Radiative forcing over China due to albedo change caused by land cover change during 1990–2010

Land cover change affects surface radiation budget and energy balance by chang- ing surface albedo and further impacts the regional and global climate. In this article, high spatial and temporal resolution satellite products were used to analyze the driving mechanism for surface albedo change caused by land cover change during 1990-2010. In addition, the annual-scale radiative forcing caused by surface albedo changes in China＇s 50 ecological regions were calculated to reveal the biophysical mechanisms of land cover change affecting climate change at regional scale. Our results showed that the national land cover changes were mainly caused by land reclamation, grassland desertification and urbanization in past 20 years, which were almost induced by anthropogenic activities. Grassland and forest area decreased by 0.60% and 0.11%, respectively. The area of urban and farmland increased by 0.60% and 0.19%, respectively. The mean radiative forcing caused by land cover changes during 1990-2010 was 0.062 W/m2 in China, indicating a warming climate effect. However, spatial heterogeneity of radiative forcing was huge among different ecological regions. Farmland conversing to urban construction land, the main type of land cover change for the urban and suburban agricultural ecological region in Beijing-Tianjin-Tangshan region, caused an albedo reduction by 0.00456 and a maximum positive radiative forcing of 0.863 WIm2, which was presented as warming climate effects. Grassland and forest conversing to farmland, the main type of land cover change for the temperate humid agricultural and wetland ecological region in Sanjiang Plain, caused an albedo increase by 0.00152 and a maximum negative radiative forcing of 0.184 W/m2, implying cooling climate effects.     

Nonradial eruption of a kinking filament observed from STEREO

On 5 April 2008, a filament at the periphery of an active region was observed by the Extreme Ultraviolet Imager telescope aboard the STEREO-A spacecraft, which showed up as a prominence eruption in the field-of-view from STEREO-B. The filament at STEREO-A 304 Å was first lengthened toward a region with weak overlying magnetic field so evolved as a large-scale one consisting of bright and dark threads twisting with each other, and then the portion below the weak field underwent an eruption. Meanwhile, the corresponding STEREO-B 304 Å prominence threads exhibited a kinking structure and tilting motion, with its center deflecting from the radial direction. By using three-dimension (3D) reconstruction technology, we obtain the 3D topology for the kinked prominence when its apex arrived at 1.4 radii, from which a clockwise rotation of about 90° is found in the course of the eruption. By comparing the 3D structure with the magnetic-field configuration computed by using the Potential-Field Source-Surface (PFSS) model, it is suggested that the filament erupted against the rather weaker than stronger overlying magnetic field, which make it appear to tilt toward one side.     

A new carbon and oxygen balance model based on ecological service of urban vegetation

The application of human induced oxygen consumption and carbon emission theory in urban region was summed up and on this base a new model of urban carbon and oxygen balance (UCOB) was constructed by calculating the carbon and oxygen fluxes. The purpose was to highlight the role of vegetation in urban ecosystems and evaluate the effects of various human activities on urban annual oxygen consumption and carbon emission. Hopefully,the model would be helpful in theory to keep the regional balance of carbon and oxygen,and provide guidance and support for urban vegetation planning in the future. To test the UCOB model,the Jimei District of Xiamen City,Fujian Province,China,a very typical urban region,was selected as a case study. The results turn out that Jimei′s vegetation service in oxygen emission and carbon sequestration could not meet the demand of the urban population,and more than 31.49 times of vegetation area should be added to meet the whole oxygen consumption in Jimei while 9.60 times of vegetation area are needed to meet the carbon sequestration targets. The results show that the new UCOB model is of a great potential to be applied to quantitative planning of urban vegetation and regional eco-compensation mechanisms.     

Singularly perturbed solution of coupled model in atmosphere-ocean for global climate

A box model of the interhemispheric thermohaline circulation （THC） in atmosphere-ocean for global climate is considered. By using the multi-scales method, the asymptotic solution of a simplified weakly nonlinear model is discussed. Firstly, by introducing first scale, the zeroth order approximate solution of the model is obtained. Secondly, by using the multi-scales, the first order approximate equation of the model is found. Finally, second order approximate equation is formed to eliminate the secular terms, and a uniformly valid asymptotic expansion of solution is decided. The multi-scales solving method is an analytic method which can be used to analyze operation sequentially. And then we can also study the diversified qualitative and quantitative behaviors for corresponding physical quantities. This paper aims at providing a valid method for solving a box model of the nonlinear equation.     

Vitellogenin-associated maternal transfer of exogenous and endogenous ligands in the estuarine fish, Fundulus heteroclitus

Sequestration of large quantities of vitellogenin (VTG) is critical for proper oocyte development in most oviparous vertebrates. While previous studies have shown a general correlation between oocyte growth and the accumulation of various exogenous and endogenous ligands, few studies have attempted to elucidate the role VTG plays in this maternal transfer. In the present study, we have demonstrated that oocytic accumulation of [³H]-2,3,7,8-tetrachlorodibenzo-p-dioxin (³H-TCDD) and [¹⁴C]-benzo(a)pyrene (¹⁴C-BaP) by gravid Fundulus heteroclitus is directly correlated with oocyte maturational status. A positive correlation was observed between oocyte maturational state (size) and both total quantity (total pmoles) as well as concentration (pmoles/g tissue) of TCDD and BaP. Further, the bi-phasic accumulation of both TCDD and BaP mirrors that previously observed for protein sequestration by cultured Fundulus oocytes. Additionally, both TCDD and BaP were associated with VTG in vivo. HPLC analysis of serum extracts has shown that VTG associates with both parent BaP and BaP metabolites. Studies with ¹²⁵I-T₄ (thyroxine) also suggest that this critical hormone also associates with VTG in vivo. Ongoing studies are examining the VTG-associated transport and oocytic sequestration of ¹²⁵I-T₄ in gravid Fundulus.     

Reproductive rate of a marine planktonic copepodLabidocera euchaet a Giesbrecht in Xiamen Harbor

Reproductive rate of a marine planktonic copepodLabidocera euchaeta Giesbrecht in Xiamen Harbor bor was studied during the period from April 1986 to August 1987. Results showed that rate of egg production (F, eggs/(♀, d)) was positively correlated with temperature (T,^oC) and body weight of spawning female (Wc, μgC) as:F=0.0637 (T−7)^0.7445 Wc. Each month a maximum rate of egg production occurred at one of the five experimental temperatures (10°, 15°, 25°, and 30°C) near the monthly mean field temperature. The available food density (P, μgC/ml) had significant effect on specific rate of egg production (Fc, %C ♀/d) as:Fc=0.1732 (P-0.0179)/P. The gross efficiency of egg production of ca 62% in carbon was independent of food density snd ingestion rate. Observations on in situ egg production and hatching rate demonstrated that this species reproduces continuously all the year round, with summer as its high reproductive season and winter a low one. Ten generations a year is also suggested based on the number of the peaks of average population egg production rate. This agreed well with the result obtained from the generation-time equations. Egg-laying pattern was also observed and discussed.     

A measurement of the O2 ultra-violet nightglow emission

New measurements of the Herzberg I emission height profile in the night airglow are reported and indicate a peak emission height near 96 km in agreement with previous measurements. Using an atomic oxygen concentration profile determined from the oxygen green line profile measured on the same rocket it is concluded that the O₂(A³Σ_u⁺) state is not excited in the direct three body recombination of atomic oxygen. It is suggested that the excitation mechanism is a two step process, similar to the Barth mechanism for the atomic oxygen green lineand that the excited intermediate state is C³Δ_u.     

An indirect mechanism for the production of O(1S) in the aurora

Recent laboratory measurements of the deactivation rate constants for O(¹S) have suggested that the dominant production mechanism for the green line in the nightglow is a two-step process. A similar mechanism involving energy transfer from an excited state of molecular oxygen is considered as a potential source of the OI (5577 Å) emission in the aurora. It is shown that the mechanism, $\text{O}{}_2\text{+ e → O}{}_2{}^1\text{+ e O}{}_2{}^1\text{+ O → O}{}_2\text{+ O(}{}^1\text{S}\text{)}$, is consistent with auroral observations; the intermediate excited state has been tentatively identified as the O₂(c¹∑^?_u) state. For the proposed energy transfer mechanism to be the primary source of the auroral green line, the peak electron impact cross-section for O₂¹ production must be approximately 2 × 10^?17 cm².     

Symplectic adaptive algorithm for solving nonlinear two-point boundary value problems in Astrodynamics

In this paper, from a Hamiltonian point of view, the nonlinear optimal control problems are transformed into nonlinear two-point boundary value problems, and a symplectic adaptive algorithm based on the dual variational principle is proposed for solving the nonlinear two-point boundary value problem. The state and the costate variables within a time interval are approximated by using the Lagrange polynomial and the costate variables at two ends of the time interval are taken as independent variables. Then, based on the dual variational principle, the nonlinear two-point boundary value problems are replaced by a system of nonlinear equations which can preserve the symplectic structure of the nonlinear optimal control problem. Furthermore, the computational efficiency of the proposed symplectic algorithm is improved by using the adaptive multi-level iteration idea. The performance of the proposed algorithm is tested by the problems of Astrodynamics, such as the optimal orbital rendezvous problem and the optimal orbit transfer between halo orbits.