福建黄岗山东南坡气温的垂直变化

利用HOBOOnset自动温度记录仪于 2 0 0 1年 11月～ 2 0 0 2年 11月对福建黄岗山东南坡 7个地点的气温 ,间隔15min进行了连续观测。结果显示 :黄岗山年平均气温直减率为 0 .4 3℃ / 10 0m ;不同月份的直减率有差异 ,一般来说 ,冬季小 ,夏季大 ,其中 12月最小 (0 .2 6℃ / 10 0m) ,9月最大 (0 .5 6℃ / 10 0m)。平均最高气温沿海拔高度变化并非呈线性关系 ,表现为中海拔 (16 0 0m )数值最低 ,而平均最低气温沿海拔高度呈明显线性关系 ,直减率为0 .5 4℃ / 10 0m。最高温度沿海拔高度变化不明显。月平均的日较差沿着海拔高度变化呈“U”字形 ,中海拔月平均日较差值最低。日平均气温≥ 0℃ ,≥ 5℃和≥ 10℃的积温沿海拔高度呈线性关系 ,直减率几乎相同。≥ 10℃积温从低海拔至高海拔相差约 2 0 0 0℃ ,海拔每升高 10 0m稳定初日至终日 ,积温日期间隔平均减少 7d左右。     

Differencing Reveals Hidden Changes in Baseline Length Time-series

In order to make successful earthquake predictions, detection and monitoring of baseline changes are important for investigating their origins, including precursory crustal deformations in tectonically active areas. In this study, differencing two baselines that run approximately parallel to each other and normal to the expected crustal deformations, and that share a station is proposed for analysis. Differencing reduces common systematic baseline errors, thereby enabling detection of subtle transient systematic changes in the baseline time-series that are otherwise buried in the measurement noise. Mean shift analysis, a well-known statistical technique to determine hether the mean of a stochastic process has shifted using cumulative sum charts, can then be used to locate the change points in the time-series. The application of this method to the differences of concurrently observed very long baseline interferometry (VLBI) and global positioning system (GPS) baselines in the Japanese Keystone project, where periodic and persistent baseline changes are removed, revealed transient variations in the baseline lengths several months prior to the seismic activity in the Izu Islands that started on June 26, 2000. Reproduction of the results using GPS and VLBI, two alternative baseline measurement techniques, validated the accuracy of the proposed approach for detecting previously hidden transient changes in the baseline lengths.     

COARSE-PARTICLE TRANSPORT IN A GRAVEL-BED RIVER

ＣＯＡＲＳＥ－ＰＡＲＴＩＣＬＥＴＲＡＮＳＰＯＲＴＩＮＡＧＲＡＶＥＬ－ＢＥＤＲＩＶＥＲＷｉｌｌｉａｍＷ．ＥＭＭＥＴＴ１，ＲｏｂｅｒｔＬ．ＢＵＲＲＯＷＳ２，ａｎｄＥｄｗａｒｄＦ．ＣＨＡＣＨＯ，Ｊｒ３．（１Ｕ．Ｓ．ＧｅｏｌｏｇｉｃａｌＳｕｒｖｅｙ，Ｗａｔｅ...     

MASINGA RESERVOIR IN KENYA：SEDIMENT DISCHARGE AND IMPLICATIONS FOR ITS CAPACITY

ＭＡＳＩＮＧＡＲＥＳＥＲＶＯＩＲＩＮＫＥＮＹＡ：ＳＥＤＩＭＥＮＴＤＩＳＣＨＡＲＧＥＡＮＤＩＭＰＬＩＣＡＴＩＯＮＳＦＯＲＩＴＳＣＡＰＡＣＩＴＹ￥Ｆ．Ａ．Ｏ．Ｏｔｉｅｎｏ（ＳｅｎｉｏｒＬｅｃｔｕｒｅｒｉｎＣｉｖｉｌＥｎｇｉｎｅｅｒｉｎｇ，Ｕｎｉｖｅｒｓｉ...     

北半球50hPa多年月平均经向剖面上的季节变化

我们根据1965年1月—1984年12月共20年平均的50hPa高度场资料作出的沿各经度的纬度-高度时间剖面图和逐月纬间高度梯度值表,分析得到如下结论: 1、50hPa上从冬到夏的季变,北带(60—90°N)和南带(10—30°N)中最早的时间都在3—4月,这比中带(30—60°N)各经度上和北、南带其余各地区完成季变都要早一个月。 2、50hPa上从夏到冬的季变,北带最早,大多出现在7—月,少数出现在8—9月;中带全在8—9月完成季变,南带更晚些。显然北带早于中带,中带又早于南带。 3、北半球平流层50hPa的季变,从冬到夏是来自极地和赤道两个方向共同发动的,而自夏到冬,其发动方向仅来自极地。     

Numerical experiments in the 3/1 andv 6 overlapping resonance region

Numerical experiments of fictitious small bodies with initial eccentricities e=0.1 have been performed in the overlapping region of the 3/1 mean motion resonance and of thev ₆ secular resonance 2.48a2.52AU for different values of the initial inclination 16°i20°. An analysis for thev ₆ secular resonance shows that the topology is different from the one found outside the overlapping region: the critical argument for thev ₆ resonance in the overlapping region rotates in opposite direction as compared to the purev ₆ region. In the 3/1 resonance region the secular resonancev ₅ is dominant, and some secondary secular resonances asv ₆ –v ₁₆ andv ₅ +v ₆ are present.     

A GIS-Based Model to Determine Site Suitability of Emergency Evacuation Shelters

In recent years, the increase in the number of hurricanes and other costal hazards in the US pose a tremendous threat to the residents of coastal states. According to the National Hurricane Center, Florida is the most vulnerable coastal state to hurricanes. Mitigation policies have been formulated to reduce mortality and provide emergency services by evacuating people from the hazard zone. Many of these evacuees, particularly the elderly or lower income populations, rely on evacuation shelters for temporary housing. Because of the cost and limited use, evacuation shelters are almost exclusively dual use shelters where the primary purpose of the facility is for some other public function (e.g. school, hospital, etc.). In 2000, the estimated shortage of public shelter spaces in Florida was about 1.5 million. The purpose of this study was to rank the existing and candidate shelters (schools, colleges, churches and community centers) available in the state based on their site suitability. The research questions examined in this study include: (1) How many candidate shelters are located in physically suitable areas (e.g. not in a flood prone area, not near hazardous facilities, etc.)?; (2) How many existing shelters are located in physically un suitable areas, but in socially suitable areas (situated in areas with demand)?; (3) How many alternative existing and/or candidate shelters with high/very high physical suitability are located near physically un suitable existing shelters and thus, may be better choices for a shelter?; and (4) How many existing shelters located in physically un suitable areas are not near alternative existing and/or candidate shelters? A Geographic Information System‐based suitability model integrating Weighted Linear Combination (WLC) with a Pass/Fail screening technique was implemented for the 17 counties of Southern Florida. It was found that 48% of the existing shelters are located in physically unsuitable areas. Out of all the candidate shelters, 57% are located in physically unsuitable areas. For 15 of the existing shelters in unsuitable locations, no alternative candidate or existing shelter with medium to high physical suitability exists within 10 miles (16.1 km).     

北京地区城市热岛强度变化对区域温度序列的影响

通过对北京地区20个台站1961~2000年月平均温度资料的对比分析,证实热岛效应对城市气象站记录的地表平均气温的绝对影响随时间显著增大,近20 a尤为突出,但其相对影响即热岛增温对全部增暖的贡献却呈下降趋势。近40 a来,北京地区的国家基本、基准站平均温度距平序列与被认为不受城市热岛影响的郊区站平均温度距平序列差异明显,由于热岛效应加强因素引起的国家基本、基准站平均年温度变化速率为0.16℃/(10 a),对整个时期全部增温的贡献达到71%;近20 a来热岛效应加强因素使北京地区国家基本、基准站年平均温度每10 a增暖0.33℃,对该时期全部增温的贡献达到49%。城市热岛效应加强因素对国家基本、基准站季节平均温度上升的贡献在夏、秋季高,冬季最小。本文的结果说明,目前根据国家基本、基准站资料建立的全国或较大区域平均温度序列可能在很大程度上保留着城市化的影响,有必要做进一步的检验和订正。     

一种新的基于模糊分析观测信息的局地化方法

地球表层系统是一个极其复杂的巨系统,为了更精确地表达地球表层系统各种过程的动态演进,解决数据同化系统观测误差的估计与处理已经成为地球科学领域备受关注的问题之一。在地球科学系统数值模拟中,一般采用集合数据同化来探讨地学变量预报时的各种误差。集合类卡尔曼滤波通常会由于集合数过小而带来欠采样、协方差低估、滤波发散和远距离虚假相关等问题。针对背景误差协方差被低估问题,局地分析方法（Local Analysis, LA）在一定程度上能起到抑制作用,但无法彻底解决背景误差协方差的虚假相关问题。因此,本文在集合卡尔曼滤波的算法框架下提出了一种与模糊逻辑控制算法相耦合的局地化分析方法（Fuzzy Analysis, FA）。在强非线性Lorenz-96模型中,对不同模型误差下的LA和FA方法进行了性能优劣方面的探讨,并比较分析了2种方法在集合数、观测数和观测位置、放大因子以及强迫参数变化时的同化性能。实验采用均方根误差作为算法评判依据,同时用功率谱密度（Power Spectral Density, PSD）更直接地对2种算法性能优劣作出了评价。结果表明：在完美模型下,FA相对于LA降低了17.5%的均方根误差（Root Mean Square Error, RMSE）;随着模型误差增大,RMSE减小的百分比和减小幅度都在降低;在严重模型误差下,FA降低了8.6%的RMSE。总体而言,新算法FA的有效性和鲁棒性都得到了验证,并且在EnKF同化基础下有效改进了传统的局地化分析方案,优化了观测误差处理,为今后的数据同化研究提供了一个较为全面的观测误差研究平台。