code: def temp_land(self, pcps, water):
          
          # eq 12
          clearsky_land = ~(pcps | water)
  
          # use clearsky_land to mask tirs1
          clear_land_temp = self.tirs1.copy()
          clear_land_temp[~clearsky_land] = np.nan
          clear_land_temp[~self.mask] = np.nan
  
          # take 17.5 and 82.5 percentile, eq 13
          low, high = np.nanpercentile(clear_land_temp, (17.5, 82.5))
          return low, high
docs: Derive high/low percentiles of land temperature
          Equations 12 an 13 (Zhu and Woodcock, 2012)
          Parameters
          ----------
          pcps: ndarray
              potential cloud pixels, boolean
          water: ndarray
              water mask, boolean
          tirs1: ndarray
          Output
          ------
          tuple:
              17.5 and 82.5 percentile temperature over clearsky land