The "End of growing season - First growing cycle" (Onset_Greenness_Minimum_1) is one of the 19 Science Dataset (SDS) layers generated by the VIIRS/NPP Land Surface Phenology (VNP22Q2) product and represents the date at which canopy greenness reaches a minimum (dormancy onset, end of growing season, or end of fall).
The following calculation has been used to scale the data according to the VIIRS Global Land Surface Phenology Product user guide:
Scaled Data = Unscaled data – (given year-2000)*366
The VNP22Q2 dataset provides yearly land surface phenology data for the period from 2013 to present. The VNP22Q2 product generates phenological metrics of individual vegetation growing cycles on the vegetated land surface with a spatial resolution of 500m at global level between 60°S to 80°N. It is a level 3 product and follows the structure and file format of the high level global VIIRS data.
For more detail, such as the definition of parameters and growing cycles, please visit the website of the data provider: https://lpdaac.usgs.gov/products/vnp22q2v001/.
Data publication: 2022-01-01
Citation:
Citation: Zhang, X., Friedl, M., Henebry, G. (2020). VIIRS/NPP Land Cover Dynamics Yearly L3 Global 500m SIN Grid V001 [Data set]. NASA EOSDIS Land Processes DAAC. Accessed 2022-03-03 from https://doi.org/10.5067/VIIRS/VNP22Q2.001
Contact points:
Resource Contact: Xiaoyang Zhang
Metadata Contact: Pengyu Hao
Data lineage:
The VNP22Q2 data are generated using the Hybrid Piecewise Logistic Model (HPLM)-Land Surface Phenology Detection (LSPD) algorithm, daily EVI2 time series generated from the VIIRS NBAR are used as input. The vegetation greenup phases and senescence phases are separated using a moving slope algorithm along the smoothed EVI2 time series temporal trajectory. The HPLM is finally applied for fitting the EVI2 time series, and the timing of phenological transitions during the vegetation growing season (such as the greenup onset, maturity onset) are then extracted based on curvture change rate from the reconstructed temporal trajectory and the phenology data are evaluated by the comparison with PhenoCam data and Landsat time series. In addition, the algorithm used for this product allows to record a maximum of two growing cycles in a given calendar year. The parameter used in the present layer is the minimum greenness onset of the first growing cycle (Onset_Greenness_Minimum_1) in each calendar year.
Definition of the parameters and the growing cycles are shown in the User Guide of the VNP22Q2 product. (Zhang et al. 2018).
Reference:
Zhang, X., Liu, L., Liu, Y., Jayavelu, S., Wang, J., Moon, M., Henebry, G.M., Friedl, M.A., Schaaf, C.B. (2018). Generation and evaluation of the VIIRS land surface phenology product, Remote Sensing of Environment, 216, 212-229.
More information can be found at: https://lpdaac.usgs.gov/products/vnp22q2v001/#documentation
Resource constraints:
Data Access:
All data products distributed by NASA's Land Processes Distributed Active Archive Center (LP DAAC) are available at no charge.
Data Redistribution:
All LP DAAC current data and products acquired through the LP DAAC have no restrictions on reuse, sale, or redistribution.
Online resources:
LPDAAC-USGS (NASA Earth Data) Website on VIIRS/NPP Land Surface Phenology (Land Cover Dynamics)
Documentation
