SGP/SIRS/E13 - Diffuse Pyranometer Thermal Offsets

Broadband downwelling shortwave diffuse (sky) irradiance measurements available from SIRS
during the period of this Data Quality Report (DQR), require adjustment for thermal
offsets.  These thermal, or ?zero? offsets refer to the generally reduced output signals
from a shaded pyranometer due to the exchange of longwave (infrared) irradiance between
the single black thermopile detector, the protective glass domes surrounding the
detector, and the atmosphere. Originally considered an acceptable nighttime response of
thermopile-type pyranometers, the generally negative bias is now recognized to
significantly effect the accuracy of SIRS diffuse irradiance data during daylight
periods.

Studies of the Eppley Laboratory, Inc. Model PSP (Precision Spectral Pyranometer), used
for the SIRS   measurements of diffuse irradiance, suggest the thermal offset correction
can range from near 0 to as much as 30 Watts per square meter, depending on the
coincident net longwave, or infrared irradiance [1, 2].  Under very clear-sky conditions,
the diffuse irradiance from a shaded PSP can be less than the minimum physical limit
defined by radiative transfer model estimates based only on Rayleigh scattering effects.

A correction method has been developed for adjusting SIRS diffuse irradiance data [3]. 
The resulting Value Added Product (VAP) will be applied to SIRS data for the period of
this DQR.  The VAP will not be applied to SIROS data collected before the instrument
platform was converted to SIRS.

Additionally, the Model PSP radiometer has been replaced by a Model 8-48 which uses a
black and white thermopile detector known to reduce the thermal offset errors to less
than 2 Watts per square meter [3].  The radiometer replacement at this SIRS location was
completed on the ending date of this DQR.

References:
1. Gulbrandsen, A., 1978:  On the use of pyranometers in the study of spectral solar
radiation and atmospheric aerosols.  J. Appl. Meteorol., 17, 899-904.
2. Cess, R. D., X. Jing, T. Qian, and M. Sun, 1999:  Validation strategies applied to the
measurement of total, direct and diffuse shortwave radiation at the surface.  J. Geophys.
Res.
3. Dutton, E.G., J. Michalsky, T. Stoffel, B. Forgan, J. Hickey, D. Nelson, T. Alberta,
and I. Reda, 2001:  Measurement of Broadband Diffuse Solar Irradiance Using Current
Commercial Instrumentation With a Correction for Thermal Offset Errors. J. Atmos. Oceanic
Tech.   Vol 18, No. 3, 297-314.   (March 2001)

• Shaded pyranometer voltage(short_diffuse)

• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer(down_short_diffuse_hemisp)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Minima(down_short_diffuse_hemisp_min)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Standard Deviation(down_short_diffuse_hemisp_std)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Maxima(down_short_diffuse_hemisp_max)

SGP/SIRS/E13 - Missing data due to Ice storm and clock problems

Data are missing due to power failures caused by an ice storm
and resulting system/instrument clock problems.

• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer, Maxima(down_long_hemisp_shaded_max)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyrgeometer, Maxima(down_short_hemisp_max)
• Upwelling Longwave Hemispheric Net Infrared(up_long_netir)
• Instantaneous Downwelling Pyrgeometer Case Thermistor Temperature, Shaded
  Pyrgeometer(inst_down_long_shaded_case_temp)
• Downwelling Longwave Hemispheric Net Infrared(down_long_netir)
• Upwelling (10 meter) Longwave Hemispheric Irradiance, Ventilated Pyrgeometer(up_long_hemisp)
• Instantaneous Upwelling Pyrgeometer Dome Thermistor Temperature, Pyrgeometer(inst_up_long_dome_temp)
• Upwelling (10 meter) Shortwave Hemispheric Irradiance, Ventilated Pyranometer(up_short_hemisp)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer, Minima(down_long_hemisp_shaded_min)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer(down_short_diffuse_hemisp)
• Battery voltage(vBatt)
• Time offset from base_time(base_time)
• Time offset of tweaks from base_time(time_offset)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyrgeometer, Minima(down_short_hemisp_min)
• Upwelling (10 meter) Longwave Hemispheric Irradiance, Ventilated Pyrgeometer,
  Maxima(up_long_hemisp_max)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyrgeometer(down_short_hemisp)
• Instantaneous Upwelling Pyrgeometer Case Thermistor Temperature, Pyrgeometer(inst_up_long_case_temp)
• altitude above sea levelaltunits(alt)
• east longitude for all the input platforms.(lon)
• Upwelling (10 meter) Shortwave Hemispheric Irradiance, Ventilated Pyranometer,
  Standard Deviation(up_short_hemisp_std)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Standard Deviation(down_short_diffuse_hemisp_std)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Minima(down_short_diffuse_hemisp_min)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyrgeometer, Standard
  Deviation(down_short_hemisp_std)
• Upwelling (10 meter) Longwave Hemispheric Irradiance, Ventilated Pyrgeometer,
  Minima(up_long_hemisp_min)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Standard Deviation(short_direct_normal_std)
• north latitude for all the input platforms.(lat)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer, Standard
  Deviation(down_long_hemisp_shaded_std)
• Upwelling (10 meter) Shortwave Hemispheric Irradiance, Ventilated Pyranometer,
  Minima(up_short_hemisp_min)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Maxima(down_short_diffuse_hemisp_max)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer(down_long_hemisp_shaded)
• Upwelling (10 meter) Longwave Hemispheric Irradiance, Ventilated Pyrgeometer,
  Standard Deviation(up_long_hemisp_std)
• Upwelling (10 meter) Shortwave Hemispheric Irradiance, Ventilated Pyranometer,
  Maxima(up_short_hemisp_max)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• Shortwave Direct Normal Irradiance, Pyrheliometer(short_direct_normal)
• Instantaneous Downwelling Pyrgeometer Dome Thermistor Temperature, Shaded
  Pyrgeometer(inst_down_long_shaded_dome_temp)

• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer, Maxima(down_long_hemisp_shaded_max)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer, Standard
  Deviation(down_long_hemisp_shaded_std)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Standard Deviation(down_short_diffuse_hemisp_std)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyrgeometer, Minima(down_short_hemisp_min)
• altitude above sea levelaltunits(alt)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyrgeometer, Standard
  Deviation(down_short_hemisp_std)
• Upwelling (10 meter) Longwave Hemispheric Irradiance, Ventilated Pyrgeometer,
  Minima(up_long_hemisp_min)
• east longitude for all the input platforms.(lon)
• Upwelling (10 meter) Shortwave Hemispheric Irradiance, Ventilated Pyranometer(up_short_hemisp)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Standard Deviation(short_direct_normal_std)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer(down_short_diffuse_hemisp)
• Upwelling (10 meter) Longwave Hemispheric Irradiance, Ventilated Pyrgeometer(up_long_hemisp)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Minima(down_short_diffuse_hemisp_min)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• Time offset from base_time(base_time)
• Battery voltage(vBatt)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer(down_long_hemisp_shaded)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyrgeometer(down_short_hemisp)
• Time offset of tweaks from base_time(time_offset)
• Upwelling (10 meter) Shortwave Hemispheric Irradiance, Ventilated Pyranometer,
  Standard Deviation(up_short_hemisp_std)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyrgeometer, Maxima(down_short_hemisp_max)
• Upwelling (10 meter) Longwave Hemispheric Irradiance, Ventilated Pyrgeometer,
  Standard Deviation(up_long_hemisp_std)
• Upwelling (10 meter) Longwave Hemispheric Irradiance, Ventilated Pyrgeometer,
  Maxima(up_long_hemisp_max)
• Upwelling (10 meter) Shortwave Hemispheric Irradiance, Ventilated Pyranometer,
  Minima(up_short_hemisp_min)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Maxima(down_short_diffuse_hemisp_max)
• north latitude for all the input platforms.(lat)
• Upwelling (10 meter) Shortwave Hemispheric Irradiance, Ventilated Pyranometer,
  Maxima(up_short_hemisp_max)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer, Minima(down_long_hemisp_shaded_min)
• Shortwave Direct Normal Irradiance, Pyrheliometer(short_direct_normal)

• Upwelling (10 meter) Shortwave Hemispheric Irradiance, Ventilated Pyranometer,
  Maxima(up_short_hemisp_max)
• Upwelling Longwave Hemispheric Net Infrared(up_long_netir)
• Shortwave Direct Normal Irradiance, Pyrheliometer(short_direct_normal)
• Upwelling (10 meter) Shortwave Hemispheric Irradiance, Ventilated Pyranometer,
  Standard Deviation(up_short_hemisp_std)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Maxima(down_short_diffuse_hemisp_max)
• Instantaneous Upwelling Pyrgeometer Case Thermistor Temperature, Pyrgeometer(inst_up_long_case_temp)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyrgeometer, Minima(down_short_hemisp_min)
• Time offset from base_time(base_time)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer, Minima(down_long_hemisp_shaded_min)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyrgeometer(down_short_hemisp)
• Upwelling (10 meter) Longwave Hemispheric Irradiance, Ventilated Pyrgeometer,
  Maxima(up_long_hemisp_max)
• Instantaneous Downwelling Pyrgeometer Dome Thermistor Temperature, Shaded
  Pyrgeometer(inst_down_long_shaded_dome_temp)
• Battery voltage(vBatt)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer(down_short_diffuse_hemisp)
• altitude above sea levelaltunits(alt)
• Upwelling (10 meter) Shortwave Hemispheric Irradiance, Ventilated Pyranometer(up_short_hemisp)
• Upwelling (10 meter) Longwave Hemispheric Irradiance, Ventilated Pyrgeometer,
  Minima(up_long_hemisp_min)
• Upwelling (10 meter) Longwave Hemispheric Irradiance, Ventilated Pyrgeometer(up_long_hemisp)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Standard Deviation(down_short_diffuse_hemisp_std)
• Upwelling (10 meter) Shortwave Hemispheric Irradiance, Ventilated Pyranometer,
  Minima(up_short_hemisp_min)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer, Maxima(down_long_hemisp_shaded_max)
• Upwelling (10 meter) Longwave Hemispheric Irradiance, Ventilated Pyrgeometer,
  Standard Deviation(up_long_hemisp_std)
• Downwelling Longwave Hemispheric Net Infrared(down_long_netir)
• Instantaneous Upwelling Pyrgeometer Dome Thermistor Temperature, Pyrgeometer(inst_up_long_dome_temp)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyrgeometer, Maxima(down_short_hemisp_max)
• Instantaneous Downwelling Pyrgeometer Case Thermistor Temperature, Shaded
  Pyrgeometer(inst_down_long_shaded_case_temp)
• Time offset of tweaks from base_time(time_offset)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer, Standard
  Deviation(down_long_hemisp_shaded_std)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyrgeometer, Standard
  Deviation(down_short_hemisp_std)
• east longitude for all the input platforms.(lon)
• north latitude for all the input platforms.(lat)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Minima(down_short_diffuse_hemisp_min)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer(down_long_hemisp_shaded)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Standard Deviation(short_direct_normal_std)

• Instantaneous Uncorrected Downwelling Shortwave Diffuse, Shaded Pyranometer
  Thermopile Voltage(inst_diffuse)
• Instantaneous Downwelling Pyrgeometer Thermopile Voltage, Shaded Pyrgeometer(inst_down_long_hemisp_shaded_tp)
• east longitude for all the input platforms.(lon)
• Instantaneous Downwelling Pyrgeometer Case Thermistor Resistance, Shaded
  Pyrgeometer(inst_down_long_shaded_case_resist)
• Instantaneous Downwelling Pyrgeometer Dome Thermistor Resistance, Shaded
  Pyrgeometer(inst_down_long_shaded_dome_resist)
• Instantaneous Upwelling Shortwave Irradiance, Inverted Pyranometer Thermopile
  Voltage(inst_up_short_hemisp)
• Instantaneous Upwelling Pyrgeometer Case Thermistor Resistance, Pyrgeometer(inst_up_long_case_resist)
• Time offset of tweaks from base_time(time_offset)
• Instantaneous Downwelling Hemispheric Shortwave, Unshaded Pyranometer Thermopile
  Voltage(inst_global)
• Time offset from base_time(base_time)
• Instantaneous Direct Normal Shortwave Irradiance, Pyrheliometer Thermopile
  Voltage(inst_direct_normal)
• Instantaneous Upwelling Pyrgeometer Dome Thermistor Resistance, Pyrgeometer(inst_up_long_dome_resist)
• altitude above sea levelaltunits(alt)
• north latitude for all the input platforms.(lat)
• Instantaneous Upwelling Pyrgeometer Thermopile Voltage, Pyrgeometer(inst_up_long_hemisp_tp)

• altitude above sea levelaltunits(alt)
• Measured Downwelling Diffuse Shortwave Irradiance (dif)(difswfluxdn_measured)
• Beginning Time of File (LST)(base_time_LST)
• Clear-sky Fit Estimated Downwelling Diffuse Field Shortwave Irradiance (cdif)(difswfluxdn_clearskyfit)
• Time offset of tweaks from base_time(time_offset)
• east longitude for all the input platforms.(lon)
• Clear-sky Fit Estimated Downwelling Global Shortwave Irradiance (cgsw)(gswfluxdn_clearskyfit)
• Number of 1-minute Clear-sky Detections in the 15-minute Interval (Nclr)(nsamples_clearsky_detection)
• Average over the interval of the standard deviation of difratiodn_measured
  computed using a 3-5 sample window centered at each 1-min sample(difratiodn_measured_stdev)
• Clear-sky Fit Estimated Downwelling Summed Shortwave Irradiance
  (dirfluxdn_clearskyfit+diffluxdn_clearskyfit) (cssw)(sswfluxdn_clearskyfit)
• Ratio of Clear-sky Fit Estimated Downwelling Diffuse Shortwave Irradiance to
  Clear-sky Fit Estimated Downwelling Global Shortwave Irradiance (cdifr)(difratiodn_clearskyfit)
• Measured Downwelling Summed Shortwave Irradiance
  (dirfluxdn_measured+diffluxdn_measured) (ssw)(sswfluxdn_measured)
• Difference: gswfluxdn_measured - gswfluxdn_clearskyfit (gswfcg)(gswfluxdn_cloudeffect)
• Ratio of Measured Downwelling Diffuse Shortwave Irradiance to Measured
  Downwelling Global Shortwave Irradiance (difr)(difratiodn_measured)
• Clear-sky Fit Estimated Surface Albedo from Shortwave Irradiance Measurements
  (calb)(albedosw_clearskyfit)
• Estimated Average Fractional Sky Cover over the Hemispheric Dome (cf)(cloudfraction)
• Time offset from base_time(base_time)
• Clear-sky Fit Estimated Downwelling Global UVB Irradiance (cguvb)(guvbdn_clearskyfit)
• Number of 1-minute Clear-sky Fit Downwelling Global Shortwave Irradiance
  Estimates in the 15-minute Interval (Ncsw)(nsamples_gswfluxdn_clearskyfit)
• Difference: sswfluxdn_measured - sswfluxdn_clearskyfit (sswfcg)(sswfluxdn_cloudeffect)
• Measured Downwelling Global Shortwave Irradiance (gsw)(gswfluxdn_measured)
• Arithmetic Average Distance from the Earth to the Sun (au)(sun_earth_distance)
• Clear-sky Fit Estimated Downwelling Direct Shortwave Irradiance (cdir)(dirfluxdn_clearskyfit)
• Measured Downwelling Direct Shortwave Irradiance (dir)(dirfluxdn_measured)
• Difference: difswfluxdn_measured - difswfluxdn_clearskyfit (diffcg)(difswfluxdn_cloudeffect)
• Arithmetic Average Cosine of the Solar Zenith Angle Z (CosZ)(solar_cos_z)
• north latitude for all the input platforms.(lat)
• Measured Downwelling Global UVB Irradiance (guvb)(guvbdn_measured)
• Number of 1-minute Measured Downwelling Summed Shortwave Irradiances in the
  15-minute Interval (Nssw)(nsamples_sswfluxdn_measured)
• Time Offset from base_time_LST(time_offset_LST)
• Number of 1-minute Cloud Fraction Estimates in the 15-minute Interval (Ncf)(nsamples_cloudfraction)
• Ratio of Measured minus Clear-sky Fit Estimated Downwelling Diffuse Shortwave
  Irradiance to Clear-sky Fit Estimated Downwelling Global Shortwave Irradiance
  (di(difcloudeffect_normalized)
• Measured Surface Albedo from Shortwave Irradiance Measurements (alb)(albedosw_measured)
• Site Identification(site)

• Measured Downwelling Diffuse Shortwave Irradiance (dif)(difswfluxdn_measured)
• Clear-sky Fit Coefficient b to Summed Shortwave Irradiance (CSWb)(coef_clearsky_ssw_b)
• Difference: gswfluxdn_measured - gswfluxdn_clearskyfit (gswfcg)(gswfluxdn_cloudeffect)
• altitude above sea levelaltunits(alt)
• Clear-sky Fit Coefficient a to Summed Shortwave Irradiance (CSWa)(coef_clearsky_ssw_a)
• Site Identification(site)
• Beginning Time of File (LST)(base_time_LST)
• Arithmetic Average Cosine of the Solar Zenith Angle Z (CosZ)(solar_cos_z)
• Date (YYMMDD LST) for which the Coefficients are Applicable(coef_date)
• Clear-sky Fit Coefficient a to Global UVB Irradiance (UVBa)(coef_clearsky_guvb_a)
• Difference: sswfluxdn_measured - sswfluxdn_clearskyfit (sswfcg)(sswfluxdn_cloudeffect)
• Clear-sky Fit Coefficient b to Global UVB Irradiance (UVBb)(coef_clearsky_guvb_b)
• Difference: difswfluxdn_measured - difswfluxdn_clearskyfit (diffcg)(difswfluxdn_cloudeffect)
• Measured Downwelling Global Shortwave Irradiance (gsw)(gswfluxdn_measured)
• Measured Surface Albedo from Shortwave Irradiance Measurements (alb)(albedosw_measured)
• Clear-sky Fit Estimated Surface Albedo from Shortwave Irradiance Measurements
  (calb)(albedosw_clearskyfit)
• north latitude for all the input platforms.(lat)
• Clear-sky Detection Flag (clrf)(flag_clearsky_detection)
• Arithmetic Average Distance from the Earth to the Sun (au)(sun_earth_distance)
• Clear-sky Fit Coefficient b to Global minus Summed Shortwave Irradiance
  Difference (SCORb)(coef_clearsky_dsw_b)
• Clear-sky Fit Coefficient a to Global minus Summed Shortwave Irradiance
  Difference (SCORa)(coef_clearsky_dsw_a)
• Time Offset from base_time_LST(time_offset_LST)
• Time offset from base_time(base_time)
• Measured Downwelling Summed Shortwave Irradiance
  (dirfluxdn_measured+diffluxdn_measured) (ssw)(sswfluxdn_measured)
• Clear-sky Fit Coefficient b to Albedo (Albb)(coef_clearsky_albedo_b)
• east longitude for all the input platforms.(lon)
• Measured Downwelling Global UVB Irradiance (guvb)(guvbdn_measured)
• Measured Downwelling Direct Shortwave Irradiance (dir)(dirfluxdn_measured)
• Clear-sky Fit Coefficient b to Diffuse Irradiance to Total Irradiance Ratio
  (DFRb)(coef_clearsky_difratio_b)
• Clear-sky Fit Coefficient a to Albedo (Alba)(coef_clearsky_albedo_a)
• Clear-sky Fit Coefficient a to Diffuse Irradiance to Total Irradiance Ratio
  (DFRa)(coef_clearsky_difratio_a)
• Clear-sky Fit Coefficient b to Global Shortwave Irradiance (CSWb)(coef_clearsky_gsw_b)
• Clear-sky Offset Coefficient c for Global minus Summed Shortwave Irradiance
  Difference (SCORc)(coef_clearsky_dsw_c)
• Ratio of Clear-sky Fit Estimated Downwelling Diffuse Shortwave Irradiance to
  Clear-sky Fit Estimated Downwelling Global Shortwave Irradiance (cdifr)(difratiodn_clearskyfit)
• Ratio of Measured Downwelling Diffuse Shortwave Irradiance to Measured
  Downwelling Global Shortwave Irradiance (difr)(difratiodn_measured)
• Clear-sky Fit Estimated Downwelling Direct Shortwave Irradiance (cdir)(dirfluxdn_clearskyfit)
• Clear-sky Fit Estimated Downwelling Global Shortwave Irradiance (cgsw)(gswfluxdn_clearskyfit)
• Clear-sky Fit Estimated Downwelling Diffuse Field Shortwave Irradiance (cdif)(difswfluxdn_clearskyfit)
• Daily Averaged Distance from the Earth to the Sun (auavg)(sun_earth_distance_dailyaverage)
• Clear-sky Fit Estimated Downwelling Summed Shortwave Irradiance
  (dirfluxdn_clearskyfit+diffluxdn_clearskyfit) (cssw)(sswfluxdn_clearskyfit)
• Time offset of tweaks from base_time(time_offset)
• Clear-sky Fit Coefficient a to Global Shortwave Irradiance (CSWa)(coef_clearsky_gsw_a)
• Clear-sky Fit Estimated Downwelling Global UVB Irradiance (cguvb)(guvbdn_clearskyfit)

• Raw data stream - documentation not supported(Raw data stream - documentation not supported)