GEE: Synthesize images based on statistical values of time series (standard deviation, mode, maximum, minimum, mean, median, variance, pixel sum, number of pixels)

On the Google Earth Engine (GEE) platform, we can use time-series data to generate synthetic imagery. Time series data is a set of time-ordered data, which can be remote sensing images, meteorological data, etc. Using time series data, we can analyze the changes in data at different time points, and then synthesize a more comprehensive and accurate image.

Next, let's introduce how to synthesize images based on time series statistical values ​​on the GEE platform, and introduce the calculation codes for various statistical values.

The result is shown in the figure below,

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1. Ideas

First, we need to prepare a set of time series data. Take the normalized difference vegetation index (NDVI) data calculated by Sentinel-2 as an example. NDVI is a remote sensing indicator that can be used to estimate vegetation coverage and growth. We can obtain Sentinel-2 NDVI time series data on the GEE platform. Suppose we have acquired Sentinel-2 NDVI data from 2017 to 2019.

2. Calculator

name	function
maximum value	ee.Reducer.max()