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1.
We have analyzed the solar irradiance data from the Earth Radiation Budget Satellite(ERBS)during the time period from 1984 October 15 to 2003 October 15.By first filtering the data by Simple Exponential Smoothing,we have applied the periodogram method to the processed data in order to search for its time variation.The study exhibits multi-periodicities on these data around 110,118,574 and 740d with very high confidence levels(more than 99%).These periods are significantly similar to the periods of other solar activities which may suggest that solar irradiance may be associated with other solar activities. 相似文献
2.
A. T. Mecherikunnel 《Solar physics》1994,155(2):211-221
This paper presents a statistical comparison of the solar total irradiance measured from the Nimbus-7, the Solar Maximum Mission (SMM), the Earth Radiation Budget Satellite (ERBS), and the Upper Atmosphere Research Satellite (UARS) spacecraft platforms, for the period 1985 –1992. The mean irradiance, standard deviation, and the correlation among the daily irradiance remained high during periods of high solar activity. Linear regression models are established to estimate the irradiance measurements from one platform by the others. The results are consistent with the observations. However, the Nimbus-7 ERB responses show a drift during 1989–1992. The absolute irradiance observed by each instrument varies within the uncertainty associated with the corresponding radiometer. 相似文献
3.
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
4.
太阳总辐照是指在地球大气层顶接收到的太阳总辐射照度,也叫"太阳常数",但它实际上并非常数。太阳总辐照随波长的分布即为太阳分光辐照。太阳辐照变化的研究,对理解太阳表面及内部活动的物理过程、机制,研究地球大气、日地关系,解决人类面临的全球气候变暖的挑战等,都具有重要意义。首先简单介绍了太阳辐照,回顾了太阳辐照的空间观测;接着介绍了观测数据的并合,以及对合成数据的一些研究;然后讨论了太阳辐照变化的原因,简述了太阳总辐照的重构及其在气候研究上的一些应用,并进行必要的评论;最后对未来的研究方向提出了一些看法。 相似文献
5.
We model total solar irradiance (TSI) using photometric irradiance indices from the San Fernando Observatory (SFO), and compare our model with measurements compiled from different space-based radiometers. Space-based measurements of TSI have been obtained recently from ACRIM-3 on board the ACRIMSAT. These data have been combined with other data sets to create an ACRIM-based composite. From VIRGO on board the Solar and Heliospheric Observatory (SOHO) spacecraft two different TSI composites have been developed. The VIRGO irradiance data have been combined by the Davos group to create a composite often referred to as PMOD (Physikalisch-Meteorologisches Observatorium Davos). Also using data from VIRGO, the Royal Meteorological Institute of Belgium (RMIB) has created a separate composite TSI referred to here as the RMIB composite. We also report on comparisons with TSI data from the Total Irradiance Monitor (TIM) experiment on board the Solar Radiation and Climate Experiment (SORCE) spacecraft. The SFO model correlates well with all four experiments during the seven-year SORCE interval. For this interval, the squared correlation coefficient R 2 was 0.949 for SORCE, 0.887 for ACRIM, 0.922 for PMOD, and 0.924 for RMIB. Long-term differences between the PMOD, ACRIM, and RMIB composites become apparent when we examine a 21.5-year interval. We demonstrate that ground-based photometry, by accurately removing TSI variations caused by solar activity, is useful for understanding the differences that exist between TSI measurements from different spacecraft experiments. 相似文献
6.
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
7.
As part of a program to estimate the solar spectrum back to the early twentieth century, we have generated fits to UV spectral
irradiance measurements from 1 – 410 nm. The longer wavelength spectra (150 – 410 nm) were fit as a function of two solar
activity proxies, the Mg ii core-to-wing ratio, or Mg ii index, and the total Ca ii K disk activity derived from ground based observations. Irradiance spectra at shorter wavelengths (1 – 150 nm) where used
to generate fits to the Mg ii core-to-wing ratio alone. Two sets of spectra were used in these fitting procedures. The fits at longer wavelengths (150
to 410 nm) were derived from the high-resolution spectra taken by the Solar Ultraviolet Spectral Irradiance Monitor (SUSIM)
on the Upper Atmospheric Research Satellite (UARS). Spectra measured by the Solar EUV Experiment (SEE) instrument on the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite were used for the fits at wavelengths from 1 to 150 nm. To generate fits between solar irradiance and solar
proxies, this study uses the above irradiance data, the NOAA composite Mg ii index, and daily Ca ii K disk activity determined from images measured by Big Bear Solar Observatory (BBSO). In addition to the fitting coefficients
between irradiance and solar proxies, other results from this study include an estimated relationship between the fraction
of the disk with enhanced Ca ii K activity and the Mg ii index, an upper bound of the average solar UV spectral irradiance during periods where the solar disk contains only regions
of the quiet Sun, as was believed to be present during the Maunder Minimum, as well as results indicating that slightly more
than 60% of the total solar irradiance (TSI) variability occurs between 150 and 400 nm. 相似文献
8.
We investigate the periodicity in the PMOD composite of the daily total solar irradiance (TSI) from 21 September 1978 to 9 June
2009. Besides the Schwabe cycle period (10.32 years), the quasi-rotation period is found to be statistically significant in
TSI, whose value is about 32 days, longer than that in sunspot activity (27 days), and it intermittently appears around the
sunspot maximum times. The quasi-rotation period in TSI is inferred to be mainly caused by sunspot activity, but to be modulated
by bright features as well. It was previously found that variations of TSI over a Schwabe solar cycle mainly come from the
combination of the sunspots’ blocking and the intensification due to bright faculae, plages, and network elements, with a
slight dominance of the bright-feature effect during the maximum of the Schwabe cycle. For the sunspot-blocking and the bright-feature
effect to contribute to TSI over a Schwabe solar cycle, the former is inferred to lead the latter by 29 days at least. 相似文献
9.
The study of variations in total solar irradiance (TSI) and spectral irradiance is important for understanding how the Sun affects the Earth’s climate. A data-driven approach is used in this article to analyze and model the temporal variation of the TSI and Mg?ii index back to 1947. In both cases, observed data in the time interval of the satellite era, 1978?–?2013, were used for neural network (NN) model-design and testing. For this particular purpose, the evolution of the solar magnetic field is assumed to be the main driver for the day-to-day irradiance variability. First, we design a model for the Mg?ii index data from F10.7 cm solar radio-flux using the NN approach in the time span of 1978 through 2013. Results of Mg?ii index model were tested using various numbers of hidden nodes. The predicted values of the hidden layer with five nodes correspond well to the composite Mg?ii values. The model reproduces 94% of the variability in the composite Mg?ii index, including the secular decline between the 1996 and 2008 solar cycle minima. Finally, the extrapolation of the Mg?ii index was performed using the developed model from F10.7 cm back to 1947. Similarly, the NN model was designed for TSI variability study over the time span of the satellite era using data from the Physikalisch-Meteorologisches Observatorium Davos (PMOD) as a target, and solar activity indices as model inputs. This model was able to reproduce the daily irradiance variations with a correlation coefficient of 0.937 from sunspot and facular measurements in the time span of 1978?–?2013. Finally, the temporal variation of the TSI was analyzed using the designed NN model back to 1947 from the Photometric Sunspot Index (PSI) and the extrapolated Mg?ii index. The extrapolated TSI result indicates that the amplitudes of Solar Cycles 19 and 21 are closely comparable to each other, and Solar Cycle 20 appears to be of lower irradiance during its maximum. 相似文献
10.
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.
相似文献11.
George L. Withbroe 《Solar physics》2009,257(1):71-81
The daily images and magnetograms acquired by MDI are a rich source of information about the contributions of different types
of solar regions to variations in the total solar irradiance (TSI). These data have been used to determine the temporal variation
of the MDI irradiance, the mean intensity of the solar disk in the continuum at 676.8 nm. The short-term (days to weeks) variations
of the MDI irradiance and TSI are in excellent agreement with rms differences of 0.011%. This indicates that MDI irradiance
is an excellent proxy for short-term variations of TSI from the competing irradiance contributions of regions causing irradiance
increases, such as plages and bright network, and regions causing irradiance decreases, such as sunspots. However, the long-term
or solar cycle variation of the MDI proxy and TSI differ over the 11-year period studied. The results indicate that the primary
sources of the long-term (several months or more) variations in TSI are regions with magnetic fields between about 80 and
600 G. The results also suggest that the difference in the long-term variations of the MDI proxy and TSI is due to a component
of TSI associated with sectors of the solar spectrum where the contrast in intensity between plages and the quiet Sun is enhanced
(e.g., the UV) compared to the MDI proxy. This is evidence that the long-term variation of TSI is due primarily to solar cycle
variations of the irradiance from these portions of solar spectrum, a finding consistent with modeling calculations indicating
that approximately 60% of the change in TSI between solar minimum and maximum is produced by the UV part of the spectrum shortward
of 400 nm (Solanki and Krivova, Space Sci. Rev. 125, 53, 2006). 相似文献
12.
Gary Rottman Jerald Harder Juan Fontenla Thomas Woods Oran R. White George M. Lawrence 《Solar physics》2005,230(1-2):205-224
This paper presents and interprets observations obtained by the Spectral Irradiance Monitor (SIM) on the Solar Radiation and
Climate Experiment (SORCE) over a time period of several solar rotations during the declining phase of solar cycle 23. The
time series of visible and infrared (IR) bands clearly show significant wavelength dependence of these variations. At some
wavelengths the SIM measurements are qualitatively similar to the Mg II core-to-wing ratio, but in the visible and IR they show character similar to the Total Solar Irradiance (TSI) variations.
Despite this overall similarity, different amplitudes, phases, and temporal features are observed at various wavelengths.
The TSI can be explained as a complex sum of the various wavelength components. The SIM observations are interpreted with
the aid of solar images that exhibit a mixture of solar activity features. Qualitative analysis shows how the sunspots, faculae,
plage, and active network provide distinct contributions to the spectral irradiance at different wavelengths, and ultimately,
how these features combine to produce the observed TSI variations. Most of the observed variability appears to be qualitatively
explained by solar surface features related directly to the magnetic activity. 相似文献
13.
Roy Soumya Prasad Amrita Panja Subhash Chandra Ghosh Koushik Patra Sankar Narayan 《Solar System Research》2019,53(3):224-232
The radio frequency emission at 10.7 cm (or 2800 MHz) wavelength (considered as solar flux density) out of different possible wavelengths is usually selected to identify periodicities because of its high correlation with solar extreme ultraviolet radiation as well as its complete and long observational record other than sunspot related indices. The solar radio flux at 10.7 cm wavelength plays a very valuable role for forecasting the space weather because it is originated from lower corona and chromospheres region of the Sun. Also, solar radio flux is a magnificent indicator of major solar activity. Here in the present work the solar radio flux data from 1965 to 2014 observed at the Domimion Radio Astrophysical Observatory in Penticton, British Columbiahas been processed using Date Compensated Discrete Fourier Transform (DCDFT) to identify predominant periods within the data along with their confidence levels. Also, the multi-taper method (MTM) for periodicity analysis is used to validate the observed periods. Present investigation exhibits multiperiodicity of the time series F10.7 solar radio flux data around 27, 57, 78, 127, 157, 4096 days etc. The observed periods are also compared with the periods of MgII Index data using same algorithm as MgII Index data has 99.9% correlation with F10.7 Solar Radio Flux data. It can be observed that the MgII index data exhibits similar periodicities with very high confidence levels.Present investigation also clearly indicates that the computed results are very much confining with the results obtained in different communication for the similar data of 10.7 cm Solar Radio Flux as well as for the other solar activities.
相似文献14.
The Total Irradiance Monitor (TIM): Science Results 总被引：2，自引：0，他引：2
The solar observations from the Total Irradiance Monitor (TIM) are discussed since the SOlar Radiation and Climate Experiment
(SORCE) launch in January 2003. The TIM measurements clearly show the background disk-integrated solar oscillations of generally
less than 50 parts per million (ppm) amplitude over the ∼2 ppm instrument noise level. The total solar irradiance (TSI) from
the TIM is about 1361 W/m2, or 4–5 W/m2 lower than that measured by other current TSI instruments. This difference is not considered an instrument or calibration
error. Comparisons with other instruments show excellent agreement of solar variability on a relative scale. The TIM observed
the Sun during the extreme activity period extending from late October to early November 2003. During this period, the instrument
recorded both the largest short-term decrease in the 25-year TSI record and also the first definitive detection of a solar
flare in TSI, from which an integrated energy of roughly (6± 3)×1032 ergs from the 28 October 2003 X17 flare is estimated. The TIM has also recorded two planets transiting the Sun, although
only the Venus transit on 8 June 2004 was definitive. 相似文献
15.
Analyzing daily values of the total solar irradiance (TSI), the coronal index of solar activity (CI), and the Mg II 280-nm
core-to-wing ratio (Mg II index), we have found that the temporal variations of these indices are very similar to each other
during the period from 1978 to 2005. The correlation between CI and TSI, with the PSI correction lying within the interval
under study, has been found to be 0.699, which is very close to the value of 0.703 of the correlation between Mg II and TSI
for 27-day averages (the CI – Mg correlation is 0.824). The regression equation between CI and TSI is almost linear, except
for TSI depletions when a large number of sunspots are present on the visible disk. By employing CI, an extrapolation of TSI
back to 1947 is presented. 相似文献
16.
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
17.
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
18.
Variations in total solar irradiance (TSI) correlate well with changes in projected area of photospheric magnetic flux tubes
associated with dark sunspots and bright faculae in active regions and network. This correlation does not, however, rule out
possible TSI contributions from photospheric brightness inhomogeneities located outside flux tubes and spatially correlated with them. Previous reconstructions of TSI report agreement with radiometry that seems to rule out significant “extra-flux-tube” contributions.
We show that these reconstructions are more sensitive to the facular contrasts used than has been generally recognized. Measurements
with the Solar Bolometric Imager (SBI) provide the first reliable support for the relatively high, wide-band, disk-center
contrasts required to produce 10% rms agreement. Longer term bolometric imaging will be required to determine whether the
small but systematic TSI residuals we see here are caused by remaining errors in spot and facular areas and contrasts or by
extra-flux-tube brightness structures such as bright rings around sunspots or “convective stirring” around active regions. 相似文献
19.
A NOAA-11 SBUV/2 Mgii solar activity proxy index has been created for the period February 1989 through October 1994 from the daily discrete mode solar irradiance data using an algorithm that utilizes a thorough instrument characterization. This product represents a significant improvement over the previously released NOAA-11 SBUV/2 sweep mode-based Mgii data set. As measured by the NOAA-11 Mgii index, the amplitude of solar rotational activity declined from approximately 4–7% peak-to-peak near the maximum of solar cycle 22 in 1989–1991 to roughly 1% peak-to-peak by late-1994. Corresponding to this decrease, the 27-day averaged NOAA-11 Mgii index decreased by 5.8% over this period. The NOAA-11 Mgii data set is compared with coincident data sets from the UARS SOLSTICE and SUSIM instruments. The impact of differences in instrument resolution and observation platform are examined with respect to both the absolute value and temporal variations of the Mgii index. Periodograms of the three indexes demonstrate comparable solar variation tracking. Between October 1991 and October 1994 predominate power occurs near 27 days, with secondary maxima in the power spectra near 29 and 25 days. Overall, there is low power near 13.5 days during this period. Dynamic power spectral analysis reveals the quasi-periodic and quasi-stationary nature of the middle UV variations tracked by the Mgii index, and periods of significant power near 13.5 days in mid-1991 and late-1994 through mid-1995. 相似文献
20.
Ann T. Mecherikunnel 《Solar physics》1998,177(1-2):11-23
Simultaneous solar total irradiance observations performed by absolute radiometers on board satellites during the quiet-Sun period between solar cycles 21 and 22 (1985–1987), are analyzed to determine the solar total irradiance at 1 AU for the solar minimum. During the quiet-Sun period the total solar irradiance, UV irradiance, and the various solar activity indices show very little fluctuation. However, the absolute value of the solar total irradiance derived from the observations differ within the accuracy of the radiometers used in the measurements. Therefore, the question often arises about a reference value of the solar total irradiance for use in climate models and for computation of geophysical, and atmospheric parameters. This research is conducted as a part of the Solar Electromagnetic Radiation Study for Solar Cycle 22 (SOLERS22). On the basis of the study we recommended a reference value of 1367.0 ± 0.04 W m-2 for the solar total irradiance at 1 AU for a truly quiet Sun. We also find that the total solar irradiance data for the quiet-Sun period reveals strong short-term irradiance variations. 相似文献