Mao抏rshan region is a representative natural secondary forested region in the eastern mountainous region, north-east of China. Under the support of ARC/INFO, the landscape pattern and landscape diversity of Maoerhsha...Mao抏rshan region is a representative natural secondary forested region in the eastern mountainous region, north-east of China. Under the support of ARC/INFO, the landscape pattern and landscape diversity of Maoerhshan region were studied by combining the forest type map (1:10000), which was drawn from the aerial photographs (1999), field investigation and land utilization map (1:10000). The selected indices included patch number, patch size, patch density index, richness index, dominance index, evenness index and diversity index. The results showed that the landscape dominant forest type in Mao抏rshan region was softwood broad-leaved forest. In all landscape types, the average patch area of natural secondary for-ests was bigger than that of artificial forest. The patch density index of each landscape formed in artificial forest was higher than that of natural secondary forest. The landscape diversity index and landscape evenness index of natural forest were highest, the landscape heterogeneity was also, but the landscape dominance was lower. In natural forest, the control effects of landscape elements on landscape-structure, function and its change were weakened. The artificial forest was on the contrary.展开更多
Cross-calibration of high energetic particle data is a primary requirement for the availability of multi-instrument, multi-spacecraft data. II also can provide a method to verify relative reliability of data from sing...Cross-calibration of high energetic particle data is a primary requirement for the availability of multi-instrument, multi-spacecraft data. II also can provide a method to verify relative reliability of data from single satellite measurement. This pa- per presents a case study of energetic particles data cross-calibration between FY-3B and NOAA-17. A generally good agree- ment is acquired in the flux values and distribution trend of 2.5-6.9 MeV protons and 0.3-1.1 MeV electrons between FY-3B and NOAA-17 satellites. It suggests that the data observed by FY-3B is properly cross-calibrated. We can also confirm that energetic particles data observed by FY-3B satellite is available.展开更多
The electron-cyclotron maser （ECM） emission driven by nonthermal electrons is one of the most crucial mechanisms responsible for radio emissions in magnetized planets, for the interplanetary medium （IPM） and for t...The electron-cyclotron maser （ECM） emission driven by nonthermal electrons is one of the most crucial mechanisms responsible for radio emissions in magnetized planets, for the interplanetary medium （IPM） and for the laboratory microwave generation devices. Major astrophysical observations demonstrate that nonthermal electrons frequently have a negative power-law spectrum with a lower energy cutoff and anisotropic distribution in the velocity space. In this paper, the effects of power-law spectrum behaviors of electrons on a ring-beam maser emission are considered. The results show that the growth rates of O1 and X2 modes decrease rapidly for small A （the dispersion of momentum u）. Because of the lower energy cutoff behavior, the nonthermal electrons with large a still can excite the ECM instability efficiently. The present analysis also includes the effects of parameter β （βu0 is the dispersion of perpendicular momentum ui, u0 the average value of u） on the instability. The growth rate of X2 mode decreases with parameter v0 （v0 = u⊥o/uo, U⊥0 is the average value of u⊥）. But for O1 mode, the relationship between the growth rate and v0 is complicated. It also shows that the growth rates are very sensitive to frequency ratio Ω （frequency ratio of electron cyclotron frequency to plasma frequency）.展开更多
文摘Mao抏rshan region is a representative natural secondary forested region in the eastern mountainous region, north-east of China. Under the support of ARC/INFO, the landscape pattern and landscape diversity of Maoerhshan region were studied by combining the forest type map (1:10000), which was drawn from the aerial photographs (1999), field investigation and land utilization map (1:10000). The selected indices included patch number, patch size, patch density index, richness index, dominance index, evenness index and diversity index. The results showed that the landscape dominant forest type in Mao抏rshan region was softwood broad-leaved forest. In all landscape types, the average patch area of natural secondary for-ests was bigger than that of artificial forest. The patch density index of each landscape formed in artificial forest was higher than that of natural secondary forest. The landscape diversity index and landscape evenness index of natural forest were highest, the landscape heterogeneity was also, but the landscape dominance was lower. In natural forest, the control effects of landscape elements on landscape-structure, function and its change were weakened. The artificial forest was on the contrary.
基金supported by the National Natural Science Foundation of China(Grant No.41204119)
文摘Cross-calibration of high energetic particle data is a primary requirement for the availability of multi-instrument, multi-spacecraft data. II also can provide a method to verify relative reliability of data from single satellite measurement. This pa- per presents a case study of energetic particles data cross-calibration between FY-3B and NOAA-17. A generally good agree- ment is acquired in the flux values and distribution trend of 2.5-6.9 MeV protons and 0.3-1.1 MeV electrons between FY-3B and NOAA-17 satellites. It suggests that the data observed by FY-3B is properly cross-calibrated. We can also confirm that energetic particles data observed by FY-3B satellite is available.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10973043 and 41074107)the Ministry of Science and Technology of China (Grant No. 2011CB811402)the Key Laboratory of Solar Activity at National Astronomical Observatories,CAS
文摘The electron-cyclotron maser （ECM） emission driven by nonthermal electrons is one of the most crucial mechanisms responsible for radio emissions in magnetized planets, for the interplanetary medium （IPM） and for the laboratory microwave generation devices. Major astrophysical observations demonstrate that nonthermal electrons frequently have a negative power-law spectrum with a lower energy cutoff and anisotropic distribution in the velocity space. In this paper, the effects of power-law spectrum behaviors of electrons on a ring-beam maser emission are considered. The results show that the growth rates of O1 and X2 modes decrease rapidly for small A （the dispersion of momentum u）. Because of the lower energy cutoff behavior, the nonthermal electrons with large a still can excite the ECM instability efficiently. The present analysis also includes the effects of parameter β （βu0 is the dispersion of perpendicular momentum ui, u0 the average value of u） on the instability. The growth rate of X2 mode decreases with parameter v0 （v0 = u⊥o/uo, U⊥0 is the average value of u⊥）. But for O1 mode, the relationship between the growth rate and v0 is complicated. It also shows that the growth rates are very sensitive to frequency ratio Ω （frequency ratio of electron cyclotron frequency to plasma frequency）.
