diff --git a/credit/postblock.py b/credit/postblock.py
index b475b73..e380b2f 100644
--- a/credit/postblock.py
+++ b/credit/postblock.py
@@ -715,11 +715,20 @@ def cycle_pattern(self, spec_coef):
         new_coef = (1.0 - self.alpha) * spec_coef + self.g_n * torch.sqrt(self.alpha) * noise  # (lmax, mmax)
         return new_coef
 
-    def initialize_mass_calc(self):
-        a_vals = self.level_info["a_model"].sel(level=self.level_list).to_numpy()
+    def initialize_hya_b_era5(self):
+        a_vals = self.level_info["a_model"].sel(level=self.level_list).to_numpy() / 100
         b_vals = self.level_info["b_model"].sel(level=self.level_list).to_numpy()
+        return a_vals, b_vals
+    
+    def initialize_hya_b_cesm(self):
+        a_vals = self.level_info["hyam"].to_numpy()
+        b_vals = self.level_info["hybm"].to_numpy()
+        return a_vals, b_vals
+
+    def initialize_mass_calc(self):
+        a_vals, b_vals = self.initialize_hya_b_cesm(self)
         self.register_buffer('a_tensor',
-                         torch.from_numpy(a_vals).view(1, self.levels, 1, 1, 1) / 100,
+                         torch.from_numpy(a_vals).view(1, self.levels, 1, 1, 1),
                          persistent=False)
         self.register_buffer('b_tensor',
                              torch.from_numpy(b_vals).view(1, self.levels, 1, 1, 1),
@@ -728,7 +737,8 @@ def initialize_mass_calc(self):
                              torch.from_numpy(self.surface_area).view(1, 1, 1, self.nlat, 1),
                              persistent=False)
         self.compute_plev_quantities = compute_pressure_on_mlevs(a_vals=self.a_tensor, b_vals=self.b_tensor, plev_dim=1)
-        
+
+
     def calculate_mass(self, sp):
         # 1 / g * A * integral(dp) [thickness]
         return (1.0 / GRAVITY