Subseasonal variability and predictability of the Arctic Oscillation/North Atlantic Oscillation in BCC_AGCM2.2     

《Dynamics of Atmospheres and Oceans》2016

The subseasonal variability and predictability of the Arctic Oscillation/North Atlantic Oscillation (AO/NAO) is evaluated using a full set of hindcasts generated from the Beijing Climate Center Atmospheric General Circulation Model version 2.2 (BCC_AGCM2.2). It is shown that the predictability of the monthly mean AO/NAO index varies seasonally, with the highest predictability during winter (December–March) and the lowest during autumn (August–November), with respect to both observations and BCC_AGCM2.2 results. As compared with the persistence prediction skill of observations, the model skillfully predicts the monthly mean AO/NAO index with a one-pentad lead time during all winter months, and with a lead time of up to two pentads in December and January. During winter, BCC_AGCM2.2 exhibits an acceptable skill in predicting the daily AO/NAO index of ∼9 days, which is higher than the persistence prediction skill of observations of ∼4 days. Further analysis suggests that improvements in the simulation of storm track activity, synoptic eddy feedback, and troposphere–stratosphere coupling in the Northern Hemisphere could help to improve the prediction skill of subseasonal AO/NAO variability by BCC_AGCM2.2 during winter. In particular, BCC_AGCM2.2 underestimates storm track activity intensity but overestimates troposphere–stratosphere coupling, as compared with observations, thus providing a clue to further improvements in model performance.  相似文献   

Temperature dependence of variations in the end of the growing season from 1982 to 2012 on the Qinghai–Tibetan Plateau     

Mingjun Ding  Qian Chen  Lanhui Li  Zhaofeng Wang  Linshan Liu 《地理信息系统科学与遥感》2016,53(2):147-163

A growing number of studies have focused on variations in vegetation phenology and their correlations with climatic factors. However, there has been little research on changes in spatial heterogeneity with respect to the end of the growing season (EGS) and on responses to climate change for alpine vegetation on the Qinghai–Tibetan Plateau (QTP). In this study, the satellite-derived normalized difference vegetation index (NDVI) and the meteorological record from 1982 to 2012 were used to characterize the spatial pattern of variations in the EGS and their relationship to temperature and precipitation on the QTP. Over the entire study period, the EGS displayed no statistically significant trend; however, there was a strong spatial heterogeneity throughout the plateau. Those areas showing a delaying trend in the EGS were mainly distributed in the eastern part of the plateau, whereas those showing an advancing trend were mostly scattered throughout the western part. Our results also showed that change in the vegetation EGS was more closely correlated with air temperature than with precipitation. Nonetheless, the temperature sensitivity of the vegetation EGS became lower as aridity increased, suggesting that precipitation is an important regulator of the response of the vegetation EGS to climate warming. These results indicate spatial differences in key environmental influences on the vegetation EGS that must be taken into account in current phenological models, which are largely driven by temperature.  相似文献   

卤水镁矿产资源开发态势计量分析          下载免费PDF全文

吕俊生  吴志坚  王臣松 《盐湖研究》2016,24(1):58-65

从专利视角出发,对全球卤水镁矿产资源开发技术的发展现状与态势进行了分析,通过专利量的年度走势、区域分布、申请人分布、IPC分布、文本聚类、主题关联等信息,展示了百年卤水镁矿产资源开发的技术概况;为了解近期卤水镁资源开发的状况,分析了近5年全球卤水镁矿产资源开发技术的专利,通过对比分析,展现了卤水镁矿产资源研发的热点与态势。  相似文献   

Radar speckle reduction and derived texture measures for land cover/use classification: a case study     

Terry Idol  Barry Haack 《国际地球制图》2017,32(1):18-29

This study examined the appropriateness of radar speckle reduction for deriving texture measures for land cover/use classifications. Radarsat-2 C-band quad-polarised data were obtained for Washington, DC, USA. Polarisation signatures were extracted for multiple image components, classified with a maximum-likelihood decision rule and thematic accuracies determined. Initial classifications using original and despeckled scenes showed despeckled radar to have better overall thematic accuracies. However, when variance texture measures were extracted for several window sizes from the original and despeckled imagery and classified, the accuracy for the radar data was decreased when despeckled prior to texture extraction. The highest classification accuracy obtained for the extracted variance texture measure from the original radar was 72%, which was reduced to 69% when this measure was extracted from a 5 × 5 despeckled image. These results suggest that it may be better to use despeckled radar as original data and extract texture measures from the original imagery.  相似文献   

Extending the conversation on socially engaged geographic visualization: representing spatial inequality in Buffalo,New York   总被引：1，自引：1，他引：0  

Jin-Kyu Jung  Christian Anderson 《Urban geography》2017,38(6):903-926

This paper is situated at the intersections among GIS and geovisualization, critical social theory, and urban studies. It presents an analysis of housing segregation and unequal food and transportation access in Buffalo, New York. We demonstrate how the representation and examination of this socially complex multi-scalar issue benefits from deliberate, reflexive conversation between different critical social-spatial epistemologies. We begin with a relatively simple GIS analysis of spatial segregation and arrive through critical iteration at a more qualitatively nuanced cartogram which moves beyond representations of fixed space to reveal a much more relational situation—a case of “time-space expansion” in which the travel time needed to meet a basic daily need is much greater for the poor and people of color than it is for whiter, more affluent populations. We conclude by infusing this narrative with additional considerations from social theory to show how even a limited visualization such as ours might better critically engage broader social and discursive processes in and across urban space.  相似文献   

江苏沿海滩涂资源及发展趋势遥感分析   总被引：10，自引：1，他引：10  

吴曙亮  蔡则健 《海洋通报》2003,22(2):60-68,82

遥感技术用于广袤宽阔、复杂多变而难以实地勘测的潮间带资源调查是科学和最有效的选择。作者以三期低潮位卫星遥感数据图像为基础，对江苏沿海潮间带滩涂资源的总量、分布特点、发展趋势及开发利用前景进行了分析，指出了江苏滩涂资源总量呈减少趋势，匡围量大于可供匡围的滩涂资源生长量，应加强对滩涂资源开发利用规划和统一管理。  相似文献   

略论渔业资源学的数学化趋势   总被引：1，自引：0，他引：1  

王艳君  叶振江  尤凯  刘晖 《海洋湖沼通报》2001,(4):75-80

本文主要从渔业资源学中数学方法的应用起源，渔业资源评估学，数量分类学，统计生态学，种群营养动力学等数学分支在渔业资源中的应用发展及其动因分析等几个方面论述了渔业资源学的数学化趋势。  相似文献   

Age and growth of John Dory, Zeus faber (Linnaeus, 1758), in the East China Sea     

Yoneda  Michio; Yamasaki  Shunji; Yamamoto  Keisuke; Horikawa  Hiroshi; Matsuyama  Michiya 《ICES Journal of Marine Science》2002,59(4):749-756

  相似文献   

最平滤波器在分析月平均潮位资料中的应用     

杨清书  杨干然  方畴军 《热带海洋学报》1996,(1)

应用数字滤波方法来消除验潮资料中的高频扰动而分离出海平面的趋势性变化，并设计了最平滤波器；对其幅频响应特性和相位特性的验证表明，最平滤波器的技术性能基本上是可靠的。应用最平滤波器对月平均验潮序列进行低通数字滤波，可以有效地消除验潮资料中的高频扰动，分离出低频变化。从数值计算过程、高频扰动机制及实测验潮资料的估算结果来看，低通数字滤波在确定海平面长期变化趋势中，对消除高频扰动的影响是非常重要而有效的。  相似文献   

Long-term fluctuations in the eastern Atlantic and Mediterranean bluefin tuna population   总被引：1，自引：1，他引：1  

Ravier  Christelle; Fromentin  Jean-Marc 《ICES Journal of Marine Science》2001,58(6):1299-1317

  相似文献