3.3. Phenological Metrics

The annual phenological metrics provide information on surface reflectance and land surface phenology to a land cover mapping model. Metrics represent a set of statistics extracted from the normalized surface reflectance time-series within a calendar year (January 1 – December 31). These statistics are stored as a set of 16-bit unsigned raster files in the same tile system as 16-day composites (see Landsat ARD Structure for details).

 

The GLAD system is designed to provide different sets of phenological metrics for various applications. Based on our ongoing research projects and feedback from the user community, our team will develop new metric types. We will add new metric types to this section and provide the corresponding codes for metric generation and application. Data users are encouraged to request new types of phenological metrics for their specific applications (contact Peter Potapov potapov@umd.edu). Each metric set has a specific letter code. Before using a new metric set, do the following:

  • Read the metrics methodology and understand the naming convention.
  • Make sure that the computer resources (disk volume, RAM) are suitable for the selected metric type.
  • Download 16-day ARD data following specific requirements.
  • Download and install all the required codes.

Supported metric types:

Phenological metrics type A (pheno_A)

Purpose: Annual land cover and vegetation structure mapping.

ARD requirement: Four years of data is recommended for metric processing (e.g., to generate 2018 metrics we recommend to download data from 2015 to 2018).

Computer requirement: At least 13GB RAM required for metric calculation.  The metrics dataset size for one tile / one year is 9GB.

 

Phenological metrics type B (pheno_B)

Purpose: Annual land cover mapping. Specifically designed for low capacity PC.

ARD requirement: One year of data is required. Two to four years of data is recommended for metric processing (e.g., to generate 2018 metrics we recommend downloading data from 2015 to 2018).

Computer requirement: At least 8GB RAM required for metric calculation.  The metrics dataset size for one tile / one year is 2.3GB.