共查询到19条相似文献，搜索用时 156 毫秒
1.
2.
湖南省近60年雨凇的气候特征 总被引：2，自引：0，他引：2
采用湖南97个地面气象站点气象观测资料、运用经验正交函数、旋转经验正交函数、一元线性回归、Mann-Kendall、小波分析等方法分析了湖南雨凇的时空分布特征及变化趋势,并与高山站的变化趋势进行了比较.结果表明:湖南雨凇发生在11月至翌年3月,空间分布特征呈现为南多北少、东多西少、迎风坡多、背风坡少、“三心二带”、高低交错.湖南雨凇日数空间分布既有全区一致性,也存在着南北反向变化的差异,空间分布大致可分为湖南南部、北部及中部、西北部3个异常区.湖南年雨凇日数和南岳高山站年雨凇日数呈现出的周期变化相同,即均存在2a、4a、9a和24 a左右的准周期,2a和4a周期尺度雨凇日数多和少转换频繁,9a周期尺度在1970年代末以前振荡明显,在24 a准周期尺度上经历了1960年代初期、1970年代中期、1990年代初期、2000年代中期4个转折年份.在过去60年全省年雨凇日数呈显著减少趋势,南岳高山站年雨凇日数趋势变化不明显,但存在明显的年际和年代际变化. 相似文献
3.
该文利用1971-2005年六盘水市3个测站的平均气温资料,采用线性倾向估计、小波分析等统计方法,对六盘水地区倒春寒天气的分布情况、年际变化及倒春寒发生的总次数及总日数的气候变化特征等进行了分析,结果表明:近35a倒春寒天气东部、北部较重,南部较轻;倒春寒天气总日数和总次数近35a来均呈下降趋势;倒春寒天气总日数在年代际尺度上存在显著的16a、准10a周期振荡,在年际尺度上,存在准6a和2~4a的振荡周期;倒春寒天气总次数存在显著的准10a周期振荡和一个较弱的准4a振荡周期;目前倒春寒天气由偏少向偏多的趋势转变。 相似文献
4.
利用1961～2012年宁夏22个气象台站逐日天气现象、能见度、相对湿度资料,采用气候倾向率、趋势系数、最大熵谱分析、突变分析等方法,分析了宁夏各区域雾日数和霾日数的空间分布及变化趋势。结果表明：宁夏雾目数、霾日数均呈南北多、中间少的空间特征,但雾日数南部最多,而霾日数北部最多。近52a来,雾日数除南部山区呈不显著的减少趋势外,其他3个区域均呈增多趋势,而霾日数各区域均呈显著的增多趋势;另外,二者均有明显的阶段性演变特征,1961—1980年为明显偏少阶段,1981～2000年为波动变化阶段,2001年以后为明显偏多阶段;雾日数具有较明显的准7．5a,4．3a周期振荡,霾日数具有较明显的准4．6a、3,0a周期振荡;各区域雾日数与霾日数均未发生突变现象。 相似文献
5.
利用喀什市1961—2012年逐日最高、最低、平均气温资料,采用回归分析、R/S分析、Morlet小波分析及Mann-kendall突变检验等方法,分析了喀什市极端气温长期变化趋势、持续性、周期变化及突变特征。结果表明:喀什市年平均气温呈显著上升趋势,升温率高于全球及全国水平且主要变暖从20世纪90年代开始,较全国同期增温时间滞后;极端高温、夏季日数呈显著增加趋势,极端低温、霜冻日数呈减少趋势,经R/S分析,极端气温指数及年平均气温序列具有较好的连续性,未来喀什市气温保持升高,极端高温、夏季日数增加,极端低温、霜冻日数减少;喀什市极端气温指数在时间域上包含了多个尺度的周期变化,各类极端气温指数具有不同强度的周期变化特征;近52a极端高温日数在1995年发生突变,夏季日数、极端低温、霜冻日数的突变均发生在2001年左右。 相似文献
6.
利用河源市观象台1953～2010年最低气温≤5℃的低温日数和霜冻日数资料,运用线性倾向估计、Mann-Kendal突变检验和小波分析等方法,对河源市近58年来低温和霜冻的主要特征进行分析。结果表明:近58年来河源低温日数和霜冻日数呈显著减少趋势;12月和1月是低温和霜冻天气出现最多的2个月份;初低温日和初霜冻日存在较明显退后趋势,终霜冻日存在明显提前趋势,但终低温日的提前趋势不明显;低温日数和霜冻日数分别在1976年和1994年发生突变;低温日数存在2～4年、8年左右和准14年的周期变化;霜冻日数存在2～3年、5～7年和准13年左右的周期变化。 相似文献
7.
8.
利用宜昌市9个观测站1966-2010年的逐13降水资料,采用线性趋势分析、小波分析和Mann-Kendall法等方法分析了近45a来宜昌市暴雨日数的变化趋势、多时间尺度的时频特征和气候突变特征。结果表明：宜昌市暴雨日数空间分布存在明显差异,基本表现为南多北少;近45a暴雨日数呈现不明显增加趋势,且存在明显的两次波动;暴雨日数存在2-4a、6a、准10a、准16a的4类尺度的周期变化规律,其中在2-4a时间尺度下周期振荡最强,从准10a和准16a时间尺度来看,在2010年后一段时间宜昌市暴雨日数还是处于相对偏多期;突变检测显示,暴雨日数在1979年前后发生了气候突变。 相似文献
9.
贵州夏季暴雨的气候特征 总被引：3，自引：0，他引：3
利用贵州52个测站的1961-2006年历年夏季（6-8月）逐日降水资料,分析了贵州夏季暴雨的时空分布特征、周期振荡及其突变特征。结果表明：46 a来贵州夏季暴雨量呈增加趋势,并存在明显的年际、年代际变化特征;暴雨日数和暴雨量在1985年发生突变;暴雨日数和暴雨量均存在15 a和准10 a的周期振荡;暴雨日数和暴雨量EOF分解的第一特征向量的荷载场空间分布基本一致,表明全省呈偏多（少）的一致型同位相分布。 相似文献
10.
利用贵州52个测站的1961-2006年历年夏季（6-8月）逐日降水资料,分析了贵州夏季暴雨的时空分布特征、周期振荡及其突变特征。结果表明：46 a来贵州夏季暴雨量呈增加趋势,并存在明显的年际、年代际变化特征;暴雨日数和暴雨量在1985年发生突变;暴雨日数和暴雨量均存在15 a和准10 a的周期振荡;暴雨日数和暴雨量EOF分解的第一特征向量的荷载场空间分布基本一致,表明全省呈偏多（少）的一致型同位相分布。 相似文献
11.
利用梅州市气象观测站1952—2012年低温、霜冻资料,采用线性回归、小波分析和Mann-Kendall非参数检验等方法,分析梅州市近61 a来的低温、霜冻气候变化特征。结果表明,梅州低温、霜冻日数呈明显减少趋势;12月和1月是低温、霜冻天气出现最多的2个月份,占总日数的70%以上。初低温日和初霜冻日存在延后趋势,终低温日和终霜冻日存在提前趋势。20世纪80年代初低温、霜冻强度开始减弱,低温、霜冻日数也在此时期发生突变减少。低温日数存在2—4 a、7 a和10 a的周期变化,霜冻日数存在2—4 a、6—7 a和10 a的周期变化。根据低温、霜冻天气出现的主要两类天气形势,再结合单站气象要素特征,归纳总结低温、霜冻天气的预报指标和经验。 相似文献
12.
13.
MULTIPLE TIME SCALE ANALYSIS OF CLIMATE VARIATION IN MACAU DURING THE LAST 100 YEARS 总被引：1，自引：1，他引：0
The multiple time scale climate changes are studied and calculated with statistical analysis and wavelet transformation on the basis of daily series of observed data over the period 1901-2007 in Macau.The result shows that statistically significant oscillations with 2 to 5 years of period generally exist in the series of climate variables(e.g.annual mean surface air temperature and precipitation as well as evaporation etc.),but with obvious locality in time domain.The variation of annual mean surface air temperature has a quasi 60-year period.The phases of the 60-year variation approximately and consistently match that of Atlantic Multidecadal Oscillation(AMO).The oscillations of seasonal mean surface air temperature in summer and winter have the periods of quasi 30-year and quasi 60-year,respectively.These two periods of oscillations have statistically significant correlation with Pacific decadal oscillation(PDO) and AMO,individually.The multidecadal variations of the precipitation of the annually first flood period and annual evaporation are dominated by periods of quasi 30-year and quasi 50-year,respectively. 相似文献
14.
R. N. C. Anyadike 《Theoretical and Applied Climatology》1992,45(4):285-292
Summary Previous work on rainfall variations over Nigeria has concentrated on country-wide averages, which approach has tended to mask the regional contrasts in the country's rainfall. In this paper, variations of rainy season rainfall over the Southern, Middle Belt, and Northern regions of Nigeria as well as the country as a whole are examined over a 72-year secular period (1916–1987). The extent and nature of nonrandom changes, such as fluctuations, trend and persistence, are investigated.The trend analysis showed a tendency towards decreasing seasonal rainfall totals in all the regions, though only those for the Northern region and the country as a whole were significant. No significant persistence was however evident in any of the regions.Power spectrum analysis revealed the occurrence of significant oscillations with time periods of 2.53 to 2.67 and 3.69 to 4.36 years only in the Middle Belt, and 8.00 to 9.60 years in all the regions. The climatological identity of the Middle Belt and the implications of its rainfall oscillations for the large scale agricultural projects planned for the region are pointed out.With 3 Figures 相似文献
15.
The association between heat waves and the urban heat island effect can increase the impact on environment and society inducing biophysical hazards. Heat stress and their associated public health problems are among the most frequent. This paper explores the heat waves impact on surface urban heat island and on the local economy loss during three heat periods in Cluj-Napoca city in the summer of 2015. The heat wave events were identified based on daily maximum temperature, and they were divided into three classes considering the intensity threshold: moderate heat waves (daily maximum temperature exceeding the 90th percentile), severe heat waves (daily maximum temperature over the 95th percentile), and extremely severe heat waves (daily maximum temperature exceeding the 98th percentile). The minimum length of an event was of minimum three consecutive days. The surface urban heat island was detected based on land surface temperature derived from Landsat 8 thermal infrared data, while the economic impact was estimated based on data on work force structure and work productivity in Cluj-Napoca derived from the data released by Eurostat, National Bank of Romania, and National Institute of Statistics. The results indicate that the intensity and spatial extension of surface urban heat island could be governed by the magnitude of the heat wave event, but due to the low number of satellite images available, we should consider this information only as preliminary results. Thermal infrared remote sensing has proven to be a very efficient method to study surface urban heat island, due to the fact that the synoptic conditions associated with heat wave events usually favor cloud free image. The resolution of the OLI_TIRS sensor provided good results for a mid-extension city, but the low revisiting time is still a drawback. The potential economic loss was calculated for the working days during heat waves and the estimated loss reached more than 2.5 mil. EUR for each heat wave day at city scale, cumulating more than 38 mil. EUR for the three cases considered. 相似文献
16.
T. N. Krishnamurti Ruby Krishnamurti Anitha D. Sagadevan Arindam Chakraborty William K. Dewar Carol Anne Clayson James F. Tull 《Meteorology and Atmospheric Physics》2009,105(1-2):69-83
Using the United States Geological Survey global daily data sets for 31 years, we have tabulated the earthquake intensities on a global latitude longitude grid and represented them as a finite sum of spherical harmonics. An interesting aspect of this global view of earthquakes is that we see a low frequency modulation in the amplitudes of the spherical harmonic waves. There are periods when these waves carry larger amplitudes compared to other periods. A power spectral analysis of these amplitudes clearly shows the presence of a low frequency oscillation in time with a largest mode around 40 days. That period also coincides with a well-know period in the atmosphere and in the ocean called the Madden Julian Oscillation. This paper also illustrates the existence of a spatial oscillation in strong earthquake occurrences on the western rim of the Pacific plate. These are like pendulum oscillations in the earthquake frequencies that swing north or south along the western rim at these periods. The spatial amplitude of the oscillation is nearly 10,000 km and occurs on an intraseasonal time scale of 20–60 days. A 34-year long United States Geological Survey earthquake database was examined in this context; this roughly exhibited 69 swings of these oscillations. Spectral analysis supports the intraseasonal timescale, and also reveals higher frequencies on a 7–10 day time scale. These space-time characteristics of these pendulum-like earthquake oscillations are similar to those of the MJO. Fluctuations in the length of day on this time scale are also connected to the MJO. Inasmuch as the atmospheric component of the MJO will torque the solid earth through mountain stresses, we speculate the MJO and our proposed earthquake cycle may be connected. The closeness of these periods calls for future study. 相似文献
17.
We examined the changes in streamflow on the northern slopes of the Tianshan Mountains in northern Xinjiang, China, over two time scales: the past 500 years, based on dendrochronology data; and the past 50 years, based on streamflow data from hydrological stations. The method of artificial neural networks built from the data of the 50-year period was used to reconstruct the streamflow of the 500-year period. The results indicate that streamflow has undergone seven high-flow periods and four low-flow periods during the past 500 years. To identify possible transition points in the streamflow, we applied the Mann–Kendall and running T tests to the 50- and 500-year periods, respectively. During the past 500 years, streamflow has changed significantly from low to high flow about three to four times, and from high to low flow about three to five times. Over the recent 50 years, there have been three phases of variation in river runoff, and the most distinct transition of streamflow occurred in 1996. 相似文献
18.
On the basis of NOAA/CPC data of sea surface temperature anomaly in the Nino regions during Jan. 1950 - Dec. 2003, the wavelet power spectrum of SST were studied with significance and confidence testing at different scales in this paper. It shows that the SST are provided with multi-time scales structure nested one another, and vary on scales of 2 - 7 years, 8 - 20 years and ＞30 years. The most significant variation of the warm and cold episodes is in the 4-year band of period. The power, frequency structure and confidence of the same episode are different in different Nino regions. The intensity of oscillations is increasing at low frequency bands and decreasing at high frequency bands from east to west in the Nino regions, especially after 1970. 相似文献