Galactic cosmic rays are one of the possible mediators of the solar influence on climate. However, the impacts of GCR on clouds and climate systems are not fully understood. In this paper, we show ...that the high-altitude clouds associated with deep convective activities are responding to the decadal-scale cycles of GCRs and that the susceptible areas are seasonally variable. Most notable responses were found in August over tropical land areas, suggesting that the susceptivity of clouds to GCRs depends on the depth of convective activities and the abundance of aerosol precursor materials. Furthermore, following the activation of high-altitude cloud formation, an increase in sea surface temperature (SST) gradient was observed over the Pacific. Although the response of sea surface temperature to solar activity has mostly been discussed as mediated by solar radiations, we propose that another mechanism is possible: through the impact of GCRs on clouds and the resultant changes in atmospheric circulations.
Abstract
Records of observations of sunspots and auroras in pre-telescopic historical documents provide useful information about past solar activity both in long-term trends and short-term space ...weather events. In this study, we present the results of a comprehensive survey of the records of sunspots and aurora candidates in the Yuánshĭ and Míngshĭ, Chinese Official Histories spanning 1261–1368 and 1368–1644, based on continuous observations with well-formatted reportds conducted by contemporary professional astronomers. We then provide a brief comparison of these data with Total Solar Irradiance (TSI) as an indicator of the solar activity during the corresponding periods to show significant active phases between the 1350s–80s and 1610s–30s. We then compared the former with contemporary Russian reports concerning naked-eye sunspots and the latter with contemporary sunspot drawings based on Western telescopic observations. Especially some of the latter are consistent with nitrate signals preserved in ice cores. These results show us some insights on and beyond minima and maxima of solar activity during the 13th–17th centuries.
Abstract
We present the result of a survey of sunspots and auroras in Qíngshǐgǎo (清史稿), a draft chronicle of Qíng dynasty, for the period of 1559–1912 CE. This is a sequel to a series of works ...surveying historical sunspot and aurora records, and providing online data to the scientific community regarding the attained results. In total of this Qíngshǐgǎo survey, we found 111 records of night-sky luminous events with such keywords as vapor (氣, qì), cloud (雲, yún), and light (光, guāng), which may indicate auroras as well as some other phenomena. Similarly, a keyword survey for sunspots was conducted, but no sunspot record was found. In comparison with the aurora records in the western world, we found that 14 of the 111 records have a corresponding record of simultaneous observation in the western world, and hence are very likely to be aurora. In order to investigate the likeliness of the remainder of the record being aurora, we calculated the lunar age and the phase of a solar cycle for each record. After these calculations, a notable fraction of these records clustered near the full moon were to be found statistically doubtful in considerations with atmospheric optics; meanwhile, a few records of observations near the new moon could be more likely interpreted as being auroras, including three records during the Maunder minimum.
A solar rotational period of approximately 27 days has been detected in cloud and lightning activities, although the mechanism of the sun–climate connection remains unclear. In previous studies, ...lightning activity in Japan showed a significant signal of the solar rotational period, especially around the maxima of the decadal solar cycles. Here we analyze the time series of lightning activity in the AD 1668–1767 period, extracted from old diaries in Kyoto, Japan, and search for the signal of solar rotational cycles. The 27-day cycles were detected in the lightning data and occurred only around the maxima of the decadal sunspot cycles. The signal disappeared during AD 1668–1715, which corresponds to the latter half of the Maunder Minimum when both radiative and magnetic disturbances were thought to have been weak. These findings provide insight into the connection between solar activity and the Earth's climate.
The spring Arctic Oscillation (AO) significantly affects the subsequent summer rainfall in the East Asian summer monsoon (EASM) region, and analysis of meteorological data indicates this ...teleconnection strength varied on interdecadal timescales during the late 20th century. Tree‐ring records may be able to extend the relatively short observational record, but the extent to which these proxy reconstructions correspond to AO variability has yet to be explored in this region. Therefore, we present new tree‐ring cellulose oxygen isotope (δ18O) records from northeastern Japan (Akita, northern limit of EASM), spanning a.d. 1950 to 2003 which overlaps with the instrumental record. Tree‐ring δ18O is used for reconstructing the past hydroclimate variability and allows us to consider whether tree‐ring δ18O has the potential to clarify the longer‐term interdecadal changes in the spring AO‐EASM relationship. Measurements and analyses show that our tree‐ring δ18O data sets have a significant negative correlation with May‐June‐July relative humidity, and the tree‐ring δ18O in northeastern Japan also significantly correlates with the summer EASM index. Temporal comparisons between our record and observed monthly AO index indicate that reconstructed following early summer relative humidity significantly correlates to the previous March‐April‐May AO. This linkage changes on interdecadal timescales, and the linkage is relatively strong during early 1970s through early 1990s. Similar results are also obtained using a separate tree‐ring δ18O record from a separate location about 200 km to the southeast, suggesting that tree‐ring cellulose δ18O in northeastern Japan is indeed useful for better understanding the long‐term teleconnection between the spring AO and EASM.
Key Points
New tree‐ring cellulose oxygen isotope chronologies in northeastern Japan are reported
Tree‐ring oxygen isotope record significantly correlates to the Spring Arctic Oscillation
Tree‐ring cellulose oxygen isotope in northeastern Japan can be applied to better understand the long‐term spring AO‐EASM relationship
The linkage between multi-decadal climate variability and activity of the sun has been long debated based upon observational evidence from a large number of instrumental and proxy records. It is ...difficult to evaluate the exact role of each of solar parameters on climate change since instrumentally measured solar related parameters such as Total Solar irradiance (TSI), Ultra Violet (UV), solar wind and Galactic Cosmic Rays (GCRs) fluxes are more or less synchronized and only extend back for several decades. Here we report tree-ring carbon-14 based record of 11-year/22-year solar cycles during the Maunder Minimum (17th century) and the early Medieval Maximum Period (9–10th century) to reconstruct the state of the sun and the flux of incoming GCRs. The result strongly indicates that the influence of solar cycles on climate is persistent beyond the period after instrumental observations were initiated. We find that the actual lengths of solar cycles vary depending on the status of long-term solar activity, and that periodicity of the surface air temperatures are also changing synchronously. Temperature variations over the 22-year cycles seem, in general, to be more significant than those associated with the 11-year cycles and in particular around the grand solar minima such as the Maunder Minimum (1645–1715 AD). The polarity dependence of cooling events found in this study suggests that the GCRs can not be excluded from the possible drivers of decadal to multi-decadal climate change.
The aim of this study was to elucidate the effect of fish-oil-derived monounsaturated fatty acids (MUFAs) containing large amounts of C20:1 and C22:1 isomers on metabolic disorders in mice. Male ...C57BL/6J mice were fed a 32% lard diet (control) or a 27% lard plus 5% saury-oil-derived MUFA diet for 6 weeks. Dietary MUFA improved insulin resistance and alleviated metabolic syndrome risk factors by reducing blood glucose and lipids. These favorable changes may be attributed to an improved adipocytokine profile. MUFA ingestion resulted in favorable changes in mRNA expression of genes involved in glucose/lipid metabolism (SCD-1, CPT1a, UCPs, and CS) as well as inflammation (MAC1, MMP3, and SAA3) and alterations in fatty acid composition. Our data suggest that marine MUFA improved glucose/lipid homeostasis and hindered the development of metabolic syndrome in obese mice.
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