# ARTS built-in documentation server

## Workspace Method psdFieldEtAl07

### Description

The Field et al. [2007] particle size distribution for snow and cloud ice. This is a 1-parameter PSD, i.e. pnd_agenda_input shall have one column and pnd_agenda_input_names shall contain a single string. The input data in pnd_agenda_input shall be ice hydrometeor mass content in unit of [kg/m3]. The naming used is pnd_agenda_input_names is free but the same name must be used in particle_bulkprop_names and dpnd_data_dx_names. psd_size_grid shall contain size in terms of maximum diameter. Derivatives are obtained by perturbation of 0.1%, but not less than 1e-9 kg/m3. Both parametrization for tropics and midlatitudes are handled, governed by setting of *regime*, where "TR" selectes the tropical case, and "ML" the midlatitude one. The validity range of mass content is not limited. Negative mass contents will produce negative psd values following a distribution given by abs(IWC), ie. abs(psd)=f(abs(IWC)). If temperature is outside [*t_min*,*t_max*] psd=0 and dpsd=0 if picky=0, or an error is thrown if picky=1. For temperatures below *t_min_psd*, the size distribution is calculated for T = *t_min_psd*. Likewise, for temperatures above *t_max_psd*, the distribution is derived for T = *t_max_psd*. Defaults of *t_min_psd* and *t_max_psd* were set considering that the parametrization has been derived from measurements over temperatures of -60C to 0C. Checks of the sanity of the mass-dimension relationship are performed Errors are thrown if: - Mass-dimension relation exponent scat_species_b is outside [*beta_min*, *beta_max*].

**Authors: **Jana Mendrok

### Synopsis

psdFieldEtAl07( | psd_data, dpsd_data_dx, psd_size_grid, pnd_agenda_input_t, pnd_agenda_input, pnd_agenda_input_names, dpnd_data_dx_names, scat_species_a, scat_species_b, regime, t_min, t_max, t_min_psd, t_max_psd, beta_min, beta_max, picky ) |

### Variables

OUT | psd_data | (Matrix) | Particle size distribution values for a set of points. |

OUT | dpsd_data_dx | (Tensor3) | Partial derivates of psd_data. |

IN | psd_size_grid | (Vector) | The particle sizes associated with psd_data. |

IN | pnd_agenda_input_t | (Vector) | Temperature input to one element of pnd_agenda_array. |

IN | pnd_agenda_input | (Matrix) | The variable input to one element of pnd_agenda_array. |

IN | pnd_agenda_input_names | (ArrayOfString) | Naming of (existing or expected) data in pnd_agenda_input. |

IN | dpnd_data_dx_names | (ArrayOfString) | Selection of partial derivatives of pnd_data. |

IN | scat_species_a | (Numeric) | Mass-size relationship parameter, for one scattering species. |

IN | scat_species_b | (Numeric) | Mass-size relationship parameter, for one scattering species. |

GIN | regime | (String) | Parametrization regime ("TR"=tropical or "ML"=midlatitude). |

GIN | t_min | (Numeric, Default: 0) | Low temperature limit to calculate a psd. |

GIN | t_max | (Numeric, Default: 290.) | High temperature limit to calculate a psd. |

GIN | t_min_psd | (Numeric, Default: 200.) | Low temperature limit to use as paramtrization temperature. |

GIN | t_max_psd | (Numeric, Default: 273.15) | High temperature limit to use as paramtrization temperature. |

GIN | beta_min | (Numeric, Default: 1.01) | Low *b* limit (only if picky). |

GIN | beta_max | (Numeric, Default: 4) | High *b* limit (only if picky). |

GIN | picky | (Index, Default: 0) | Flag whether to be strict with parametrization value checks. |