PrecipitationScaling.hh

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#ifndef PRECIPITATIONSCALING_H
#define PRECIPITATIONSCALING_H
 
#include "pism/coupler/AtmosphereModel.hh"
 
namespace pism {
 
class ScalarForcing;
 
namespace atmosphere {
 
/** Scaling precipitation using air temperature offsets
 *
 * This class implements the adjustment used to capture the influence of changing air
 * temperature on precipitation. It uses scalar temperature offsets read from a file as an
 * input.
 *
 * @f[
 * P_{G}(x,y,t) = P_{G}(x,y,0)exp\left[\frac{0.169}{d}\left({\Delta}T(t)+ {\Delta}T_{SC}(t)\right)\right]
 * @f]
 
 * where @f$P_G(x,y,0)@f$ is the precipitation for the present
 * Greenland ice sheet, obtained from the atmosphere model used as an
 * input of this class. The time dependent precipitation is
 * @f$P_G(x,y,t)@f$, @f$d@f$ is the @f${\delta}_{18}@f$ conversion factor
 * of @f$2.4^{\circ}C/\frac{0}{00}@f$, and @f${\Delta}T_{SC}@f$ is a
 * correction term for the change of altitude of the central dome
 * during the Greenland ice sheet's evolution. The coefficient
 * " @f$ 0.169/d @f$ " corresponds to a 7.3% change of precipitation rate
 * for every @f$1^{\circ}C@f$ of temperature change (Huybrechts et al.
 * 2002).
 *
 * One possible scheme for @f${\Delta}T_{SC}(t)@f$ (used in PISM) is
 * to take it to be zero, which regards the height correction as
 * belonging to the set of uncertainties related to the conversion
 * between isotopic and temperature signals.
 */
class PrecipitationScaling : public AtmosphereModel {
public:
  PrecipitationScaling(std::shared_ptr<const Grid> g, std::shared_ptr<AtmosphereModel> in);
  virtual ~PrecipitationScaling() = default;
 
protected:
  void init_impl(const Geometry &geometry);
  void update_impl(const Geometry &geometry, double t, double dt);
 
  void init_timeseries_impl(const std::vector<double> &ts) const;
 
  const array::Scalar& precipitation_impl() const;
 
  void precip_time_series_impl(int i, int j, std::vector<double> &values) const;
 
protected:
  double m_exp_factor;
  std::shared_ptr<ScalarForcing> m_forcing;
  mutable std::vector<double> m_scaling_values;
 
  std::shared_ptr<array::Scalar> m_precipitation;
};
 
} // end of namespace atmosphere
} // end of namespace pism
 
#endif /* PRECIPITATIONSCALING_H */