Add polychromatic T_b correction for VIIRS

viirs_bright.py

@@ -9,14 +9,26 @@ from bright import bright_wavelength, bright_wavenumber
 
 # band center wavelengths in microns
 centroid_wl = np.array([
-    4.0670,   # M13
-    10.7343,  # M15
-    11.8478   # M16
+    4.06703067365, # M13
+    10.7343306552, # M15
+    11.8477889286  # M16
 ]).reshape([3, 1])
 
 # center wavenumbers in inverse centimeters
 centroid_wn = 1.0e4 / centroid_wl
 
+a1 = np.array([
+    1.0006825717,   # M13
+    1.00002170808,  # M15
+    0.999660182876, # M16
+]).reshape([3, 1])
+
+a0 = np.array([
+    -0.272777656231, # M13
+     0.111109266746, # M15
+     0.165817224275, # M16
+]).reshape([3, 1])
+
 # helper function to make an array 2-dimensional. the first dimension
 # is always left the same size. if there is only 1 dimension, a 2nd
 # dimension of size 1 is added. if there are more than 2 dimensions,
@@ -40,6 +52,9 @@ def viirs_bright(rad):
     # apply the Planck
     bt = bright_wavelength(centroid_wl, rad)
 
+    # apply the temperature correction coeffiecients
+    bt = a1 * bt + a0
+
     # return an array shaped like the one passed in
     return bt.reshape(in_shape)
 
@@ -52,9 +67,12 @@ def viirs_bright_from_cris(rad):
     in_shape = rad.shape
     rad = make_2d(rad)
 
-    # apply the Planck then the band-specific correction
+    # apply the Planck
     bt = bright_wavenumber(centroid_wn, rad)
 
+    # apply the temperature correction coeffiecients
+    bt = a1 * bt + a0
+
     # return an array shaped like the one passed in
     return bt.reshape(in_shape)