Vector magnetograms taken at Huairou Solar Observing Station (HSOS) and Mees Solar Observatory (MSO) reveal that the super
active region (AR) NOAA 10486 was a complex region containing current helicity flux of opposite signs. The main positive sunspots
were dominated by negative helicity fields, while positive helicity patches persisted both inside and around the main positive
sunspots. Based on a comparison of two days of deduced current helicity density, pronounced changes associated with the occurrence
of an X10 flare that peaked at 20:49 UT on 29 October 2003 were noticed. The average current helicity density (negative) of
the main sunspots decreased significantly by about 50%. Accordingly, the helicity densities of counter-helical patches (positive)
were also found to decay by the same proportion or more. In addition, two hard X-ray (HXR) “footpoints” were observed by the
Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) during the flare in the 50 – 100 keV energy range. The cores
of these two HXR footpoints were adjacent to the positions of two patches with positive current helicity that disappeared
after the flare. This strongly suggested that the X10 flare on 29 October 2003 resulted from reconnection between magnetic
flux tubes having opposite current helicity. Finally, the global decrease of current helicity in AR 10486 by ∼50% can be understood
as the helicity launched away by the halo coronal mass ejection (CME) associated with the X10 flare.
Electronic Supplementary Material The online version of this article () contains supplementary material, which is available to authorized users. 相似文献
Urban agglomeration is caused by the continuous acceleration of the urbanization process in China. Studying the expansion of construction land can not only know the changes and development of urban agglomeration in time, but also obtain the great significance of the future management. In this study, taking Changsha-Zhuzhou-Xiangtan (Chang-Zhu-Tan) urban agglomeration in Hunan province as a study area, Landsat images from 1995 to 2014 and Autologistic-CLUE-S model simulation data were used. Moreover, several factors including gravity center, direction, distance and landscape index were considered in the analysis of the expansion. The results revealed that the construction area increased by 132.18%, from 372.28 km2 in 1995 to 864.37 km2 in 2014. And it might even reach 1327.23 km2 in 2023. Before 2014, three cities had their own respective and discrete development directions. However, because of the integration policy implementation in 2008, the Chang-Zhu-Tan began to gather, the gravity center moved southward after 2014, and the distance between cities decreased, which was in line with the development plan of urban expansion. The research methods and results were relatively reliable, and these results could provide some reference for the future land use planning and spatial allocation in the urbanization process of Chang-Zhu-Tan urban agglomeration.
After the earthquake (Ms = 6.1) occurred in Luquan county of Yunnan province on April 18, 1985, the relationship between major
earthquakes and astronomical time-latitude residuals (ATLR) of a photoelectric astrolabe in Yunnan Observatory was analyzed.
ATLR are the rest after deducting the effects of Earth’s whole motion from the observations of time and latitude. It was found
that there appeared the anomalies of the ATLR before earthquakes which happened in and around Yunnan, a seismic active region.
The reason of the anomalies is possibly from change of the plumb line due to the motion of the groundmass before earthquakes.
Afterwards, using studies of the anomalous characters and laws of ATLR, we tried to provide the warning information prior
to the occurrence of a few major earthquakes in the region. The significant synchronous anomalies of ATLR of the observatory
appeared before the earthquake of magnitude 6.2 in Dayao county of Yunnan province, on July 21, 2003. It has been again verified
that the anomalies possibly provide the prediction information for strong earthquakes around the observatory. 相似文献
We made model fitting to the mid-to-far infrared spectral energy distributions (SEDs) for different categories of galaxies in the main extragalactic field of the Spitzer First Look Survey with the aid of spectroscopic information from the Sloan Digital Sky Survey. We find that the mid-to-far infrared SEDs of HII galaxies, mixture type galaxies and LINERs can be well fitted by the one-parameter (α) dust model of Dale et al. plus the 13 Gyr dust-free elliptical galaxy model. The statistics of α values indicates that all these galaxies tend to be quiescent, although the HII galaxies are relatively more active than the LINERs. The mid- infrared SEDs of absorption galaxies are well fitted simply by the 13 Gyr dust-free elliptical galaxy template, and the near-to-mid infrared SEDs of QSOs can be represented by AGN NGC 5506. 相似文献
Land-cover change significantly influences hydrologic processes at the watershed level. The mountainous Duoyingping watershed in upstream Yangtze River, China, has undergone dramatic land-cover change in the past three decades. It is likely to maintain this trend in the future, inevitably altering hydrologic processes in the region to a certain degree. Therefore, the effects of land-cover change on runoff, evapotranspiration (ET), and soil moisture in the watershed were assessed using a large-scale Variable Infiltration Capacity (VIC) hydrologic model.To minimize the effect of climate change on simulation results, we used detrended climate data over the period 1980–2005 in forcing the VIC model. The dynamics in the spatial distribution of land-cover types in the Duoyingping watershed from 1980 to 2000 were first examined, revealing that reforestation and deforestation were the major change patterns. On the basis of various land-use policies, potential land-cover scenarios for 2030 were established using an integrated land-use change model (CLUE-S). The scenarios were developed using 2000 land-use data as bases. Finally, the calibrated VIC model was applied in the scenarios to assess land-cover effects on hydrology. Hydrologic simulations showed that the effects of historical land-cover change on hydrology were discernible in the sub-watersheds of Nanba, Yingjing, and Yuxi. The annual ET was projected to decrease by 0.8–22.3% because of deforestation, and increase by 2.3–27.4% because of shrubland–forest conversion. Different potential land-cover scenarios play various roles in the effect on hydrology because of various land-use policies. In the scenario concerning forest protection policy, annual ET increased by more than 15%, while annual runoff decreased by 6%. However, a negligible effect on hydrology was found under the scenario involving cropland expansion. On the basis of the results, it is concluded that ET is more sensitive to land-cover change than are other hydrologic components. Hydrologic alteration caused by reforestation and deforestation during the dry season was more significant than that during wet season. Generally, the proposed approach in the study can be a useful means of assessing hydrologic responses to land-cover change. 相似文献
Using photospheric vector magnetograms of the Huairou Solar Observing Station and coronal X-ray images from the Yohkoh Soft X-Ray Telescope, we calculate the helicity patterns of 43 pairs of active regions and the chirality of 50 pairs of opposite
magnetic polarity regions that are connected by transequatorial loops (TLs). To make the results more convincing, two helicity
proxies including the local current helicity hc and the force-free factor αbest are computed. The results, which are similar for both parameters, are as follows: (1) Current helicity of the active regions
pairs connected by transequatorial loops have no obvious regularity: About 50% of the active region pairs carry the same current
helicity sign and about 50% of them have the opposite. (2) If we consider the magnetic polarity pairs connected by the TLs,
the result is almost the same as that for the active region pairs, with a little more than half of them showing the same chirality.
We also make linear force-free extrapolations for 33 TLs and determine their force-free parameter α by comparing extrapolated field lines to X-ray images of the TLs. Out of the 19 cases when the footpoints of the TLs have
the same current helicity sign, we find that the sign of α of the TLs is the same as the sign of the current helicity in the footpoints in 12 cases, whereas it is of opposite sign
in 4 cases, and in 3 cases the TLs were found to be potential. 相似文献
Because of complexity and diversity of toxicants in effluent, chemical analysis alone gives very limited information on identifying toxic chemicals to test organisms. Toxicity identification evaluation (TIE) techniques have been widely used to identify toxicants in various samples including industrial wastewater as well as natural waters. In response to new regulation for effluent discharge in Korea, which will be effective from 2011, a necessity of studies emerges that investigates toxicity levels in industrial effluents. This work was a preliminary study examining toxicity levels in effluent from one metal plating factory using Daphnia magna (48 h immobility) and identifying toxicity-causing substances. Toxicity tests showed variability on different sampling occasions and the results of TIE methods indicated that both organic compounds and metals contributed to the observed toxicity in metal plating effluent. Further studies are necessary to help reduce effluent toxicity especially from direct dischargers, who will have to comply with the new regulation. 相似文献