Centennial Total Solar Irradiance Variation

Astronomy & Astrophysics, 2012

Astronomy & Astrophysics

Context. There is no consensus on the amplitude of historical solar forcing. The estimated magnitude of the total solar irradiance (TSI) difference between the Maunder minimum and the present time ranges from 0.1 to 6 W m−2 making the simulation of the past and future climate uncertain. One reason for this disagreement is the applied evolution of the quiet Sun brightness in solar irradiance reconstruction models. This work addresses the role of the quiet Sun model choice and updated solar magnetic activity proxies on the solar forcing reconstruction. Aims. We aim to establish a plausible range for the solar irradiance variability on decadal to millennial timescales. Methods. The spectral solar irradiance (SSI) is calculated as a weighted sum of the contributions from sunspot umbra, sunspot penumbra, faculae, and quiet Sun, which are pre-calculated with the NLTE Spectral SYnthesis code (NESSY). We introduce activity belts of the contributions from sunspots and faculae and a new struc...

Solar Physics, 1994

For more than a decade total solar irradiance has been monitored simultaneously from space by different satellites. The detection of total solar irradiance variations by satellite-based experiments during the past decade and a half has stimulated modeling efforts to help identify their causes and to provide estimates of irradiance data, using ‘proxy’ indicators of solar activity, for time intervals when no satellite observations exist. In this paper total solar irradiance observed by the Nimbus-7/ERB, SMM/ACRIM I, and UARS/ACRIM II radiometers is modeled with the Photometric Sunspot Index and the Mg II core-to-wing ratio. Since the formation of the Mg II line is very similar to that of the Ca II K line, the Mg core-to-wing ratio, derived from the irradiance observations of the Nimbus-7 and NOAA9 satellites, is used as a proxy for the bright magnetic elements. It is shown that the observed changes in total solar irradiance are underestimated by the proxy models at the time of maximum and during the beginning of the declining portion of solar cycle 22 similar to behavior just before the maximum of solar cycle 21. This disagreement between total irradiance observations and their model estimates is indicative of the fact that the underlying physical mechanism of the changes observed in the solar radiative output is not well-understood. Furthermore, the uncertainties in the proxy data used for irradiance modeling and the resulting limitation of the models should be taken into account, especially when the irradiance models are used for climatic studies.

Variability of the Total Solar Irradiance, 2021

Correlating the emissions of carbon dioxide (CO2) to the rapid increases in the measured average global temperature (AGT) anomaly does not confirm that the emissions of CO2 are the cause of the increasing AGT anomaly. The article, The Issue with Carbon Dioxide as the Primary Driver of Global Warming, Fiori, W., 2021, identifies CO2 as being the primary driver of biomass. It excludes CO2 from having the properties to drive global warming. Considering that the increasing AGT anomaly is not caused by the emissions of CO2, however, poses the question of what could be an alternative cause. The sun, the principle driver of earth's temperature and climate, emits an amount of irradiation, called the Total Solar Irradiance (TSI) that could be responsible for the rate of increase of the AGT as measured and assessed during the last 120 years. The suspicion that the sun could be the driver of the current rate of global warming is reinforced by the knowledge that the sun is known to exhibit short term periods when its TSI increases and decreases. This paper discusses the TSI and the manner that it applies when assessed in terms of the varying average global temperature during the last 610 million years. Turn points in the average global temperature are considered and the value for the TSI at a plateau of a turn point is determined. Average global temperature trends are shown to proceed at an average rate of +/-0.3W/m2 with infrequent higher rates of change. A conclusion reached is that the TSI is not the driver of the current rate of warming as measured.

Geophysical Research Letters, 2011

Advances in Space Research, 2002

Geophysical Research Letters, 1999

arXiv: Solar and Stellar Astrophysics, 2020

In this study we overview recent advances with prediction of solar activity using as a proxy solar background magnetic field and detection of grand solar cycles of about 400 years separated by grand solar minima (GSMs).The previous GSM known as the Maunder minimum was recorded from 1645 to 1715. The terrestrial temperature during Maunder Minimum was reduced by up to 1.0C that led to freezing rivers, cold winters and summers. The modern GSM started in 2020 and will last for three solar cycles until 2053. During this GSM two processes will affect the input of solar radiation: a decrease of solar activity and an increase in total solar irradiance because of solar inertial motion (SIM). For evaluation of the latter this study uses daily ephemeris of the Sun-Earth (SE) distances in two millennia from 600 to 2600 showing significant decreases of SE distances in the first 6 months of a year by 0.005 au in 600 to 1600 and by more than 0.01 au in 1600 to 2600 with consequent increases of SE ...

Love in South Asia: a cultural history, 2006