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1.
H. Feidas Ch. Noulopoulou T. Makrogiannis E. Bora-Senta 《Theoretical and Applied Climatology》2007,87(1-4):155-177
Summary In this study, the trends of annual and seasonal precipitation time series were examined on the basis of measurements of 22
surface stations in Greece for the period 1955–2001, and satellite data during the period 1980–2001. For this purpose, two
statistical tests based on the least square method and one based on the Mann-Kendall test, which is also capable of detecting
the starting year of possible climatic discontinuities or changes, are applied. Greece, in general, presents a clear significant
downward trend in annual precipitation for the period 1955–2001, which is determined by the respective decreasing trend in
winter precipitation. Both winter and annual series exhibit a downward trend with a starting year being 1984. Satellite-derived
precipitation time series could be an alternative means for diagnosing the variability of precipitation in Greece and detecting
trends provided that they have been adjusted by surface measurements in the wider area of interest. The relationship between
precipitation variability in Greece and atmospheric circulation was also examined using correlation analysis with three circulation
indices: the well-known North Atlantic Oscillation Index (NAOI), a Mediterranean Oscillation Index (MOI) and a new Mediterranean
Circulation Index (MCI). NAOI is the index that presented the most interesting correlation with winter, summer and annual
precipitation in Greece, whereas the MOI and MCI were found to explain a significant proportion of annual and summer precipitation
variability, respectively. The observed downward trend in winter and annual precipitation in Greece is linked mainly to a
rising trend in the hemispheric circulation modes of the NAO, which are connected with the Mediterranean Oscillation Index. 相似文献
2.
基于1951—2018年再分析资料和观测的降水量资料,采用联合经验正交函数分解的方法,分析了华南冬末春初(2、3月)降水年际变异特征,并讨论了相应的环流背景及物理机制。华南2、3月降水变异的第一关联主模态反映出全区2、3月同相变化,第二模态呈现反相变化。第一模态的降水异常与ENSO关联的热带海温异常分布有关,其导致的西太平洋异常反气旋的维持使得2、3月的降水持续出现同相异常。第二模态的降水异常与中高纬度的大气环流异常有关：2月表现为欧亚遥相关型,3月则表现为北极涛动型。第二模态2、3月位势高度异常型的转变分别与北大西洋的热通量的异常变化及平流层极涡信号的下传有关：当2月北大西洋热通量正异常显著时,500 hPa高度场呈现欧亚遥相关(EU)负位相的分布;平流层极涡异常信号在3月下传达到对流层低层,使得3月对流层极涡增强,有利于北极涛动(AO)正位相的形成。2、3月欧亚大陆上空分别在EU遥相关型和AO型环流异常的影响下,导致了华南地区上空的大气环流的辐合辐散异常,并最终造成2、3月华南的降水量反相异常的出现。 相似文献
3.
The impacts of four teleconnection patterns on atmospheric circulation components over Eurasia and the Pacific region, from low to high latitudes in the Northern Hemisphere (NH), were investigated comprehensively in this study. The patterns, as identified by the Climate Prediction Center (USA), were the East Atlantic (EA), East Atlantic/Western Russia (EAWR), Polar/Eurasia (POLEUR), and Scandinavian (SCAND) teleconnections. Results indicate that the EA pattern is closely related to the intensity of the subtropical high over different sectors of the NH in all seasons, especially boreal winter. The wave train associated with this pattern serves as an atmospheric bridge that transfers Atlantic influence into the low-latitude region of the Pacific. In addition, the amplitudes of the EAWR, SCAND, and POLEUR patterns were found to have considerable control on the “Vangengeim–Girs” circulation that forms over the Atlantic–Eurasian region in winter or spring. The EA and EAWR mainly affect the westerlies in winter and spring and the POLEUR and SCAND, respectively, in summer and winter. Strong westerlies confine the extension of the North Polar vortex, which generally results in a small weak vortex and a shallow East Asian trough located in a position further east than normal. Furthermore, the North Polar vortex presents significant connections with the patterns during winter and summer. Analyses in this work suggest that the teleconnection patterns in summer could be driven, at least partly, by the Atlantic Multidecadal Oscillation, which to some degree might transmit the influence of the Atlantic Ocean to Eurasia and the Pacific region. 相似文献
4.
塞罕坝地区是我国生态文明建设的典范区,本文对塞罕坝地区多年气温和降水的大尺度环流异常进行合成分析,研究其环流特征及关键环流因子。结果表明：1962-2020年塞罕坝地区气温总体呈偏高趋势,春、秋、冬季降水呈偏多趋势,夏季降水呈偏少趋势。大尺度环流背景下,各季节影响塞罕坝地区气温和降水的主要因子不同,通过挑选最优因子分析得出：塞罕坝地区受大气环流指数影响明显,春季太平洋-北美遥相关型指数（PNA）、夏季北大西洋涛动指数（NAO）、秋季西太平洋遥相关型指数（WP）、冬季高原季风指数（PMI）与该地气温和降水有较好的关系。 相似文献
5.
The objective of this paper is to determine the influence of circulation factors on precipitation in Bulgaria. The study succeeds investigation on the influence of circulation factors on air temperatures in Bulgaria, as the focus here is directed toward precipitation amounts. Circulation factors are represented through two circulation indices, showing west-east or south-north transport of air masses over Bulgaria and four teleconnection indices (patterns)—North Atlantic Oscillation, East Atlantic, East Atlantic/Western Russia, and Scandinavian. Omega values at 700-hPa level show vertical motions in the atmosphere. Annual precipitation trends are mixed and not statistically significant. A significant decrease of precipitation in Bulgaria is observed in November due to the strengthening of the eastward transport of air masses (strengthening of EA teleconnection pattern) and anticyclonal weather (increase of descending motions in the atmosphere). There is also a precipitation decrease in May and June due to the growing influence of the Azores High. An increase of precipitation happens in September. All this leads to a redistribution of annual precipitation course, but annual precipitation amounts remain the same. However, this redistribution has a negative impact on agriculture and winter ski tourism. Zonal circulation has a larger influence on precipitation in Bulgaria compared to meridional. Eastward transport throughout the year leads to lower than the normal precipitation, and vice versa. With regard to the four teleconnection patterns, winter precipitation in Bulgaria is determined mainly by EA/WR teleconnection pattern, spring and autumn by EA teleconnection pattern, and summer by SCAND teleconnection pattern. 相似文献
6.
D. Gellens 《Theoretical and Applied Climatology》2000,66(1-2):117-129
Summary
k-day extreme precipitation depths (k=1,2,3, … 30) for the climatological network of Belgium (165 stations) are analysed to detect a possible evolution in the
occurrence of extreme rainfall events during the 1951–1995 reference period. The calendar year and the hydrological summer
and winter are considered separately. Spearman’s rank correlation coefficient shows a strong spatial correlation between extreme
k-day precipitation events, depending on the time of the year (lower during summer than during winter) and increasing with
k. In some cases the distances of de-correlation exceed 200 km which is comparable to the size of the country. Due to this
correlation, tests for trends have been carried out on the leading principal components (PC) derived from the covariance matrix.
Various PC selection rules have been applied to identify the number of components to analyse. The number of components needed
to reproduce a given proportion of the total variance varies, with larger values for summer than for winter and a decrease
with growing k. The Fisher test is used as a global test. It combines the individual Mann-Kendall trend tests carried out on the selected
PC scores. Significant trends have been found in extreme winter k-day precipitation for all the values of k and none in extreme summer precipitation. The results for the annual k-day precipitation depths are between those for the two seasons: no trend for small k because summer events dominate and a significant trend for k larger than 7 due to the winter events. Analysis of a few stations with long-term series shows no significant trend for the
period 1910–1995, these series also reproduce almost the same trends as those found for the shorter 1951–1995 period.
Received April 23, 1999 Revised December 6, 1999 相似文献
7.
Summary ?The variability of the winter mean precipitation observed at 40 rainfall stations in Emilia-Romagna (a region in northern
Italy) from 1960 to 1995 is examined. The results are compared with those obtained for the whole of Italy using records from
32 stations. Temporal variability of the time series is investigated by means of Mann-Kendall and Pettitt tests, in order
to estimate the presence of trends and “change points”. Before analysis the original precipitation data set have been tested
to detect the inhomogeneity points, using the Standard Normal Homogeneity Test (SNHT). Almost all stations situated in Emilia
Romagna exhibit a significant decreasing trend in winter precipitation during the 1960–1995 period. The same characteristics
are revealed, more significant in the northern and central part of the region, when the stations for all Italy are analysed.
A significant downward shift in the winter precipitation is detected through the Pettitt test in Emilia Romagna, around 1980 at some stations, while the rest of the stations reveal the shift point occurrence around 1985. A significant downward shift in the winter precipitation is detected around 1985, when analysing the time series for all Italy. Spatial variability of winter precipitation is studied using the Empirical
Orthogonal Function. The first pattern indicates that a common large-scale process could be responsible for the winter precipitation
variability. The second EOF pattern shows an opposite sign of climate variability, which highlights the influence of relief
on the precipitation regime. The time series associated with the first precipitation pattern (PC1) at both scales emphasises
a significant decreasing trend and a downward shift point around 1985. The internal structure analysis of the North Atlantic
Oscillation (NAO) index during the 1960–1995 period reveals a significant increasing trend and an upward shift around 1980.
Strong correlation is also detected between PC1 (Emilia Romagna and at the scale of all Italy) and the NAO index. Thus, the
changes detected in the winter precipitation around 1985 could be due to an intensification of the positive phase of the [NAO],
especially after 1980.
Received March 23, 2001; revised February 20, 2002; accepted March 3, 2002 相似文献
8.
A teleconnection is analyzed which exists between long-term variations of temperature and precipitation in St. Petersburg in March and April and North Atlantic and European atmospheric zonal circulation during the 20th century. It is shown that current climate warming in the region is almost entirely explained by a significant enhancement of warm advection of Atlantic air onto the continent. 相似文献
9.
10.
Influence of North Atlantic sea surface temperature (SST) anomalies on tropical Pacific SST anomalies is examined. Both summer and winter North Atlantic SST anomalies are negatively related to central-eastern tropical Pacific SST anomalies in the subsequent months varying from 5 to 13?months. In particular, when the North Atlantic is colder than normal in the summer, an El Ni?o event is likely to be initiated in the subsequent spring in the tropical Pacific. Associated with summer cold North Atlantic SST anomalies is an anomalous cyclonic circulation at low-level over the North Atlantic from subsequent October to April. Corresponded to this local response, an SST-induced heating over the North Atlantic produces a teleconnected pattern, similar to the East Atlantic/West Russia teleconnection. The pattern features two anticyclonic circulations near England and Lake Baikal, and two cyclonic circulations over the North Atlantic and near the Caspian Sea. The anticyclonic circulation near Lake Baikal enhances the continent northerlies, and strengthens the East-Asian winter monsoon. These are also associated with an off-equatorial cyclonic circulation in the western Pacific during the subsequent winter and spring, which produces equatorial westerly wind anomalies in the western Pacific. The equatorial westerly wind anomalies in the winter and spring can help initiate a Pacific El Ni?o event following a cold North Atlantic in the summer. 相似文献
11.
Summary An attempt has been made to relate a large-scale airflow classification to the local weather at two stations in Estonia.
To describe the features of the general circulation over Europe, the large-scale circulation patterns (Grosswetterlagen) of the German Weather Service have been chosen. Daily precipitation and temperature deviations from the monthly mean in
P?rnu and Tartu for 1961–1993 have been used. It can be said that the weather in Estonia shows a good relationship with the
general circulation types (Zirkulationsformen) that are defined by means of the Grosswetterlagen. Zonal circulation brings to Estonia wet weather that in winter is warmer than average and in summer cooler than average.
Mixed circulation is associated with warmer winters and average summers. Meridional circulation brings cold winters and variable
weather in summer. To explain the large dispersion of values of meteorological elements within any one circulation type, a
more detailed analysis of the relationships between circulation patterns and meteorological situation in Estonia is needed.
Received June 17, 1998 Revised January 13, 1999 相似文献
12.
Seasonality of the Interaction between Convection over the Western Pacific and General Circulation in the Northern Hemisphere 总被引：2，自引：0，他引：2
The seasonality of the interaction between convection over the western Pacific and general circulation in the Northern Hemisphere (NH) is analyzed in the present paper with singular value decomposition (SVD) and empirical orthogonal function (EOF) analysis approaches, based on 500 hPa monthly mean geopotential height data and high-cloud amount data. The analyses demonstrate that coupled dominant patterns in the interaction between the convection over the western Pacific and the general circulation in NH are different in various seasons. In spring, the convection over the western Pacific is closely related with the western Atlantic (WA) and North Pacific (NP) like patterns of the general circulation in NH, and some associations between the WA and NP like pat?terns and the El Ni?o / Southern Oscillation (ENSO) cycle are also existed. The Pacific Japan (PJ) pattern is the dom?inant pattern in the interaction between the interannual variabilities of the convection over the western Pacific and the general circulation in NH summer. The WA like pattern and 3-4 year period oscillation are also relatively obvious for the summer case. In autumn, the convection over the western Pacific is closely linked with the Eurasian (EU) like pattern and the Atlantic oscillation in the general circulation in NH, it is suggested that in autumn the vitiation of convective activity over the western Pacific is largely affected by the general circulation anomaly (cold air from high latitudes) through EU like teleconnection pattern. Abrupt change happened by the end of 1980’s in the autumn interaction. The strong interaction between the western Pacific (WP) and EU like patterns in the general circulation in NH and the convection over the western Pacific and a linear trend of increasing of this interaction are also suggested in winter. It is also demonstrated that the interaction in summer and winter is stronger than in the transition seasons (spring and autumn). 相似文献
13.
Sebastian Wagner Martin Widmann Julie Jones Torsten Haberzettl Andreas Lücke Christoph Mayr Christian Ohlendorf Frank Schäbitz Bernd Zolitschka 《Climate Dynamics》2007,29(4):333-355
This study investigates the atmospheric circulation in transient climate simulations with a coupled atmosphere–ocean general
circulation model (GCM) for the mid-Holocene (MH) period 7–4.5 ka BP driven with combinations of orbital, solar and greenhouse
gas forcings. The focus is on southern South America. Statistical downscaling models are derived from observational data and
applied to the simulations to estimate precipitation in south-eastern Patagonia during the MH. These estimates are compared
with lake level estimates for Laguna Potrok Aike (LPA) from sediments. Relative to pre-industrial conditions (i.e. 1550–1850),
which show extraordinarily high lake levels, the proxy-based reconstructed lake levels during the MH are lower. The downscaled
simulated circulation differences indicate higher LPA precipitation during the MH from March to August, higher annual means,
and reduced precipitation from September to February. Thus the reconstructed lower LPA lake levels can not be explained solely
by the simulated precipitation changes. Possible reasons for this discrepancy are discussed. Based on proxy data from southern
South America hypotheses have also been proposed on the latitudinal position of the southern hemispheric westerlies (SHWs).
In agreement with some of these hypotheses our simulations show an increased seasonal cycle of the latitudinal position of
the SHWs during the MH, which can be explained by the orbital forcing. The simulations also show stronger SHWs over southern
Patagonia during austral summer and weaker SHWs during winter. The downscaling model associates weaker SHWs with increased
precipitation in the LPA region. However, this relationship is only moderate, and therefore the downscaling model does not
support the assumption of a strong link between mean SHWs and precipitation over south-eastern Patagonia, which is the basis
of many proxy-based hypotheses about the SHWs. 相似文献
14.
Results from nine coupled ocean-atmosphere simulations have been used to investigate changes in the relationship between the
variability of monsoon precipitation over western Africa and tropical sea surface temperatures (SSTs) between the mid-Holocene
and the present day. Although the influence of tropical SSTs on the African monsoon is generally overestimated in the control
simulations, the models reproduce aspects of the observed modes of variability. Thus, most models reproduce the observed negative
correlation between western Sahelian precipitation and SST anomalies in the eastern tropical Pacific, and many of them capture
the positive correlation between SST anomalies in the eastern tropical Atlantic and precipitation over the Guinea coastal
region. Although the response of individual model to the change in orbital forcing between 6 ka and present differs somewhat,
eight of the models show that the strength of the teleconnection between SSTs in the eastern tropical Pacific and Sahelian
precipitation is weaker in the mid-Holocene. Some of the models imply that this weakening was associated with a shift towards
longer time periods (from 3–5 years in the control simulations toward 4–10 years in the mid-Holocene simulations). The simulated
reduction in the teleconnection between eastern tropical Pacific SSTs and Sahelian precipitation appears to be primarily related
to a reduction in the atmospheric circulation bridge between the Pacific and West Africa but, depending on the model, other
mechanisms such as increased importance of other modes of tropical ocean variability or increased local recycling of monsoonal
precipitation can also play a role. 相似文献
15.
有关南半球大气环流与东亚气候的关系研究的若干新进展 总被引：14，自引：15，他引：14
南半球大气环流是全球大气环流的重要组成部分,也是影响气候变化和亚洲季风系统的一个重要因素.中国气象学家很早就注意到南半球大气环流对东亚夏季风降水的影响.近年来,有关南半球气候变率的研究目前正受到世界气象学家越来越多的关注.南半球中高纬大气资料的丰富及南极涛动的确定,使得认识南半球高中纬环流的年际变动规律及其与东亚气候关系成为可能.本文主要介绍近年来有关南极涛动的年际变化与沙尘天气发生频次及东亚冬春季气候的关系,古气候资料揭示的南极涛动与华北降水的关系,以及南半球大气环流与长江中下游夏季降水的关系和南极涛动变率的可预测性等方面的研究进展.并对未来研究方向作了初步的展望. 相似文献
16.
T&#;mea Kocsis Ilona Kov&#;cs-Sz&#;kely Ang&#;la Anda 《Theoretical and Applied Climatology》2020,139(3):849-859
This study aims to investigate the precipitation trends in Keszthely (Western Hungary, Central Europe) through an examination of historical climate data covering the past almost one and a half centuries. Pettitt’s test for homogeneity was employed to detect change points in the time series of monthly, seasonal and annual precipitation records. Change points and monotonic trends were analysed separately in annual, seasonal and monthly time series of precipitation. While no break points could be detected in the annual precipitation series, a significant decreasing trend of 0.2–0.7 mm/year was highlighted statistically using the autocorrelated Mann-Kendall trend test. Significant change points were found in those time series in which significant tendencies had been detected in previous studies. These points fell in spring and winter for the seasonal series, and October for the monthly series. The question therefore arises of whether these trends are the result of a shift in the mean. The downward and upward shift in the mean in the case of spring and winter seasonal amounts, respectively, leads to a suspicion that changes in precipitation are also in progress in these seasons. The study concludes that homogeneity tests are of great importance in such analyses, because they may help to avoid false trend detections. 相似文献
17.
C. Serra A. Burgueño M. D. Martínez X. Lana 《Theoretical and Applied Climatology》2006,85(3-4):165-183
Summary A spatiotemporal trend analysis of different magnitudes related to the number and length of the dry spells in Catalonia (NE
Spain) has been conducted based on daily rainfall records taken from 40 rain gauges during the second half of the 20th century. Dry spells have been computed for threshold levels of 0.1, 1, 5 and 10 mm/day at annual and semi-annual scales.
The winter half-year is defined from October to March and the summer half-year from April to September. The magnitudes considered
are the number, the maximum length and the mean length of the dry spells for every year and half-year. The spatial patterns
of the average values of these magnitudes at the annual scale show a greater similarity with those of the summer half-year
than with those of the winter half-year. A S–N or SW–NE gradient of the number of dry spells appears during the summer half-year
for every threshold level. Trends of the analysed magnitudes are derived from linear regression and local statistical significances
at the 95% confidence level are established using the Mann-Kendall test. Field significant trends are investigated by means
of Monte Carlo simulations. The most relevant finding is that the number of dry spells per year depicts significant trends
for the annual and winter-half series, with an overall decreasing trend for 5 and 10 mm/day thresholds. These observed trends
are in agreement with changes in North Atlantic cyclone tracks and in Mediterranean Low dynamics, due to increasing greenhouse
gas concentrations. 相似文献
18.
根据阜新地区2个观测站1951-2010年逐月和逐年降水资料,通过趋势分析、Mexicohat小波变换和Mann-Kendall突变检验等方法,分析了阜新地区降水的气候变化特征。结果表明：阜新地区近60 a来年降水量呈下降趋势,下降速率为10.7 mm/10a;降水量年际变化明显,极易出现旱涝灾害。除春季降水略有增加外,其他三季均呈减少趋势。年降水量和季节降水量均有准12 a和18 a的周期振荡。除春季降水量没有明显突变点外,夏、秋、冬三季均存在突变点,其中夏季降水量存在3个突变年份,分别为1967年、1978年和1986年,秋季降水量在1996年存在突变,冬季降水量在2004年存在突变。 相似文献
19.
Upper-level cut-off lows in southern South America 总被引：2，自引：0，他引：2
Summary This paper presents a statistical study of the spatial and seasonal distribution and duration of cut-off low systems over
the southern South American region based on the NCEP- NCAR reanalysis data for the period 1979–1988. Cut-off lows were first
objectively determined as minimum geopotential values at the 250 hPa level and then subjectively imposing a cut-off circulation
and a cold core. A total of 171 cut-off low events were detected, being more frequent in austral autumn followed by winter,
spring and summer. There is a preferential region of occurrence in spring and autumn located between 68°–80° W and 30°–45° S.
The Pacific area showed the greatest frequency of occurrence followed by the Atlantic and the continental areas. Most of the
cut-off lows last 2 or 3 days (around 90% of the cases) though there is a tendency of the continental events to be longer.
The cut-off low event developed upwind the Andes on 22–28 September 1986 was selected as a case study. Low-level cold air
advection was the main forcing of the deepening of the upper level low system. 相似文献
20.
Summary The spatial and temporal variability of winter precipitation and its links to the large-scale atmospheric circulation patterns in Romania are examined. The data set is composed of observed rainfall at 30 meteorological stations during the 1961–1996 period. The large-scale field is represented by the observed geopotential height at 500 hPa (Z500) over the same period, covering the latitudinal belt between 20° N–90° N (resolution 2.5°×2.5°).The Standard Normal Homogeneity Test (SNHT) is applied to detect inhomogeneities in the data, and the Mann-Kendall and Pettitt non-parametric tests are used in order to identify trends and change points in the winter precipitation time series. The empirical orthogonal functions (EOF) technique is used for data reduction in order to highlight the basic patterns of rainfall variability in Romania. The covariance map between precipitation EOF time series (PCs) and the Z500 field, as well as the correlation coefficients between the PCs and circulation indices are calculated in order to identify the influence of large-scale circulation patterns on winter precipitation in Romania.A significant decreasing trend is identified in winter precipitation with a downward shift in winter 1969/1970, most significant from a statistical point of view in the extra-Carpathian region. This change seems to be real since the SNHT test does not reveal any inhomogeneity during the period tested. Significant relationships are found between winter precipitation variability in Romania and the large-scale circulation pattern, such as the North Atlantic Oscillation and the blocking phenomenon in the Atlantic-European sector. The positive phase of the NAO and the reduction in blocking activity could be one of the causes of the decrease in winter precipitation in Romania. 相似文献