Phenological metrics for Protected Area "OhridPrespa", MODIS aqua tile h19v04

Phenological metrics derived from satellite data by use of R-package "phenex" (Lange (2017)). NDVI is filtered by modified BISE algorithm (see Viovy (1992)). NDVI curve is modelled with method DLogistic (see Doktor (2017), Lange (2017)). Phenological metrics include:

(1) Start of season / green-up (GU);
(2) End of season / senescence (SEN);
(3) Length of vegetation period (VP);
(4) GPP proxy (integral over vegetation period, GSIVI);
(5) minimum NDVI (MinNDVI);
(6) maximum NDVI (MaxNDVI);
(7) day of minimum NDVI as julian date (MinDOY);
(8) day of maximum NDVI as julian date (MaxDOY);
(9) r-square of modelled NDVI curve;

(1)-(4) are derived by using local threshold (LT) and global threshold (GT) method (see Doktor (2017), Lange (2017)).

(1)-(6) include mean and standard deviation;

References: [Viovy 1992]: Viovy N, Arino O, Belward A (1992) The Best Index Slope Extraction (BISE): A method for reducing noise in NDVI time-series. International Journal of Remote Sensing 13(8):1585–1590;

[Doktor 2017]: Doktor D, Lange M (2017) Disparate applicability and broad spatio-temporal satellite resolution affects extracted trends of European spring phenology for 1989-2007. In preparation for Global Ecology and Biogeographie;

[Lange 2017]: Lange M, Doktor D (2017) phenex: Auxiliary Functions for Phenological Data Analysis. R package version 1.4-5, https://CRAN.R-project.org/package=phenex, Last accessed on 2017-05-29;

本数据集的物候指标通过R包"phenex"（Lange, 2017）基于卫星数据推导得到。归一化差分植被指数（Normalized Difference Vegetation Index，NDVI）经修正的最佳指数斜率提取（BISE）算法进行滤波处理（详见Viovy, 1992）。NDVI曲线采用DLogistic方法进行建模（详见Doktor, 2017；Lange, 2017）。

本数据集包含以下物候指标：
1. 生长季起始期/返青期（GU）；
2. 生长季结束期/植被衰老期（SEN）；
3. 植被生长期长度（VP）；
4. 总初级生产力代用指标（植被周期内积分值，GSIVI）；
5. NDVI最小值（MinNDVI）；
6. NDVI最大值（MaxNDVI）；
7. NDVI最小值对应的儒略日（MinDOY）；
8. NDVI最大值对应的儒略日（MaxDOY）；
9. 建模所得NDVI曲线的决定系数（r-square）。

上述第(1)至(4)项指标通过局部阈值（LT）法与全局阈值（GT）法推导得到（详见Doktor, 2017；Lange, 2017）。

上述第(1)至(6)项指标均包含均值与标准差两项统计量。

参考文献：
[Viovy 1992]：Viovy N, Arino O, Belward A. 最佳指数斜率提取（BISE）：一种降低NDVI时间序列噪声的方法. 《国际遥感学报》（International Journal of Remote Sensing）, 1992, 13(8): 1585–1590;
[Doktor 2017]：Doktor D, Lange M. 不同适用性与宽时空卫星分辨率对1989-2007年欧洲春季物候提取趋势的影响. 拟发表于《Global Ecology and Biogeographie》（全球生态学与生物地理学）;
[Lange 2017]：Lange M, Doktor D. phenex：物候数据分析辅助函数. R包版本1.4-5，https://CRAN.R-project.org/package=phenex，最后访问时间：2017-05-29;