山东省干旱演变规律及其影响   总被引：2，自引：0，他引：2  

杨志刚  杨洪昌 《气象》1996,22(5):25-29

利用近５００年旱涝资料分析了干旱对山东省农业，工业及环境的危害。利用功率谱和模糊判别函数研究了旱涝的周期性和阶段性，指出旱涝的演变规律可为气候预测提供依据。  相似文献   

1995年我国天气气候特点     

徐良炎 《气象》1996,22(4):17-19

１９９５年，我国大部地区降水正常或偏多，但季节分配不均。春季，北方干旱范围较大，陕、甘等省冬春夏连旱，旱情严重。汛期，江南及东北南部暴雨频繁，赣、湘、辽、吉等省发展严重洪涝。全国大部地区热量比较充足，但光照条件欠佳，部分地区作物遭受低温寡照或霜冻危害。登陆台风和热带风暴偏多，两广局地损失严重。部分地区遭受风雹或沙尘暴袭击。  相似文献   

1995年世界气候概况     

王丽华  李晓燕 《气象》1996,22(4):24-26

１９９５年，世界气候普遍偏暖。欧亚大陆大部、北美大陆中部、南美大陆中部、非洲西北部的年平均气温大多偏高１－２℃，其中俄罗斯大部、美国西南部显著偏高，部分地区偏高４℃，北半球中高纬度地区冬暖非常显著。由于北半球中纬度地区，许多测站气温高达３５－４０℃，为近几十年乃至百年一遇。年内，全球许多地区旱涝频繁，诸如年初欧洲的暴风雪与美国加利福尼亚洲的特大洪水及夏季朝鲜、与中南半岛的大水灾、加勒比海的飓风等危  相似文献   

一种干旱指数计算方法的研究和应用   总被引：2，自引：1，他引：2  

金龙  罗莹 《南京气象学院学报》1992,15(4):584-590

  相似文献   

Some features of the arid area variations over India: 1871–1984     

Nityanand Singh  S. S. Mulye  G. B. Pant 《Pure and Applied Geophysics》1992,138(1):135-150

Spatial variability of the annual rainfall over drier regions of India is studied by examining the variations in the arid areas. A long period (1871–1984) arid area series has been prepared for the entire country, including the two broad subregions of North India and Peninsular India, using annual rainfall data from 306 well distributed stations. Following an objectively determined criterion based on rainfall amount alone, the yearly area under arid conditions is obtained by totalling areas which received annual rainfall totals less than 560 mm. The interannual variability of the arid area series is large and its distribution is highly right-skewed, demonstrating large spatial variations in the annual rainfall over India. Statistical tests do not suggest any significant long-term trend in the arid area series, but persistently low values of the arid area after 1941 are noteworthy. Implications for the study of risk analysis and assessment of drought and desertification processes are discussed.  相似文献   

中国及邻近地区冬到夏的季节变化   总被引：1，自引：0，他引：1  

张家诚  张先恭  魏凤英 《气象》1995,21(7):3-8

南亚地区在冬到夏的转变过程中有显著的热力学与环境变化特征，是北半球季节变化的敏感区，对我国长期变化有十分重要的意义。根据这一特点，设计计算了南支西风指数，并将副高面积指数分南北区统计，更地地反映了季节变化特征。统计结果表明，这个指数组对梅雨与华北雨季有天气气候学意义。同时还找到了这个指数组对我国一些地区旱涝的前期指标。  相似文献   

Drought assessment in a south Mediterranean transboundary catchment     

Khouloud Gader  Ahlem Gara  Marnik Vanclooster  Slaheddine Khlifi  Mohamed Slimani 《水文科学杂志》2020,65(8):1300-1315

ABSTRACT

Predicting the impacts of climate change on water resources remains a challenging task and requires a good understanding of the dynamics of the forcing terms in the past. In this study, the variability of precipitation and drought patterns is studied over the Mediterranean catchment of the Medjerda in Tunisia based on an observed rainfall dataset collected at 41 raingauges during the period 1973–2012. The standardized precipitation index and the aridity index were used to characterize drought variability. Multivariate and geostatistical techniques were further employed to identify the spatial variability of annual rainfall. The results show that the Medjerda is marked by a significant spatio-temporal variability of drought, with varying extreme wet and dry events. Four regions with distinct rainfall regimes are identified by utilizing the K-means cluster analysis. A principal component analysis identifies the variables that are responsible for the relationships between precipitation and drought variability.  相似文献   

Evaluating simulated daily discharge for operational hydrological drought monitoring in the Global Drought Observatory (GDO)     

C. Cammalleri  P. Barbosa  J. V. Vogt 《水文科学杂志》2020,65(8):1316-1325

ABSTRACT

Hydrological drought is currently underrepresented in global monitoring systems, mainly due the shortage of near real-time estimates of river discharge at the global scale. In this study, the outputs of the Lisflood model are used to define a low-flow drought index, which shows a good correspondence with long-term records of the Global Runoff Data Centre in the period 1980–2014, as well as with verified information from the literature on six major drought events (covering different regions and watershed sizes). In contrast, the near real-time simulation (from 2015 onward) provides temporally inconsistent estimates over about 20% of the modelled cells (mostly over South America and Central Africa), even if reasonable results are obtained over other regions, as confirmed by intercomparison with the operational outcomes of the European Drought Observatory for the 2018 drought. In spite of the highlighted limitations, valuable information for operational drought monitoring can be retrieved from these simulations.  相似文献   

黄淮海平原冬小麦生长期旱情分析   总被引：7，自引：2，他引：5  

赵昕奕  刘继韩 《地理科学》1999,19(2):181-185

黄淮海平原降水较少且年际、季际变化大,因此水分供应状况成为该区作物,特别是以冬春季为主要生育期的冬小麦的主限制因素。鉴于作物实际蒸散量与潜在蒸散量关系依赖于作物生长状况和土壤水分的事实,提出反映作物缺水状况的干旱指标———作物水分胁迫指数（ＣＷＳＩ）。计算黄淮海平原冬小麦生长期间的ＣＷＳＩ,并分析其在自然降水条件及适量灌溉条件下的时空分异规律  相似文献   

A hyperspectral experiment over tropical forests based on the EO-1 orbit change and PROSAIL simulation     

Lênio Soares Galvão  Alana Almeida de Souza  Fábio Marcelo Breunig 《地理信息系统科学与遥感》2020,57(1):74-90

ABSTRACT

We designed a unique hyperspectral experiment from the Earth Observing One (EO-1) orbit change to evaluate solar illumination effects over tropical forests in Brazil. Ten nadir-viewing Hyperion images collected over a fixed site and period of the year (July to August) were selected for analysis. We evaluated variations in reflectance and in 16 narrowband vegetation indices (VIs) with increasing solar zenith angle (SZA) from the pre-drift (2004–2008) to the EO-1 drift period (2011–2016). To detect changes in reflectance and shadows, we applied spectral mixture analysis (SMA) and principal component analysis (PCA) and calculated the similarity spectral angle (θ) between the vegetation spectra measured with variable SZA. The magnitude of the illumination effects was also evaluated from change-point analysis and nonparametric Mann-Whitney U tests applied over the time series. Finally, we complemented our experiment using the PROSAIL model to simulate the VIs variation with increasing SZA resultant from satellite drift. The results showed significant changes in Hyperion reflectance and VIs, especially when the EO-1 crossed the study area at earlier times and larger SZA in 2015 (9:05 a.m.; SZA = 59°) and 2016 (8:30 a.m.; SZA = 67°). Compared to the pre-drift period (10:30 a.m.; SZA = 45°), the SZA differences of 14° (2015) and 22° (2016) increased the shade fractions and decreased the vegetation brightness. PCA separated the pre-drift and drift reflectance datasets, showing shifts in scores due to changes in brightness. θ increased with SZA, indicating changes in the shape of the vegetation spectra with drift. For most VIs, the change-point analysis indicated 2015 (SZA = 59°) as the predominant year of detected changes. Compared to the EO-1 original orbit, the Plant Senescence Reflectance Index (PSRI), Anthocyanin Reflectance Index (ARI) and Structure Insensitive Pigment Index (SIPI) presented the largest positive changes during drift, while the Photochemical Reflectance Index (PRI), Visible Atmospherically Resistant Index (VARI) and Enhanced Vegetation Index (EVI) had the largest negative changes. The effect size of the illumination geometry on these VIs was large, as indicated by increasing values of the Cohen’s r metric toward 2016. The anisotropy of the Hyperion VIs was generally consistent with that from PROSAIL in the simulated pre-drift and drift periods. Focusing on structural indices, it affected the relationships between VIs and simulated leaf area index (LAI) at large SZA.  相似文献