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1.
Total solar irradiance (TSI) measurements have been available from the TIM instrument on the SORCE spacecraft since 2003. We compare TSI data, both 24-h and 6-h averages, with photometric indices from red and K-line images obtained on a daily basis at the San Fernando Observatory (SFO). For 1253 days of data from 2 March 2003 to 5 May 2010 we compare the data in linear multiple regression analyses. The best results come from using two photometric indices, the red and K-line photometric sums, and SORCE TSI 6-h averages interpolated to the SFO time of observation. For this case, we obtain a coefficient of multiple determination, R 2, of 0.9495 and a quiet-Sun irradiance S 0?=?1360.810?±?0.004?W?m?2. These results provide further support for the hypothesis that the quiet Sun is constant over time.  相似文献   

2.
Thirty active regions were observed on the Sun during the period from October 19 to November 20, 2003. Hard X-ray and gamma-ray radiation was detected from four active regions (10484, 10486, 10488, and 10490): 14 solar flares stronger than M5.0 according to the GOES classification were recorded during this period by detectors onboard the Geostationary Operational Environmental Satellite (GOES), Ramaty High Energy Solar Spectroscopic Imager (RHESSI), and other satellites. Five of these flares (and also the M2.7 flare of October 27, 2003) were also observed by the AVS-F apparatus onboard the CORONAS-F satellite. This paper discusses the time profiles and energy spectra of the solar flares of October 26, 2003 (M7.6), and October 29, 2003 (X10), and of the initial phase of the flare of November 4, 2003 (X18), obtained by the AVS-F instrument during the passage of the satellite over the regions near the geomagnetic equator. The spectra of the M7.6 flare of October 26, 2003, and of the initial phase of the X18 flare of November 4, 2003, in the energy band from 0.1 to 17 MeV contain no lines, whereas the spectrum of the flare of October 29, 2003, exhibits nuclear lines and the 2.2-MeV line during the entire flare gamma-ray emission registration. We also report the time profiles of the flare of October 29, 2003, in the energy bands corresponding to the continuum in the energy band 0.3–0.6 MeV, the nuclear lines of 56Fe, 24Mg, 20Ne, 28Si, 12C, and 16O, and the 2.2-MeV neutron-capture line. The analysis of these temporal profile periodograms shows the presence of a thin structure with characteristic scales from 34 to 158 s at the 99% confidence level. The AVS-F apparatus analyzes temporal profiles of low-energy gamma-ray emission with a temporal resolution of 1 ms within the first 4.096 seconds of solar flares. The analysis of the data reveals no regularities in the time series on time scales ranging from 2 to 100 ms at a confidence level of 99% for these three solar flares.  相似文献   

3.
Aparicio  A. J. P.  Lefèvre  L.  Gallego  M. C.  Vaquero  J. M.  Clette  F.  Bravo-Paredes  N.  Galaviz  P.  Bautista  M. L. 《Solar physics》2018,293(12):1-23

The Spectral Irradiance Monitor (SIM) instrument on board the Solar Radiation and Climate Experiment (SORCE) performs daily measurements of the solar spectral irradiance (SSI) from 200 to 2400 nm. Both temporal and spectral corrections for instrument degradation have been built on physical models based on comparison of two independent channels with different solar exposure. The present study derives a novel correction for SIM degradation using the total solar irradiance (TSI) measurements from the Total Irradiance Monitor (TIM) on SORCE. The correction is applied to SIM SSI data from September 2004 to October 2012 over the wavelength range from 205 nm to 2300 nm. The change in corrected, integrated SSI agrees within \(0.1~\mbox{W}\,\mbox{m}^{-2}\) (\(1\sigma\)) with SORCE TIM TSI and independently shows agreement with the SATIRE-S and NRLSSI2 solar models within measurement uncertainties.

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4.
The total solar irradiance (TSI) has been recorded daily since October 2013 by the Total Solar Irradiance Monitor (TSIM) onboard the FY-3C satellite, which is mainly designed for Earth observation. The TSIM has a pointing system to perform solar tracking using a sun sensor. The TSI is measured by two electrical substitution radiometers with traceability to the World Radiation Reference. The TSI value measured with the TSIM on 2 October 2013 is \(1364.88~\mbox{W}\,\mbox{m}^{-2}\) with an uncertainty of \(1.08~\mbox{W}\,\mbox{m}^{-2}\). Short-term TSI variations recorded with the TSIM show good agreement with SOHO/VIRGO and SORCE/TIM. The data quality and accuracy of FY-3C/TSIM are much better than its predecessors on the FY-3A and FY-3B satellites, which operated in a scanning mode.  相似文献   

5.
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6.
Ulysses was launched in October 1990, and its Solar X-ray/Cosmic Gamma-Ray Burst Experiment (GRB) has provided more than 13 years of uninterrupted observations of solar X-ray flare activity. Due to the large variation of the relative solar latitude and longitude of the spacecraft orbit with respect to the Earth, the perspective of the GRB instrument often differed significantly from that of X-ray instruments on Earth-orbiting satellites. During extended periods the GRB experiment made direct observations of flares on the hidden face of the Sun, providing a unique record of events not visible to other instruments. The small detector area of GRB and its optimization for very high counting rates minimized the effects of pulse pile-up. We interpret the spectra, time histories, and occurrence distribution patterns of GRB data in terms of “thermal feed-through”, the confusion of thermal soft X-rays and non-thermal hard X-rays. This effect is a systematic problem for scintillation-counter spectrometers observing the solar hard X-ray spectrum. This paper provides a definitive catalog of the Ulysses X-ray flare observations and discusses various features of this unique database. For the equivalent GOES range X2 – X25, we find a power-law fit for the (differential) occurrence frequency at >25 keV with slope −1.61±0.04, with no evidence for a downturn at the highest event magnitudes (for the relatively small sample of such events available in this study). If the nine most intense events are excluded because of concerns about the effects of pulse pile-up, the slope steepens to −1.75±0.08.  相似文献   

7.
Relations between basic indices of the Sun and the cosmogenic isotope 14C and 10Be records were derived using the Artificial Neural Network (ANN) technique. A reconstruction of the sunspot indices and changes in Total Solar Irradiance (TSI) was carried out. Long-term changes in TSI appear in the amplitude modulation of its 11-year cyclic variation as well as in its lower envelope describing variability of the background irradiance of the Sun. According to the reconstruction the irradiance has increased about 2.5 W m−2 since 1441.  相似文献   

8.
The Picard spacecraft was successfully launched on 15 June 2010, into a Sun-synchronous orbit. The mission represents one of the European contributions to solar observations and Essential Climate Variables (ECVs) measurements. The payload is composed of a Solar Diameter Imager and Surface Mapper (SODISM) and two radiometers: SOlar VAriability Picard (SOVAP) and PREcision MOnitor Sensor (PREMOS). SOVAP, a dual side-by-side cavity radiometer, measures the total solar irradiance (TSI). It is the sixth of a series of differential absolute-radiometer-type instruments developed and operated in space by the Royal Meteorological Institute of Belgium. The measurements of SOVAP in the summer of 2010 yielded a TSI value of 1362.1 W?m?2 with an uncertainty of ±?2.4 W?m?2 (k=1). During the periods of November 2010 and January 2013, the amplitude of the changes in TSI has been on the order of 0.18 %, corresponding to a range of about 2.4 W?m?2.  相似文献   

9.
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10.
In the current solar cycle, the concentration of flare activity peaked during the period from October 19 to November 5, 2003, 3.5 years after the maximum point of the current solar-activity cycle. During this time, 56 high-(16) and medium-class flares occurred on the Sun, including 11 X flares. The flux of every such flare exceeded by a factor of 30 to 600 the 1–8 Å soft X-ray background flux of the entire Sun during flare-free periods. The disturbances caused by these flares produced six major S2-to S4-level proton events and four G1-to G5-class magnetic storms in the Earth’s space environment. Among the solar events observed were the most powerful X-ray flare of the current solar cycle, the eighth solar proton event in terms of particle flux during the entire history of observations, and the seventh magnetic storm in terms of Ap index. The most powerful flare resulted in the fastest coronal mass ejection during the current solar cycle with the solar plasma moving through interplanetary space at a velocity of 106 km/s, which is about four times higher than the average velocity. Severe magnetic storms during the period from September 29 through October 3 posed a lot of problems for research and technological satellites (Advanced Composition Explorer (ACE), Aqua, Chandra, Chips, Cluster, Geostationary Operational Environmental Satellites (GOES) 9, 10, and 12, etc.) and spacecraft in interplanetary space (Mars Explorer Rover and Microwave Anisotropy Probe). The Advanced Earth Observing Satellite 2 (ADEOS 2), a Japanese satellite for monitoring the Earth’s environment, was disabled at the time of the arrival of the powerful interplanetary shock from the superflare of October 28, 2003. During this period, the ISS astronauts were forced to escape into the aft part of the station five times, which ensured the strongest protection against radiation. This paper is dedicated to the study of the solar situation and individual flare events.  相似文献   

11.
The satellite total solar irradiance (TSI) database provides a valuable record for investigating models of solar variation used to interpret climate changes. The 35-year ACRIM total solar irradiance (TSI) satellite composite time series has been revised using algorithm updates based on 13 years of accumulated mission experience and corrections to ACRIMSAT/ACRIM3 results for scattering and diffraction derived from recent testing at the Laboratory for Atmospheric and Space Physics/Total solar irradiance Radiometer Facility (LASP/TRF). The net correction lowers the ACRIM3 scale by ～3000 ppm, in closer agreement with the scale of SORCE/TIM results (average total solar irradiance ≈1361.5 W/m2). Differences between the ACRIM and PMOD TSI composites are investigated, particularly the decadal trending during solar cycles 21–22 and the Nimbus7/ERB and ERBS/ERBE results available to bridge the ACRIM Gap (1989–1992), are tested against a set of solar proxy models. Our findings confirm the following ACRIM TSI composite features: (1) The validity of the TSI peak in the originally published ERB results in early 1979 during solar cycle 21; (2) The correctness of originally published ACRIM1 results during the SMM spin mode (1981–1984); (3) The upward trend of originally published ERB results during the ACRIM Gap; (4) The occurrence of a significant upward TSI trend between the minima of solar cycles 21 and 22 and (5) a decreasing trend during solar cycles 22–23. The same analytical approach does not support some important features of the PMOD TSI composite: (1) The downward corrections applied to the originally published ERB and ACRIM1 results during solar cycle 21; (2) The step function sensitivity change in ERB results at the end-of-September 1989; (3) The downward trend of ERBE results during the ACRIM Gap and (4) the use of ERBE results to bridge the ACRIM Gap. Our analysis provides a first order validation of the ACRIM TSI composite approach and its 0.037 %/decade upward trend during solar cycles 21–22. The implications of increasing TSI during the global warming of the last two decades of the 20th century are that solar forcing of climate change may be a significantly larger factor than represented in the CMIP5 general circulation climate models.  相似文献   

12.
During two extreme bursts of solar activity in March–April 2001 and October–November 2003, the ground-based neutron monitor network recorded a series of outstanding events distinguished by their magnitude and unusual peculiarities. The important changes that lead to increased activity initiated not with the sunspot appearance, but with the large-scale solar magnetic field reconfiguration. A series of strong and moderate magnetic storms and powerful proton events (including ground-level enhancements, GLE) were registered during these periods. The largest and most productive in the 23rd solar cycle, active region 486, generated a significant series of solar flares among which the 4 November 2003 flare (X28/3B) was the most powerful X-ray solar event ever observed. The fastest arrival of the interplanetary disturbance from the Sun (after August 1972) and the highest solar wind velocity and IMF intensity were recorded during these events. Within 1 week, three GLEs of solar cosmic rays were registered by the neutron monitor network (28 and 29 October and 2 November 2003). In this work, we perform a tentative analysis of a number of the effects seen in cosmic rays during these two periods, using the neutron monitor network and other relevant data.  相似文献   

13.
Solar empirical models based on regression of two variability indices for radiation from the photosphere and chromosphere fit total solar irradiance (TSI) observations with accuracy comparable to the precision reported for the observations themselves. However, the physical meaning of the fitting coefficients and their stability during different phases of the solar cycle has not been examined in detail. We test the stability of the coefficients in regression models of the VIRGO TSI observations over the nine years from the minimum of Cycle 23 in 1996 through the maximum to 2005. We also show how the coefficients converge to the ‘`best fit’' using a search in the coefficient space. Analysis of TSI variability in different phases of this cycle shows little change in regression models as long as the time periods used in the regression are long enough to show the slow solar cycle variation in TSI. We extend our analysis to TSI observations from ERB, ACRIM2, ACRIM3, DIARAD, and TIM. The regression models from these time series show large systematic differences in fitting coefficients for the plage and sunspot indices that we used. These differences are significantly larger than the estimated uncertainties in the coefficients and point to the difficulty of combining observations from different instruments to create an accurate composite TSI record over several solar cycles. Our results clearly demonstrate the improvement in precision of TSI measurements from the Nimbus 7 ERB in Cycle 22 to the latest SORCE TIM data in Cycle 23.  相似文献   

14.
The effects of scattering and diffraction on the observations of the ACRIMSAT/ACRIM3 satellite TSI monitoring mission have been characterized by the preflight calibration approach for satellite total solar irradiance (TSI) sensors implemented at the LASP/TRF (Laboratory for Atmospheric and Space Physics/Total Solar Irradiance Radiometer Facility). The TRF also calibrates the SI (International System of units) traceability to the NIST (National Institute of Standards and Technology) cryo-radiometric scale. ACRIM3’s self-calibration agrees with NIST to within the uncertainty of the test procedure (～500 ppm). A correction of ～5000 ppm was found for scattering and diffraction that has significantly reduced the scale difference between the results of the ACRIMSAT/ACRIM3 and SORCE/TIM satellite experiments. Algorithm updates reflecting more than 10 years of mission experience have been made that further improve the ACRIM3 results by eliminating some thermally driven signal and increasing the signal to noise ratio. The result of these changes is a more precise and detailed picture of TSI variability. Comparison of the results from the ACRIM3, SORCE/TIM and SOHO/VIRGO satellite experiments demonstrate the near identical detection of TSI variability on all sub-annual temporal and amplitude scales during the TIM mission. The largest occurs at the rotational period of the primary solar activity longitudes. On the decadal timescale, while ACRIM3 and VIRGO results exhibit close agreement throughout, TIM exhibits a consistent 500 ppm upward trend relative to ACRIM3 and VIRGO. A solar magnetic activity area proxy for TSI has been used to demonstrate that the ACRIM TSI composite and its +0.037 %/decade TSI trend during solar cycles 21–23 is the most likely correct representation of the extant satellite TSI database. The occurrence of this trend during the last decades of the 20th century supports a more robust contribution of TSI variation to detected global temperature increase during this period than predicted by current climate models.  相似文献   

15.
Cosmic rays registered by Neutron Monitor on the surface of the Earth are believed to originate from outer space, and sometimes also from the exotic objects of the Sun. Whilst the intensities of the cosmic rays are observed to be enhanced with sudden, sharp and short-lived increases, they are termed as ground level enhancements (GLEs). They are the occurrences in solar cosmic ray intensity variations on short-term basis, so different solar factors erupted from the Sun can be responsible for causing them. In this context, an attempt has been made to determine quantitative relationships of the GLEs having peak increase >5% with simultaneous solar, interplanetary and geophysical factors from 1997 through 2006, thereby searching the responsible factors which seem to cause the enhancements. Results suggest that GLE peaks might be caused by solar energetic particle fluxes and solar flares. The proton fluxes which seemed to cause GLE peaks were also supported by their corresponding fluences. For most of the flares, the time integrated rising portion of the flare emission refers to the strong portion of X-ray fluxes which might be the concern to GLE peak. On an average, GLE peak associated X-ray flux (0.71×10−4 w/m2) is much stronger than GLE background associated X-ray flux (0.11×10−6 w/m2). It gives a general consent that the GLE peak is presumably caused by the solar flare. Coronal mass ejection alone does not seem to cause GLE. Coronal mass ejection presumably causes geomagnetic disturbances characterized by geomagnetic indices and polarities of interplanetary magnetic fields.  相似文献   

16.
The “Fast X-ray Monitor” (BRM) instrument operated in the complex of the scientific instruments onboard the CORONAS-PHOTON satellite from February 19, 2009, until December 1, 2009. The instrument is intended for the registration of the hard X-ray radiation of solar flares in the 20–600 keV energy range in six differential energy channels (20–30, 30–40, 40–50, 50–70, 70–130, and 130–600 keV) with temporal resolution to 1 ms. In the instrument, a detector based on the YAP: Ce scintillator is used; this detector is 70 mm in diameter and 10 mm thick (the decay time is about 28 ns). For the decrease of the back-ground charge of the detector, the collimator limiting the angle of view of the instrument of value 12° is mounted over the scintillator. The effective area of the detector amounts to 27.7 cm2 (at the X-ray radiation energy 80 keV), and the dead time of the detector is 1 μs. Over the operation onboard the CORONAS-PHOTON satellite, the BRM instrument has registered gamma ray burst series and, perhaps, one solar flare of the class C1.3 on October 26, 2009.  相似文献   

17.
Total Solar Irradiance Measurement and Modelling during Cycle 23   总被引：1，自引：0，他引：1  
S. Mekaoui  S. Dewitte 《Solar physics》2008,247(1):203-216
During solar cycle 23, which is now close to its end, variations of the total solar irradiance were measured by six different instruments, providing four independent time series of the irradiance variation over the complete solar cycle. A new composite time series constructed using five of these six instruments provides unprecedented instrument stability for the study of the open question of solar irradiance variations between minima. An independent analysis of the different composite time series is performed through an empirical proxy model fit. The new composite is fitted with 0.96 correlation (R 2=93%) and RMS error of 0.15 W m−2, thus reaching the limit of the individual instrument stabilities. Both the measurements and the model indicate that for the current cycle the minimum irradiance level has not yet been reached. Therefore we use the model to extrapolate measurements up to 2008 when the minimum irradiance level is expected. If we assume that there will be no changes in the solar irradiance from 2006 to 2008 that are not captured by the regression model, it can be predicted that there will be no variation of the solar minimum irradiance level during cycle 23 with an uncertainty of ±0.14 W m−2.  相似文献   

18.
An analysis of spatially-resolved measurements of the intensity of the photospheric continuum by the Michelson Doppler Imager (MDI) on the SOHO spacecraft indicates that these data can be used to study variations of the Total Solar Irradiance (TSI). Since the techniques employed depend upon ratios of intensities measured by MDI, they are independent of the absolute photometric calibration of the instrument. The results suggest that, while it is possible to account for short-term (weeks to months) variation in TSI by variations in the irradiance contributions of regions with enhanced magnetic fields (larger than ten G as measured by MDI), the longer-term variations are influenced significantly by variations in the brightness of the quiet Sun, defined here as regions with magnetic field magnitudes smaller than ten G. The latter regions cover a substantial fraction of the solar surface, ranging from approximately 90% of the Sun near solar minimum to 70% near solar maximum. The results provide evidence that a substantial fraction, 50% or more, of the longer term (≥one year) variation in TSI is due to changes in the brightness of the quiet Sun.  相似文献   

19.
We present the results using the AutoClass analysis application available at NASA/Ames Intelligent Systems Div. (2002) which is a Bayesian, finite mixture model classification system developed by Cheeseman and Stutz (1996). We apply this system to Mount Wilson Solar Observatory (MWO) intensity and magnetogram images and classify individual pixels on the solar surface to calculate daily indices that are then correlated with total solar irradiance (TSI) to yield a set of regression coefficients. This approach allows us to model the TSI with a correlation of better than 0.96 for the period 1996 to 2007. These regression coefficients applied to classified pixels on the observed solar surface allow the construction of images of the Sun as it would be seen by TSI measuring instruments like the Solar Bolometric Imager recently flown by Foukal et al. (Astrophys. J. 611, L57, 2004). As a consequence of the very high correlation we achieve in reproducing the TSI record, our approach holds out the possibility of creating an on-going, accurate, independent estimate of TSI variations from ground-based observations which could be used to compare, and identify the sources of disagreement among, TSI observations from the various satellite instruments and to fill in gaps in the satellite record. Further, our spatially-resolved images should assist in characterizing the particular solar surface regions associated with TSI variations. Also, since the particular set of MWO data on which this analysis is based is available on a daily basis back to at least 1985, and on an intermittent basis before then, it will be possible to estimate the TSI emission due to identified solar surface features at several solar minima to constrain the role surface magnetic effects have on long-term trends in solar energy output.  相似文献   

20.
The spectra of two powerful flares with approximately the same intensities in the optical region but with different spectral features and power in other regions are studied. One of them is the unique flare which occurred on October 28, 2003, importance X17.2/4B, ranking third in magnitude among the recorded flares. Another occurred on September 1, 1990, 3B importance. The flares vary in the Balmer decrement. The flare of October 28, 2003, has a ratio of I(Hβ)/I(Hα) = 1.47. This is the largest value for solar flares ever observed. The flares also differ in magnitude of the D Na I lines emission: the emission of the flare of October 28, 2003, is substantially larger than that of the other flare. The chromosphere models of the flares are computed using the observed profiles of Balmer lines and D Na I lines. The satisfactory agreement of the calculated and observed profiles is obtained for the two-component models in which a hot component occupies 6% of the area. The hot component of the chromosphere model is characterized with the dense condensation available in the upper layers. For the flare of October 28, 2003, this condensation is located deeper and its substance concentration is greater than that for another flare. The Hα line intensity for the model hot component alone is approximately 30 and the continuous spectrum intensity is approximately 3% of the undisturbed level. The photosphere model is computed using the observed profiles of photosphere lines for the flare of October 28, 2003. It is found that very broad profiles of individual sigma-components of the Fe I λ 525.0 nm line may be only explained by the presence of magnetic fields having different directions. A great difference is detected between values of the magnetic field strength obtained in the splitting of sigma-components and those provided by simulation.  相似文献   

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