Rotation of the cluster of galaxies A2107

We present indications of rotation in the galaxy cluster A2107 by a method that searches for the maximum gradient in the velocity field in a flat disc-like model of a cluster. Galaxies from cumulative subsamples containing more and more distant members from the cluster centre are projected on to an axis passing through the centre and we apply a linear regression model on the projected distances x and the line-of-sight velocities V . The axis with the maximum linear correlation coefficient   r _max= max[ r ( V , x )]  defines the direction of the maximum velocity gradient, and consequently it presents the major axis of the apparently elliptical cluster. Because the effects of rotation are subtle, we put strong emphasis on the estimation of the uncertainties of the results by implementing different bootstrap techniques. We have found that rotational effects are more strongly expressed at distances of 0.26–0.54 Mpc from the cluster centre. The total virial mass of the cluster is  (3.2 ± 0.6) × 10¹⁴ M_⊙  , while the virial mass, corrected for rotation, is  (2.8 ± 0.5) × 10¹⁴ M_⊙  .     

Sidebands to the lower kilohertz quasi-periodic oscillation in 4U 1636–53

In this paper we report on further observations of the third and fourth kilohertz quasi-periodic oscillations (QPOs) in the power spectrum of the low-mass X-ray binary (LMXB) 4U 1636−53. These kilohertz QPOs are sidebands to the lower kilohertz QPO. The upper sideband has a frequency  55.5 ± 1.7 Hz  larger than that of the contemporaneously measured lower kilohertz QPO. Such a sideband has now been measured at a significance  >6σ  in the power spectra of three neutron-star LMXBs (4U 1636−53, 1728−34 and 1608−52). We also confirm the presence of a sideband at a frequency ∼55 Hz less than the frequency of the lower kilohertz QPO. The lower sideband is detected at a 3.5σ level only when the lower kilohertz QPO frequency is between 800 and 850 Hz. In that frequency interval, the sidebands are consistent with being symmetric around the lower kilohertz QPO frequency. The upper limit to the rms amplitude of the lower sideband is significantly lower than that of the upper sideband for lower kilohertz QPO frequencies >850 Hz. Symmetric sidebands are unique to 4U 1636−53. This might be explained by the fact that lower kilohertz QPO frequencies as high as 800–850 Hz are rare for 4U 1728−34 and 1608−52. Finally, we also measured a low-frequency QPO at a frequency of ∼43 Hz when the lower kilohertz QPO frequency is between 700 and 850 Hz. A similar low-frequency QPO is present in the power spectra of the other two systems for which a sideband has been observed. We briefly discuss the possibility that the sideband is caused by Lense–Thirring precession.     

Automated observing with CGS4 on UKIRT

We describe the four software modules that have lead to highly automated observing with CGS4 on UKIRT.     

重庆辐射雾的声雷达回波与大气污染特征

结合气象观测和大气边界层探测资料，分析了１９９０年１月２日重庆雾的声雷达回波特征，并与１９８９年１２月３０日雾的回波作了比较。结果表明，雾顶回波高度与逆温和相对湿度的转折高度一致；雾顶回波在雾的成熟期呈现波动，在消散期有一下降过程。上午大气污染物地面浓度的变化与逆温混合层状况有密切关系，混合层较薄且持续时间较长时，地面浓度较大     

贵州省未来气候变化(2018—2050年)预估分析

针对贵州省年平均降水量,年平均气温,年平均最高气温和年平均最低气温四个特征量,从空间分布上的定性比较,从年际、年代际的时间演变比较以及从泰勒图的定量比较来看,RegCM4模式的模拟效果优于CMIP5模式,因此本研究在RCP4.5排放情景下利用RegCM4模式数据预估未来2018—2050年贵州省年平均降水量,年平均气温,年平均最高气温和年平均最低气温。结果表明:21世纪Ⅰ阶段(2018—2028年)相对于基准期年平均降水在全省大部地区均是偏少的,偏少幅度在8.5%以内,其中贵州省北部地区偏少幅度最大;21世纪Ⅱ阶段(2029—2039年)相对于基准期贵州省中西部降水偏少东部降水偏多,变化幅度基本上在7%以内;21世纪Ⅲ阶段(2040—2050年)相对于基准期贵州省南部和东部降水偏少西北部降水偏多,变化幅度基本上在7.5%以内。贵州省21世纪Ⅰ阶段、Ⅱ阶段、Ⅲ阶段年平均气温、年平均最高气温和年平均最低气温相对于基准期均是偏暖的,偏暖幅度在0.6～1.3℃之间,越到后期,偏暖幅度越大,且空间差异不大。     

基于MICAPS 4的精细化天气预报平台设计及应用

基于气象信息综合分析处理系统第4版(Meteorology Information Comprehensive Analysis Process System4,MICAPS 4)的精细化天气预报平台的设计与应用。从我国精细化气象格点预报业务需求出发,介绍了精细化预报系统的总体组织结构和数据流程,基于MVVM模式的总体架构设计、功能设计以及实现。平台采用高性能的分布式内存对象缓存技术,提高了系统运行效率;采用模型视图分离,将数据逻辑与用户界面剥离,增强其可扩展性,更便于省级本地化应用;开发了要素场协调性处理功能,集成了降水、温度等客观预报算法,并提供丰富的主/客观交互工具。目前,该平台已在业务中应用,为全国精细化预报业务提供了重要支撑。     

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.     

基于Sentinel-1A的南昌市时间序列InSAR地面沉降监测

本文基于2016-01~2018-07的Sentinel-1A数据,采用PS-InSAR和SBAS-InSAR时序处理方法获取南昌市主城区地面形变信息,对比2种监测结果,分析产生不均匀地面形变的原因。结果表明,2种时序技术的监测结果相关性较高,南昌市主城区的形变趋势为西北抬升、东南下沉。形变区空间分布存在梅岭抬升区、南昌西火车站沉降区、赣江东岸沉降区、邓家埠沉降区和南钢沉降区,主要受地质构造、含水层介质、地下水开采和城市建设等因素影响。     

North Indian Ocean warming and sea level rise in an OGCM

The variability in the long-term temperature and sea level over the north Indian Ocean during the period 1958–2000 has been investigated using an Ocean General Circulation Model, Modular Ocean Model version 4. The model simulated fields are compared with the sea level observations from tide-gauges, Topex/Poseidon (T/P) satellite, in situ temperature profile observations from WHOI moored buoy and sea surface temperature (SST) observations from DS1, DS3 and DS4 moored buoys. It is seen that the long (6–8 years) warming episodes in the SST over the north Indian Ocean are followed by short episodes (2–3 years) of cooling. The model temperature and sea level anomaly over the north Indian Ocean show an increasing trend in the study period. The model thermocline heat content per unit area shows a linear increasing trend (from 1958–2000) at the rate of 0.0018 × 10¹¹ J/m² per year for north Indian Ocean. North Indian Ocean sea level anomaly (thermosteric component) also shows a linear increasing trend of 0.31 mm/year during 1958–2000.     

基于凸集投影的高分四号卫星影像超分辨率重建

基于凸集投影(projection on convex sets,POCS)对GF-4数据进行超分辨率重建处理。利用能量连续降减法构造参考帧以减少迭代次数,提高算法效率;利用Vandewalle配准法对图像块进行运动估计从而获取精确的运动参数有利于图像的分块处理。通过对GF-4真实数据进行试验与分析,表明超分图像结果的清晰度与序列影像帧数呈正相关;信噪比与帧数呈负相关。应用5帧数据进行超分重建,清晰度(平均梯度)从7.803提高到14.386;信噪比会略有下降,从3.411下降到3.336。试验表明该方法可以有效提高图像清晰度,增加图像细节信息,提升图像判别能力,扩展数据的应用范围。