北半球中高纬度地区近30年植被春季物候温度敏感性

丛楠, 张扬建, 朱军涛

Temperature sensitivity of vegetation phenology in spring in mid- to high-latitude regions of Northern Hemisphere during the recent three decades

CONG Nan, ZHANG Yang-Jian, ZHU Jun-Tao

表1 植被物候提取方法核心计算公式

Table 1 Core formulas for extraction of vegetation spring phenology

方法名称 Name of method 滤波核心公式 Core formula for filtering 阈值确定方式 Threshold algorithm Gauss-Midpoint $NDVI(t)=a+b\times {{\text{e}}^{-{{(({{x}_{t}}-c)/d)}^{2}}}}$ \[NDV{{I}_{\text{ratio}}}(t)=\frac{NDV{{I}_{t}}-NDV{{I}_{\min }}}{NDV{{I}_{\max }}-NDV{{I}_{\min }}}\] Spline-Midpoint $NDVI(t)={{a}_{t}}{{t}^{3}}+{{b}_{t}}{{t}^{2}}+{{c}_{t}}t+{{d}_{t}}$ \[NDV{{I}_{\text{ratio}}}(t)=\frac{NDV{{I}_{t}}-NDV{{I}_{\min }}}{NDV{{I}_{\max }}-NDV{{I}_{\min }}}\] HANTS-Maximum $NDVI(t)={{a}_{0}}+\underset{i=1}{\overset{n}{\mathop \sum }}\,{{a}_{i}}\cos ({{\omega }_{i}}t-{{\varphi }_{i}})$ \[NDV{{I}_{\text{ratio}}}(t)=\frac{NDVI(t+1)-NDVI(t)}{NDVI(t)}\] Polyfit-Maximum $NDVI(t)={{a}_{0}}+{{a}_{1}}t+{{a}_{2}}{{t}^{2}}+{{a}_{3}}{{t}^{3}}+\cdots {{a}_{n}}{{t}^{n}}$ \[NDV{{I}_{\text{ratio}}}(t)=\frac{NDVI(t+1)-NDVI(t)}{NDVI(t)}\] Timesat-SG $NDVI(t)=\frac{\sum\limits_{i=-m}^{i=m}{{{C}_{i}}NDV{{I}_{j+i}}}}{N}$ \[\text{Threshold}=20%\times (NDV{{I}_{\max }}-NDV{{I}_{\min }})\]