基于遥感的dryness Index(aridy Index)指数提取

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1. 目的：提取给定站点（经纬度）的aridity index值

2. 数据来源：Zomer R J, Xu J, Trabucco A. Version 3 of the global aridity index and potential evapotranspiration database[J]. Scientific Data, 2022, 9(1): 409. link

3. 数据简介

4. 代码

1. GEE: link

2. GEE提取给定经纬度AI值

我当时是将link 中的文件下载下来，传到GEE再提取，后来发现它直接提供了aridity index image的链接，可以跳过这一步。

// 以Global-AI_ET0_v3_annual/ai_v3_yr.tif为例


// step1: 将本地的"ai_v3_yr.tif"和经纬度shapefile文件"site_LATLON"分别上传到GEE

// step2: GEE code 

/*---------------------------------*/
// 1. 导入数据
/*---------------------------------*/
var aridity_index = ee.Image("users/xxx/ai_v3_yr") //aridity index文件
var table = ee.FeatureCollection("projects/xxx/assets/site_LATLON"); //经纬度文件
var fluxnetsite = ee.FeatureCollection(table3);
//print('fluxnetsite',fluxnet2015site);


/*---------------------------------*/
// 2. Display AI map 
/*---------------------------------*/

//==================
// 2.1 显示底图
//==================

//(1) Import palette
var palettes = require('users/gena/packages:palettes')

/*
(2) Convert back by multiplying by 10,000 [The Aridity Index values reported within the Global Aridity Index_ET0 geodataset
have been multiplied by a factor of 10,000 to derive and distribute the data as integers (with 4 decimal accuracy).
This multiplier has been used to increase the precision of the variable values without using decimals.]
*/
var image = ee.Image(aridity_index.multiply(0.0001))


// (3) Define an SLD style of discrete intervals to apply to the i