Untitled

var a=function(image){
  
  var m1= image.expression(
  'm = 0.03229 + 0.281073*RH - 0.000578 *RH *T ',
  {
    'T':image.select("Temperature_height_above_ground").multiply(9/5).add(32).subtract(273.15),
    'RH':image.select("Relative_humidity_entire_atmosphere_single_layer").lte(10).multiply(image.select("Relative_humidity_entire_atmosphere_single_layer"))
  });
  
  
  var m2= image.expression(
  'm = 2.22749 + 0.160107*RH - 0.01478  *T ',
  {
    'T':image.select("Temperature_height_above_ground").multiply(9/5).add(32).subtract(273.15),
    'RH':image.select("Relative_humidity_entire_atmosphere_single_layer").gt(10).and(image.select("Relative_humidity_entire_atmosphere_single_layer").lte(50)).multiply(image.select("Relative_humidity_entire_atmosphere_single_layer"))
  });
  
  
  var m3= image.expression(
  'm = 21.0606 + 0.005565*pow(RH,2) - 0.00035 *RH *T -0.483199 * RH',
  {
    'T':image.select("Temperature_height_above_ground").multiply(9/5).add(32).subtract(273.15),
    'RH':image.select("Relative_humidity_entire_atmosphere_single_layer").gt(50).multiply(image.select("Relative_humidity_entire_atmosphere_single_layer"))
  });
  
  var m = ee.ImageCollection([m1, m2,m3]).mosaic();
  return image.addBands(m.divide(30).rename("a")).copyProperties(image).set('system:time_start', image.get('system:time_start'));
}


var ima=imf1.map(a);
print("total",ima.mean());



var a_num=function(image){
  var num= image.expression(
    'num= 1-2*a+1.5*pow(a,2)-0.5*pow(a,3)',
    {
      'a':image.select("a")
      
    });
    
    return image.addBands(num.rename("numerator")).copyProperties(image).set('system:time_start', image.get('system:time_start'));
}

var total=ima.map(a_num);
print("complete total",total.mean());


var ffwi=function(image){
  
  var ffwi=image.expression(
    'ffwi=numerator * f1',
    {"numerator":image.select("numerator"),
      "f1":image.select("f1")
    });
    return image.addBands(ffwi.rename("FFWI")).copyProperties(image).set('system:time_start', image.get('system:time_start'));
  
}


var image_ffwi=total.map(ffwi);
print("ffwi image",image_ffwi.mean());