Elimination of Computational Systematic Errors and Improvements of Weather and Climate System Models in Relation to Baroclinic Primitive Equations

The design of a total energy conserving semi-implicit scheme for the multiple-level baroclinic primitive equation has remained an unsolved problem for a long time. In this work, however, we follow an energy perfect conserving semi-implicit scheme of a European Centre for Medium-Range Weather Forecasts (ECMWF) type sigma-coordinate primitive equation which has recently successfully formulated. Some real-data contrast tests between the model of the new conserving scheme and that of the ECMWF-type of global spectral semi-implicit scheme show that the RMS error of the averaged forecast Height at 850 hPa can be clearly improved after the first integral week. The reduction also reaches 50 percent by the 30th day. Further contrast tests demonstrate that the RMS error of the monthly mean height in the middle and lower troposphere also be largely reduced, and some well-known systematical defects can be greatly improved. More detailed analysis reveals that part of the positive contributions comes from improvements of the extra-long wave components. This indicates that a remarkable improvement of the model climate drift level can be achieved by the actual realizing of a conserving time-difference scheme, which thereby eliminates a corresponding computational systematic error source/sink found in the currently-used traditional type of weather and climate system models in relation to the baroclinic primitive equations.

Penalized total least squares method for dealing with systematic errors in partial EIV model and its precision estimation

When the total least squares(TLS)solution is used to solve the parameters in the errors-in-variables(EIV)model,the obtained parameter estimations will be unreliable in the observations containing systematic errors.To solve this problem,we propose to add the nonparametric part(systematic errors)to the partial EIV model,and build the partial EIV model to weaken the influence of systematic errors.Then,having rewritten the model as a nonlinear model,we derive the formula of parameter estimations based on the penalized total least squares criterion.Furthermore,based on the second-order approximation method of precision estimation,we derive the second-order bias and covariance of parameter estimations and calculate the mean square error(MSE).Aiming at the selection of the smoothing factor,we propose to use the U curve method.The experiments show that the proposed method can mitigate the influence of systematic errors to a certain extent compared with the traditional method and get more reliable parameter estimations and its precision information,which validates the feasibility and effectiveness of the proposed method.

Systematic error suppression scheme of the weak equivalence principle test by dual atom interferometers in space based on spectral correlation

Systematic error suppression and test data processing are very important in improving the accuracy and sensitivity of the atom interferometer(AI)-based weak-equivalence-principle(WEP) test in space. Here we present a spectrum correlation method to investigate the test data of the AI-based WEP test in space by analyzing the characteristics of systematic errors and noises. The power spectrum of the Eotvos coefficient η, systematic errors, and noises in AI-based WEP test in space are analyzed and calculated in detail. By using the method, the WEP violation signal is modulated from direct current(DC) frequency band to alternating current(AC) frequency band. We find that the signal can be effectively extracted and the influence of systematic errors can be greatly suppressed by analyzing the power spectrum of the test data when the spacecraft is in an inertial pointing mode. Furthermore, the relation between the Eotvos coefficient η and the number of measurements is obtained under certain simulated parameters. This method will be useful for both isotopic and nonisotopic AI-based WEP tests in space.

The Influence of Systematic Errors on the Asian Summer Monsoon Circulation

The systematic errors of wind field associated with the prediction of Asian summer monsoon and their impact on the monsoon circulation have been studied in this paper. The daily operational analyses and fore-casts (up to day-5) of the National Centre for Medium Range Weather Forecasting (NCMRWF), India, over the Asian summer monsoon domain for the period June, July and August of 1995 are made use for the purpose. The systematic errors associated with the low level flow delineate, reduction in the strength of trade winds leading to weakening of cross equatorial flow as well as westerly flow over Indian Ocean. The upper level errors connote weakening of Tibetan anticyclone and reduction in the strength of return flow into the Southern Hemisphere. Further, these errors evince growing tendency with increase in the forecast period. Apart from the general underestimation of kinetic energy budget terms, the model forecasts fail to represent the transient eddies. The forecasts show increasing trend in the conversion of eddy to mean kinetic energy. These errors enfeeble Asian summer monsoon circulation with increase in the forecast period. Key words Monsoon - Systematic errors - Kinetic energy budget The author is grateful to the NCMRWF for providing data and computing facilities to carry out the present study.

The error research on vertical rigidity theory’s formula of airborne air spring

On the basis of analyzing the result of numerical simulation and that of theoretical analysis,the systematic error of some air spring's theoretical formula is researched. The result shows that the vertical stiffness's theoretical formula of air spring owes the systematic error. And the systematic error is relative to the three supposed conditions which are used in the process of theoretical deduction. However,the systematic error is small enough so that the supposed conditions of theoretical formula are reasonable. Moreover,with the increase of initial inner pressure,the systematical error increases.

Systematic error real-time registration based onmodified input estimation

In order to estimate the systematic error in the processof maneuvering target adaptive tracking, a new method is proposed.The proposed method is a linear tracking scheme basedon a modified input estimation approach. A special augmentationin the state space model is considered, in which both the systematicerror and the unknown input vector are attached to thestate vector. Then, an augmented state model and a measurementmodel are established in the case of systematic error, andthe corresponding filter formulas are also given. In the proposedscheme, the original state, the acceleration and the systematicerror vector can be estimated simultaneously. This method can notonly solve the maneuvering target adaptive tracking problem in thecase of systematic error, but also give the system error value inreal time. Simulation results show that the proposed tracking algorithmoperates in both the non-maneuvering and the maneuveringmodes, and the original state, the acceleration and the systematicerror vector can be estimated simultaneously.

SYSTEMATIC ERROR FROM Th/U RATIO IN LUMINESCENCE AND ESR DATING

In luminescence and ESR dating methods,total count rate from thick source alpha counting is commonly used fox estimating annual dose with assumption of equal activities for both uranium and thorium decay chains.This is equal to a Th/U weight ratio of 3.2.The systematic error in total dose rate due to uncertainty of the ratio is calculated.It is found that the error is insignificant for uniformly distributed samples such as sediment,but can be significant for some extreme circumstances.

The Orbital Error Analysis and Study of Space Vehicle Active Phase

In this paper we solve the three-dimensional coordinate that the satellite is relative to the geocentric coordinate under certain conditions, making use of the satellite orbit standard trajectory differential equations. By means of the method of tri-parametric equation fitting, we confirm the three-dimensional trajectory function of target flying object to geocentric coordinate in double satellites observation conditions, and analyze theoretical errors.

STUDY OF THE EFFECTS OF REDUCING SYSTEMATIC ERRORS ON MONTHLY REGIONAL CLIMATE DYNAMICAL FORECAST

A nested-model system is constructed by embedding the regional climate model RegCM3 into a general circulation model for monthly-scale regional climate forecast over East China. The systematic errors are formulated for the region on the basis of 10-yr (1991-2000) results of the nested-model system, and of the datasets of the Climate Prediction Center (CPC) Merged Analysis of Precipitation (CMAP) and the temperature analysis of the National Meteorological Center (NMC), U.S.A., which are then used for correcting the original forecast by the system for the period 2001-2005. After the assessment of the original and corrected forecasts for monthly precipitation and surface air temperature, it is found that the corrected forecast is apparently better than the original, suggesting that the approach can be applied for improving monthly-scale regional climate dynamical forecast.

Autonomous relative optical navigation based on unified modeling of external systematic errors

To solve the problem that external systematic errors of the optical camera cannot be fully estimated due to limited computing resources,a unified dimensionality reduction representation method for the external systematic errors of the optical camera is proposed,and autonomous relative optical navigation is realized.The camera translational and misalignment errors are converted into a three-dimensional rotation error,whose differential model can be established through specific attitude control and appropriate assumption.Then,the rotation error and the relative motion state are jointly estimated in an augmented Kalman filter framework.Compared with the traditional method that estimates the camera translational and misalignment errors,the proposed method reduces the computational complexity in that the estimated state dimension is reduced.Furthermore,as demonstrated by numerical simulation,the estimation accuracy is improved significantly.

Calibration of a compact absolute atomic gravimeter

Compact atomic gravimeters are the potential next generation precision instruments for gravity survey from fundamental research to broad field applications.We report the calibration results of our home build compact absolute atomic gravimeter USTC-AG02 at Changping Campus,the National Institute of Metrology(NIM),China in January 2019.The sensitivity of the atomic gravimeter reaches 35.5μGal/√Hz(1μGal=1×10-8 m/s2)and its long-term stability reaches 0.8μGal for averaging over 4000 seconds.Considering the statistical uncertainty,the dominant instrumental systematic errors and environmental effects are evaluated and corrected within a total uncertainty(2σ)of 15.3μGal.After compared with the reference g value given by the corner cube gravimeter NIM-3A,the atomic gravimeter USTC-AG02 reaches the degree of equivalence of 3.7μGal.

Novel method to calibrate kinematic parameters for mobile robots

In order to reduce the system errors of dead reckoning and improve the localization accu- racy, a new model for systematic error of mobile robot was defined and a UMBmark-based method for calibrating and compensating systematic error was presented. Three dominant reasons causing systematic errors were considered： imprecise average wheel diameter, uncertainty about the effec- tive wheelbase and unequal wheel＇ s diameter. The new model for systematic errors is considering the coupling effect of the three factors during the localization of mobile robot. Three coefficients to calibrate average wheel diameter, effective wheelbase, left and right wheels＇ diameter were ob- tained. Then these three coefficients were used to make improvements on robot kinematic equations. The experiments on the dual-wheel drive mobile robot DaNI show that the presented method has achieveda significant improvement in the location accuracy compared with the UMBmark calibration.

The 3-Hour-Interval Prediction of Ground-Level Temperature in South Korea Using Dynamic Linear Models

The 3-hour-interval prediction of ground-level temperature from +00 h out to +45 h in South Korea (38 stations) is performed using the DLM (dynamic linear model) in order to eliminate the systematic error of numerical model forecasts. Numerical model forecasts and observations are used as input values of the DLM. According to the comparison of the DLM forecasts to the KFM (Kalman filter model) forecasts with RMSE and bias, the DLM is useful to improve the accuracy of prediction.

MOTION COMPENSATION FOR HIGH RESOLUTION AIRBORNE SAR WITH IMU & GPS

Inertial measurement unit (IMU) is a standard motion sensor in modern airborne SAR systems. But how to remove its systematic error is a difficult problem, which impacts the improvement of resolution in azimuth. The technique of motion compensation presented in this paper, uses the GPS as a reference system to estimate and correct the systematic error of the IMU on the concept of linear unbiased minimum variance (LUMV). This new and effective method achieves very accurate position measurement (both high and low frequency) of the APC in not only short but also long terms, so that it can satisfy the requirement of high resolution airborne SAR. In the last section of the paper, some experimental simulations from raw data are given.

The Development of a Physical Conservation Fidelity Global Spectral Model-From Dynamic Framework to a Full Model

The fidelity scheme of physical conservation laws has been applied in the dynamic framework of a global spectral model. In this study, a set of diabatic physical processes are also involved. Based on six 30-day numerical integrations of real-time data, we show that the full model is able to reproduce the primary features of global energy cycle and hydrological distribution. Additionally, the root-mean-square error is dramatically decreased when diabatic processes are considered. Another advantage is that the false structure of ＂double Intertropical Convergence Zone （ITCZ）＂ is not seen in the result, although the orecioitation rate becomes lower.

Unitary Noise and the Mermin-GHZ Game

Communication complexity is an area of classical computer science which studies how much communication is necessary to solve various distributed computational problems.Quantum information processing can be used to reduce the amount of communication required to carry out some distributed problems.We speak of pseudo-telepathy when it is able to completely eliminate the need for communication.Since it is generally very hard to perfectly implement a quantum winning strategy for a pseudo-telepathy game,quantum players are almost certain to make errors even though they use a winning strategy.After introducing a model for pseudotelepathy games,we investigate the impact of erroneously performed unitary transformations on the quantum winning strategy for the Mermin-GHZ game.The question of how strong the unitary noise can be so that quantum players would still be better than classical ones is also dealt with.

Tilt adjustment for a portable absolute atomic gravimeter

For an atomic gravimeter,the measured value of the Earth’s gravity acceleration g is the projection of the local gravity on the direction of Raman laser beams.To accurately measure the g,the Raman laser beams should be parallel to the g direction.We analyze the tilt effect of the Raman beams on g measurement and present a general method for the tilt adjustment.The systematic error caused by the tilt angle is evaluated as 0(+0,0.8)µGal(1µGal=10 nm/s^2)and the drift is also compensated in real time.Our method is especially suitable for the portable atomic gravimeter which focuses on the mobility and field applications.

Retesting Early Generation Stability of a Japonica Rice Variety 84-15 by Using Allelic Differences of Two Qualitative Traits

Early generation stability of a japonica rice variety, 84-15, was retested by using the allelic differences of two qualitative traits, i.e., glume tip color and waxy endosperm. Results showed that both glurne tip color and waxy endosperm segregated in progenies of single F1 plants derived from two crosses of 84-15/Zi 18 （purple color） and 84-15/Dahuaxiangnuo （waxy）. The results denied the conclusion obtained in previous studies that 84-15 had a characteristic of early generation stability. Moreover, it was found that using the coefficient of variation as an indicator of early generation stability was unreasonable by analyzing plant height as an example. Importance of avoiding systematic error in research works was also discussed.

Prediction of Typhoon Tracks Using Dynamic Linear Models

This paper presents a study on the statistical forecasts of typhoon tracks. Numerical models have their own systematic errors, like a bias. In order to improve the accuracy of track forecasting, a statistical model called DLM (dynamic linear model) is applied to remove the systematic error. In the analysis of typhoons occurring over the western North Pacific in 1997 and 2000, DLM is useful as an adaptive model for the prediction of typhoon tracks.

Analysis of the merged quasi-geoid of neighbouring areas

Employing the merged quasi-geoid, we analyses the causes of systematic errors in modelling of quasigeoid of neighbouring areas in the paper, and the efficient method is introduced to improve the accuracy of quasi-geoid. First, the systematic error is weakened with the moving window method applied to established quasi-geoids in two adjacent regions, and the accuracy of the merged quasi-geoid in the stitching region is checked using the measured GPS benchmark data; Second, the whole quasi-geoid is recomputed with data obtained from two adjacent regions if the accuracy of the quasi-geoid obtained from the first step in the stitching region is low; Finally, the quasi-geoids in two adjacent regions are recomputed respectively using GPS benchmark data of own region and adjacent region with the same solution if the accuracy of whole quasi-geoid obtained from the second step also is low. Actual data sets from Sichuan Province and Chongqing City are employed to test the moving window method. It is shown that the quasi-geoid models with high resolution and accuracy were obtained.