近55年来河西地区季节开始日及长短变化特征

利用河西地区15个气象站点1955～2009年日平均气温资料,采用5d滑动平均、气候倾向率、Mann-Kendall和滑动t检验,ArcGIS中的反距离加权插值等方法分析河西地区四季开始日及其长短变化特征,以揭示气候季节变化对全球气候变暖的响应.结果表明:近55年来,河西地区四季开始日主要表现为春、夏和秋季提早,冬季推...     

Effectiveness of three post‐fire rehabilitation treatments in the Colorado Front Range

Post‐fire rehabilitation treatments are commonly implemented after high‐severity wildfires, but few data are available about the efficacy of these treatments. This study assessed post‐fire erosion rates and the effectiveness of seeding, straw mulching, and contour felling in reducing erosion after a June 2000 wildfire northwest of Loveland, Colorado. Site characteristics and sediment yields were measured on 12 burned and untreated control plots and 22 burned and treated plots from 2000 to 2003. The size of the hillslope plots ranged from 0·015 to 0·86 ha. Sediment yields varied significantly by treatment and were most closely correlated with the amount of ground cover. On the control plots the mean sediment yield declined from 6–10 Mg ha^?1 in the first two years after burning to 1·2 Mg ha^?1 in 2002 and 0·7 Mg ha^?1 in 2003. Natural regrowth caused the amount of ground cover on the control plots to increase progressively from 33% in fall 2000 to 88% in fall 2003. Seeding had no effect on either the amount of ground cover or sediment yields. Mulching reduced sediment yields by at least 95% relative to the control plots in 2001, 2002, and 2003, and the lower sediment yields are attributed to an immediate increase in the amount of ground cover in the mulched plots. The contour‐felling treatments varied considerably in the quality of installation, and sediment storage capacities ranged from 7 to 32 m³ ha^?1. The initial contour‐felling treatment did not reduce sediment yields when subjected to a very large storm event, but sediment yields were significantly reduced by a contour‐felling treatment installed after this large storm. The results indicate that contour felling may be able to store much of the sediment generated in an average year, but will not reduce sediment yields from larger storms. Copyright © 2006 John Wiley & Sons, Ltd.     

软包装即食食品——鲻鱼皮加工工艺

研究了鲻鱼皮的加工工艺 ,筛选出鲻鱼皮加工成软包装即食食品的最佳工艺条件。结果表明 :鲻鱼皮的爽脆性主要与鲻鱼皮的烫煮和冰水浸泡工艺条件有关 ,最佳条件是先用 0 8g/L的保水剂浸泡3h,然后用低浓度的有效氯杀菌 ,再在 90℃中烫煮 60s,最后迅速放进无菌冰水中浸泡。研制出的产品为螺纹状 ,具有鱼皮特有的银灰色 ,爽脆且富有韧性 ,在 0～ 5℃下可保质 45d。     

适用于古天文研究的计算机软件

天文软件是进行古天文研究非常有用的辅助工具。对一些常见的商业软件与专业软件的计算结果进行了分析比较,发现它们在两三百年的短期内都是足够可靠的,但是若干商业软件并不适用于涉及几千年跨度的古天文研究。分析表明:无论从数据精确度和长期稳定性,还是从功能的强大程度来说,SkyMap都是值得推广的天文计算软件。     

2008年奥运会开幕式日人工消减雨作业中尺度数值模拟的初步结果

2008年8月8日,在2008年北京奥运会开幕式举行之际,北京及周边地区出现了较强对流云团,给国家体育场内开幕式活动的顺利进行带来了极大威胁。根据云系的发展状况,北京市人工影响天气办公室有针对性地组织实施了大规模地面火箭人工消减雨作业,对抑制云、降水的形成和发展起到了一定作用。在中尺度数值模式MM5的Reisner2方案中引入了AgI粒子与云相互作用的过程,在MM5中实现了催化功能。参照2008年8月8日20:05至20:12进行的消减雨作业情况,利用加入催化方案的中尺度数值模式对该作业进行了数值模拟试验,就不同的播撒量对催化效果的影响进行了研究,并对其中的微物理机制进行了分析。研究结果表明:AgI播撒率对降水量改变影响很明显,当以5g·s-1的速率持续播撒AgI7min,在播撒作业后2h,催化区域内均表现为减雨,2h后为增雨。对于减雨的微物理机制主要是由于大量播撒AgI后导致空中云水大量减少,进一步导致霰减少,霰的减少导致雨水的减少;而2h后的增雨机制则是由于在雨水、云水、霰以及温度之间形成了正反馈,最终导致地面降水的增加。需要指出的是由于单参数方案的局限性,模拟的最大减雨率仅为8%～12%,离消雨的要求尚有差距,应利用双参数云方案作进一步模拟研究。     

1954-2005年长江以北地区初霜期变化趋势

 采用长江以北地区65个测站1954-2005年秋冬季逐日地面最低温度资料,计算分析长江以北地区初霜出现日期的年代际时空变化特征。结果表明：中国北方地区初霜是由北向南逐渐出现的,初霜发生日期具有明显的年代际变化特征,在20世纪90年代之后,大部分地区初霜日期偏晚的年份逐渐增多。中国北方地区初霜发生日期的早晚与北极涛动的强弱密切相关：当北极涛动处于正位相时,北半球以纬向型环流为主,中国北方大部分地区的初霜期偏晚;反之,当北极涛动处于负位相时,北半球以经向型环流为主,中国北方大部分地区的初霜期偏早。     

气候变暖对河南省蚱蝉始鸣期的影响

 利用河南省驻马店、沈丘和太康3个农业气象观测站1990-2004年的蚱蝉物候观测资料和气象资料,研究了气候变暖对蚱蝉始鸣期的影响。结果表明：在气温升高的气候背景下,蚱蝉始鸣期呈提前趋势;3-6月平均气温对蚱蝉始鸣期有显著的影响,始鸣期与1月1日至平均始鸣期期间＞5℃有效积温关系最为密切。用积温法以5℃为发育起点温度,＞5℃初日为起始日期对各站蚱蝉始鸣期进行模拟和预报,其效果优于平均法。     

台湾大青枣在钦州种植的气象条件分析

通过对台湾大青枣的生物特性及其气象条件进行分析,并指出影响其果品品质的主要气象因素及应对措施。     

长江中下游水患区大地变形监测数据的分析与处理

介绍了长江中下游水患区沉降监测工程概况,阐述了在变形监测数据处理中“平均间隙法”的原理与应用,结合三年的监测数据得出了具体的结论。     

Spatial and Temporal Features and Trend of Different Level Heat Waves Over China

Heat wave has become a severe problem over China in recent year. Based on daily air temperature data from 719 meteorological stations in China in the period of 1961-2012, the heat wave events were classified into three levels by duration: weak HW, medium heat wave and strong heat wave. This paper describes the spatial and temporal characteristics among three levels of heat wave over China during the period 1961-2013. The results showed that the number of hot days displayed a weakening trend from the 1960s to the early 1990s, followed by a strengthening trend from the late 1990s up to now. Long-term linear trends in hot days had significant regional differences, for instance, the number of hot days in southwest and southern China growing sharply than other regions; three levels heat wave occurred in different regions that weak heat wave usually occurred in the northwest and middle part of China while strong heat wave mainly happened in the southern part of China. When it came to the first day of heat wave, weak heat wave occurred earliest in China, and it happened around July 3rd while medium heat wave and strong heat wave always started on July 13th and July 14th, respectively. In general, the earliest heat wave was always found in southwest China while the last ones usually occurred in southern part and southwest China. Increasing trend of three levels heat wave were found in the entire country, except for southwest China. The trend of the last day of heat waves showed significant difference between northern and southern part of China. The last day of weak and medium heat wave occurred later in the south China, while strong heat wave happened earlier in north China.