VI/152 SOVAP-PICARD total solar irradiance (Meftah+, 2016)
Total solar irradiance as measured by the SOVAP radiometer onboard PICARD.
Meftah M., Chevalier A., Conscience C., Nevens S.
<J. Space Weather Space Clim., 6, A34 (2016),
https://doi.org/10.1051/swsc/2016027 >
=2017yCat.6152....0M 2017yCat.6152....0M
ADC_Keywords: Sun ; Spectroscopy
Keywords: Sun - Total Irradiance - Solar activity - Solar Cycle - Spacecraft
Abstract:
From the SOlar VAriability PICARD (SOVAP) space-based radiometer, we
obtained a new time series of the total solar irradiance (TSI) during
Solar Cycle 24. Based on SOVAP data, we obtained that the TSI input at
the top of the Earth's atmosphere at a distance of one astronomical
unit from the Sun is 1361.8±2.4W/m2 (1σ) representative of
the 2008 solar minimum period. From 2010 to 2014, the amplitude of the
changes has been of the order of ±0.1%, corresponding to a range of
about 2.7W/m2. To determine the TSI from SOVAP, we present here an
improved instrument equation. A parameter was integrated from a
theoretical analysis that highlighted the thermo-electrical
non-equivalence of the radiometric cavity. From this approach, we
obtained values that are lower than those previously provided with the
same type of instrument. The results in this paper supersede the
previous SOVAP analysis and provide the best SOVAP-based TSI-value
estimate and its temporal variation.
Description:
The Royal Meteorological Institute of Belgium (RMIB) has in its
33-year space history, since Spacelab in November 1983, launched six
different TSI instruments of the DIfferential Absolute RADiometer
(DIARAD) type on 11 space flights.
The determination of the SOVAP TSI time series has required the
establishment of modified instrument equations. For the nominal modes,
a parameter (ΔPo) has been integrated from a theoretical
analysis, which highlights the thermo-electrical non-equivalence of
the radiometric cavity (open and closed). For the "Rad 10" mode,
another parameter (KRad10) has been integrated from space calibration,
which highlights the thermo-electrical non-equivalence between the
right and the left cavity. TSI time series for different operation
modes of SOVAP-DIARAD are displayed in Figure 3 using instrument
equations. Thus, continuous time series of TSI observations have been
constructed from the set of measurements made by the SOVAP radiometer
from the different operation modes. The presented SOVAP composite
includes all measurement modes normalised to the mean TSI of the
"Auto 2" and "Auto 3" modes at the beginning of the PICARD
mission.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
composit.dat 51 3756 *PICARD/SOVAP Total Solar Irradiance - Composite
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Note on composit.dat: Date range: 2010-07-22 to 2014-03-02, cadence: 6 hours .
Version: 1 Date: 2015-12-20.
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See also:
J/A+A/531/A6 : Evolution of solar irradiance during Holocene (Vieira+, 2011)
J/AJ/112/2274 : Spectral irradiance calibration. VII. (Cohen+ 1996)
J/AJ/112/241 : Spectral irradiance calibration. VI. (Cohen+ 1996)
J/ApJ/789/117 : Solar spectral irradiance (Marchenko+, 2014)
J/A+A/562/A133 : Irradiated atmospheres analytical model (Parmentier+, 2014)
J/A+A/574/A35 : Irradiated atmospheres analytical model (Parmentier+, 2015)
J/A+A/581/A26 : Solar Lyman irradiance line profiles (Lemaire+, 2015)
J/other/SoPh/291.3527 : SOLAR/SOLSPEC UV SSI from 2008-2015 (Meftah+, 2016)
J/A+A/600/A21 : Sun UV spectrum (06/06/2008-26/04/2009) (Bolsee+, 2017)
Byte-by-byte Description of file: composit.dat
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Bytes Format Units Label Explanations
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1- 10 A10 "date" Obs.Date Observation date
12- 19 A8 "h:m:s" Obs.Time Observation time
21- 33 F13.8 W/m2 TSI Mean Total Solar Irradiance (Composite),
35- 44 F10.8 W/m2 e_TSI ?=- Standard deviation of the mean TSI (k=1), I
46- 48 I3 --- o_TSI Number of data points used for the mean values
50- 51 I2 --- Chan Channel Measurements (1)
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Note (1): Channel measurements as follows:
2 = AUTO02, Absolute accuracy (k=1) - AUTO02: 1.39W/m2
3 = AUTO03, Absolute accuracy (k=1) - AUTO03: 1.52W/m2
10 = RAD10, Absolute accuracy (k=1) - RAD10 : 1.73W/m2
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Acknowledgements:
Mustapha Meftah, MUSTAPHA.MEFTAH(at)latmos.ipsl.fr
(End) Patricia Vannier [CDS] 23-Oct-2017