import numpy

data = numpy.random.rand(10,10)
area = numpy.random.rand(10,10)

data

area

i,j = numpy.where((data>0.2)&(data<0.8))

data[i,j]

area_between_contours = area[i,j] 

area_between_contours

area_between_contours.sum()

area[i,j].sum()