The Maintenance of Conservative Physical Laws within Data Assimilation Systems

Jacobs, G.A.; Ngodock, H.B.
November 2003
Monthly Weather Review;Nov2003, Vol. 131 Issue 11, p2595
Academic Journal
In many data assimilation applications, adding an error to represent forcing to certain dynamical equations may be physically unrealistic. Four-dimensional variational methods assume either an error in the dynamical equations of motion (weak constraint) or no error (strong constraint). The weak-constraint methodology proposes the errors to represent uncertainties in either forcing of the dynamical equations or parameterizations of dynamics. Dynamical equations that represent conservation of quantities (mass, entropy, momentum, etc.) may be cast in an analytical or control volume flux form containing minimal errors. The largest errors arise in determining the fluxes through control volume surfaces. Application of forcing errors to conservation formulas produces nonphysical results (generation or destruction of mass or other properties), whereas application of corrections to the fluxes that contribute to the conservation formulas maintains the physically realistic conservation property while providing an ability to account for uncertainties in flux parameterizations. The results suggest that advanced assimilation systems must not be liberal in applying errors to conservative equations. Rather systems must carefully consider the points at which the errors exist and account for them correctly. Though careful accounting of error sources is certainly not an entirely new idea, this paper provides a focused examination of the problem and examines one possible solution within the 4D variational framework.


Related Articles

  • An Efficient Method of Key-Frame Extraction Based on a Cluster Algorithm. Qiang Zhang; Shao-Pei Yu; Dong-Sheng Zhou; Xiao-Peng Wei // Journal of Human Kinetics;2013, Vol. 39, p5 

    This paper proposes a novel method of key-frame extraction for use with motion capture data. This method is based on an unsupervised cluster algorithm. First, the motion sequence is clustered into two classes by the similarity distance of the adjacent frames so that the thresholds needed in the...

  • Foot-contacting Graphs for Data-Driven Motion Synthesis. Xiaopeng Wei; Pengfei Yi; Qiang Zhang // International Journal of Advancements in Computing Technology;Jan2013, Vol. 5 Issue 1, p884 

    In this paper, foot-contacting graphs are proposed to generate new foot-skate free motion sequences from motion samples. At first, motion capture data are separated to segments and intervals between them, according to the contacting status of feet onto the ground. Then, a weighted directed graph...

  • Application of Motion Estimation in Football Video's Analysis Based on Kill man Filter. Feng Xiao; Hai Ying Fan; DongMei Li // Information Technology Journal;2013, Vol. 12 Issue 18, p3865 

    Football game video contains huge data and information of the event, in the race study course, the segmentation extraction of the targeted players, football and stadium's flags line and prediction tracking is an important technique of video analysis. In this study, it uses the Kalman filter to...

  • Did we get it wrong?  // Hub (Hay River, NT);11/18/2015, Vol. 43 Issue 39, p3 

    No abstract available.

  • Confidence Intervals for a Proportion Using Inverse Sampling when the Data is Subject to False-positive Misclassification. Riggs, Kent // Journal of Data Science;2015, Vol. 13 Issue 4, p623 

    Of interest in this paper is the development of a model that uses inverse sampling of binary data that is subject to false-positive misclassification in an effort to estimate a proportion. From this model, both the proportion of success and false-positive misclassification rate may be estimated....

  • Types and Frequency of Preanalytical Errors in Haematology Lab. UPRETI, SHASHI; UPRETI, SANJAY; BANSAL, RANI; JEELANI, NADIA; BHARAT, VINAY // Journal of Clinical & Diagnostic Research;Nov2013, Vol. 7 Issue 11, p2491 

    Aim: This study was conducted to evaluate the frequency of the preanalytical errors occurring in a haematology laboratory. Material and Methods: A retrospective study was conducted by collecting and analyzing data in duration of one year in the haematology section of the laboratory. Data for all...

  • Acute Effect of Cigarette Smoking on Pupil Size and Ocular Aberrations: A Pre- and Postsmoking Study. Erdem, Uzeyir; Gundogan, Fatih C.; Dinc, Umut Aslı; Yolcu, Umit; Ilhan, Abdullah; Altun, Salih // Journal of Ophthalmology;1/29/2015, Vol. 2015, p1 

    Aim. To evaluate the acute effects of cigarette smoking on photopic and mesopic pupil sizes and wavefront aberrations. Methods. Cigarette smoker volunteers were recruited in the study. Photopic and mesopic pupil sizes and total ocular aberrations were measured before smoking and immediately...

  • Pre-Analytical Data Entry Errors: What is Measured can be Improved. Dawson, Jennifer; Phommarath, Monica // Clinical Leadership & Management Review;2013 Quater3, Vol. 27 Issue 3, p17 

    The article discusses a study on what the present pre-analytical data entry error rate at Forensic Laboratories is and how these errors can be reduced. Topics discussed include the intention of Forensic Laboratories to initiate a temporary billing audit process, a reduction in the overall...

  • Status and prospects for Lorentz invariance and CPT violation tests at KLOE and KLOE-2. Santis, Antonio De; collaborations, KLOE/KLOE-2 // AIP Conference Proceedings;3/29/2012, Vol. 1424 Issue 1, p407 

    The neutral kaon system offers a unique possibility to perform fundamental tests of CPT invariance. In this contribution the KLOE prospects for the measurements of CPT violation in the context of the Standard-Model Extension are presented. Preliminary results on the CPT violating parameters...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics