code: def temp_water(self):
          
          # eq7
          th_swir2 = 0.03
          water = self.water_test()
          clear_sky_water = water & (self.swir2 < th_swir2)
  
          # eq8
          clear_water_temp = self.tirs1.copy()
          clear_water_temp[~clear_sky_water] = np.nan
          clear_water_temp[~self.mask] = np.nan
          pctl_clwt = np.nanpercentile(clear_water_temp, 82.5)
          return pctl_clwt
docs: Use water to mask tirs and find 82.5 pctile
          Equation 7 and 8 (Zhu and Woodcock, 2012)
          Parameters
          ----------
          is_water: ndarray, boolean
              water mask, water is True, land is False
          swir2: ndarray
          tirs1: ndarray
          Output
          ------
          float:
              82.5th percentile temperature over water