# nband¶

class climlab.radiation.nband.FourBandLW(**kwargs)[source]

Closely following SPEEDY / MITgcm longwave model band 0 is window region (between 8.5 and 11 microns) band 1 is CO2 channel (the band of strong absorption by CO2 around 15 microns) band 2 is weak H2O channel (aggregation of spectral regions with weak to moderate absorption by H2O) band 3 is strong H2O channel (aggregation of regions with strong absorption by H2O)

Attributes: absorptivity band_fraction depth Depth at grid centers (m) depth_bounds Depth at grid interfaces (m) diagnostics Dictionary access to all diagnostic variables emissivity input Dictionary access to all input variables lat Latitude of grid centers (degrees North) lat_bounds Latitude of grid interfaces (degrees North) lev Pressure levels at grid centers (hPa or mb) lev_bounds Pressure levels at grid interfaces (hPa or mb) lon Longitude of grid centers (degrees) lon_bounds Longitude of grid interfaces (degrees) reflectivity timestep The amount of time over which step_forward() is integrating in unit seconds. transmissivity

Methods

 add_diagnostic(name[, value]) Create a new diagnostic variable called name for this process and initialize it with the given value. add_input(name[, value]) Create a new input variable called name for this process and initialize it with the given value. add_subprocess(name, proc) Adds a single subprocess to this process. add_subprocesses(procdict) Adds a dictionary of subproceses to this process. compute() Computes the tendencies for all state variables given current state and specified input. compute_diagnostics([num_iter]) Compute all tendencies and diagnostics, but don’t update model state. declare_diagnostics(diaglist) Add the variable names in inputlist to the list of diagnostics. declare_input(inputlist) Add the variable names in inputlist to the list of necessary inputs. flux_components_bottom() Compute the contributions to the downwelling flux to surface due to emissions from each level. flux_components_top() Compute the contributions to the outgoing flux to space due to emissions from each level and the surface. integrate_converge([crit, verbose]) Integrates the model until model states are converging. integrate_days([days, verbose]) Integrates the model forward for a specified number of days. integrate_years([years, verbose]) Integrates the model by a given number of years. remove_diagnostic(name) Removes a diagnostic from the process.diagnostic dictionary and also delete the associated process attribute. remove_subprocess(name[, verbose]) Removes a single subprocess from this process. set_state(name, value) Sets the variable name to a new state value. set_timestep([timestep, num_steps_per_year]) Calculates the timestep in unit seconds and calls the setter function of timestep() step_forward() Updates state variables with computed tendencies. to_xarray([diagnostics]) Convert process variables to xarray.Dataset format.
class climlab.radiation.nband.FourBandSW(emissivity_sfc=0.0, **kwargs)[source]

A four-band mdoel for shortwave radiation.

The spectral decomposition used here is largely based on the “Moist Radiative-Convective Model” by Aarnout van Delden, Utrecht University a.j.vandelden@uu.nl http://www.staff.science.uu.nl/~delde102/RCM.htm

Four SW channels:
channel 0 is Hartley and Huggins band (UV, 6%, <340 nm) channel 1 is part of visible with no O3 absorption (14%, 340 - 500 nm) channel 2 is Chappuis band (27%, 500 - 700 nm) channel 3 is near-infrared (53%, > 700 nm)
Attributes: absorptivity band_fraction depth Depth at grid centers (m) depth_bounds Depth at grid interfaces (m) diagnostics Dictionary access to all diagnostic variables emissivity input Dictionary access to all input variables lat Latitude of grid centers (degrees North) lat_bounds Latitude of grid interfaces (degrees North) lev Pressure levels at grid centers (hPa or mb) lev_bounds Pressure levels at grid interfaces (hPa or mb) lon Longitude of grid centers (degrees) lon_bounds Longitude of grid interfaces (degrees) reflectivity timestep The amount of time over which step_forward() is integrating in unit seconds. transmissivity

Methods

 add_diagnostic(name[, value]) Create a new diagnostic variable called name for this process and initialize it with the given value. add_input(name[, value]) Create a new input variable called name for this process and initialize it with the given value. add_subprocess(name, proc) Adds a single subprocess to this process. add_subprocesses(procdict) Adds a dictionary of subproceses to this process. compute() Computes the tendencies for all state variables given current state and specified input. compute_diagnostics([num_iter]) Compute all tendencies and diagnostics, but don’t update model state. declare_diagnostics(diaglist) Add the variable names in inputlist to the list of diagnostics. declare_input(inputlist) Add the variable names in inputlist to the list of necessary inputs. flux_components_bottom() Compute the contributions to the downwelling flux to surface due to emissions from each level. flux_components_top() Compute the contributions to the outgoing flux to space due to emissions from each level and the surface. integrate_converge([crit, verbose]) Integrates the model until model states are converging. integrate_days([days, verbose]) Integrates the model forward for a specified number of days. integrate_years([years, verbose]) Integrates the model by a given number of years. remove_diagnostic(name) Removes a diagnostic from the process.diagnostic dictionary and also delete the associated process attribute. remove_subprocess(name[, verbose]) Removes a single subprocess from this process. set_state(name, value) Sets the variable name to a new state value. set_timestep([timestep, num_steps_per_year]) Calculates the timestep in unit seconds and calls the setter function of timestep() step_forward() Updates state variables with computed tendencies. to_xarray([diagnostics]) Convert process variables to xarray.Dataset format.
emissivity
class climlab.radiation.nband.NbandRadiation(absorber_vmr=None, **kwargs)[source]

Process for radiative transfer. Solves the discretized Schwarschild two-stream equations with the spectrum divided into N spectral bands.

Every NbandRadiation object has an attribute self.band_fraction with sum(self.band_fraction) == 1 that gives the fraction of the total beam in each band

Also a dictionary self.absorber_vmr that gives the volumetric mixing ratio of every absorbing gas on the same grid as temperature

and a dictionary self.absorption_cross_section that gives the absorption cross-section per unit mass for each gas in every spectral band

Attributes: absorptivity band_fraction depth Depth at grid centers (m) depth_bounds Depth at grid interfaces (m) diagnostics Dictionary access to all diagnostic variables emissivity input Dictionary access to all input variables lat Latitude of grid centers (degrees North) lat_bounds Latitude of grid interfaces (degrees North) lev Pressure levels at grid centers (hPa or mb) lev_bounds Pressure levels at grid interfaces (hPa or mb) lon Longitude of grid centers (degrees) lon_bounds Longitude of grid interfaces (degrees) reflectivity timestep The amount of time over which step_forward() is integrating in unit seconds. transmissivity

Methods

 add_diagnostic(name[, value]) Create a new diagnostic variable called name for this process and initialize it with the given value. add_input(name[, value]) Create a new input variable called name for this process and initialize it with the given value. add_subprocess(name, proc) Adds a single subprocess to this process. add_subprocesses(procdict) Adds a dictionary of subproceses to this process. compute() Computes the tendencies for all state variables given current state and specified input. compute_diagnostics([num_iter]) Compute all tendencies and diagnostics, but don’t update model state. declare_diagnostics(diaglist) Add the variable names in inputlist to the list of diagnostics. declare_input(inputlist) Add the variable names in inputlist to the list of necessary inputs. flux_components_bottom() Compute the contributions to the downwelling flux to surface due to emissions from each level. flux_components_top() Compute the contributions to the outgoing flux to space due to emissions from each level and the surface. integrate_converge([crit, verbose]) Integrates the model until model states are converging. integrate_days([days, verbose]) Integrates the model forward for a specified number of days. integrate_years([years, verbose]) Integrates the model by a given number of years. remove_diagnostic(name) Removes a diagnostic from the process.diagnostic dictionary and also delete the associated process attribute. remove_subprocess(name[, verbose]) Removes a single subprocess from this process. set_state(name, value) Sets the variable name to a new state value. set_timestep([timestep, num_steps_per_year]) Calculates the timestep in unit seconds and calls the setter function of timestep() step_forward() Updates state variables with computed tendencies. to_xarray([diagnostics]) Convert process variables to xarray.Dataset format.
band_fraction
climlab.radiation.nband.SPEEDY_band_fraction(T)[source]

Python / numpy implementation of the formula used by SPEEDY and MITgcm to partition longwave emissions into 4 spectral bands.

Input: temperature in Kelvin

returns: a four-element array of band fraction

Reproducing here the FORTRAN code from MITgcm/pkg/aim_v23/phy_radiat.F

 EPS3=0.95 _d 0

DO JTEMP=200,320
FBAND(JTEMP,0)= EPSLW
FBAND(JTEMP,2)= 0.148 _d 0 - 3.0 _d -6 *(JTEMP-247)**2
FBAND(JTEMP,3)=(0.375 _d 0 - 5.5 _d -6 *(JTEMP-282)**2)*EPS3
FBAND(JTEMP,4)= 0.314 _d 0 + 1.0 _d -5 *(JTEMP-315)**2
FBAND(JTEMP,1)= 1. _d 0 -(FBAND(JTEMP,0)+FBAND(JTEMP,2)
&                           +FBAND(JTEMP,3)+FBAND(JTEMP,4))
ENDDO

DO JB=0,NBAND
DO JTEMP=lwTemp1,199
FBAND(JTEMP,JB)=FBAND(200,JB)
ENDDO
DO JTEMP=321,lwTemp2
FBAND(JTEMP,JB)=FBAND(320,JB)
ENDDO
ENDDO

class climlab.radiation.nband.ThreeBandSW(emissivity_sfc=0.0, **kwargs)[source]

A three-band mdoel for shortwave radiation.

The spectral decomposition used here is largely based on the “Moist Radiative-Convective Model” by Aarnout van Delden, Utrecht University a.j.vandelden@uu.nl http://www.staff.science.uu.nl/~delde102/RCM.htm

Three SW channels:
channel 0 is Hartley and Huggins band (UV, 1%, 200 - 340 nm) channel 1 is Chappuis band (27%, 450 - 800 nm) channel 2 is remaining radiation (72%)
Attributes: absorptivity band_fraction depth Depth at grid centers (m) depth_bounds Depth at grid interfaces (m) diagnostics Dictionary access to all diagnostic variables emissivity input Dictionary access to all input variables lat Latitude of grid centers (degrees North) lat_bounds Latitude of grid interfaces (degrees North) lev Pressure levels at grid centers (hPa or mb) lev_bounds Pressure levels at grid interfaces (hPa or mb) lon Longitude of grid centers (degrees) lon_bounds Longitude of grid interfaces (degrees) reflectivity timestep The amount of time over which step_forward() is integrating in unit seconds. transmissivity

Methods

 add_diagnostic(name[, value]) Create a new diagnostic variable called name for this process and initialize it with the given value. add_input(name[, value]) Create a new input variable called name for this process and initialize it with the given value. add_subprocess(name, proc) Adds a single subprocess to this process. add_subprocesses(procdict) Adds a dictionary of subproceses to this process. compute() Computes the tendencies for all state variables given current state and specified input. compute_diagnostics([num_iter]) Compute all tendencies and diagnostics, but don’t update model state. declare_diagnostics(diaglist) Add the variable names in inputlist to the list of diagnostics. declare_input(inputlist) Add the variable names in inputlist to the list of necessary inputs. flux_components_bottom() Compute the contributions to the downwelling flux to surface due to emissions from each level. flux_components_top() Compute the contributions to the outgoing flux to space due to emissions from each level and the surface. integrate_converge([crit, verbose]) Integrates the model until model states are converging. integrate_days([days, verbose]) Integrates the model forward for a specified number of days. integrate_years([years, verbose]) Integrates the model by a given number of years. remove_diagnostic(name) Removes a diagnostic from the process.diagnostic dictionary and also delete the associated process attribute. remove_subprocess(name[, verbose]) Removes a single subprocess from this process. set_state(name, value) Sets the variable name to a new state value. set_timestep([timestep, num_steps_per_year]) Calculates the timestep in unit seconds and calls the setter function of timestep() step_forward() Updates state variables with computed tendencies. to_xarray([diagnostics]) Convert process variables to xarray.Dataset format.
emissivity