CLDAS温湿产品在贵州的适用性评估及订正

使用贵州自动观测站逐时资料对2019年中国气象局陆面数据同化系统（CLDAS）温度、相对湿度产品进行了检验评估及线性订正。结果表明,CLDAS温度同观测有较好的一致性,相对湿度产品系统性低于观测,使用本地资料订正CLDAS温湿产品提高了产品的可用性。全年CLDAS温度产品在贵州的平均误差为0.2985℃,均方根误差为1.5578℃,相关系数为0.9822。12.4%的站点温度年均方根误差超过了2℃。从00:00-23:00（北京时）温度平均误差先减小后增大,均方根误差在中午前后存在最大值。订正后,CLDAS温度产品平均误差绝对值、均方根误差缩小,相关系数增大,全年均方根误差减小至1.2369℃。订正格点产品时有效距离越小订正效果越好。全年CLDAS相对湿度产品在贵州的平均误差为-4.501%,均方根误差为9.021%,相关系数为0.863,夜间相关系数为0.711。相对湿度产品平均误差及相关系数在中午前后达到最大值,均方根误差则是在日夜交换之际存在最值。线性订正对相对湿度产品有明显的正效果。订正后全年相对湿度均方根误差减小了2.317%,夜间相关系数较订正前增加了0.104。夜间时刻相...     

华南3 km高分辨率区域模式气温预报在贵州的质量检验

利用2018年1—10月华南3 km区域高分辨率模式08时、20时起报的气温预报和实况资料,采用线性内插法进行站点预报值处理,并从平均均方根误差及预报准确率的角度,检验分析了贵州省72 h预报内逐24 h最高(低)气温预报质量。结果表明,72 h内随着预报时效的增加,预报准确率差异较小;日最低气温预报准确率相对最高气温平均高出20%左右;08时起报的最高(低)气温预报优于20时的。同时发现,最高(低)气温的预报能力在月份上存在明显差异,6—8月预报性能总体优于其它月份;在24~48 h预报中,东北—西南向一带较贵州其它区域展现出更高的预报能力。在9个主要城市站上,最高(低)气温均表现出较高的预报技巧,其中,20时起报的兴义站24 h最低气温准确率100%。通过对2018年7月18日气温预报质量检验,最高(低)气温及35.0℃以上高温事件预报准确率均在80%左右,较好反映了天气实况。因此,华南3 km高分辨率区域模式对贵州气温预报具有较好的参考价值。     

Summer hypoxia in the northern Gulf of Mexico and its prediction from 1978 to 1995

An 18-year monitoring record (1978-1995) of dissolved oxygen within a region having hypoxia (dissolved oxygen less than 2 mgl(-1)) in the bottom layer was examined to describe seasonal and annual trends. The monitoring location was near or within a well-described summer hypoxic zone whose size has been up to 20,000 km(2). The monitoring data were used to hindcast the size of the hypoxic zone for before consistent shelfwide surveys started, and to predict it for 1989, when a complete shelfwide survey was not made. The concentration of total Kjeldahl nitrogen (TKN) in surface waters and concentration of bottom water oxygen were directly related, as anticipated if organic loading from surface to bottom was from in situ processes. The TKN data were used to develop a predictive relationship that suggested there was no substantial hypoxia before the 1970s, which was before nitrate flux from the Mississippi River to the Gulf of Mexico began to rise. The peak frequency in monthly hypoxic events is two to three months after both the spring maximum in discharge and nitrate loading of the Mississippi River. These results support the conclusion that persistent, large-sized summer hypoxia is a recently-developed phenomenon that began in the 1970s or early 1980s.     

贵州夏季最高气温变率的时空分布特征

选取贵州19个代表站点47 a夏季日最高气温月平均及季平均资料,采用EOF分解方法对贵州夏季最高气温的变化进行分析,结果表明:前两个模态的累积方差贡献在82%~89.7%,特征值对应特征向量和时间系数能够较好地反映时空分布特征,第一特征向量代表的空间分布显示:全省变化趋势一致,东北部变化较西南部大,北部、东北部变率变化较南部西南部大;相应地时间系数变化幅度大,都有2~4 a的周期振荡;从第二特征向量代表的空间分布可知:各时段呈现出不一样的变化趋势,时间系数的值也普遍较第一特征向量小,突变不明显。     

抗干扰编码电法仪的实现及应用

为了提高电法或电磁法仪器的抗干扰能力,采用伪随机编码的脉冲序列作为激励源,应用通讯领域的伪随机编码相关检测技术和信号过采样等先进技术,开发出具有强抗干扰能力的电法勘探硬件采集系统和资料处理软件系统.通过仿真检测和在不同勘探领域的实测试验,证明了该方法的可行性与有效性.实现的抗干扰编码电法仪达到了预期效果,展示了优越的抗干扰能力,可以用于城市、矿山、电站和铁路周边等强干扰地区的电法勘探.     

Impacts of diverted freshwater on dissolved organic matter and microbial communities in Barataria Bay, Louisiana, U.S.A

Here we present results of an initial assessment of the impacts of a water diversion event on the concentrations and chemical composition of dissolved organic matter (DOM) and bacterioplankton community composition in Barataria Bay, Louisiana U.S.A, an important estuary within the Mississippi River Delta complex. Concentrations and spectral properties of DOM, as reflected by UV/visible absorbance and fluorescence, were strikingly similar at 26 sites sampled along transects near two western and two eastern areas of Barataria Bay in July and September 2010. In September 2010, dissolved organic carbon (DOC) was significantly higher (568.1-1043 μM C, x=755.6+/-117.7 μM C, n=14) than in July 2010 (249.1-577.1 μM C, x=383.7+/-98.31 μM C, n=14); conversely, Abs254 was consistently higher at every site in July (0.105-0.314) than in September (0.080-0.221), averaging 0.24±0.06 in July and 0.15±0.04 in September. Fluorescence data via the fluorescence index (FI450/500) revealed that only 30% (8 of 26) of the July samples had an FI450/500 above 1.36, compared to 96% (25 of 26) for the September samples. This indicates a more terrestrial origin for the July DOM. Bacterioplankton from eastern sites differed in composition from bacterioplankon in western sites in July. These differences appeared to result from reduced salinities caused by the freshwater diversion. Bacterioplankton communities in September differed from those in July, but no spatial structure was observed. Thus, the trends in bacterioplankton and DOM were likely due to changes in water masses (e.g., input of Mississippi River water in July and a return to estuarine waters in September). Discharge of water from the Davis Pond Freshwater Diversion (DPFD) through Barataria Bay may have partially mitigated some adverse effects of the oil spill, inasmuch as DOM is concerned.     

Resurvey of a reef flat in American Samoa after 85 years reveals devastation to a soft coral (Alcyonacea) community

One of the earliest quantitative surveys of soft corals, on a reef flat in Pago Pago Harbour, American Samoa, was repeated 85 years later. The alcyoniid communities there, which were the dominant benthic organisms during the initial survey, have suffered a drastic decline of 99% cover in the interim. The most likely causes of the decline are anthropogenic disturbance associated with reclamation along the harbour from the 1940s to early 1960s, compounded by chronic pollution from industrial wastewater discharge from the mid-1950s to late 1980s. The decline in one dominant species, Sinularia polydactyla, is likely to have serious consequences for the reef as unusually for a soft coral, this had been the major reef building species. Life-history traits of certain Sinularia and Sarcophyton, such as slow growth and low rates of sexual reproduction, mean they will be slower to recover from severe disturbance than many scleractinian corals.     

Bioconcentration and distribution of 4-tert-octylphenol residues in tissues of the rainbow trout (Oncorhynchus mykiss)

Branched chain alkylphenols are weak oestrogen mimics which are present in the aquatic environment and have been implicated in the feminisation of fish. This study reports the biotransformation, bioconcentration and tissue distribution of the xenoestrogen 4-tert-octylphenol (t-OP) in juvenile rainbow trout. Fish were exposed for 10 days to a concentration of 4 micrograms/l of [14C] t-OP in a flow-through system and were sampled after 1, 4, 7 and 10 days of exposure. t-OP residues were extracted from all tissues and analysed by radio-high-performance liquid chromatography. After 1 day of exposure radioactive residues were detected in all tissues and reached steady state conditions in the whole fish after 4 days of exposure. The concentration of t-OP residues were highest in bile, followed by faeces, pyloric caeca, liver and intestine. In these tissues the majority of alkylphenol was in the form of two metabolites which were identified by gas chromatography-mass spectroscopy as the glucuronide conjugates of t-OP and t-octylcatechol. t-OP accumulated as the parent compound in fat with a bioconcentration factor (BCF) of 1190, and in brain, muscle, skin, bone, gills, and eye with BCFs of between 100 and 260. This study suggests that exposure to water-borne alkylphenols results in rapid conjugation and elimination of the chemical via the liver/bile route, but that high amounts of the parent xenoestrogen can accumulate in a variety of other fish tissues.