#ifndef CONDUCTANCE_H
#define CONDUCTANCE_H

/**
 * \file Conductance.h
 * \brief Conductance class declaration
 * \class Conductance
 * 
 * \brief Class contains functions for calculation of auroral
 * precipitation and ionospheric conductance.
 *
 * \author Slava Merkin (vgm at bu.edu)
 * \since 08-2005
 *
 * The Conductance class contains functions for calculation of auroral
 * precipitation parameters (energy and number flux of particles) as
 * well as functions calculating the ionospheric conductances locally
 * based on the EUV background ionization and precipitation
 * contributions *(Robinson's formula). The local conductance
 * calculation accords with the legacy LFM conductance model (Fedder
 * et al., [1995]) and is adapted to a large extent from
 * M. Wiltberger's set of subroutines developed for the OMP version of
 * the LFM code.
 *
 * The functions in this class assume that grid functions are defined
 * on the Solver grid. Therefore the functions of the class should be
 * called separately for the two hemispheres.
 *
 * \b References:
 * 
 * Y. T. Chiu, A. L. Newman, J. M. Cornwall, "On the structures and
 * mapping of auroral electrostatic potentials", J. Geophys. Res.,
 * V. 86, No. A12, pp. 10,029--10,037, 1981.
 *
 * J. A. Fedder, S. P. Slinker, J. G. Lyon, and R. D. Elphinstone,
 * "Global numerical simulation of the growth phase and the expansion
 * onset for a substorm observed by Viking", J. Geophys. Res., V. 100,
 * No. A10, pp. 19,083--19,093, 1995.
 *
 * M. Fridman and J. Lemaire, "Relationship between auroral electrons
 * fluxes and field aligned electric potential difference",
 * J. Geophys. Res., V. 85, N. A2, pp. 664--670, 1980.
 *
 * J. Moen and A. Brekke, The solar flux influence on quiet time
 * conductances in the auroral ionosphere, Geophys. Res. Lett.,
 * 20(10), 971-974, 10.1029/92GL02109, 1993.
 *
 * R. M. Robinson, R. R. Vondrak, K. Miller, T. Dabbs, and D. Hardy,
 * "On calculating ionospheric conductances from the flux and energy
 * of precipitating electrons", J. Geophys. Res., V. 92, No. A3,
 * pp. 2,565--2,569, 1987.
*/

#include "Overture.h"
#include "const.h"
#include "Solver.h"
#include "Params.h"

class Conductance {

 public:
  enum EUV_MODEL {AMIE,MOEN_BREKKE}; 

  /**\brief The class constructor.*/
  Conductance(Solver *solver, const Params * const params);

  /**\brief This function calculates the average precipitation energy
     and number flux */
  void precipitation(realCompositeGridFunction &solverFunctions, const real &tilt, const bool &HEMISPHERE);

  /**\brief The main function which calculates the ionospheric
     conductances.*/
  void getTotal(realCompositeGridFunction &solverFunctions, const real &tilt, const bool &HEMISPHERE);

  void applyCap(realCompositeGridFunction &solverFunctions);

 private:
  /**********************************************************//**
   * \name Constants used in the local conductance model
   *
   * These variables are defined in the parameter file and are
   * initialized in the constructor.
   **************************************************************/

  const int euvModelType; //!< O: AMIE; 1: MOEN_BREKKE

  const real alpha; //!< Enters \f$ E = \alpha c_s^2 \f$ (see fedder95())
 
  const real beta; //!< Enters \f$ \Phi = \beta \rho E^{1/2} \f$  (see fedder95())

  const real r;//!< Enters \f$ E_\parallel = R j_\parallel E_0^{1/2}/\rho \f$  (see fedder95())

  const real f107;   //!< F10.7 flux

  const real pedMin;  //!< Minimum value of the Pedersen conductance allowed (see euv())

  const real hallMin; //!< Minimum value of the Hall conductance allowed (see euv())

  const real ped0;   /*!<\brief When #constSigma is 1, the value of
			the Pedersen conductance is set to this value
			uniformly */

  const real sigmaRatio;   /*!<\brief If \f$\Sigma_H < \Sigma_P \cdot
			      sigmaRatio\f$ then \f$\Sigma_H =
			      \Sigma_P \cdot sigmaRatio\f$ */

  const bool constSigma;  /*!<\brief A boolean variable that specifies
			    whether to use the ionospheric model or to
			    set the Pedersen conductivity to ped0 and
			    Hall to 0. */


  /**********************************************************//**
   * \name Physical variables
   *
   * Arrays used to store the calculated physical variables
   **************************************************************/
  realArray pedersen;        //!< Pedersen conductance
  realArray hall;                //!< Hall conductance
  realArray avgEng;           //!< Average energy of precipitating electrons (keV)
  realArray numFlux;          //!< Number flux of precipitating electrons (1/cm^2/s)
  realArray engFlux;           //!< Energy flux of precipitating electrons ( ergs/cm^2/s)
  realArray deltaSigmaP;     //!< Auroral contribution to Pedersen conductance
  realArray deltaSigmaH;     //!< Auroral contribution to Hall conductance
  realArray euvSigmaP;       //!< EUV ionization contribution to Pedersen conductance
  realArray euvSigmaH;       //!< EUV ionization contribution to Hall conductance
  realArray sigmaP;            //!< Total Pedersen conductance
  realArray sigmaH;            //!< Total Hall conductance


  /**
   * \name External data
   * These are the dimensions and vertices of the Solver grid. They
   * are passed inside the Solver class and initialized in the
   * constructor.
   */
  //@{
  realArray x,y; 
  int nLat,nLon;
  //@}

  /** \name External data
   * These are passed to precipitation() as grid functions on the
   * Solver grid. These functions are converted to #jpara, #cs, and
   * #rho in precipitation().
   */
  //@{  
  realArray jpara,cs,rho;
  //@}

  /**\brief Calculates the average energy and number flux of
   * precipitating electrons */
  void fedder95(const real &tilt, const bool &HEMISPHERE);

  /**\brief Calculates auroral precipitation contribution to the
   * conductances (Robinson's formula essentially)*/
  void aurora();

  /**\brief Calculates EUV ionization contribution to the conductances */
  void euv(const real);
};

#endif