程的物理变化和时间变化。开展冰情调查和光谱采样，研究不同类型的水、积雪、湖冰光谱特性及光学遥感识别机理，确定湖冰遥感反演的敏感波段。基于湖冰遥感信息的时间序列，设计湖冰物候多源遥感自动提取算法，自动获取不同尺度的湖冰物候遥感参数，利用水文年鉴和中高分辨遥感数据验证精度。本项目的实施能够提高对湖冰遥感识别机理、区域湖冰物候变化趋势的认知水平，探讨东北地区湖冰物候变化趋势及区域一致性，研究地理位置（纬度、海拔）、湖泊形态参数（湖泊面积、湖泊深度等）和气象因子对湖冰物候变化的影响，为监测和评估湖泊环境变化提供数据支持，为认识区域气候变化机制、应对全球气候变化提供机理研究和技术支持。

湖冰变化是全球气候变化敏感指示器，监测湖冰物候变化对湖泊环境具有重要的科学意义。利用MODIS遥感数据实现对东北地区8个大型湖泊的湖冰生消时间监测，东北地区湖冰物候周期仍然呈现区域一致性变化趋势：结冰时间区域延后，融化日期趋于提前，而湖冰冰期呈现缩短趋势，融冰过程的年变化率明显大于结冰过程的年变化率。气温是区域指标中对湖冰物候变化影响最大的因素。基于水文年鉴数据解释积雪对河湖冰生消过程的影响，积雪在河冰稳定期的作用更明显，能够提高冰厚模拟的精度；当考虑湖泊年内生消变化过程，累积负温是河湖冰生消过程的关键因素。我们发现了查干湖遥感影像上重复出现西北-东南走向的图像裂缝，利用基于分形理论的边缘检测方法提获取2018年冬季裂缝的平均角度和平均长度分别为65°28′34″±0°13′34″、21141.57±68.36 km，在野外调查处中发现图像裂缝的东南端存在冰脊。冰封期冰裂缝的走向与冬季的主风向垂直，与风场、冰下流场、水下地形等因素密切相关。