SUN MONITORING ON THE EXTERNAL PAYLOAD FACILITY OF COLUMBUS –SOLAR VARIABLE AND
IRRADIANCE MONITOR (SOLAR- SOVIM)
Research Area: Heliophysics
Expedition(s): 16, 17
Principle Investigator(s): ● Claus Fröhlich, Physikalisch-Meteorologisches Observatorium
World Radiation Centre, Davos, Switzerland
RESEARCH OBJECTIVES
The SOlar Variable and Irradiance Monitor (SOVIM) measures solar spectral irradiance via filter-
radiometers in the near-UV (402
nanometers), visible (500 nanometers)
and near-IR (862 nanometers) regions
together with the total solar irradiance
(TSI), using 2 types of radiometers
covering the range from 200 nanometers
to 100 micrometers. SOVIM measures the
total and spectral solar irradiance and
calibration of TSI. The investigation
studies the irradiance of the sun, with
high precision and high stability.
RESULTS
The SOVIM package was composed of 3
PMO6 absolute radiometers, 2
sunphotometers, 1 pointing sensor
(TASS), and 1 DIARAD radiometer. This summary came from the DIARAD/SOVIM TSI results (and
their associated uncertainties). Concerning the acquired data, the TSI value from
DIARAD/SOVIM for 3 days of measurements (June 13, 14 and 15 of 2008) was 1364.50 ± 1.38 W
m-2 (watt per square meter) for the left channel and 1364.75 ± 1.38 W m-2 for the right channel.
The uncertainty of ±1.38 W m-2 was obtained when the individual contributions of the
instrument equation were added. If they were combined in quadrature, the uncertainty was
around ±0.497 W m-2. The difference between the independent left and right channel
measurements as low as 0.25 W m-2, which is within the absolute uncertainty limit of ±1.38 W
m-2 (Total) and ±0.497 W m-2 (RSS). Although DIARAD/SOVIM TSI measurements were 1.2 W m-2
lower than DIARAD/ VIRGO TSI value, it was still 4 W m-2 higher than TIM/ SORCE TSI
measurements.
PUBLICATION(S)
Mekaoui S, Dewitte S, Conscience C, Chevalier A. Total solar irradiance absolute level from
DIARAD/SOVIM on the International Space Station. Advances in Space Research. 2010;45:1393–
1406.
This investigation is complete; however additional results are pending publication.
Solar Facility on the International Space Station highlights the
location of the different instruments. ESA image.