1 Introduction

The following workflow can be used to extract a time series of Landsat Normalized Burn Ratio (NBR) using Google Earth Engine and the LandTrendr change detection algorithm.1 See (1.1) for a definitions of the spectral change metrics extracted via Landtrendr.

The workflow presented was developed and provided to me by Jen Hird (University of Calgary | Alberta Biodiversity Monitoring Institute, 2020). I adapted it for chapter 3 of my PhD thesis.

The following code javascript and r code are used in this workflow:

Google Earth Engine Lnadtrendr script

Download all2017HAs_UpdatedBatchReformattingScript_20200204.R

Table 1.1: NBR metric descriptions
metric description
preDistMean For each polygon, the average NBR value for the 5 years pre-disturbance
yod_mean Year of disturbance
eoc_year year when NBR values started to increase
totDistb Difference between pre-disturbance NBR and the NBR at the start of regeneration
relDistbVal_mean (totDistb)/SQRT(ABS(preDistMean/1000)) Calculation from @MillerThode2007
regen5yr, regen10yr, regen15yr, regen20yr Percent of totDistb values regained after 5, 10, 15, and 20 years after the disturbance
yrTo30, yrTo50, yrTo80, yrTo100 Time taken for 30%, 50%, 80%, and 100% of thetotDistb to be regained
regen_survey Percent of totDistb values regained at the year of the bird survey.
lengthDistb time between yod and eoc
length of Regen end year - eocYr
TOT_PIXELS number of pixels used for change detection (Landsat has a 30m resolution)
PERC_UNMSKD percent of pixels not masked by clouds or atmospheric conditions


Kennedy, R. E. et al. Implementation of the LandTrendr algorithm on Google Earth Engine. Remote Sensing 10, 691 (2018).