Homogenization of the Daily Land Surface Temperature over the Mainland of China from 1960 through 2017

Land surface temperature(LST) is one of the most important factors in the land-atmosphere interaction process. Raw measured LSTs may contain biases due to instrument replacement, changes in recording procedures, and other non-climatic factors. This study attempts to reduce the above biases in raw daily measurements and achieves a homogenized daily LST dataset over China using 2360 stations from 1960 through 2017. The high-quality land surface air temperature(LSAT)dataset is used to correct the LST warming biases especially evident during cold months in regions north of 40°N due to the replacement of observation instruments around 2004. Subsequently, the Multiple Analysis of Series for Homogenization(MASH) method is adopted to detect and then adjust the daily observed LST records. In total, 3.68 × 103 effective breakpoints in 1.65 × 106 monthly records(about 20%) are detected. A large number of these effective breakpoints are located over large parts of the Sichuan Basin and southern China. After the MASH procedure, LSTs at more than 80% of the breakpoints are adjusted within +/– 0.5°C, and of the remaining breakpoints, only 10% are adjusted over 1.5°C.Compared to the raw LST dataset over the whole domain, the homogenization significantly reduces the mean LST magnitude and its interannual variability as well as its linear trend at most stations. Finally, we perform preliminary analysis upon the homogenized LST and find that the annual mean LST averaged across China shows a significant warming trend [0.22°C(10 yr)–1]. The homogenized LST dataset can be further adapted for a variety of applications(e.g.,model evaluation and extreme event characterization).     

南方低山丘陵地区汛期短时强降水特征分析

研究汛期短时强降水特征,对于南方低山丘陵地区山洪灾害的预报具有重要指导意义。以怀化市为研究区域,基于该区域11个国家站和403个区域自动气象站的2012-2017年4-9月期间逐小时降水量以及相对应的NCEP资料,分析了怀化市短时强降水的时空分布特征,得出了产生短时强降水天气系统模型,结果显示：①汛期短时强降水发生频率较高,时间集中,分布不均。主要出现在5～7月,占4～9月的72.9%,其次在8～9月;北部频数多,中南部少,西部最少,辰溪、麻阳和怀化三县交界处及沅陵县的大合坪附近是频发区域。②短时强降水日变化呈单峰型,4～10时最容易发生,峰值在8时,谷值在23时。③强度越强出现的频次越少;北部的强度和次数大于其它区域;50～79.9 mm/h,占总站数的68.4%;各月国家站的极值乘以2约等于区域站极值。④低涡型短时强降水出现概率最高,低涡位置和移动路径是短时强降水预报的关键点。     

贵德盆地热结构及地热成因机制

贵德盆地位于青藏高原东北缘黄河谷地之中, 四周环山, 为新生代断陷盆地, 地貌单元位于青藏块体, 地处祁连、昆仑和秦岭三大褶皱系交汇地带; 新构造活动强烈, 发育一系列NWW向、NW向及NNW向断裂, 为区内高温地热系统提供了较好的地热地质条件。区内地热显示类型多样, 水热活动剧烈, 尤其是盆地西部的扎仓寺热田, 水温高达 93℃, 蕴藏着丰富的地热资源。但是由于客观条件限制, 区内地热资源的开发利用及相关研究尚有不足之处。     

利用天气数值预报产品建立贵州黔西南州分县温度预报方程的方法及应用

利用2002～2004年1～12月EC、T213天气数值产品的温度格点实时分析资料、预报资料以及贵州省黔西南州8个测站观测资料,从160个样本中筛选出相关较好的因子,利用多元回归统计模型,以及根据地理环境,天气形势分型造成的温度差值(ΔT)为逐步订正值,建立黔西南州分县温度预报方程。在2005年11月～2006年2月应用中取得较好效果,预报误差小于±3.0℃,平均误差1.3℃。     

干旱区典型绿洲地表温度与植被覆盖度相关性研究

 绿洲空间热环境的研究是深入了解绿洲-沙漠间,以及绿洲内部物质能量流动机理的重要手段。利用TM/ETM+遥感影像反演了于田地区地表温度以及植被覆盖度,在统计地表温度-植被覆盖度二维散点图的基础上,研究不同结构区域下绿洲地表温度与植被覆盖度的相关关系。结果表明:①于田地区地表温度与植被覆盖度呈显著负相关关系,相关系数在-0.79158和-0.48816范围之间。②从1991年到2002年,于田绿洲内部区域地表温度与植被覆盖度散点图上各点分布由密集到分散,表明原有相对整体的植被覆盖地块被打散,成为多种土地类型交错的破碎化地块。③外部荒漠带及绿洲与荒漠交错带区域地表温度与植被覆盖度散点图上各点分布由分散到集中,表明绿洲外部荒漠化程度的逐年加剧,导致了绿洲外围植被覆盖有所降低,植被物种单一,植被多样性也呈现下降趋势。     

两类中太平洋El Nio特征的对比分析

利用1979—2012年逐月Hadley中心海表温度、欧洲中期天气预报中心次表层海温、NCEP/NCAR风场再分析资料,对两类中太平洋(CP)El Nio及耦合的大气环流特征进行分析。结果表明,第一类CP El Nio(CP-ⅠEl Nio)增暖中心位于Nio4区且关于赤道对称;第二类CP El Nio(CP-ⅡEl Nio)的Nio4区与热带东北太平洋区域(NEP,130~110°W、15~25°N)同位相变化,冬季成熟后形成关于赤道非对称的带状增暖结构。进一步的研究表明,两类CP El Nio次表层结构存在差异:CP-ⅠEl Nio冬季次表层海温异常(SOTA)在中东太平洋与西太平洋呈显著偶极分布;CP-ⅡEl Nio在中、西太平洋位相相反但东太平洋异常较弱,且经向异常主要在赤道及其以北。两类CP El Nio耦合的大气环流特征不同:CP-ⅠEl Nio冬季异常Walker环流上升中心位于赤道上空,经向风向赤道辐合,低纬地区Hadley环流加强;CP-ⅡEl Nio冬季低层向北越赤道气流加强,Walker环流上升中心移到赤道以北,低纬地区Hadley环流减弱。     

Air-sea interaction over the tropical Indian Ocean during several contrasting monsoon seasons

Monthly mean anomaly fields of various parameters like sea surface temperature, air temperature, wind stress, effective radiation at the surface, heat gain over the ocean and the total heat loss between a good and bad monsoon composite and the evaporation rates over the Arabian Sea and southern hemisphere have been studied over the tropical Indian Ocean. The mean rates of evaporation on a seasonal scale over the Arabian Sea during a good and bad monsoon composites were equal (about 2·48 × 10¹⁰ tons/day). The evaporation rates over the southern hemisphere were greater during all the months. The mean evaporation rates over the southern hemisphere on a seasonal scale for the good and bad monsoon composites were 4·4 × 10¹⁰ and 4·6 × 10¹⁰ tons/day respectively. The maximum evaporation rates over the southern hemisphere were observed in August. The anomalies of wind stress, effective radiation at the surface and the heat gain over the ocean also exhibit large variations in August, as compared to other monsoon months.     

Stream Temperature Trends in Turkey

Stream temperature is an important property of water and affects most other water quality constituents. It is also a property which is very much influenced by exogenous factors like air temperature and stream flow. This study investigates long‐term trends in stream temperatures measured at various stream monitoring stations in Turkey to better understand links with climate change. It was found by statistical trend analysis that more streams have experienced decreasing trends than increasing ones. Moreover, stream temperatures show a rising tendency in most stations over Turkey. Flow‐adjusted temperatures were computed to eliminate flow dependency and these show more positive than negative trends. Management plans of streams and watersheds need to take this into account and incorporate the implications into plans.     

海口ZK26井多层位水温对比观测

在系统清理海口ZK26井3个不同层位(-153 m、-336 m、-510 m)近10年观测资料对比的基础上,对比单井多层位水温动态多年趋势、年、月、日动态类型,并对其不同动态类型的成因及影响因素进行分析.对比观测结果表明,海口ZK26井不同层位的水温表现出不同的正常动态特征,与观测层位的水文条件、水力性质有着密切的联...     

Comparison of temperature extremes between Zhongshan Station and Great Wall Station in Antarctica

Although temperature extremes have led to more and more disasters, there are as yet few studies on the extremes and many disagreements on temperature changes in Antarctica. Based on daily minimum, maximum, and mean air temperatures(Tmin, Tmax, Tmean) at Great Wall Station(GW) and Zhongshan Station(ZS), we compared the temperature extremes and revealed a strong warming trend in Tmin, a slight warming trend in Tmean, cooling in Tmax, a decreasing trend in the daily temperature range, and the typical characteristic of coreless winter temperature. There are different seasonal variabilities, with the least in summer. The continentality index and seasonality show that the marine air mass has more effect on GW than ZS. Following the terminology of the Fifth Assessment Report of the Intergovernmental Panel on Climate Change(IPCC AR5), we defined nine indices of temperature extremes, based on the Antarctic geographical environment. Extreme-warm days have decreased, while extreme-warm nights have shown a nonsignificant trend. The number of melting days has increased at GW, while little change at ZS. More importantly, we have found inverse variations in temperature patterns between the two stations, which need further investigation into the dynamics of climate change in Antarctica.