http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : Krivova N. A. (검색결과 26 건)
- 무료
- 기관 내 무료
- 유료
-
Solar total and spectral irradiance reconstruction over the last 9000 years
Wu, C.-J.,Krivova, N. A.,Solanki, S. K.,Usoskin, I. G. Springer-Verlag 2018 Astronomy and astrophysics Vol.620 No.-
<P><I>Context.</I> Changes in solar irradiance and in its spectral distribution are among the main natural drivers of the climate on Earth. However, irradiance measurements are only available for less than four decades, while assessment of solar influence on Earth requires much longer records.</P><P><I>Aims.</I> The aim of this work is to provide the most up-to-date physics-based reconstruction of the solar total and spectral irradiance (TSI/SSI) over the last nine millennia.</P><P><I>Methods.</I> The concentrations of the cosmogenic isotopes <SUP>14</SUP>C and <SUP>10</SUP>Be in natural archives have been converted to decadally averaged sunspot numbers through a chain of physics-based models. TSI and SSI are reconstructed with an updated SATIRE model. Reconstructions are carried out for each isotope record separately, as well as for their composite.</P><P><I>Results.</I> We present the first ever SSI reconstruction over the last 9000 years from the individual <SUP>14</SUP>C and <SUP>10</SUP>Be records as well as from their newest composite. The reconstruction employs physics-based models to describe the involved processes at each step of the procedure.</P><P><I>Conclusions.</I> Irradiance reconstructions based on two different cosmogenic isotope records, those of <SUP>14</SUP>C and <SUP>10</SUP>Be, agree well with each other in their long-term trends despite their different geochemical paths in the atmosphere of Earth. Over the last 9000 years, the reconstructed secular variability in TSI is of the order of 0.11%, or 1.5 W m<SUP>−2</SUP>. After the Maunder minimum, the reconstruction from the cosmogenic isotopes is consistent with that from the direct sunspot number observation. Furthermore, over the nineteenth century, the agreement of irradiance reconstructions using isotope records with the reconstruction from the sunspot number by Chatzistergos et al. (2017, A&A, 602, A69) is better than that with the reconstruction from the WDC-SILSO series (Clette et al. 2014, Space Sci. Rev., 186, 35), with a lower <I>χ</I><SUP>2</SUP>-value.</P>
-
Solar activity over nine millennia: A consistent multi-proxy reconstruction
Wu, C. J.,Usoskin, I. G.,Krivova, N.,Kovaltsov, G. A.,Baroni, M.,Bard, E.,Solanki, S. K. Springer-Verlag 2018 Astronomy and astrophysics Vol.615 No.-
<P><I>Aims.</I> The solar activity in the past millennia can only be reconstructed from cosmogenic radionuclide proxy records in terrestrial archives. However, because of the diversity of the proxy archives, it is difficult to build a homogeneous reconstruction. All previous studies were based on individual, sometimes statistically averaged, proxy datasets. Here we aim to provide a new consistent multi-proxy reconstruction of the solar activity over the last 9000 yr, using all available long-span datasets of <SUP>10</SUP>Be and <SUP>14</SUP>C in terrestrial archives.</P><P><I>Methods.</I> A new method, based on a Bayesian approach, was applied for the first time to solar activity reconstruction. A Monte Carlo search (using the <I>χ</I><SUP>2</SUP> statistic) for the most probable value of the modulation potential was performed to match data from different datasets for a given time. This provides a straightforward estimate of the related uncertainties. We used six <SUP>10</SUP>Be series of different lengths (from 500-10 000 yr) from Greenland and Antarctica, and the global <SUP>14</SUP>C production series. The <SUP>10</SUP>Be series were resampled to match wiggles related to the grand minima in the <SUP>14</SUP>C reference dataset. The stability of the long data series was tested.</P><P><I>Results.</I> The Greenland Ice-core Project (GRIP) and the Antarctic EDML (EPICA Dronning Maud Land) <SUP>10</SUP>Be series diverge from each other during the second half of the Holocene, while the <SUP>14</SUP>C series lies in between them. A likely reason for the discrepancy is the insufficiently precise beryllium transport and deposition model for Greenland, which leads to an undercorrection of the GRIP series for the geomagnetic shielding effect. A slow 6-7 millennia variability with lows at ca. 5500 BC and 1500 AD in the long-term evolution of solar activity is found. Two components of solar activity can be statistically distinguished: the main component, corresponding to the “normal” moderate level, and a component corresponding to grand minima. A possible existence of a component representing grand maxima is indicated, but it cannot be separated from the main component in a statistically significant manner.</P><P><I>Conclusions.</I> A new consistent reconstruction of solar activity over the last nine millennia is presented with the most probable values of decadal sunspot numbers and their realistic uncertainties. Independent components of solar activity corresponding to the main moderate activity and the grand-minimum state are identified; they may be related to different operation modes of the dynamo.</P>
-
Recent variability of the solar spectral irradiance and its impact on climate modelling
Ermolli, I.,Matthes, K.,Dudok de Wit, T.,Krivova, N. A.,Tourpali, K.,Weber, M.,Unruh, Y. C.,Gray, L.,Langematz, U.,Pilewskie, P.,Rozanov, E.,Schmutz, W.,Shapiro, A.,Solanki, S. K.,Woods, T. N. Copernicus GmbH 2013 Atmospheric chemistry and physics Vol.13 No.8
<P>Abstract. The lack of long and reliable time series of solar spectral irradiance (SSI) measurements makes an accurate quantification of solar contributions to recent climate change difficult. Whereas earlier SSI observations and models provided a qualitatively consistent picture of the SSI variability, recent measurements by the SORCE (SOlar Radiation and Climate Experiment) satellite suggest a significantly stronger variability in the ultraviolet (UV) spectral range and changes in the visible and near-infrared (NIR) bands in anti-phase with the solar cycle. A number of recent chemistry-climate model (CCM) simulations have shown that this might have significant implications on the Earth's atmosphere. Motivated by these results, we summarize here our current knowledge of SSI variability and its impact on Earth's climate. We present a detailed overview of existing SSI measurements and provide thorough comparison of models available to date. SSI changes influence the Earth's atmosphere, both directly, through changes in shortwave (SW) heating and therefore, temperature and ozone distributions in the stratosphere, and indirectly, through dynamical feedbacks. We investigate these direct and indirect effects using several state-of-the art CCM simulations forced with measured and modelled SSI changes. A unique asset of this study is the use of a common comprehensive approach for an issue that is usually addressed separately by different communities. We show that the SORCE measurements are difficult to reconcile with earlier observations and with SSI models. Of the five SSI models discussed here, specifically NRLSSI (Naval Research Laboratory Solar Spectral Irradiance), SATIRE-S (Spectral And Total Irradiance REconstructions for the Satellite era), COSI (COde for Solar Irradiance), SRPM (Solar Radiation Physical Modelling), and OAR (Osservatorio Astronomico di Roma), only one shows a behaviour of the UV and visible irradiance qualitatively resembling that of the recent SORCE measurements. However, the integral of the SSI computed with this model over the entire spectral range does not reproduce the measured cyclical changes of the total solar irradiance, which is an essential requisite for realistic evaluations of solar effects on the Earth's climate in CCMs. We show that within the range provided by the recent SSI observations and semi-empirical models discussed here, the NRLSSI model and SORCE observations represent the lower and upper limits in the magnitude of the SSI solar cycle variation. The results of the CCM simulations, forced with the SSI solar cycle variations estimated from the NRLSSI model and from SORCE measurements, show that the direct solar response in the stratosphere is larger for the SORCE than for the NRLSSI data. Correspondingly, larger UV forcing also leads to a larger surface response. Finally, we discuss the reliability of the available data and we propose additional coordinated work, first to build composite SSI data sets out of scattered observations and to refine current SSI models, and second, to run coordinated CCM experiments. </P>
-
-
-
-
-
Yeo, K. L.,Krivova, N. A.,Solanki, S. K.,Glassmeier, K. H. EDP Sciences 2014 Astronomy and astrophysics Vol.570 No.-
<P>Context. Total and spectral solar irradiance are key parameters in the assessment of solar influence on changes in the Earth’s climate. Aims. We present a reconstruction of daily solar irradiance obtained using the SATIRE-S model spanning 1974 to 2013 based on full-disc observations from the KPVT, SoHO/MDI, and SDO/HMI. Methods. SATIRE-S ascribes variation in solar irradiance on timescales greater than a day to photospheric magnetism. The solar spectrum is reconstructed from the apparent surface coverage of bright magnetic features and sunspots in the daily data using the modelled intensity spectra of these magnetic structures. We cross-calibrated the various data sets, harmonizing the model input so as to yield a single consistent time series as the output. Results. The model replicates 92% (R,<SUP>2</SUP> = 0.916) of the variability in the PMODTSI composite including the secular decline between the 1996 and 2008 solar cycle minima. The model also reproduces most of the variability in observed Lyman-α irradiance and the MgII index. The ultraviolet solar irradiance measurements from the UARS and SORCE missions are mutually consistent up to about 180 nm before they start to exhibit discrepant rotational and cyclical variability, indicative of unresolved instrumental effects. As a result, the agreement between model and measurement, while relatively good below 180 nm, starts to deteriorate above this wavelength. As with earlier similar investigations, the reconstruction cannot reproduce the overall trends in SORCE/SIM SSI. We argue, from the lack of clear solar cycle modulation in the SIM record and the inconsistency between the total flux recorded by the instrument and TSI, that unaccounted instrumental trends are present. Conclusions. The daily solar irradiance time series is consistent with observations from multiple sources, demonstrating its validity and utility for climate models. It also provides further evidence that photospheric magnetism is the prime driver of variation in solar irradiance on timescales greater than a day.</P>
-
-
연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
