Subseasonal Reversal of East Asian Surface Temperature Variability in Winter 2014/15

Although there has been a considerable amount of research conducted on the East Asian winter-mean climate, subseasonal surface air temperature(SAT) variability reversals in the early and late winter remain poorly understood. In this study,we focused on the recent winter of 2014/15, in which warmer anomalies dominated in January and February but colder conditions prevailed in December. Moreover, Arctic sea-ice cover(ASIC) in September–October 2014 was lower than normal,and warmer sea surface temperature(SST) anomalies occurred in the Ni ?no4 region in winter, together with a positive Pacific Decadal Oscillation(PDO|+) phase. Using observational data and CMIP5 historical simulations, we investigated the PDO|+ phase modulation upon the winter warm Ni ?no4 phase(autumn ASIC reduction) influence on the subseasonal SAT variability of East Asian winter. The results show that, under a PDO|+ phase modulation, warm Ni ?no4 SST anomalies are associated with a subseasonal delay of tropical surface heating and subsequent Hadley cell and Ferrel cell intensification in January–February, linking the tropical and midlatitude regions. Consistently, the East Asian jet stream(EAJS) is significantly decelerated in January–February and hence promotes the warm anomalies over East Asia. Under the PDO|+ phase,the decrease in ASIC is related to cold SST anomalies in the western North Pacific, which increase the meridional temperature gradient and generate an accelerated and westward-shifted EAJS in December. The westward extension of the EAJS is responsible for the eastward-propagating Rossby waves triggered by declining ASIC and thereby favors the connection between ASIC and cold conditions over East Asia.     

Recent Researches on the Short-Term Climate Prediction at IAP－A Brief Review

Studies on the seasonal to extraseasonal climate prediction at the Institute of Atmospheric Physics (IAP) in recent years were reviewed. The first short-term climate prediction experiment was carried out based on the atmospheric general circulation model (AGCM) coupled to a tropical Pacific oceanic general circulation model (OGCM). In 1997, an ENSO prediction system including an oceanic initialization scheme was set up. At the same time, researches on the SST-induced climate predictability over East Asia were made. Based on the biennial signal in the interannual climate variability, an effective method was proposed for correcting the model predicted results recently. In order to consider the impacts of the initial soil mois ture anomalies, an empirical scheme was designed to compute the soil moisture by use of the atmospheric quantities like temperature, precipitation, and so on. Sets of prediction experiments were carried out to study the impacts of SST and the initial atmospheric conditions on the flood occurring over China in 1998.     

唐山地震前地震活动模糊熵值的异常特征

定义了地震活动模糊熵概念，计算了唐山地震前地震活动模糊熵随时间，空间的变化，发现唐山Ｍｓ７．８地震发生前，地震活动模糊熵值下降，唐山Ｍｓ７．８地震发生在地震活动模糊熵值较低的地方，这符合大地震前震源区地震活动从无序趋向有序的规律，地震活动模糊熵反模糊因子与震群活动熵统一起来，比震群活动熵更突出地反映地震活动异常。     

冰期气候的数值模拟

应用CLIMAP重建的18000年以前的地表条件,作者用大气所两层大气环流模式模拟了冰极盛期7月份的气候。结果表明:全球气温明显低于模拟的现在7月份的气温,降水和总云量减少了,海平面气压升高了,而这些变化尤其是气温的变化以北半球高纬陆地区域和南极区为甚;CO_2含量改变到现代值以后,引起的气候反响很小,说明必须用联合模式来研究。作者还指出,冰期边条件引起的气候反响与CO_2含量加倍引起的气候反响有某种一致,这对我们理解气候系统如何响应外界的强迫是一个启发。     

The seasonal climatic simulation of 9000 years before present by using the IAP atmospheric general circulation model

The seasonal cycle of the climate of 9000 years before present was simulated with the IAP two-level atmospheric general circulation model. The incoming solar radiation was specified from the orbital parameters for 9000 years Ago. The boundary conditions of that time were prescribed to the present value because of the small differences between the two. The change in radiation makes temperature to be higher in summer and lower in winter over large areas of the land; and the increased temperature contrast between the land and the ocean strengthens the summer monsoon circulation and increases the precipitation over there. The asymmetry of temperature change between the Northern Hemisphere and the Southern Hemisphere and between summer and winter still exists, which agrees with that get from the previous perpetual experiments.     

Variability in latent heat flux over the tropical pacific in association with recent two ENSO events

This paper analyzed the variations of latent heat flux (LHF) over the tropical Pacific in the period 1978-1988 by using COADS (Comprehensive Ocean and Atmospheric Data Set). It has been founded that the interannual variabili ty of LHF exhibits strong ENSO signal, with the significant increasing LHF during the recent two warm events, i.e., 1982 / 83 and 1986 / 87 and decreasing LHF in the cold episodes. However the longitudinal distribution of the LHF departures varies from event to event. In the eastern Pacific, the specific humidity difference at air-sea interface (qs -qa) makes a dominant contribution to the interannual variability of LHF ( r = 0.73 ), while in the western Pacific the surface wind speed, W and the qs - qa make nearly equal contribution to that of LHF.     

Effects of dietary carbohydrate-to-lipid ratio on the growth performance and feed utilization of juvenile turbot (<Emphasis Type="Italic">Scophthalmus maximus</Emphasis>)

A 9-week feeding trial was conducted to investigate the effects of dietary carbohydrate to lipid ratio(CHO:LIP) on the growth performance and feed utilization of juvenile turbot Scophthalmus maximus(initial body weight 8.75 g ± 0.04 g). Four isonitrogenous and isoenergetic low protein level(39%) diets were formulated with increasing ratios of dietary carbohydrate to lipid(2:18, 6:18, 18:12 and 28:6). A high protein level(50%) diet with the 2:12 ratio of carbohydrate to lipid was used as the control. Results showed that the survival rate, contents of moisture, crude protein and ash in muscle were not significantly affected by dietary treatments. With the dietary CHO:LIP ratio increased from 2:18 to 18:12, weight gain rate significantly increased(P < 0.05). Higher dietary CHO:LIP ratio(28:6) resulted in the significantly decreased weight gain rate(P < 0.05). Meanwhile, this treatment also resulted in the highest daily feed intake and liver glycogen content, as well as the lowest feed efficiency(P < 0.05). Muscle glycogen content in fish fed the diet with 2:12 or 2:18 CHO:LIP ratio was significantly lower than those fed with the other three diets(P < 0.05). The present results confirmed that the juvenile turbot can utilize carbohydrate. Furthermore, the appropriate ratio of dietary carbohydrate to lipid was important to the growth and feed utilization of turbot. The proper CHO:LIP ratio based on the growth performance in the present study was determined to be 18:12 when the dietary protein level was 39%.     

Calculation and accuracy evaluation of TGD from IFB for BDS

With the development of new global navigation satellite system applications, the demand of high accurate positioning navigation timing (PNT) service becomes urgent. For precise PNT, the timing group delay (TGD) is regarded as an important parameter in the satellite navigation message. Instead of using the absolute receiver hardware delay, a method based on receiver inter-frequency bias (IFB, i.e., differential receiver hardware delay between different frequencies) calibration is presented to deal with the rank deficiency of a calculation matrix and to reduce jumps in TGD solutions in BDS. The double-differenced pseudorange obtained from a pair of zero baseline receivers is used to evaluate the IFB calibration accuracy. The estimated precision of TGD is evaluated and compared with GPS TGD provided by IGS. In order to ensure the quality of assessment, a method based on the difference of dual-frequency ionospheric delay is proposed to compare the accuracy of the estimated TGD and broadcast TGD. Finally, the effect of TGD on the user equivalent range error is analyzed. The analysis result shows that for BDS IGSO satellites, the precision of TGD1, which is the differential hardware delay between B1 (1561.098 MHz) and B3 (1268.52 MHz) frequencies, is better than 0.5 ns, and for GEO and MEO satellites the TGD1 is better than 1 and 2 ns, respectively. The precision of TGD2 of all satellites, which is the differential hardware delay between B2 (1207.14 MHz) and B3 frequencies, is better than 0.5 ns. The accuracy analysis result reveals that the proposed TGD estimation method can provide better results when compared with the broadcast data.     

黑龙江省非典型环境条件强迫下短时强对流天气特征研究

本文利用常规气象观测资料、区域自动站加密观测资料、FY-2卫星云图、新一代天气雷达及NECP的1°×1°再分析资料对黑龙江省的2006-2014年冰雹和2008-2014年的强降水在非典型环境条件下表现出的局地要素特征以及卫星和雷达特征进行分析。分析结果显示：较大的对流有效位能、低层强暖空气为对流发生提供了热力不稳定;700hPa湿区配合冰雹500hPa干区和强降水低层弱水汽辐合使得对流具备了有利的水汽垂直分布条件;最终在地面局地辐合的触发下产生了对流;冰雹有较高的0℃层高度和较低的气压;冰雹和强降水有利的海拔高度分别在200-500m和100-200m。卫星云图和雷达上的表现往往比较孤立,移动较快,产生的时间和位置与两个小云块或小云块与大云团合并的时间及位置一致,低层水汽辐合明显时可能会伴有大的云团。雷达回波上冰雹云但很难探测到钩状回波等特征回波,强降水多为原地生消火或列车效应产生。