An observing system simulation experiment (OSSE) using an ensemble coupled data assimilation system was designed to investigate the impact of deep ocean Argo profile assimilation in a biased numerical climate system. Based on the modern Argo observational array and an artificial extension to full depth, “observations” drawn from one coupled general circulation model (CM2.0) were assimilated into another model (CM2.1). Our results showed that coupled data assimilation with simultaneous atmospheric and oceanic constraints plays a significant role in preventing deep ocean drift. However, the extension of the Argo array to full depth did not significantly improve the quality of the oceanic climate estimation within the bias magnitude in the twin experiment. Even in the “identical” twin experiment for the deep Argo array from the same model (CM2.1) with the assimilation model, no significant changes were shown in the deep ocean, such as in the Atlantic meridional overturning circulation and the Antarctic bottom water cell. The small ensemble spread and corresponding weak constraints by the deep Argo profiles with medium spatial and temporal resolution may explain why the deep Argo profiles did not improve the deep ocean features in the assimilation system. Additional studies using different assimilation methods with improved spatial and temporal resolution of the deep Argo array are necessary in order to more thoroughly understand the impact of the deep Argo array on the assimilation system. 相似文献
Sufficient low‐frequency information is essential for full‐waveform inversion to get the global optimal solution. Multi‐scale envelope inversion was proposed using a new Fréchet derivative to invert the long‐wavelength component of the model by directly using the low‐frequency components contained in an envelope of seismic data. Although the new method can recover the main structure of the model, the inversion quality of the model bottom still needs to be improved. Reflection waveform inversion reduces the dependence of inversion on low‐frequency and long‐offset data by using travel‐time information in reflected waves. However, when the underground medium contains strong contrast or the initial model is far away from the true model, it is hard to get reliable reference reflectors for the generation of reflected waves. Here, we propose a combination inversion algorithm, i.e., reflection multi‐scale envelope inversion, to overcome the limitations of multi‐scale envelope inversion and reflection waveform inversion. First, wavefield decomposition was introduced into the multi‐scale envelope inversion to improve the inversion quality of the long‐wavelength components of the model. Then, after the initial model had been established to be accurate enough, migration and de‐migration were introduced to achieve multi‐scale reflection waveform inversion. The numerical results of the salt‐layer model and the SEG/EAGE salt model verified the validity of the proposed approach and its potential. 相似文献
Super Typhoon Haiyan devastated portions of Southeast Asia, particularly the Philippines, on November 8, 2013. In this paper, observational data are used to analyze the intensification process of Super Typhoon Haiyan. Observational data showed that Typhoon Haiyan intensified and the maximum sustained winds increased to 59 ms?1 after it encountered a double warm-core ocean eddy, while the central pressure of the typhoon dropped from 970 hPa to 920 hPa. Numerical simulations and observational data show that the presence of the warm-core eddy combined with SST increases due to climate change led to the rapid intensification of Super Typhoon Haiyan. Comparing these two factors, the warm-core ocean eddy, which brings significantly more heat into the upper ocean, plays the leading role in the intensification, with climate warming making a lesser contribution. Moreover, due to the increased thickness of the mixed layer associated with the warm-core ocean eddy, Super Typhoon Haiyan did not significantly decrease the sea surface temperature to the east of the Philippines, as is typical of typhoons, and the largest decrease was approximately 1 °C. 相似文献
Meridional heat transport of the western Pacific boundary current (the Kuroshio Current) is one of the key factors in global climate change. This current is important because it controls the temperature gradient between low latitudes and the North Pacific and so significantly influences mid-latitude atmosphere-ocean interactions. Here we reconstruct changes in hydrological conditions within the mid-latitude mainstream of the Kuroshio Current based on faunal analysis of planktonic foraminifera in core DSDP 296 from the Northwest Pacific Ocean. This approach enabled us to deduce evolutionary processes within the Kuroshio Current since the Pliocene. A total of 57 species in the coarser section (>150 µim) were identified; results indicate that planktonic foraminiferal faunal evolution has mainly been characterized by three major stages, the first of which comprised mixed-layer warm-water species of Globigerinoides ruber which first appeared between 3.5 and 2.7 Ma and then gradually increased in content. Percentages of another warm-water species of G. conglobatus also gradually increased in number over this interval. Variations in warm-water species indicate a gradual rise in sea surface temperature (SST) and imply initiation of Kuroshio Current impact on the Northwest Pacific Ocean since at least 3.5 Ma. Secondly, over the period between 2.7 and 2.0 Ma, thermocline species of Globigerina calida, Neogloboquadrina humersa, Neogloboquadrina dutertrei, and Pulleniatina obliquiloculata started to appear in the section. This fauna was dominated by G. ruber as well as increasing G. conglobatus contents. These features imply a further rise in SST and its gradually enhanced influence on thermocline water, suggesting strengthening of the Kuroshio Current since 2.7 Ma. Thirdly, between 2.0 Ma and present, increasing contents of thermocline species (i.e., G. calida, N. dutertrei and P. obliquiloculata) indicate a gradual rise in seawater temperature at this depth and also imply more intensive Kuroshio Current during this period. On the basis of comparative records from cores ODP 806 and DSDP 292 from the low latitude Western Pacific, we propose that initiation of the impact of the Kuroshio Current in the Northwest Pacific and it subsequent stepwise intensifications since 3.5 Ma can be closely related to the closure and restriction of the Indonesian and Central American seaways as well as variations in the Western Pacific Warm Pool (WPWP) and equatorial Pacific region.
