PMOD/WRC Weltstrahlungszentrum Centre Mondial de Rayonnement World Radiation Center 
Physikalisch-Meteorologisches Observatorium Davos 


  Total Solar Irradiance from VIRGO Onboard SOHO

New!!   The SOHO Recovery

Two active-cavity radiometer - DIARAD (Differential Absolute RADiometer) and PMO6-V (V indicates the VIRGO version of the PMO6 type radiometer) - are part of VIRGO to investigate the Total Solar Irradiance(TSI), also called the solar constant. A description of the instruments can be found in Fröhlich et al. (1995) and the in-flight performance is described in Fröhlich et al. (1997). The determination of the TSI from the SOHO/VIRGO experiment is made by first correcting the time series for all a priori known influences and, second, to correct the data for instrumental sensitivity changes, using the back-up instruments. A detailed description of the degradation characteristics can be found in Anklin et al. (1998). The time series of the VIRGO TSI are shown below.

New! The following figure shows new data of the PMO6-V and the DIARAD radiometers from VIRGO after the recovery of SOHO. The most recent VIRGO TSI is about 1366.6 Wm-2, which fits well to the trend observed before SOHO went on vacation last June.

VIRGO Total Solar Irradiance
Click here to get a full size view
 
 
 
 
 
 
 
 

Image: postscript

Data (daily): ASCIIData (hourly): ASCII
 

References:
Anklin, M. and Fröhlich, C. and Finsterle, W. and Crommelynck, D. A. and Dewitte, S.; 1998, Assessment of Degradation of VIRGO Radiometers Onboard SOHO, Metrologia 35, in press.

Fröhlich, C. and Romero, J. and Roth, H. and Wehrli, C. and Andersen, B. N. and Appourchaux, T. and Domingo, V. and Telljohann, U. and Berthomieu, B. and Delache, P. and Provost, J. and Toutain, T. and Crommelynck, D. and Chevalier, A.and Fichot, A. and Däppen, W. and Gough, D. O. and Hoeksema, T. and Jiménez and Gómez, M. and Herreros, J. and Roca-Cortés, T. and Jones, A. R. and Pap, J.and Willson, R. C.: 1995, VIRGO: Experiment for Helioseismology and Solar Irradiance Monitoring, Sol. Phys. 162, 101-128.

Fröhlich, C. and Crommelynck, D. and Wehrli, C. and Anklin, M. and Dewitte, S. and Fichot, A. and Finsterle, W. and Jiménez, A. and Chevalier, A. and Roth, H. J.; 1997, In-Flight Performances of VIRGO Solar Irradiance Instruments on SOHO,  Sol. Phys. 175, 267-286.

See also:
The VIRGO homepage
Total Solar Irradiance: Composite