The secular variation of inner zone high energy proton environment in the SAA

The main portion of the inner radiation belt en-countered by spacecraft in low-Earth orbits (LEOs) is concentrated over the South Atlantic Anomaly (SAA) where satellites observed the highest particle flux. The anomaly arises from the Earth’s magnetic field being less intense in the region centered near the east of the Atlantic coast of South America. The trapped radiation belt particles therefore have their lowest mirroring altitudes over the center region of the SAA. Drift shells in t…     

Bioaccumulation of polychlorinated biphenyls in mullet fish in a former ship dismantling harbour, a contaminated estuary, and nearby coastal fish farms

This study investigated the bioaccumulation of polychlorinated biphenyls (PCBs) toward mullet fish (Liza macrolepis) living in former PCB contaminated areas, the Ann-Ping harbour and the Er-Jen estuary, and fish farms located near the above two areas in 2003. The PCB body burdens of collected fish samples are proportional to the contamination level of their locations with the following rank order (greatest to least) from the Er-Jen estuary, the Ann-Ping harbour to the fish farms. Concentration of PCBs of the estuarine mullet has been approximately decreased to one-half of the peak concentration of the 1990s. Although the concentration of PCBs in farmed fish inhabiting near the two contaminated areas was greater than the average of those of fish from local fish markets in Taiwan, no particularly great contamination level was observed in their bodies. Using the less chlorinated PCB fraction (triCB + tetraCB)/total PCBs as the indicator of the origins of PCBs, fish near former contaminated areas had greater body burdens of the more chlorinated PCB congeners, while the farmed fish exhibited a PCB pattern more like that known to originate from air–water exchange with less chlorinated PCBs predominating. Although the PCB contamination has been stopped for a decade, the residual contaminants, supposedly existing in soil and sediments, still contribute to the body burden of fish residing in the estuary and the harbour.     

Perturbation equations of the elements of Vinti's intermediate orbit

Perturbation equations of the elements a, e, s, M_s, Ψ_s,Ω_sof Vinti's intermediate orbit are derived here correct to the second-order. Poisson terms have been eliminated from these equations.     

Composition and exhalation flux of gases from mud volcanoes in Taiwan

Many mud volcanoes are distributed along the tectonic sutures in southern Taiwan and can be divided into five zones based on their relative positions in different tectonic domains. Most active mud volcanoes are exhaling methane-dominated gases. Nevertheless, some gases show unusual carbon dioxide-dominated and/or nitrogen-excess compositions. This implies that there are multiple sources for the gas compositions of mud volcanoes in Taiwan.For better understanding the total amount of exhalation gases and its flux, the gas flow and compositions were continuously measured in the interval of two minutes at Chung-lun (CL) bubbling mud pool for a few months. The major compositions of gases exhaling from this site were 75~90% of CO₂ and 5~12% of CH₄. The amount of gases exhaling from the mud pool can be estimated to be about 1.4 ton/year for CH₄ and 28 ton/year for CO₂, respectively. The preliminary results of exhaling gas flux from the major vents of representative active mud volcanoes, yielded an estimated total CH₄ output of the mud volcanoes in Taiwan of ca. 29 ton/year during quiescent period.     

Is TOL 1326-379 a Prototype of γ-Ray Emitting FR0 Radio Galaxy?

With the possible spacial association to the Fermi/LAT source 3FGL J 1330.0-3818,TOL 1326-379 may be the first one that is identified as a γ-ray emitting Fanaro...     

组合电离层残差与改进的码相伪距探测与修复周跳研究

传统码相组合算法能探测7～8周以上大周跳,而传统的电离层残差法仅对于±4周以内的周跳可实现唯一分离,这限制了两者组合的应用.针对这一问题,对码相组合探测与修复周跳方法进行改进,使得改进的码相组合与电离层残差法能够完全探测周跳.经理论与实验分析,组合改进的码相组合法与电离层残差法两者结合能够完全探测采样间隔小于10 s观测数据中的周跳,对动态非差观测值数据的周跳自动探测与修复有极佳的效果.     

Formation of the anomalous summer precipitation in east China in 2010 and 1998: A comparison of the impacts of two kinds of El Niño

In the summers of 1998 and 2010, severe floods occurred in the middle and lower reaches of the Yangtze River. Although an El Niño event took place preceding each of the summer floods, significant differences between the two summer floods and the two El Niño events were identified. The 1997/98 El Niño is a conventional one with strongest warming in the central-eastern Pacific, whereas the 2009/10 event is an El Niño Modoki with strongest warming in the central Pacific. In this study, summer rainfall anomalies (SRA) in the two years were first compared based on the rainfall data at 160 stations in mainland China, and a significant difference in SRA was found. To understand the underlying mechanism for the difference, the atmospheric circulation systems, particularly the western North Pacific anticyclone (WNPAC), the western Pacific subtropical high (WPSH), and the low-level air flows, were compared in the two years by using the NCEP/NCAR reanalysis data. The results display that the WNPAC was stronger in 2010 than in 1998, along with a northwestward shift, causing weakened southwesterly from the Bay of Bengal to the South China Sea but intensified southerly in eastern China. This resulted in less water vapor transport from the tropical Indian Ocean and the South China Sea but more from the subtropical western Pacific to East Asia. Subsequently, the rainband in 2010 shifted northward. The difference in the WNPAC was caused by the anomalous ascending motion associated with the warming location in the two El Niño events. Furthermore, the role of tropical sea surface temperature (SST) in modulating these differences was investigated by conducting sensitivity experiments using GFDL AM2.1 (Geophysical Fluid Dynamics Laboratory Atmospheric Model). Two experiments were performed, one with the observed monthly SST and the other with June SST persisting through the whole summer. The results suggest that the model well reproduced the primary differences in the atmospheric circulation systems in the two years. It is found that the difference in El Niño events has shaped the rainfall patterns in the two years of 1998 and 2010. At last, the case of 2010 was compared with the composite of historical El Niño Modoki events, and the results indicate that the impact of El Niño Modoki varies from case to case and is more complicated than previously revealed.     

Subarea characteristics of the long-range correlations and the index χ for daily temperature records over China

Daily temperature records including daily minimum, maximum, and average temperature from 190 meteorological stations over China during 1951–2000 are analyzed from two perspectives: (a) long-term persistence in direction of time varies, and (b) standard deviation in direction of amplitude varies. By employing the detrended fluctuation analysis (DFA), we find all the temperature records are long-term correlated, while the exponent α obtained from DFA varies from different districts of China due to different climate conditions, such as the southwest monsoon, subtropical high, northeast cold vortex, and the Tibetan plateau, etc. After we take the standard deviation into account, a new index χ?=?α?×?σ, which has been proposed recently, can be obtained. By further rescaling it as $ \chi = \overline \chi - {{1} \left/ {5} \right.} \times {\sigma_{{\overline \chi }}} $ , we find an obvious change of χ for these three kinds of time series, from which the whole China can be divided into two groups, which are comparatively consistent with dry/wet distributions in the south–north areas over China.     

风廓线雷达资料在暴雨天气过程特征分析中的应用

为了研究风廓线雷达在暴雨天气过程预报中的作用,对2008年6月1日至6月2日云南大理发生的一次暴雨过程进行研究。结果表明,降水前三维风的脉动变化较大,水平风在垂直方向上存在风速切变,最大探测高度明显升高;降水期间可以对降水性质进行判断;降水期间功率谱密度出现双峰谱,能测出垂直气流速度及下降粒子速度,通过这样的分析,便于开展更深层次的降水物理过程研究。     

Advance and prospectus of seasonal prediction: assessment of the APCC/CliPAS 14-model ensemble retrospective seasonal prediction (1980–2004)

We assessed current status of multi-model ensemble (MME) deterministic and probabilistic seasonal prediction based on 25-year (1980–2004) retrospective forecasts performed by 14 climate model systems (7 one-tier and 7 two-tier systems) that participate in the Climate Prediction and its Application to Society (CliPAS) project sponsored by the Asian-Pacific Economic Cooperation Climate Center (APCC). We also evaluated seven DEMETER models’ MME for the period of 1981–2001 for comparison. Based on the assessment, future direction for improvement of seasonal prediction is discussed. We found that two measures of probabilistic forecast skill, the Brier Skill Score (BSS) and Area under the Relative Operating Characteristic curve (AROC), display similar spatial patterns as those represented by temporal correlation coefficient (TCC) score of deterministic MME forecast. A TCC score of 0.6 corresponds approximately to a BSS of 0.1 and an AROC of 0.7 and beyond these critical threshold values, they are almost linearly correlated. The MME method is demonstrated to be a valuable approach for reducing errors and quantifying forecast uncertainty due to model formulation. The MME prediction skill is substantially better than the averaged skill of all individual models. For instance, the TCC score of CliPAS one-tier MME forecast of Niño 3.4 index at a 6-month lead initiated from 1 May is 0.77, which is significantly higher than the corresponding averaged skill of seven individual coupled models (0.63). The MME made by using 14 coupled models from both DEMETER and CliPAS shows an even higher TCC score of 0.87. Effectiveness of MME depends on the averaged skill of individual models and their mutual independency. For probabilistic forecast the CliPAS MME gains considerable skill from increased forecast reliability as the number of model being used increases; the forecast resolution also increases for 2 m temperature but slightly decreases for precipitation. Equatorial Sea Surface Temperature (SST) anomalies are primary sources of atmospheric climate variability worldwide. The MME 1-month lead hindcast can predict, with high fidelity, the spatial–temporal structures of the first two leading empirical orthogonal modes of the equatorial SST anomalies for both boreal summer (JJA) and winter (DJF), which account for about 80–90% of the total variance. The major bias is a westward shift of SST anomaly between the dateline and 120°E, which may potentially degrade global teleconnection associated with it. The TCC score for SST predictions over the equatorial eastern Indian Ocean reaches about 0.68 with a 6-month lead forecast. However, the TCC score for Indian Ocean Dipole (IOD) index drops below 0.40 at a 3-month lead for both the May and November initial conditions due to the prediction barriers across July, and January, respectively. The MME prediction skills are well correlated with the amplitude of Niño 3.4 SST variation. The forecasts for 2 m air temperature are better in El Niño years than in La Niña years. The precipitation and circulation are predicted better in ENSO-decaying JJA than in ENSO-developing JJA. There is virtually no skill in ENSO-neutral years. Continuing improvement of the one-tier climate model’s slow coupled dynamics in reproducing realistic amplitude, spatial patterns, and temporal evolution of ENSO cycle is a key for long-lead seasonal forecast. Forecast of monsoon precipitation remains a major challenge. The seasonal rainfall predictions over land and during local summer have little skill, especially over tropical Africa. The differences in forecast skills over land areas between the CliPAS and DEMETER MMEs indicate potentials for further improvement of prediction over land. There is an urgent need to assess impacts of land surface initialization on the skill of seasonal and monthly forecast using a multi-model framework.