Application of an inverse model in the community modeling effort results

Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 1995Inverse modeling activities in oceanography have recently been intensified, aided by the oncoming observational data stream of WOCE and the advance of computer power. However, interpretations of inverse model results from climatological hydrographic data are far from simple. This thesis examines the behavior of an inverse model in the WOCE CME (Community Modeling Effort) results where the physics and the parameter values are known. The ultimate hypotheses to be tested are whether the inferred circulations from a climatological hydrographic data set (where limited time means and spatial smoothing are usually used) represent the climatological ocean general circulations, and what the inferred "diffusion" coefficients really are. The inverse model is first tested in a non-eddy resolving numerical GCM ocean. Numerical/scale analyses are used to test whether the inverse model properly represents the GCM ocean. Experiments show how biased answers could result from an incorrect model, and how a correct model must produce the right answers. When the inverse model is applied to the time-mean hydrographic data of an eddy-resolving GCM ocean in the fine grid resolution of the GCM, the estimated horizontal circulation is statistically consistent with the EGCM time means in both patterns and values. Although the flow patterns are similar, the uncertainties for the GCM time means and the inverse model estimates are different. The former are very large, such that the GCM time-mean circulation has no significance in the deep ocean. The latter are much smaller, and with them the estimated circulations are well defined. This is consistent with the concept that ocean motions are very energetic, while variations of tracers (temperature, salinity) are low frequency. The inverse model succeeded in extracting the ocean general circulation from the "climatological" hydrographic data. The estimated vertical velocities are also statistically indistinguishable from the GCM time means. However, significant differences between the estimated "diffusion" coefficients and the EGCM eddy diffusion coefficients are found at certain locations. These discrepancies are attributed to the differences in physics of the inverse model and the EGCM ocean. The "diffusion" coefficients from the inversion parameterize not only the eddy fluxes, but also (part of) the temporal variation and biharmonic terms which are not explicitly included in the inverse model. Given the essentially red spectrum of the ocean, it makes sense to look for smooth solutions. Aliasing due to subsampling on a coarse grid and the effects of spatial smoothing are addressed in the last part of this thesis. It is shown that this aliasing could be greatly reduced by spatial smoothing. The estimated horizontal circulation from the spatially smoothed time-mean EGCM hydrographic data with a coarse grid resolution (2.4° longitude by 2.0° latitude) is generally consistent with the spatially smoothed EGCM time means. Significant differences only occur at some grid points at great depths, where the GCM circulations are very weak. The conclusions of this study are different from some previous studies. These discrepancies are explained in the concluding chapter. Finally, it should be pointed out that the issue of properly representing a GCM ocean by an inverse model is not identical to the issue of represent ing the real ocean by the same inverse model, since the GCM ocean is not identical to the real ocean. Numerical calculations show that both the non-eddy resolving and the eddy-resolving GCM oceans used in this work are evolving towards a statistical equilibrium. In the real ocean, the importance of temporal variation terms in the property conservation equations should also be analyzed when a steady mverse model is applied to a limited time-mean (the climatological) data set.This research was carried out under National Science Foundation grant OCE- 90-04396

Circulation and water mass balance in the Brazil Basin

Analysis of data from the Levitus (1982) atlas shows that the application of the Montgomery streamfunction to the potential density surfaces induces an error which cannot be ignored in some regions in the ocean. The error arises from the variation of the specific volume anomaly along isopycnal surfaces. By including the major part of this effect, new streamfunctions, named the pressure anomaly and mean pressure streamfunctions, are suggested for use in potential density coordinates. By including the variations of specific volume anomaly and pressure along isopycnal surfaces, the inverse model proposed by Hogg (1987) is modified for increased accuracy and then applied to the Brazil Basin to study the circulation, diffusion and water mass balances. The system of equations with constraints of positive diffusivities and oxygen consumption rates is solved by the inverse method. By using multiple tracers and controlling the scale of variation of the diffusion coefficients we are able to construct an overdetermined system whose solution is by a least-square approach. The results indicate that the circulation in the upper ocean is consistent with previous work, but that in the deep ocean differs from some previous analyses. In the NADW depth, we find a coincidence of flow with tongues of water properties. The diffusivities and diapycnal velocities seem stronger in the region near the equator than in the south, with reasonable values. Diffusion plays an important role in the water property balances. Examples show that similar property patterns may result from different processes

Deducing dynamic properties from simulated hydrographic data: Part I. Results from a non-eddy-resolving model

Inverse models are widely used in oceanography. However, their reliability remains an open question, as comparison of inverse model results with real values of ocean parameters is difficult due to insufficient knowledge of the latter. The feasibility of extracting the ocean general circulation, mixing rates, as well as air-sea heat and freshwater fluxes from hydrographic data is studied by applying an inverse model to the CME (Community Modeling Effort) results where both the physics and parameter values are known. The inverse model assumes approximate thermal wind balance and steady state conservation laws for mass, heat, and salt, assumptions satisfied by the GCM ocean although the residuals in the tracer conservation equations are comparable to the diffusion terms in the deep ocean. Effects of errors in these equations on inverse model solutions for different variables are studied in detail. A surface layer model is designed to estimate the air-sea heat and freshwater fluxes and the results are compared to their “true” values. Experiments on various parameterizations of different variables are carried out in the hope of getting some guidance in applying the inverse model to the real ocean. The inverse model estimates for horizontal circulation are relatively robust—they are consistent with the GCM ocean circulations in most of the experiments, and effects of equation errors are more pronounced in the estimates for diffusivity and air-sea fluxes. Residuals in the equations are noisy and resemble a random distribution. In such cases, the estimates for all the parameters are very close to their true values. The conclusions of this work are different from previous works, and the discrepancies are explained

Aqua­(propane­dioato-κ2 O 1,O 3)[2-(1H-pyrazol-1-yl-κN 2)-1,10-phenanthroline-κ2 N,N′]nickel(II) trihydrate

In the title mononuclear complex, [Ni(C3H2O4)(C15H10N4)(H2O)]·3H2O, the metal center is coordinated in a distorted NiN3O3 geometry. In the crystal structure, inter­molecular O—H⋯O hydrogen bonds link the components into a two-dimensional network. In addition, there are weak π–π stacking inter­actions between symmetry-related phenanthroline rings, with a centroid–centroid distance of 3.6253 (17) Å

Mining Word Boundaries in Speech as Naturally Annotated Word Segmentation Data

Inspired by early research on exploring naturally annotated data for Chinese word segmentation (CWS), and also by recent research on integration of speech and text processing, this work for the first time proposes to mine word boundaries from parallel speech/text data. First we collect parallel speech/text data from two Internet sources that are related with CWS data used in our experiments. Then, we obtain character-level alignments and design simple heuristic rules for determining word boundaries according to pause duration between adjacent characters. Finally, we present an effective complete-then-train strategy that can better utilize extra naturally annotated data for model training. Experiments demonstrate our approach can significantly boost CWS performance in both cross-domain and low-resource scenarios.Comment: latest versio

A new stripe rust resistance gene transferred from Thinopyrum intermedium to hexaploid wheat (Triticum aestivum)

Wheat stripe rust (Puccinia striiforis f. sp. tritici) races CYR31 and CYR32, prevalent in China, are virulent to many wheat stripe rust resistance genes (Yr genes). To expand the availability of effective resistance to CYR31 and CYR32, stripe rust resistance was transferred from intermediate wheatgrass (Thinopyrum intermedium) to common wheat (Triticum aestivum). The susceptible wheat cultivar CM107 was crossed with amphiploid TAI7047, derived from the wide cross Taiyuan768/Thinopyrum intermedium//76(64). Two wheat lines originating from the cross, YU24 and YU25, were resistant to CYR31 and CYR32. Pedigree analysis showed that the resistance to stripe rust in YU24 and YU25 originated from intermediate wheatgrass. Genetic analyses indicated that the resistance to stripe rust is controlled by a single dominant gene. Allelic tests determined that the resistance gene(s) in YU24 and YU25 are identical. The new gene has temporarily been designated as YrYU25. SSR and RAPD analyses showed that YrYU25 was introduced by cryptic translocation into common wheat.Les races CYR31 et CYR32 de la rouille jaune du blé (Puccinia striiforis f. sp. tritici), très répandues en Chine, sont virulentes pour plusieurs gènes de résistance à cette maladie (gènes Yr). Afin d'accroître la disponibilité d'une résistance efficace aux races CYR31 et CYR32, la résistance à la rouille jaune du blé a été transférée de l'agropyre intermédiaire (Thinopyrum intermedium) au blé tendre (Triticum aestivum). CM107, un cultivar de blé sensible, a été croisé avec l'amphiploïde AI7047 dérivé du croisement éloigné Taiyuan768/Thinopyrum intermedium//76(64). Deux lignées de blé provenant de ce croisement, soit YU24 et YU25, étaient résistantes aux races CYR31 et CYR32. Une analyse généalogique a démontré que la résistance à la rouille jaune du blé chez les lignées YU24 et YU25 provenait de l'agropyre intermédiaire. Des analyses génétiques ont indiqué que cette résistance était contrôlée par un seul gène dominant. Des tests d'allélisme ont révélé que le(s) gène(s) de résistance dans les lignées YU24 et YU25 étaient identiques. Le nouveau gène a temporairement été nommé YrYU25. Des analyses SSR et RAPD ont démontré que le gène YrYU25 avait été introduit dans le blé tendre par translocation cryptique

Efficient Document-level Event Extraction via Pseudo-Trigger-aware Pruned Complete Graph

Most previous studies of document-level event extraction mainly focus on building argument chains in an autoregressive way, which achieves a certain success but is inefficient in both training and inference. In contrast to the previous studies, we propose a fast and lightweight model named as PTPCG. In our model, we design a novel strategy for event argument combination together with a non-autoregressive decoding algorithm via pruned complete graphs, which are constructed under the guidance of the automatically selected pseudo triggers. Compared to the previous systems, our system achieves competitive results with 19.8\% of parameters and much lower resource consumption, taking only 3.8\% GPU hours for training and up to 8.5 times faster for inference. Besides, our model shows superior compatibility for the datasets with (or without) triggers and the pseudo triggers can be the supplements for annotated triggers to make further improvements. Codes are available at https://github.com/Spico197/DocEE .Comment: Accepted to IJCAI'202

Application of an inverse model in the community modeling effort results

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1995.Includes bibliographical references (p. 255-262).by Huai-Min Zhang.Ph.D

Circulations and water mass balances in the Brazil Basin

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences and Woods Hole Oceanographic Institution, 1991.Bibliography: p.151-155.by Huai-Min Zhang.M.S