Assessment of the performance of the TOPGNSS and ANN-MB antennas for ionospheric measurements using low-cost u-blox GNSS receivers

Low-cost GNSS receivers have recently been gaining reliability as good candidates for ionospheric studies. In line with these gains are genuine concerns about improving the performance of these receivers. In this work, we present a comprehensive investigation of the performances of two antennas(the u-blox ANN-MB and the TOPGNSS TOP-106) used on a low-cost GNSS receiver known as the u-blox ZED-F9P. The two antennas were installed on two identical and co-located u-blox receivers. Data used from both receivers cover the period from January to June 2022. Results from the study indicate that the signal strengths are dominantly greater for the receiver with the TOPGNSS antenna than for the receiver with the ANN-MB antenna, implying that the TOPGNSS antenna is better than the ANN-MB antenna in terms of providing greater signal strengths. Summarily, the TOPGNSS antenna also performed better in minimizing the occurrence of cycle slips on phase TEC measurements. There are no conspicuous differences between the variances(computed as 5-min standard deviations) of phase TEC measurements for the two antennas, except for a period around May-June when the TOPGNSS gave a better performance in terms of minimizing the variances in phase TEC. Remarkably, the ANN-MB antenna gave a better performance than the TOPGNSS antenna in terms of minimizing the variances in pseudorange TEC for some satellite observations. For precise horizontal(North and East) positioning, the receiver with the TOPGNSS antenna gave better results, while the receiver with the ANN-MB antenna gave better vertical(Up) positioning. The errors for the receivers of both antennas are typically within about 5 m(the monthly mean was usually smaller than 1 m) in the horizontal direction and within about 10 m(the monthly mean was usually smaller than 4 m) in the vertical direction.

Dual Actions for Born-Infeld and Dp-Brane Theories

Dual actions with respect to U(1) gauge fields for the Born-Infeld and Dp-brane theories are reexamined.Taking into account an additional condition,i.e.a corollary to the field equation of the auxiliary metric,one obtainsan alternative dual action that does not involve the infinite series in the auxiliary metric given by [M.Abou Zeid andC.M.Hull,Phys.Lett.B 428 (1998) 277],but just picks out the first term from the series formally.New effectiveinteractions of the theories are revealed.That is,the new dual action gives rise to an effective interaction in terms ofone interaction term rather than infinitely many terms of different (higher) orders of interactions physically.However,the price paid for eliminating the infinite series is that the new action is not quadratic but highly nonlinear in the Hodgedual of a (p-1)-form field strength.This non-linearity is inevitable under the requirement that the two dual actionsare equivalent.

A geometric phase for superconducting qubits under the decoherence effect

We propose a relaxation rate or dissipative cavity-based parameters that can be used as indicators of the stationary limit of a mixed state geometric phase. We perform our considerations for the system of a superconducting qubit in an open transmission line or interacting with a dissipative cavity. This system is very useful for performing an effective quantum computation by exhibiting the long collapse time of the geometric phase. It is shown that the geometric phase in the stationary limit does not depend on interaction time if the decay time exceeds an upper bound.

Comparison of convective parameterizations in RegCM4 experiments over China with CLM as the land surface model

区域气候模式Reg CM最新版中引入了新的陆面模式CLM,为了考察在选用CLM时不同对流参数化方案在中国地区的表现,本文进行了五种不同对流参数化方案下—Grell、Emanuel、Tiedtke,Mix(陆地上位Emanuel方案,海洋上为Grell方案)和Mix2(陆地上为Grell方案,海洋上为Emanuel方案)的模拟试验。将模拟的冬、夏季平均气温和降水与观测进行了对比分析,结果表明,Emanuel方案是综合模拟效果最好的。在使用Reg CM-CLM进行中国区域模拟研究时,对流参数化方案推荐选为Emanuel。

Projection of the Future Changes in Tropical Cyclone Activity Affecting East Asia over the Western North Pacific Based on Multi-RegCM4 Simulations

Future changes in tropical cyclone(TC)activity over the western North Pacific(WNP)under the representative concentration pathway RCP4.5 are investigated based on a set of 21 st century climate change simulations over East Asia with the regional climate model RegCM4 driven by five global models.The RegCM4 reproduces the major features of the observed TC activity over the region in the present-day period of 1986-2005,although with the underestimation of the number of TC genesis and intensity.A low number of TCs making landfall over China is also simulated.By the end of the 21st century(2079-98),the annual mean frequency of TC genesis and occurrence is projected to increase over the WNP by16%and 10%,respectively.The increase in frequency of TC occurrence is in good agreement among the simulations,with the largest increase over the ocean surrounding Taiwan Island and to the south of Japan.The TCs tend to be stronger in the future compared to the present-day period of 1986-2005,with a large increase in the frequency of strong TCs.In addition,more TCs landings are projected over most of the China coast,with an increase of~18%over the whole Chinese territory.

Performance of RegCM4 over Major River Basins in China

A long-term simulation for the period 1990–2010 is conducted with the latest version of the International Centre for Theoretical Physics＇ Regional Climate Model（RegCM4）, driven by ERA-Interim boundary conditions at a grid spacing of 25 km. The Community Land Model（CLM） is used to describe land surface processes, with updates in the surface parameters,including the land cover and surface emissivity. The simulation is compared against observations to evaluate the model performance in reproducing the present day climatology and interannual variability over the 10 main river basins in China,with focus on surface air temperature and precipitation. Temperature and precipitation from the ERA-Interim reanalysis are also considered in the model assessment. Results show that the model reproduces the present day climatology over China and its main river basins, with better performances in June–July–August compared to December–January–February（DJF）.In DJF, we find a warm bias at high latitudes, underestimated precipitation in the south, and overestimated precipitation in the north. The model in general captures the observed interannual variability, with greater skill for temperature. We also find an underestimation of heavy precipitation events in eastern China, and an underestimation of consecutive dry days in northern China and the Tibetan Plateau. Similar biases for both mean climatology and extremes are found in the ERA-Interim reanalysis, indicating the difficulties for climate models in simulating extreme monsoon climate events over East Asia.

On the Conversion of High-Frequency Soliton Solutions to a （1＋1）-Dimensional Nonlinear Partial Differential Evolution Equation

从在压力不安下面放松媒介的 barotropic 的动态方程，并且用减少的 perturbative 分析，我们调查 soliton 结构一( 1+1 )维的非线性的部分微分进化( NLPDE )方程部分衍生物(y)(部分衍生物(希腊语字母的第七字)+ u 部分衍生物(y)+( u ( 2 ) /2 )部分衍生物(y)) u +高山哈 u (y)+ u = 0 ，描述不安的高周波的政体。借助于 Hirota 的 bilinearization 方法，因此，强烈取决于一个典型驱散参数的三个典型答案被发掘。

Stochastic Approximation Method for Fixed Point Problems

We study iterative processes of stochastic approximation for finding fixed points of weakly contractive and nonexpansive operators in Hilbert spaces under the condition that operators are given with random errors. We prove mean square convergence and convergence almost sure (a.s.) of iterative approximations and establish both asymptotic and nonasymptotic estimates of the convergence rate in degenerate and non-degenerate cases. Previously the stochastic approximation algorithms were studied mainly for optimization problems.

Floquet Theory in Electron-Helium Scattering in a Nd:YAG Laser Field

The dynamics of laser-assisted elastic collisions in helium is studied. The formalism which will be developed to describe such laser-assisted collisions, treats the laser-projectile interaction to all orders, while the electron-helium interaction is treated within the first Born-approximation. Detailed calculations are performed for the elastic scattering of 50 eV electrons by helium accompanied by the transfer of photons. The numerical results show that the good physical interpretation of relevant processes needs to consider the maximum of atomic states.

Energy and Thermodynamics of the Quantum-Corrected Schwarzschild Black Hole

Energy and thermodynamics are investigated in the Schwarzschild black hole spacetime when considering corrections due to quantum vacuum fluctuations. The Einstein and M？ller prescriptions are used to derive the expressions of the energy in the background. The temperature and heat capacity are also derived. The results show that due to the quantum fluctuations in the background of the Schwarzschild black hole, all the energies increase and the Einstein energy differs from M？ller＇s one. Moreover, when increasing the quantum correction factor aa, the difference between Einstein and M？ller energies, the Unruh–Verlinde temperature as well as the heat capacity of the black hole increases while the Hawking temperature remains unchanged.

Affine Quantization on the Half Line

The similarity between classical and quantum physics is large enough to make an investigation of quantization methods a worthwhile endeavour. As history has shown, Dirac's canonical quantization method works reasonably well in the case of conventional quantum mechanics over Rn but it may fail in non-trivial phase spaces and also suffer from ordering problems. Affine quantization is an alternative method, similar to the canonical quantization, that may offer a positive result in situations for which canonical quantization fails. In this paper we revisit the affine quantization method on the half-line. We formulate and solve some simple models, the free particle and the harmonic oscillator.

Projected changes in Köppen-Trewartha climate zones under 1.5-4℃global warming targets over mid-high latitudes of Northern Asia using an ensemble of RegCM4 simulations

Mid-high latitude Northern Asia is one of the most vulnerable and sensitive areas to global warming,but relatively less studied previously.We used an ensemble of a regional climate model(RegCM4)projections to assess future changes in surface air temperature,precipitation and Köppen-Trewartha(K-T)climate types in Northern Asia under the 1.5-4℃global warming targets.RegCM4 is driven by five CMIP5 global models over an East Asia domain at a grid spacing of 25 km.Validation of the present day(1986-2005)simulations shows that the ensembles of RegCM4(ensR)and driving GCMs(ensG)reproduce the major characters of the observed temperature,precipitation and K-T climate zones reasonably well.Greater and more realistic spatial detail is found in RegCM4 compared to the driving GCMs.A general warming and overall increases in precipitation are projected over the region,with these changes being more pronounced at higher warming levels.The projected warming by ensR shows different spatial patterns,and is in general lower,compared to ensG in most months of the year,while the percentage increases of precipitation are maximum during the cold months.The future changes in K-T climate zones are characterized by a substantial expansion of Dc(temperature oceanic)and retreat of Ec(sub-arctic continental)over the region,reaching∼20%under the 4℃warming level.The most notable change in climate types in ensR is found over Japan(∼60%),followed by Southern Siberia,Mongolia,and the Korean Peninsula(∼40%).The largest change in the K-T climate types is found when increasing from 2 to 3℃.The results will help to better assess the impacts of climate change and in implementation of appropriate adaptation measures over the region.

数值模式不同分辨率和地形对东亚降水模拟影响的试验

为探讨东亚地区降水数值模拟中水平分辨率和地形的作用,使用RegCM2区域气候模式,采用不同的模式分辨率和地形,对东亚降水进行对比模拟试验。结果表明,东亚地区降水的模拟效果取决于模式的水平分辨率,模式分辨率越高,模拟的效果越好。使用实际地形的模拟效果好于使用平滑地形的。但同时,使用较高分辨率的平滑地形的模拟,效果好于使用次高分辨率的实际地形的模拟。这表明在东亚地区降水模拟中,分辨率与地形相比,起着至少同样重要的作用。结果指出,对东亚地区降水的模拟而言,使用60 km及以上分辨率可能是必需的。

中国高精度土地覆盖数据在RegCM4/CLM模式中的引入及其对区域气候模拟影响的分析

基于中国1∶100万植被图和1∶600万植被区划图,按照通用陆面模式CLM植被功能型分类标准,制作了可用于CLM及RegCM4区域气候模式的25 km×25 km分辨率的中国高精度土地覆盖数据(简称VEG数据).相比CLM默认使用的土地覆盖数据(简称ORG数据),VEG数据不仅能提供更多的土地覆盖局地特征,还纠正了ORG数据中裸地和农作物的比例偏高、灌木的比例偏低等误差.对比使用两套土地覆盖数据的RegCM4多年连续积分结果,分析了不同土地覆盖分布对气温、降水等的影响,并从地表能量收支的角度给出影响机理解释.结果显示:VEG数据的使用,使得模式对冬季气温和降水的模拟能力有一定提高,模式在南部区域偏干偏冷的系统误差有所减弱;采用VEG数据后,由于粗糙度、反照率等下垫面参数的改变及云量的变化,使得地表能量收支发生显著调整.青藏高原地区的气温变化与湍流通量和长波辐射的变化有密切的联系,主要源自粗糙度引起的湍流通量增加、以及云量引起的向下净长波辐射增加.而在中国中部和南部,短波辐射变化更为明显,它与地表反照率的变化相一致.基于所制作的土地覆盖数据,可广泛应用于CLM模式在中国区域的应用之中.

全球变暖背景下中国区域不同强度降水事件变化的高分辨率数值模拟

对一个20km高水平分辨率区域气候模式(RegCM3)所模拟的全球变暖背景下,中国区域未来不同强度降水事件变化进行了分析。以日降水量的大小,将降水划分为不同等级。首先检验了模式对当代(1961—1990年)各等级降水日数的模拟能力,结果表明,与观测相比,模式模拟的小雨事件偏多而大雨事件在南方过少。21世纪末(2071—2100年)在IPCC SRES A2温室气体排放情景下,中国区域不同强度降水的变化在各地表现不同,同时其对各个地区降水总量变化的贡献也表现出较大不同,但在大部分地区,模式给出了未来强降水事件将增加的结果。

华北地区未来气候变化的高分辨率数值模拟

使用20km高水平分辨率的区域气候模式RegCM3,单向嵌套FvGCM/CCM3全球模式,进行了中国区域气候变化的数值模拟试验,分析华北地区夏半年4-9月的气温、降水和高温、干旱事件的变化。模式积分时间分为两个时段,分别为当代的1961-1990年和在IPCC SRES A2温室气体排放情景下的21世纪末2071-2100年。模式检验结果表明:在大部分月份,区域模式对当代气候的模拟都较全球模式更好。两个模式模拟的未来气温和降水变化,在空间分布型和量级上都有一定不同,如区域模式的升温更高,降水出现大范围减少等。此外,使用日最高气温不低于35℃的日数(D_(T35))和考虑了湿度因素的炎热指数(I_(H))不低于35℃的日数(D_(H135)),分析了区域模式模拟的未来高温事件变化,结果表明:未来华北地区D_(T35)和平原地区D_(H135)均有较大增加。未来华北地区的连续干旱日数(CDD)将增加,依照UNEP(United Nations Environment Programme)干旱指数(A_(U))给出的气候湿润区将有较大幅度减少,而半湿润半干旱区和半干旱区面积将增加。

新疆21世纪气候变化的高分辨率模拟

使用一个25km高水平分辨率区域气候模式(RegCM3),嵌套MIROC3.2_hires全球气候模式结果,进行了IPCC SRES A1B情景下,东亚区域21世纪气候变化的模拟,针对新疆地区进行了分析.首先对模式模拟的当代(1981—2000年)气候进行检验,结果表明:模式对年平均气温、降水的空间分布和数值均具有较好的模拟能力,但与观测相比,模拟的气温一般在盆地偏高、山区偏低,降水则在盆地偏少、山区偏多.在IPCC SRES A1B温室气体排放情景下,21世纪中期(2041—2060年)及末期(2081—2100年)新疆地区冬、夏季气温均将升高,末期的增温幅度更大,特别是在末期的冬季.降水除个别地区外将普遍增加,同样末期增加更多.在不同地形条件下,气温和降水的变化特点均有所不同,其中盆地增温大、山区增温小,降水量在山区和盆地过渡地带的变化最明显,以增加为主并表现出一定的季节特征.相对于全国平均而言,新疆地区的增温和降水量增加更显著.

RegCM3区域气候模式对中国气候的模拟

使用RegCM3区域气候模式嵌套ERA40再分析资料,对东亚地区进行了15 a(1987-2001年)时间长度的数值积分试验。结果表明:模式可较好地模拟中国地面气温的分布和季节变化,但存在系统性的冷偏差;对降水的变化模拟也较好,但其地理分布模拟存在一定偏差。

A Daily Temperature Dataset over China and Its Application in Validating a RCM Simulation

This paper describes the construction of a 0.5°× 0.5° daily temperature dataset for the period of 1961- 2005 over China's Mainland for the purpose of climate model validation. The dataset is based on the interpolation from 751 observing stations in China and comprises 3 variables： daily mean, minimum, and maximum temperature. The ＂anomaly approach＂ is applied in the interpolation. The gridded climatology of 1971-2000 is first calculated and then a gridded daily anomaly for 1961-2005 is added to the climatology to obtain the final dataset. Comparison of the dataset with CRU （Climatic Research Unit） observations at the monthly scale shows general agreement between the two datasets. The differences found can be largely attributed to the introduction of observations at new stations. The dataset shows similar interannual variability as does CRU data over North China and eastern part of the Tibetan Plateau, but with a slightly larger linear trend. The dataset is employed to validate the simulation of three extreme indices based on daily mean, minimum, and maximum temperature by a high-resolution regional climate model. Results show that the model reproduces these indices well. The data are available at the National Climate Center of China Meteorological Administration, and a coarser resolution （1°× 1°） version can be accessed via the World Wide Web.