AMIP模式对大气经向质量输送的模拟评估

从描述南、北半球间大气经向质量传输的角度人手,考察IPCC第4次评估报告提供的8个AMIP大气环流模式对越赤道质量通量输送的模拟性能。结果表明:NCAR、MPI和UKMO模式模拟出的越赤道整层大气质量通量与观测大体相一致;MIROC3模拟的整层大气质量通量年循环与观测结果相去甚远,尤其在夏季模拟出较强的虚假向北大气质量输送;IAP模拟的整层大气质量通量年循环方向与观测结果在7个月份中相反;把垂直大气分为4层.各模式对700 hPa以下(I_1)和300-70 hPa(I_3)两层质量通量的模拟能力普遍较好;对700-300 hPa层(I_2)质量通量模拟结果偏差较大;除MIROC3外,其余模式基本能够模拟出70-10 hPa(I_4)大气质量通量的季节变化.显然,不仅南、北半球间大气存在质量交换,越过其他纬度同样存在着经向大气质量输送,无论冬季、夏季还是年平均,各模式对越过其他纬度(60°S-60°N)经向大气质量输送的模拟结果与观测差异明显。整体权衡,UKMO_HADGEMl在模拟越赤道大气质量通量方面表现突出,MPI_ECHAM5模式优势较明显;NCAR、GISS和GFDL 3个模式在某些压力层内具有较好的模拟水平;MIROC模式对整层、700-300 hPa层的模拟能力较低,而对700 hPa以下层和300-70 hPa层的模拟水平较高;IAP_FGOALS和CNRM模式在模拟越赤道大气质量通量方面存在一定的不足.     

提高暗筒式日照纸感光质量的技巧

暗筒式日照计日照纸所用药品品质好坏、配药比例和涂药方法是否得当,是造成日照纸感光质量好坏的主要原因。本文针对部分测报员在日照纸配药、涂药和浸漂操作处理过程中存在的问题提出相关改进措施和建议。     

Magnetic connection and current distribution in black hole accretion discs

We discuss one of the possible origins of large-scale magnetic fields based on a continuous distribution of toroidal electric current flowing in the inner region of the disc around a Kerr black hole (BH) in the framework of general relativity. It turns out that four types of configuration of the magnetic connection (MC) are generated, i.e. MC of the BH with the remote astrophysical load (MCHL), MC of the BH with the disc (MCHD), MC of the plunging region with the disc (MCPD) and MC of the inner and outer disc regions (MCDD). It turns out that the Blandford–Znajek process can be regarded as one type of MC, i.e. MCHL. In addition, we propose a scenario for fitting the quasi-periodic oscillations in BH binaries based on MCDD associated with the magnetic reconnection.     

顾及大气角动量的Prophet-VAR日长变化预报方法

针对日长变化参数序列中蕴含的复杂非线性特征会严重影响其预报精度的问题,同时为探讨引入大气角动量序列是否有助于提升预报精度,提出一种Prophet拟合外推联合向量自回归(vector autoregression,VAR)残差补偿的组合模型用于日长预报.选用2008～2020年的日长变化参数序列进行实验,同时设计不顾及大...     

粟类作物稃片植硅体形态研究回顾与展望

中国是粟、黍的起源地,但受植物遗存保存状况及研究方法的限制,对粟类旱作农业起源与驯化的时间、地点、种类、过程等的认识仍然存在不同观点。植硅体分析为准确鉴定粟、黍及其野生祖本和亲缘物种提供了新的途径。本文总结了近几年来针对粟、黍种子稃片植硅体研究取得的新进展,获得以下认识:1)进一步明确了稃片表皮长细胞植硅体的形态特征、大小、数量是鉴定考古文化堆积中粟、黍及其野生祖本和亲缘野生物种的可靠指标;2)通过对比我国北方常见的狗尾草属稃片植硅体,发现了ΩⅢ型仅发育于粟和青狗尾草的稃片中部,且其大小与狗尾草属野生植物差异显著;3)分析和说明了稃片植硅体鉴定流程和方法、重点强调了稃片Ω/η类型的鉴定特征和应用范围,以及植硅体统计量等关键问题;4)讨论了粟类稃片植硅体产量与农作物产量的关系以及植硅体埋藏学问题,最后对深化粟类植硅体形态学研究提出了初步建议。希望通过本文的总结与讨论,能够使植硅体分析方法在粟类作物起源和传播的研究中得到更准确、更广泛的应用。     

基于问题探究式学习开展初中跨学科教学的研究——以九年级"小龙虾的'逆袭'"为例

在新一轮课改的指引下,如何将不同学科知识体系融合在真实情境中,引导学生解决具体问题,以培养学生跨学科的学习意识和分析能力,成为教学实践者普遍关心的问题。本文对基于问题探究式的初中跨学科教学的背景、意义与教学模式展开研究,并以九年级“小龙虾的‘逆袭’”为例,进行了基于问题探究式学习的课堂教学设计。     

Effects of a Dry-Mass Conserving Dynamical Core on the Simulation of Tropical Cyclones

The accurate forecasting of tropical cyclones(TCs) is a challenging task. The purpose of this study was to investigate the effects of a dry-mass conserving(DMC) hydrostatic global spectral dynamical core on TC simulation. Experiments were conducted with DMC and total(moist) mass conserving(TMC) dynamical cores. The TC forecast performance was first evaluated considering 20 TCs in the West Pacific region observed during the 2020 typhoon season. The impacts of the DMC dynamical core on forecasts o...     

地基微波辐射计遥感人工触发闪电的观测研究

为了深入研究雷电产生的微波热辐射特征,从2016年初夏开始利用地基微波辐射计在中国气象局雷电野外科学实验基地开展了连续4年的观测实验,根据雷电热效应的特征,制定了观测方案,并为地基微波辐射计设置了“引雷观测模式”。结果表明,地基微波辐射计具有对雷电热效应产生响应的能力。2017—2019年,辐射计一共成功捕获了30次人工触发闪电,观测效率逐年增长,平均为71.4 %;微波亮温脉冲幅度的最大值约125 K。结合其中28次触发事件的雷电流数据,分析了亮温脉冲幅度和雷电流积分量之间的相关性,并发现了最大亮温脉冲幅度与总电流作用积分之间可能存在指数关系。根据亮温观测数据估算了雷电热效应的持续时间,平均约0.5 s,其中25次触发事件的雷电流热效应持续时间与雷电流持续时间变化较为一致,相关系数约0.73。     

Baseline predictability of daily east Asian summer monsoon circulation indices

The nonlinear local Lyapunov exponent (NLLE) method is adopted to quantitatively determine the predictability limit of East Asian summer monsoon (EASM) intensity indices on a synoptic timescale. The predictability limit of EASM indices varies widely according to the definitions of indices. EASM indices defined by zonal shear have a limit of around 7 days, which is higher than the predictability limit of EASM indices defined by sea level pressure (SLP) difference and meridional wind shear (about 5 days). The initial error of EASM indices defined by SLP difference and meridional wind shear shows a faster growth than indices defined by zonal wind shear. Furthermore, the indices defined by zonal wind shear appear to fluctuate at lower frequencies, whereas the indices defined by SLP difference and meridional wind shear generally fluctuate at higher frequencies. This result may explain why the daily variability of the EASM indices defined by zonal wind shear tends be more predictable than those defined by SLP difference and meridional wind shear. Analysis of the temporal correlation coefficient (TCC) skill for EASM indices obtained from observations and from NCEP’s Global Ensemble Forecasting System (GEFS) historical weather forecast dataset shows that GEFS has a higher forecast skill for the EASM indices defined by zonal wind shear than for indices defined by SLP difference and meridional wind shear. The predictability limit estimated by the NLLE method is shorter than that in GEFS. In addition, the June-September average TCC skill for different daily EASM indices shows significant interannual variations from 1985 to 2015 in GEFS. However, the TCC for different types of EASM indices does not show coherent interannual fluctuations.     

Modulation of the Intensity of Nascent Tibetan Plateau Vortices by Atmospheric Quasi-Biweekly Oscillation

The modulation of the intensity of nascent Tibetan Plateau vortices(ITPV) by atmospheric quasi-biweekly oscillation(QBWO) is investigated based on final operational global analysis data from the National Centers for Environmental Prediction. The spatial and temporal distributions of the ITPV show distinct features of 10–20-day QBWO. The average ITPV is much higher in the positive phases than in the negative phases, and the number of strong TPVs is much larger in the former,with a peak that appears in phase 3. In addition, the maximum centers of the ITPV stretch eastward in the positive phases,indicating periodic variations in the locations where strong TPVs are generated. The large-scale circulations and related thermodynamic fields are discussed to investigate the mechanism by which the 10–20-day QBWO modulates the ITPV. The atmospheric circulations and heating fields of the 10–20-day QBWO have a major impact on the ITPV. In the positive QBWO phases, the anomalous convergence at 500 hPa and divergence at 200 hPa are conducive to ascending motion. In addition, the convergence centers of the water vapor and the atmospheric unstable stratification are found in the positive QBWO phases and move eastward. Correspondingly, condensational latent heat is released and shifts eastward with the heating centers located at 400 hPa, which favors a higher ITPV by depressing the isobaric surface at 500 hPa. All of the dynamic and thermodynamic conditions in the positive QBWO phases are conducive to the generation of stronger TPVs and their eastward expansion.