Re: [arts-users] Fwd: Direct radiation is subtracted when it should not
Hi Freddy, Thanks for getting back to me. My question is about the result of using a specular reflective surface versus using a Lambertian surface. I was thinking the ratio should be pi (the specular one is larger) because when there is no scattering the only difference is the BRDF evaluation. However, I observed the Lambertian result is much smaller, more than 1e4 times smaller than the specular result. I tried "Test_iySurfaceLambertian.py" and it is also the case there when I change the Lambertian surface to specular. Thanks, Mengqi From: Manfred Brath Sent: Wednesday, October 19, 2022 5:19:20 PM To: Xia Mengqi; arts_users.mi@lists.uni-hamburg.de Subject: Re: Fwd: [arts-users] Direct radiation is subtracted when it should not Hi Mengqi, I do not understand your problem from the information of your email, but maybe you can have a look in "Test_iySurfaceLambertian.py", which you can find in your arts-folder: controlfiles-python/artscomponents/surface/ Another thing, how do you calculate your pi-ratio? When I use the above mentioned test script and set the sun at 0 lat and 0 lon and divide the top of the atmosphere (TOA) solar radiation F by pi I got the same value as from yCalc. F=ws.stars.value[0].spectrum.value*scale_factor scale_factor=sun_radius**2/(sun_radius**2+sun2TOA_distance**2) The scale factor is needed, because the star irradiance spectrum in ARTS is defined at the surface of the sun and not at TOA. Cheers, Freddy Am 18.10.22 um 12:56 schrieb Xia Mengqi: Thank you Freddy! This makes sense. I tried with flat reflective surface and lambertian surface with absorption only. I extended the 1D atmosphere to 3D so I can provide surface temperature (set it to a really small value) but in theory since there is no scattering the path that contributes is unchanged. I found that the flat reflective surface result is correct but the lambertian one is much smaller than the expected pi ratio. I tried to print ppath and I found los changing quite a lot. I am wondering if this is the expected behavior and maybe there is something about the 3D setup I did not understand properly. I copied the main part of the code below. Thanks! Mengqi @arts_agenda def propmat_clearsky_agenda(ws): ws.Ignore(ws.rtp_mag) ws.Ignore(ws.rtp_los) ws.propmat_clearskyInit() ws.propmat_clearskyAddConts() ws.propmat_clearskyAddLines() @arts_agenda def gas_scattering_agenda(ws): ws.Ignore(ws.rtp_vmr) ws.gas_scattering_coefXsecConst(ConstXsec=4.65e-31) ws.gas_scattering_matIsotropic() # surface scattering agenda # lambertian @arts_agenda def iy_surface_agenda(ws): ws.iySurfaceInit() ws.Ignore(ws.dsurface_rmatrix_dx) ws.Ignore(ws.dsurface_emission_dx) ws.iySurfaceLambertian() ws.iySurfaceLambertianDirect() # flat reflective surface # @arts_agenda # def iy_surface_agenda(ws): # ws.iySurfaceInit() # ws.iySurfaceFlatReflectivity() # ws.iySurfaceFlatReflectivityDirect() # generate atmosphere data dataset_path = '/home/mandy/Github/arts/build_new/afgl_1986-us_standard.nc' save_path = '/home/mandy/Github/arts/controlfiles/testdata/' data = generate_atmos_arts(dataset_path, save_path) # = # open workspace # = ws = Workspace() ws.verbositySetScreen(level=2) # = # generate atmosphere data # = dataset_path = '/home/mandy/Github/arts/build_new/afgl_1986-us_standard.nc' save_path = '/home/mandy/Github/arts/controlfiles/testdata/' data = generate_atmos_arts(dataset_path, save_path) ws.ReadHITRAN(filename='/home/mandy/Github/MiAtmosphere/HITRAN/ALL.par', hitran_type="Online", abs_lines=ws.abs_lines) # = # select/define agendas # = ws.LegacyContinuaInit() ws.PlanetSet(option="Earth") # cosmic background radiation ws.iy_space_agendaSet( option="CosmicBackground" ) # sensor-only path ws.ppath_agendaSet( option="FollowSensorLosPath" ) # no refraction ws.ppath_step_agendaSet( option="GeometricPath" ) # main agenda ws.iy_main_agendaSet( option="Clearsky") # water agenda ws.water_p_eq_agendaSet() # surface agenda ws.iy_surface_agenda = iy_surface_agenda ws.ArrayOfStringSet( ws.iy_aux_vars, [ "Optical depth", "Radiative background" ] ) ws.propmat_clearsky_agenda=propmat_clearsky_agenda # gas scattering agenda ws.gas_scattering_agenda = gas_scattering_agenda ws.NumericSet( ws.ppath_lmax, 1e10) # = # basic conditions # ===
Re: [arts-users] Fwd: Direct radiation is subtracted when it should not
Hi Mengqi, I do not understand your problem from the information of your email, but maybe you can have a look in "Test_iySurfaceLambertian.py", which you can find in your arts-folder: controlfiles-python/artscomponents/surface/ Another thing, how do you calculate your pi-ratio? When I use the above mentioned test script and set the sun at 0 lat and 0 lon and divide the top of the atmosphere (TOA) solar radiation F by pi I got the same value as from yCalc. F=ws.stars.value[0].spectrum.value*scale_factor scale_factor=sun_radius**2/(sun_radius**2+sun2TOA_distance**2) The scale factor is needed, because the star irradiance spectrum in ARTS is defined at the surface of the sun and not at TOA. Cheers, Freddy Am 18.10.22 um 12:56 schrieb Xia Mengqi: Thank you Freddy! This makes sense. I tried with flat reflective surface and lambertian surface with absorption only. I extended the 1D atmosphere to 3D so I can provide surface temperature (set it to a really small value) but in theory since there is no scattering the path that contributes is unchanged. I found that the flat reflective surface result is correct but the lambertian one is much smaller than the expected pi ratio. I tried to print ppath and I found los changing quite a lot. I am wondering if this is the expected behavior and maybe there is something about the 3D setup I did not understand properly. I copied the main part of the code below. Thanks! Mengqi @arts_agenda def propmat_clearsky_agenda(ws): ws.Ignore(ws.rtp_mag) ws.Ignore(ws.rtp_los) ws.propmat_clearskyInit() ws.propmat_clearskyAddConts() ws.propmat_clearskyAddLines() @arts_agenda def gas_scattering_agenda(ws): ws.Ignore(ws.rtp_vmr) ws.gas_scattering_coefXsecConst(ConstXsec=4.65e-31) ws.gas_scattering_matIsotropic() # surface scattering agenda # lambertian @arts_agenda def iy_surface_agenda(ws): ws.iySurfaceInit() ws.Ignore(ws.dsurface_rmatrix_dx) ws.Ignore(ws.dsurface_emission_dx) ws.iySurfaceLambertian() ws.iySurfaceLambertianDirect() # flat reflective surface # @arts_agenda # def iy_surface_agenda(ws): # ws.iySurfaceInit() # ws.iySurfaceFlatReflectivity() # ws.iySurfaceFlatReflectivityDirect() # generate atmosphere data dataset_path = '/home/mandy/Github/arts/build_new/afgl_1986-us_standard.nc' save_path = '/home/mandy/Github/arts/controlfiles/testdata/' data = generate_atmos_arts(dataset_path, save_path) # = # open workspace # = ws = Workspace() ws.verbositySetScreen(level=2) # = # generate atmosphere data # = dataset_path = '/home/mandy/Github/arts/build_new/afgl_1986-us_standard.nc' save_path = '/home/mandy/Github/arts/controlfiles/testdata/' data = generate_atmos_arts(dataset_path, save_path) ws.ReadHITRAN(filename='/home/mandy/Github/MiAtmosphere/HITRAN/ALL.par', hitran_type="Online", abs_lines=ws.abs_lines) # = # select/define agendas # = ws.LegacyContinuaInit() ws.PlanetSet(option="Earth") # cosmic background radiation ws.iy_space_agendaSet( option="CosmicBackground" ) # sensor-only path ws.ppath_agendaSet( option="FollowSensorLosPath" ) # no refraction ws.ppath_step_agendaSet( option="GeometricPath" ) # main agenda ws.iy_main_agendaSet( option="Clearsky") # water agenda ws.water_p_eq_agendaSet() # surface agenda ws.iy_surface_agenda = iy_surface_agenda ws.ArrayOfStringSet( ws.iy_aux_vars, [ "Optical depth", "Radiative background" ] ) ws.propmat_clearsky_agenda=propmat_clearsky_agenda # gas scattering agenda ws.gas_scattering_agenda = gas_scattering_agenda ws.NumericSet( ws.ppath_lmax, 1e10) # = # basic conditions # = # Postion and line-of-sight of sensor sensor_pos = np.array([[600e+3, 0., 0.]]) # Sensor looking direction in zenith angle (0 = upwards, 180 = downward) and # azimuth angle ( 0 = North, 90 = east) sensor_los = np.array([[180, 0]]) ws.sensor_pos = sensor_pos ws.sensor_los = sensor_los ws.VectorSet(ws.rte_pos2, []) # define environment # = # Number of Stokes components to be computed ws.IndexSet(ws.stokes_dim, 1) # Read the spectroscopic line data from the ARTS catalogue and # create the workspace variable `lines'. ws.ReadHITRAN(filename='/home/mandy/Github/MiAtmosphere/HITRAN/ALL.par', hitran_type="Online", abs_lines=ws.abs_lines) ws.abs
[arts-users] Does the current retrieval pipeline work with star and scattering?
Dear ARTS team, I'm interested in retrieval problems and I'm wondering if it's possible to use the current retrieval pipeline with star and gas scattering together. It seems that in TestOEM.arts we only have gas absorption and the emission agenda. Thanks, Mengqi
