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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)> =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:
FileName Lrecl Records Explanations
ReadMe 80 . This file composit.dat 51 3756 *PICARD/SOVAP Total Solar Irradiance - Composite
Note on composit.dat: Date range: 2010-07-22 to 2014-03-02, cadence: 6 hours . Version: 1 Date: 2015-12-20.
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
Bytes Format Units Label Explanations
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)
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
Acknowledgements: Mustapha Meftah, MUSTAPHA.MEFTAH(at)
(End) Patricia Vannier [CDS] 23-Oct-2017
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