Study Of Oscillations In Solar – Terrestrial Variables Associated To Magnetic Flux Emergence
The aim of this research is to track a fundamental oscillation in the solar activity, through the global earth temperature and geomagnetic storms sudden commencement SSC ( as solar -terrestrial link), and the geomagnetic index aa, and its temporal evolution. Also, the chaotic changes of the solar dynamo levels are analized in the terrestrial variables. The cited oscillation is associated to magnetic flux emergence, that is in turn a link between solar activity and space – earth weather. Hence, the monitoring of these signals can be a usefull tool in the terrestrial parameters forecast. In this work we show the results of the multiresolved wavelet analysis of oscillations with periods in the 100 to 1000 days range in the sunspot areas, solar number Rz, SSC index, earth average temperature Tav and geomagnetic index aa, for the solar cycles 19 to the cycle 24 beginning. I have discovered the excitation of submodes of the 160 days wave in all the solar cycles considered. This wave set also appears with a corresponding lags in the terrestrial variables. The relative intensity of normalized harmonics is analyzed, since it could be a important clue to understand the evolution of this plasma wave. From a chaotic increase in the solar activity level ocurred during 1920 to 1930, the 160 days wave is excited, and the process that drives to cascades of energy flares begins, as those starting from the cycle 19, that affect the terrestrial space climate drastically. It is found that the amplitude of the terrestrial variables change together, affected by the increasing switch in the solar dynamo process. An existing model that correlates the SSC index and Tav is tested and modified for cycle 23 and the start of 24. This approach explains almost the 75 percent of variations of global earth temperature. A general discussion of several founded correlations is made. http://www.espaciotiempo.org
Influence of the solar cycle on the Quasi-Biennial Oscillation period
From the 1960s to the early 90s, the westerly phase of the Quasi-Biennial Oscillation (QBO) was observed to have a longer period during the solar minima [Salby and Callaghan, 2000]. During the same period, the stratosphere was contaminated by volcanic aerosols. For the two solar cycles before and after this interval, the QBO period exhibited the opposite behavior. To determine the true dependence of the QBO period on the solar cycle in the absence of volcanic aerosols, we performed an 82-year model simulation of the QBO using a two- and-a-half-dimension model. Analysis of the model simulation indicates a positive correlation between the QBO period and the solar flux. Above 30 hPa, the easterly phase QBO duration increases more rapidly with solar flux than that of the westerly phase. However, below 50 hPa the westerly QBO duration increases faster. The mechanism for these changes is discussed.
Suggested Physics Between Cosmic Ray Flux and Regional Hydroclimate
The effects of solar variability on regional hyroclimate were examined using a sequence of physical connections between total solar irradiance (TSI) modulated by galactic cosmic rays (GCRs), and ocean and atmospheric patterns that affect precipitation and streamflow. The solar energy reaching the Earth's surface and its oceans is thought to be controlled through an interaction between GCRs, which are known to ionize the atmosphere and increase cloud formation, and TSI. High (low) GCR flux may promote cloudiness (clear skies) and higher (lower) albedo at the same time that TSI is lowest (highest) in the solar cycle which in turn creates cooler (warmer) ocean temperature anomalies. These anomalies have been shown to affect atmospheric flow patterns and ultimately precipitation over the Midwestern United States. This investigation identified a relation among TSI and geomagnetic index aa (GI-AA), and streamflow in the Mississippi River Basin for the period 1878-2004. The GI-AA was used as a proxy for GCRs. There appears to be a solar "fingerprint" that can be seen in climatic time series in other regions of the world, with each series having a unique lag time between the solar signal and the hydroclimatic response. A progression of increasing lag times can be spatially linked to the ocean conveyor belt, which transports the solar signal over a time span of several decades. The lag times for any one region vary slightly and may be linked to the fluctuations in the velocity of the ocean conveyor belt. The lag time between the solar signal and streamflow in the Mississippi River at St. Louis, Missouri, is approximately 34 years. The current drought (1999-2006) in the Mississippi River Basin appears to be caused by a period of lower solar activity that occurred between 1963 and 1977.
Variation of Atmospheric Heating Rates Derived from SORCE Solar Spectra and the SRPM Model
Measurements from the SOLSTICE and SIM instruments on board the Solar Radiation and Climate Experiment (SORCE) cover the 200-2400 nm region and span a time frame from August 2003 to the present and are able to characterize the solar spectral irradiance variability during the descending phase of Solar Cycle 23. Because absorption and scattering processes in the Earth's atmosphere are highly spectrally dependent, the spectral distribution and variability of the Sun's radiative energy is an important boundary condition for quantifying Earth's radiation budget as well as the vertical deposition of solar radiation in the atmosphere. The SORCE observations allow for the very first time the derivation of spectral atmospheric heating rates from measured spectral variability. The variability in spectral irradiance exhibited in the plage- versus sunspot-dominated cases leads to significant differences in atmospheric heating compared to the Quiet Sun, particularly evident in the mid-visible ozone Chappuis continuum and in the near infrared water bands. When integrated over the visible and near-infrared spectral bands these differences are on the order of 0.1 K per day. The findings from the SORCE observations and results derived from Solar Radiation Physical Modeling (SRPM) project will be presented in this study.
Solar Cycle Dependence of Solar UV Irradiance
For the past 30 years during solar cycles 21, 22, and 23, the solar ultraviolet (UV) spectral irradiance has been measured by a series of several long-term space-based experiments, including the NOAA SBUV/SBUV2 series, the UARS experiments (SOLSTICE and SUSIM), and the instruments aboard SORCE. Accurate, absolutely calibrated spectral irradiances can be difficult to obtain from these daily measurements because the changing optical characteristics of measuring instruments are often uncertain, especially over the long-term. Accordingly, the resulting UV irradiance data can sometimes contain unwanted instrumental trends. These solar UV irradiance time series are dominated by two periodicities: solar rotation (~27 days) and solar activity (~11 years). They have also been shown to correlate very well with indices of solar activity, particularly the Mg~II core-to-wing ratio. The relative variation of the solar UV ranges from nearly a factor of two at Ly-α, about 10% at 200nm, to less than 1% above 320 nm. For the long wavelength portion of the UV spectrum, above about 263~nm, the long-term accuracy is typically comparable to the solar cycle variation. However, because the level of UV irradiance increases strongly with wavelength, most of the variation in total UV irradiance is provided by wavelengths above 250~nm. Using the latest versions of the various solar UV irradiance time series, the level of agreement of the relative changes of the various data sets is examined. From this, an assessment may be made as to the accuracy of the irradiances which is compared with the reported uncertainties. Using the correspondence with the solar Mg~II index, the solar cycle variation based on the available maximum to minimum or minimum to maximum transitions is analyzed to reveal differences among the three solar cycles.
Do Photospheric Brightness Structures Outside Magnetic Flux Tubes Contribute to Solar Luminosity Variation?
Variations in total solar irradiance (TSI) correlate well with changes in projected area of photospheric magnetic flux tubes associated with spots, faculae 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 report 10% amplitude agreement with radiometry that seems to rule out significant extra-flux tube contributions. We show that, while these reconstructions are insensitive to behavior of near- limb facular contrast, their sensitivity to contrasts on the disc is relatively high. Given this sensitivity, previously used observational and theoretical approximations to wide-band facular contrast are too uncertain to support claims of 10% reconstruction accuracy. Recent measurements with the Solar Bolometric Imager (SBI) provide the first observational support for the relatively high wide-band, disc-center contrasts required to produce 10% rms agreement. Longer-term bolometric imaging to measure areas and bolometric contrasts homogeneously will be required to determine whether the systematic TSI residuals we see are caused mainly by uncertainties in sunspot contrasts, or by extra-flux tube brightness structures due to bright spot rings or convective stirring. http://sd-www.jhuapl.edu/SBI/
The Belgian DIARAD Total Solar Irradiance Observations, Historical Objectives, Achievements and Particularities.
The origin of the Total Solar Irradiance (TSI) observations at the Royal Meteorological Institute of Belgium is the will to monitor the Earth Radiation Budget (ERB) whereoff the TSI is one of the terms, the two others are the reflected solar radiation and the Earth emitted radiation actually measured operationnaly by the Geostationnary Earth Radiation Budget (GERB) experiment on board of EUMETSAT MSG. This concerns atmospheric physics as well as climate. The new design of a differential absolute radiometer (DIARAD) characterised in air as well as in vacuum, led to its incorporation in the set of instruments defining the World Radiometric Reference (WRR); adapted for space, it flew repetitively on the space shuttle as well as on the european retrievable carrier (EURECA). Since 1996 DIARAD operates contineously without any failure from VIRGO on SOHO. Our strategic principles required to insure a long range high quality TSI data base are developed . It incorporates the usage of Space Absolute Radiometric Reference (SARR) coefficients to normalise the observations in time. The compared characteristics of DIARAD and PMO instruments are presented as well as the chronological events and behaviours of the radiometers flying on VIRGO/SOHO. It is concluded that a minimum of three simultaneous flying radiometers are required to guarantee the value of the TSI data base. http://remotesensing.oma.be
Total Solar Irradiance Modelling during cycle 23
During solar cycle 23, which is now close to its end, the variations of the Total Solar Irradiance were determined by 3 composites time series: the RMIB, ACRIM and PMOD composites. An independent analysis of the different composites is performed through an empirical proxy model fit. The RMIB composite is fitted with 0.96 correlation and RMS error of 0.15 W m-2 reaching therefore the limit of individual instruments stabilities. Both the measurements and the model indicate that for the current cycle the minimum irradiance level has not been reached yet. 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.
Spectral Decomposition of the TSI Record Using the SORCE TIM and SIM Instruments
The SORCE SIM and TIM instruments have been making concurrent measurements of the total and spectral solar irradiance (TSI and SSI, respectively) since August 2003 up to the present solar minimum time frame. The SIM instrument measures spectral irradiance in the 200-2400 nm region covering 97.6 percent of the TSI with a resolving power ranging from 280 in the near UV to a minimum of 37 at 1260 nm. With this full spectral coverage, the spectral irradiance time series can be integrated into sub-ranges and compared to the TSI record, showing that different spectral regions provide different components to the total record with some offsetting long-term trends. The SIM SSI record also provides excellent information that is used to study the wavelength dependent components of solar variability models and input for studies of Earth atmospheric heating.
Solar Spectral Irradiance Variability in the Near Infrared and Correlations to the Variability of Total Solar Irradiance During the Declining Phase of Solar Cycle 23
The Spectral Irradiance Monitor (SIM) as part of the NASA EOS SORCE mission continuously monitors the solar spectral irradiance (SSI) across the wavelength region spanning the ultraviolet, visible and near infrared (a region encompassing >97% of the TSI measured by the SORCE Total Irradiance Monitor, TIM). These are the first daily measurements from space with the required precision to detect real changes in SSI. The record of TSI measured from space tracks changes in solar total energy output and establishes the baseline for energy input for the Earth. Where this radiative energy is deposited into the Earth system, how the climate responds to solar variability, and the mechanisms of climate response, are determined by how the incident solar radiation is distributed with wavelength, the SSI. For the near IR region in particular, spectral decomposition of the TSI variability provides TOA constraints on the direct input for atmospheric heating simulations. We present here the first long-term, continuous measurements of the near infrared variability of solar spectral irradiance and establish quantitative correlations of near infrared variability across the spectral region of the solar H minus opacity minimum with TSI variability. The unprecedented precision of the SIM near-infrared measurements provide a direct determination of the wavelength dependence of the facular and sunspot contrasts and serve to refine solar atmospheric models of the solar magnetic features that produce irradiance variability in emission from the deepest photospheric layers.
How important are PMOD and ACRIM TSI satellite composites for the global warming debate?
We discuss the climate consequences of PMOD and ACRIM TSI satellite composite (1978-2006). PMOD shows a slight negative linear trend during the last three decades, while ACRIM shows a more complex 22-year cyclical trend: the average TSI value during solar cycle 22-23 (1991-2002) is higher than both averages during solar cycle 21-22 (1980-1991) and solar cycle (2002-2013) by approximately 0.5 W/m2. Several phenomenological studies have found that the 11-year solar cycle induces a global surface temperature cycle with a peak-to-trough amplitude of about 0.1K , which is about three times larger than climate model predictions. Also, the thermal inertia of the climate system has a characteristic time of about τ=5-15 years. We show that under these thermodynamic circumstances the trend of the climate signature of these two composites strongly depends on the behavior of the TSI during the entire 20th century. By using different recent reconstruction of past solar activity we show that ACRIM would cause a global warming, while PMOD could both cause a warming or a cooling according to the value of the characteristic time response of the climate adopted in the simulations.
(No?) Century-scale Secular Variation in HMF, EUV, or TSI
Recent work suggests that the Heliospheric Magnetic Field (HMF) strength, B, at each sunspot minimum varies but little (less than a nT). The variation of B within a solar cycle seems to be due to extra (and likely closed) magnetic flux added by Coronal Mass Ejections (CMEs) riding on top of a "floor" of somewhere between 4 and 5 nT, leading to the conclusion that the open magnetic flux is nearly constant with time, and that, in particular, there is no secular variation of the open flux. B inferred from geomagnetic data back to the 1840s further support this conclusion. In fact, B for the current cycle 23 matches well B for cycle 13, 107 years earlier. The amplitude rY of the diurnal variation of the geomagnetic Y-component is an excellent proxy for the F10.7 radio flux and thus also for the EUV flux (more precisely, the FUV, as the Sq current flows in the E layer). As for the HMF there seems to be a "floor" in rY and hence in F10.7 and hence in the FUV flux, thus the geomagnetic evidence is that there has been no secular change in the background solar minimum EUV (FUV) flux in the past 165 years. Direct measurements (although beset by calibration problems) of the Total Solar Irradiance (TSI) from satellites have only been available for 30 years and indicate that solar irradiance increases with solar activity. Correlating mean annual TSI and sunspot numbers allows one to estimate the part of TSI that varies with the sunspot number. If TSI only depends linearly on the sunspot number then irradiance levels during the Maunder Minimum would be similar to the levels of current solar minima. But TSI is a delicate balance between sunspot darkening and facular brightening, and although both of these increase (in opposite directions) with increasing solar activity, it is not a given that there could not be secular variations in the relative importance of these competing effects. Reconstructions of TSI, all postulate a source of long-term irradiance variability on centennial time scales. Each group of researchers have their own preferred additional source of changes of the "background" TSI, such as evidence from geomagnetic activity, open magnetic flux, ephemeral region occurrence, umbral/penumbral ratios, and the like. The existence of "floors" in HMF and FUV over ~1.6 centuries argues for a lack of secular variations of these parameters on that time scale. I would suggest that the lack of such secular variation undermines the circumstantial evidence for a "hidden" source of irradiance variability and that there therefore also might be a floor in TSI, such that TSI during Grand Minima would simply be that observed at current solar minima. This obviously has implications for solar forcing of terrestrial climate.