Calculates the pressure at sealevel when given a known altitude in
        meters. Returns a value in Pascals.

def read_sealevel_pressure(self, altitude_m=0.0):
        """Calculates the pressure at sealevel when given a known altitude in
        meters. Returns a value in Pascals."""
        pressure = float(self.read_pressure())
        p0 = pressure / pow(1.0 - altitude_m/44330.0, 5.255)
        self.logger.debug('Sealevel pressure {0} Pa', p0)
        return p0