teca_saffir_simpson.h

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#ifndef teca_saffir_simpson
#define teca_saffir_simpson
 
/// @file
 
#include "teca_config.h"
 
#include <limits>
 
/// Codes dealing with the Saffir-Simpson scale
namespace teca_saffir_simpson
{
/** Saffir-Simpson scale prescribes the following limits:
 *  CAT wind km/h
 *  -1:   0- 63  :  Tropical depression
 *   0:  63-119  :  Tropical storm
 *   1: 119-153 km/h
 *   2: 154-177 km/h
 *   3: 178-208 km/h
 *   4: 209-251 km/h
 *   5: 252 km/h or higher
 */
constexpr double low_wind_bound_kmph[] = {0.0, 63.0,
    119.0, 154.0, 178.0, 209.0, 252.0};
 
/// get the high bound for the given class of storm
constexpr double high_wind_bound_kmph[] = {63.0,
    119.0, 154.0, 178.0, 209.0, 252.0,
    std::numeric_limits<double>::max()};
 
/// get the lower bound for the given class of storm
template<typename n_t>
constexpr n_t get_lower_bound_kmph(int c)
{
    return low_wind_bound_kmph[++c];
}
 
/// get the higher bound for the given class of storm
template<typename n_t>
constexpr n_t get_upper_bound_kmph(int c)
{
    return high_wind_bound_kmph[++c];
}
 
/** given wind speed in km/hr return Saffir-Simpson category
 *  NOTE: there is some ambiguity in the above as
 *  it's defined using integers. we are not converting
 *  to integer here.
 *  get the low bound for the given class of storm
 */
template<typename n_t>
int classify_kmph(n_t w)
{
    if (w < n_t(high_wind_bound_kmph[0]))
        return -1;
    else
    if (w < n_t(high_wind_bound_kmph[1]))
        return 0;
    else
    if (w < n_t(high_wind_bound_kmph[2]))
        return 1;
    else
    if (w < n_t(high_wind_bound_kmph[3]))
        return 2;
    else
    if (w < n_t(high_wind_bound_kmph[4]))
        return 3;
    else
    if (w < n_t(high_wind_bound_kmph[5]))
        return 4;
    return 5;
}
 
/// get the low bound for the given class of storm
template<typename n_t>
constexpr n_t get_lower_bound_mps(int c)
{
    return get_lower_bound_kmph<n_t>(c)/n_t(3.6);
}
 
/// get the high bound for the given class of storm
template<typename n_t>
constexpr n_t get_upper_bound_mps(int c)
{
    return get_upper_bound_kmph<n_t>(c)/n_t(3.6);
}
 
/** given wind speed in km/hr return Saffir-Simpson category
 *  NOTE: there is some ambiguity in the above as
 *  it's defined using integers. we are not converting
 *  to integer here.
 *  get the low bound for the given class of storm
 */
template<typename n_t>
int classify_mps(n_t w)
{
    // 1 m/s -> 3.6 Km/h
    if (w < n_t(high_wind_bound_kmph[0]/3.6))
        return -1;
    else
    if (w < n_t(high_wind_bound_kmph[1]/3.6))
        return 0;
    else
    if (w < n_t(high_wind_bound_kmph[2]/3.6))
        return 1;
    else
    if (w < n_t(high_wind_bound_kmph[3]/3.6))
        return 2;
    else
    if (w < n_t(high_wind_bound_kmph[4]/3.6))
        return 3;
    else
    if (w < n_t(high_wind_bound_kmph[5]/3.6))
        return 4;
    return 5;
}
};
 
#endif