# Biomass production from NPP in the Earth Engine

Calculate world wide biomass production from the MODIS NPP.

The NPP can be used to estimate the production of biomass (kgm2). Biomass is the dry matter of vegetation that consists of carbohydrates (CH2O). Total biomass production is calculated by including the molecular masses of hydrogen and oxygen into the equation.

Biomass = NPP * (30/12)

Yearly NPP is downscaled to an 8 daily time-series in this exercise.

Step 1: Open this script

Step 2: Add code below to calculate the biomass

```// calculate the Biomass

var Biomass = function(myimg){
var biomass = myimg.multiply(2.5);
return biomass.copyProperties(myimg,['system:time_start']);
}

// map biomass production
var biomassCollection = npp8Collection.map(Biomass);
```

3. Add the fusion table of the Da basin and one of the Thai Binh province.

``` // import the sub basins as a fusion table
var Da = ee.FeatureCollection('ft:15ytieQkq3UH8DPJPFmB_YnbvhSEhOQLtLIXa6kxA').geometry();
var ThaiBinh = ee.FeatureCollection('ft:1w0nJ-In_Tabrr9zS-C6pdw1sHwuZM1_YS9mxacOf').geometry();

// Set center of map
Map.centerObject(Da, 5);

// show the layer

// create vizualtion settings
var biomass_viz = {min:300.0, max:800, palette:"b27c00,ffff33,58ff33,146003"};

```

4. Plot the temporal changes in a chart.

```// Predefine the chart titles.
var title = {
title: 'Biomass production in Da basin',
hAxis: {title: 'Time'},
vAxis: {title: 'Biomass (kg/m2)'},
};

// create chart
var biomassChartDa = ui.Chart.image.seriesByRegion(biomassCollection,
Da,
ee.Reducer.mean(),
'Gpp',
500,
'system:time_start').setOptions(title);
// plot chart
print(biomassChartDa)

// Predefine the chart titles.
var title = {
title: 'Biomass production in Thai Binh basin',
hAxis: {title: 'Time'},
vAxis: {title: 'Biomass (kg/m2)'},
};

// create chart
var biomassChartBinh = ui.Chart.image.seriesByRegion(biomassCollection,
ThaiBinh,
ee.Reducer.mean(),
'Gpp',
500,
'system:time_start').setOptions(title);
// plot chart
print(biomassChartBinh)
```

Find an example here.