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1.
Summary The analysis ofReitan's data on precipitable water vapour in the atmosphere, and data ofJunge on the nitrate content of precipitation, is extended onto a seasonal basis. Computations indicate consistency between precipitable water vapour, precipitation and its nitrate content, within a semiemprical law proposed, and especially for the warmer trimestres of the period July 1956–June 1957. A simple expression correlating the atmospheric content of precipitable water vapour over stations situated between sea level and 580 ft of altitude, with temperature, is suggested and tested. Increasing trends of atmospheric nitrate with latitude are established for all seasons of the period examined.Contribution of the Centro Nucleazione Aerosoli of the National Research Council of Italy, Via Vettore 4 (Monte Sacro),Rome. 相似文献
2.
Trend analysis in Turkish precipitation data 总被引：9，自引：0，他引：9
This study aims to determine trends in the long‐term annual mean and monthly total precipitation series using non‐parametric methods (i.e. the Mann–Kendall and Sen's T tests). The change per unit time in a time series having a linear trend was estimated by applying a simple non‐parametric procedure, namely Sen's estimator of slope. Serial correlation structure in the data was accounted for determining the significance level of the results of the Mann–Kendall test. The data network used in this study, which is assumed to reflect regional hydroclimatic conditions, consists of 96 precipitation stations across Turkey. Monthly totals and annual means of the monthly totals are formed for each individual station, spanning from 1929 to 1993. In this case, a total of 13 precipitation variables at each station are subjected to trend detection analysis. In addition, regional average precipitation series are established for the same analysis purpose. The application of a trend detection framework resulted in the identification of some significant trends, especially in January, February, and September precipitations and in the annual means. A noticeable decrease in the annual mean precipitation was observed mostly in western and southern Turkey, as well as along the coasts of the Black Sea. Regional average series also displayed trends similar to those for individual stations. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
3.
ABSTRACTThe trends in hydrological and climatic time series data of Urmia Lake basin in Iran were examined using the four different versions of the Mann-Kendall (MK) approach: (i) the original MK test; (ii) the MK test considering the effect of lag-1 autocorrelation; (iii) the MK test considering the effect of all autocorrelation or sample size; and (iv) the MK test considering the Hurst coefficient. Identification of hydrological and climatic data trends was carried out at monthly and annual time scales for 25 temperature, 35 precipitation and 35 streamflow gauging stations selected from the Urmia Lake basin. Mann-Kendall and Pearson tests were also applied to explore the relationships between temperature, precipitation and streamflow trends. The results show statistically significant upward and downward trends in the annual and monthly hydrological and climatic variables. The upward trends in temperature, unlike streamflow, are much more pronounced than the downward trends, but for precipitation the behaviour of trend is different on monthly and annual time scales. Furthermore, the trend results were affected by the different approaches. Specifically, the number of stations showing trends in hydrological and climatic variables decreased significantly (up to 50%) when the fourth test was considered instead of the first and the absolute value of the Z statistic for most of the time series was reduced. The results of correlations between streamflow and climatic variables showed that the streamflow in Urmia Lake basin is more sensitive to changes in temperature than those of precipitation. The observed decreases in streamflow and increases in temperature in the Urmia Lake basin in recent decades may thus have serious implications for water resources management under the warming climate with the expected population growth and increased freshwater consumption in this region.
Editor Z. W. Kundzewicz; Associate editor Q. Zhang 相似文献
4.
The relationship between altitude of meteorological stations and average monthly and annual precipitation 总被引：2，自引：0，他引：2
Markos Gouvas Nikolaos Sakellariou Fotios Xystrakis 《Studia Geophysica et Geodaetica》2009,53(4):557-570
The aim of this study was to prove that altitudinal variability of average monthly and annual precipitation is better summarised
when the altitude observed within a radius of several kilometres around a meteorological station is taken into consideration,
instead of the altitude of the station itself. The use of the variable Z′, which combines the altitude of the closest mountain
with its distance from the station, is compared against the use of altitude alone in simple linear and multiple quadratic
regression equations for the altitudinal interpolation of precipitation over Greece. The data-set comprised precipitation
observations from 516 meteorological stations. The comparison between the two variables is discussed on the basis of the resulting
determination coefficients (R2) and standard errors of estimate (S). For all seasons, except summer, it was found that the variable Z′ improves the predictive
ability of the regression equations, thus showing its potential for further use in interpolation procedures. 相似文献
5.
Representativeness of total ozone trends as derived from satellite BUV and ground-based measurements
The information content of the 7-year BUV data set has been reexamined by a comparison with a fairly large set of ground Dobson and M-83 instruments. The satellite-ground intercomparison of total ozone was done under different types of ground observation techniques (observation code) and different instrument exposure (exposure code) and for various distances of the subsatellite point from the station. Because of the existing latitudinal gradient in total ozone, at a given station the bias ground-BUV tends to be smaller when the subsatellite point is at a latitude higher than the station's latitude. Knowing the total ozone gradient at a given station, the BUV total ozone has been corrected to account for the ozone gradient and the correlation was calculated with the corresponding ground observations. These correlations seem to offer no improvement when compared with the correlations between the ground ozone and the actual BUV ozone at distances of the subsatellite point from the station within 200 km from the station used in previous studies. The seasonal variation of the BUV-ground correlation reveals information on the noise level of the measurements and the geographical distribution of the percentage mean bias: (Ground-BUV)×100/(Ground) is discussed. Both on short and on longer time scales it appears that the BUV derived recommended total ozone data set is reasonably good and possible instrumental drifts are not large. The analysis includes an extension through April 1977 of the BUV and contour-derived total ozone trends byLondon andLing (1980). Over the northern hemisphere both data sets (contour and BUV) show comparable trends over middle and high latitudes which range from –3 D.U./year to –5 D.U./year during the 7-year period April 1970–April 1977. In the southern hemisphere, however, long-term variation in total ozone cannot be determined from ground observations alone. It is concluded that for unknown reasons during the 7-year period of study, total ozone has been decreasing over most of the globe. The negative growth rates at high latitudes of the northern hemisphere are highly significant. 相似文献
6.
ABSTRACTThe aim of the present paper was to improve understanding of the rainfall dynamics in Bas-Congo and Kinshasa provinces, in Democratic Republic of Congo (DRC). The first objective of the study was achieved by analysing the spatial correlations of monthly, seasonal, annual and individual monthly rainfall amounts of Kinshasa and Bas-Congo. The second objective was achieved through investigating and quantifying the temporal trends and their spatial variations. The results demonstrated notably high average inter-station correlation of +0.63 for dry season series, followed by monthly rainfall series with an average inter-station correlation of +0.58. However, there was no station with a stable monthly rainfall regime, i.e. with mean precipitation concentration index lower than 10% (it varies between 14.2 and 21.9%). Moreover, Kinshasa experienced an increase of rainfall with an average annual rate of change of +4.59 mm/year for the period 1961–2006. The results will be helpful for efficient water resources management and for mitigating the adverse impacts of future extreme drought or flood occurrences.
Editor M.C. Acreman Associate editor N. Verhoest 相似文献
7.
Lunar and solar atmospheric tidal oscillations have been determined with reasonable accuracy from a ten-year record of hourly mercury-barometer readings, corrected to mean-sea-level, at Rarotonga (Cook Islands), 21.2°S. For the lunar semidiurnal tide, the annual determination shows an amplitude (56 b) slightly lower and a phase (51°) much smaller than the values (58 b, 72°) that would be derived, for the position of Rarotonga, from the spherical harmonic analysis given byHaurwitz andCowley (1969). The seasonal variation of this oscillation, as given by the monthly and J, E, D values, shows most of the characteristic features found in world-wide determinations. In particular, the near equality of the J, D amplitudes at Rarotonga tends to support theHaurwitz andCowley (1969) suggestion of negative J-D values in southern middle latitudes. For the solar tides, the semidiurnal and terdiurnal oscillations at Rarotonga are similar to those found at other stations in the south-west Pacific region. However, for the diurnal oscillation, the annual amplitude (232 b) is only about half the value (465 b) indicated for the position of Rarotonga by the world maps of theS
1(p) annual harmonic coefficients given byHaurwitz (1965). It thus seems likely that the relatively small area of lowS
1(p) annual amplitude in the eastern part of the south Pacific, as indicated by these maps, is much more extensive than formerly supposed. 相似文献
8.
ABSTRACTThe North American Regional Reanalysis (NARR) precipitation product was evaluated using station observations and catchment water yield in British Columbia (BC), Canada, at inter-annual, monthly, and daily time scales. A structural break occurred in 2003, associated with exclusion of Canadian precipitation gauge data from NARR’s data assimilation process beginning in that year. The NARR product under-predicted precipitation in mountainous regions, over-predicted in the northern region of BC’s Interior Plateau, and catchment-averaged NARR precipitation was less than observed water yield in coastal BC. The product was unable to reproduce even the seasonal pattern at three stations. This study highlights uncertainties associated with the NARR precipitation product, and presents a cautionary tale that is likely relevant not only to the application of NARR in BC, but may be relevant for other re-analysis products and other regions with complex topography and sparse station networks. 相似文献
9.
Climate changes and their impacts on water resources in semiarid regions: a case study of the Wei River basin,China 总被引：2，自引：0，他引：2
Understanding the impacts of climate change and human activity on the hydrological processes in river basins is important for maintaining ecosystem integrity and sustaining local economic development. The objective of this study was to evaluate the impact of climate variability and human activity on mean annual flow in the Wei River, the largest tributary of the Yellow River. The nonparametric Mann–Kendall test and wavelet transform were applied to detect the variations of hydrometeorological variables in the semiarid Wei River basin in the northwestern China. The identifications were based on streamflow records from 1958 to 2008 at four hydrological stations as well as precipitation and potential evapotranspiration (PET) data from 21 climate stations. A simple method based on Budyko curve was used to evaluate potential impacts of climate change and human activities on mean annual flow. The results show that annual streamflow decreased because of the reduced precipitation and increased PET at most stations. Both annual and seasonal precipitation and PET demonstrated mixed trends of decreasing and increasing, although significant trends (P < 0.05) were consistently detected in spring and autumn at most stations. Significant periodicities of 0.5 and 1 year (P < 0.05) were examined in all the time series. The spectrum of streamflow at the Huaxian station shows insignificant annual cycle during 1971–1975, 1986–1993 and 1996–2008, which is probably resulted from human activities. Climate variability greatly affected water resources in the Beiluo River, whereas human activities (including soil and water conservation, irrigation, reservoirs construction, etc.) accounted more for the changes of streamflow in the area near the Huaxian station during different periods. The results from this article can be used as a reference for water resources planning and management in the semiarid Wei River basin. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
10.
AbstractStatistically significant FAO-56 Penman-Monteith (FAO-56 PM) and adjusted Hargreaves (AHARG) reference evapotranspiration (ET0) trends at monthly, seasonal and annual time scales were analysed by using linear regression, Mann-Kendall and Spearman’s Rho tests at the 1 and 5% significance levels. Meteorological data were used from 12 meteorological stations in Serbia, which has a humid climate, for the period 1980–2010. Web-based software for conducting the trend analyses was developed. All of the trends significant at the 1 and 5% significance levels were increasing. The FAO-56 PM ET0 trends were almost similar to the AHARG trends. On the seasonal time scale, for the majority of stations significant increasing trends occurred in summer, while no significant positive or negative trends were detected by the trend tests in autumn for the AHARG series. Moreover, 70% of the stations were characterized by significant increasing trends for both annual ET0 series. Editor Z.W. Kundzewicz; Associate editor S. GrimaldiCitation Gocic, M. and Trajkovic, S., 2013. Analysis of trends in reference evapotranspiration data in a humid climate. Hydrological Sciences Journal, 59 (1), 165–180. 相似文献
11.
This study is an attempt to determine the trends in monthly, annual and monsoon total precipitation series over India by applying linear regression, the Mann-Kendall (MK) test and discrete wavelet transform (DWT). The linear regression test was applied on five consecutive classical 30-year climate periods and a long-term precipitation series (1851–2006) to detect changes. The sequential Mann-Kendall (SQMK) test was applied to identify the temporal variation in trend. Wavelet transform is a relatively new tool for trend analysis in hydrology. Comparison studies were carried out between decomposed series by DWT and original series. Furthermore, visualization of extreme and contributing events was carried out using the wavelet spectrum at different threshold values. The results showed that there are significant positive trends for annual and monsoon precipitation series in North Mountainous India (zone NMI) and North East India (NEI), whereas negative trends were detected when considering India as whole.
EDITOR A. Castellarin ASSOCIATE EDITOR S. Kanae 相似文献
12.
Summary
Reitan's data on precipitable water vapour over about 45 stations of the U.S.W.B. network are correlated with altitude and average station temperature values. Computations are carried out following a simple proposed model which is found to be obeyed with reasonably good approximation on average monthly and seasonal scales.Contribution of the Centro-Nucleazione Aerosoli of the National Research Council of Italy,Rome, Via Vettore 4. 相似文献
13.
Daily rain series from southern Sweden with records dating back to the 1870s have been analysed to investigate the trends of daily and multi‐day precipitation of different return periods with emphasis on the extremes. Probabilities of extreme storms were determined as continuously changing values based on 25 years of data. An extra set of data was used to investigate changes in Skåne, the southernmost peninsula of Sweden. Another 30‐year data set of more than 200 stations of a dense gauge network in Skåne was used to investigate the relation between very large daily rainfall and annual precipitation. The annual precipitation has increased significantly all over southern Sweden due to increased winter precipitation. There is a trend of increasing maximum annual daily precipitation at only one station, where the annual maximum often occurs in winter. The number of events with a short return period is increasing, but the number of more extreme events has not increased. Daily and multi‐daily design storms of long return periods determined from extreme value analysis with updating year by year are not higher today than during the last 100 years. The largest daily storms are not related to stations with annual rainfall but seem to occur randomly. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
14.
An analysis of spatial and temporal trends of precipitation in Beijiang River basin, Guangdong Province, China during 1959–2003 was performed using 17 time series (including monthly, annual, wet season, dry season, early flood period and late flood period totals) both on station based and sub‐basin based data sets. Two nonparametric methods (Mann–Kendall and Sen's T) were used for data analysis. The results showed that (1) downward trends of temporal distribution were mostly detected during the early flood period, especially in May, while upward trends were observed in July and the dry season; (2) downward trends of spatial distribution were mostly detected in the southern Beijiang River basin, while upward trends were observed north of this area. Our results indicated a delayed rainy season and a northward trend of the precipitation belt compared to recent years. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
15.
Rainfall trend and its implications for water resource management within the Yarra River catchment,Australia 总被引：2，自引：1，他引：1
Rainfall is the key climatic variable that governs the regional hydrologic cycle and availability of water resources. Recent studies have analysed the changes in rainfall patterns at global as well as regional scales in Australia. Recent studies have also suggested that any analysis of hydroclimatic variables should be performed at the local scale rather than at a large or global scale because the trends and their effects may be different from one location to the other. Because no studies were found specific to the Yarra River catchment, which is an important catchment in Victoria, Australia, this study performs a spatiotemporal trend analysis on long‐term rainfall records at 15 measuring stations within the catchment. The Mann–Kendall test was used to detect trends, and Sen's slope estimator was used to calculate the slopes in both monthly and annual rainfall. Moreover, a cumulative summation technique was used to identify the trend beginning year, and prewhitening criteria were tested to check for autocorrelation in the data. The results showed that the monthly rainfall has generally decreasing trends except in January and June. Significant decreasing rainfall trends were observed in May (among the autumn months of March, April and May) at most stations and also in some other months at several stations. A decreasing trend was also observed in the annual rainfall at all stations. This study indicates that there has been a consistent reduction in rainfall over the catchment, both spatially and temporally over the past 50 years, which will have important implications for the future management of water resources. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
16.
Weiguang Wang Quanxi Shao Shizhang Peng Zengxin Zhang Wanqiu Xing Guiyang An Bin Yong 《Stochastic Environmental Research and Risk Assessment (SERRA)》2011,25(7):881-895
The present study explores the spatial and temporal changing patterns of the precipitation in the Haihe River basin of North
China during 1957–2007 at annual, seasonal and monthly scales. The Mann–Kendall and Sen’s T tests are employed to detect the trends, and the segmented regression is applied to investigate possible change points. Meanwhile,
Sen’s slope estimator is computed to represent the magnitudes of the temporal trends. The regional precipitation trends are
also discussed based on the regional index series of four sub-basins in the basin. Serial correlation of the precipitation
series is checked prior to the application of the statistical test to ensure the validity of trend detection. Moreover, moisture
flux variations based on the NCEP/NCAR reanalysis dataset are investigated to further reveal the possible causes behind the
changes in precipitation. The results show that: (1) Although the directions of annual precipitation trends at all stations
are downward, only seven stations have significant trends at the 90% confidence level, and these stations are mainly located
in the western and southeastern Haihe River basin. (2) Summer is the only season showing a strong downward trend. For the
monthly series, significant decreasing trends are mainly found during July, August and November, while significant increasing
trends are mostly observed during May and December. In comparison with the annual series, more intensive changes can be found
in the monthly series, which may indicate a shift in the precipitation regime. (3) Most shifts from increasing trends to decreasing
trends occurred in May–June, July, August and December series, while opposed shifts mainly occurred in November. Summer is
the only season displaying strong shift trends and the change points mostly emerged during the late 1970s to early 1980s.
(4) An obvious decrease in moisture flux is observed after 1980 in comparison with the observations before 1980. The results
of similar changing patterns between monthly moisture budget and precipitation confirmed that large-scale atmospheric circulation
may be responsible for the shift in the annual cycle of precipitation in the Haihe River basin. These findings are expected
to contribute to providing more accurate results of regional changing precipitation patterns and understanding the underlying
linkages between climate change and alterations of hydrological cycles in the Haihe River basin. 相似文献
17.
The relationship between air (Ta) and water temperature (Tw) is very important because it shows how the temperature of a water body might respond to future changes in surface Ta. Mean monthly Tw records of three gauging stations (Bezdan, Bogojevo i Veliko Gradi?te) were analysed alongside mean monthly discharge (Q) for the same stations. Additionally, Ta series from two meteorological stations (Sombor and Veliko Gradi?te) were correlated with Tw variations over the period 1950–2012. Locally weighted scatter point smoothing (LOWESS) was used to investigate long‐term trends in the raw data, alongside the Mann–Kendall (MK) trend test. Trend significance was established using Yue–Pilon's pre‐whitening approaches to determine trends in climate data. Also, the rescaled adjusted partial sums (RAPS) method was used to detect dates of possible changes in the time series. Statistically significant warming trends were observed for annual and seasonal minimum and maximum Tw at all investigated sites. The strongest warming was observed at Bogojevo gauging station for seasonal maximum Tw, with +0.05 °C per year on average. RAPS established that the trend began in the 1980s. This behaviour is linked to climate patterns in the North and East Atlantic which determine the amount of heat advected onto mainland Europe. Statistically significant correlations were found for all Tw on an annual basis. Overall, the strongest correlations (p < 0.01) between Tw residuals and the North Atlantic Oscillation (NAO) were recorded for the winter period. These findings suggest possible predictability of Tw over seasonal time‐scales. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
18.
Abstract The trends of annual, seasonal and monthly precipitation in southern China (Guangdong Province) for the period 1956–2000 are investigated, based on the data from 186 high-quality gauging stations. Statistical tests, including Mann-Kendall rank test and wavelet analysis, are employed to determine whether the precipitation series exhibit any regular trend and periodicity. The results indicate that the annual precipitation has a slightly decreasing trend in central Guangdong and slight increasing trends in the eastern and western areas of the province. However, all the annual trends are not statistically significant at the 95% confidence level. The average precipitation increases in the dry season in central Guangdong, but decreases in the wet season, meaning that the precipitation becomes more evenly distributed within the year. Furthermore, the analysis of monthly precipitation suggests that the distribution of intra-annual precipitation changes over time. The results of wavelet analysis show prominent precipitation with periods ranging from 10 to 12 years in every sub-region in Guangdong Province. Comparing with the sunspot cycle (11-year), the annual precipitation in every sub-region in Guangdong province correlates with Sunspot Number with a 3-year lag. The findings in this paper will be useful for water resources management. Editor Z.W. Kundzewicz; Associate editor Sheng Yue Citation Dedi Liu, Shenglian Guo, Xiaohong Chen and Quanxi Shao, 2012. Analysis of trends of annual and seasonal precipitation from 1956 to 2000 in Guangdong Province, China. Hydrological Sciences Journal, 57 (2), 358–369. 相似文献
19.
Changing climate and precipitation patterns make the estimation of precipitation, which exhibits two-dimensional and sometimes chaotic behavior, more challenging. In recent decades, numerous data-driven methods have been developed and applied to estimate precipitation; however, these methods suffer from the use of one-dimensional approaches, lack generality, require the use of neighboring stations and have low sensitivity. This paper aims to implement the first generally applicable, highly sensitive two-dimensional data-driven model of precipitation. This model, named frequency based imputation (FBI), relies on non-continuous monthly precipitation time series data. It requires no determination of input parameters and no data preprocessing, and it provides multiple estimations (from the most to the least probable) of each missing data unit utilizing the series itself. A total of 34,330 monthly total precipitation observations from 70 stations in 21 basins within Turkey were used to assess the success of the method by removing and estimating observation series in annual increments. Comparisons with the expectation maximization and multiple linear regression models illustrate that the FBI method is superior in its estimation of monthly precipitation. This paper also provides a link to the software code for the FBI method. 相似文献
20.
Max Wyss 《Pure and Applied Geophysics》1975,113(1):297-309
Summary The Sitka earthquake of 30 July, 1972, was a shallow strike-slip fracture of 170 km lenght and it closed a gap defined bySykes (1971). A tide gauge station, a magnetic observatory and a seismological station are located 40 km to the east of the center of the rupture. A comparison of the sea level at Sitka with that at three tide gauges up to 430 km from Sitka indicates that the sea level at Sitka remained constant for 32 years before the earthquake (standard deviation ±1.5 cm) with the exception of the years 1966 and 1967 when the land may have been elevated by 3 cm. Preliminary analysis of mean teleseismic-P-residuals suggests that aP-wave delay may have existed under the station Sitka during 1966 and 1967. The quiet annual means of the horizontal component of the magnetic field at Sitka were compared to that at College, Alaska, and Victoria, Canada, for all years since the establishment of these stations in 1941 and 1957 respectively. Starting 7.5 years before the earthquake the field differences appear to have decreased by approximately 20, gradually returning to normal the year after the earthquake. 相似文献