Spatial and temporal variability of daily precipitation in Haihe River basin, 1958-2007

The seasonal variability and spatial distribution of precipitation are the main cause of flood and drought events. The study of spatial distribution and temporal trend of precipitation in river basins has been paid more and more attention. However, in China, the precipitation data are measured by weather stations （WS） of China Meteorological Administration and hydrological rain gauges （RG） of national and local hydrology bureau. The WS data usually have long record with fewer stations, while the RG data usually have short record with more stations. The consistency and correlation of these two data sets have not been well understood. In this paper, the precipitation data from 30 weather stations for 1958-2007 and 248 rain gauges for 1995-2004 in the Haihe River basin are examined and compared using linear regression, 5-year moving average, Mann-Kendall trend analysis, Kolmogorov-Smirnov test, Z test and F test methods. The results show that the annual precipitation from both WS and RG records are normally distributed with minor difference in the mean value and variance. It is statistically feasible to extend the precipitation of RG by WS data sets. Using the extended precipitation data, the detailed spatial distribution of the annual and seasonal precipitation amounts as well as their temporal trends are calculated and mapped. The various distribution maps produced in the study show that for the whole basin the precipitation of 1958-2007 has been decreasing except for spring season. The decline trend is significant in summer, and this trend is stronger after the 1980s. The annual and seasonal precipitation amounts and changing trends are different in different regions and seasons. The precipitation is decreasing from south to north, from coastal zone to inland area.

Temporal and spatial variation characteristics of extreme precipitation on the Loess Plateau of China facing the precipitation process

The preceding and succeeding precipitation(PSP)often act together with extreme precipitation(EP),in turn,causing floods,which is an objective component that is often overlooked with regard to summer flood hazards in the arid region of Northwest China.In this study,event-based extreme precipitation(EEP)was defined as continuous precipitation that includes at least one day of EP.We analyzed the spatiotemporal variation characteristics of four EEP types(front EEP,late EEP,balanced EEP,and single day EEP)across the Loess Plateau(LP)based on data acquired from 87 meteorological stations from 1960 to 2019.Precipitation on the LP basically maintained a spatial pattern of"low in the northwest region and high in the southeast region",and EP over the last 10 a increased significantly.The cumulative precipitation percentage of single day EEP was 34%and was dominant for 60 a,while the cumulative precipitation percentage of front,late,and balanced EEP types associated with PSP accounted for 66%,which confirms to the connotation of EEP.The cumulative frequencies of front and late EEP types were 23%and 21%,respectively,while the cumulative frequency of balanced EEP had the lowest value at only 13%.Moreover,global warming could lead to more single day EEP across the LP,and continuous EEP could increase in the northwestern region and decrease in the eastern region in the future.The concept of process-oriented EP could facilitate further exploration of disaster-causing processes associated with different types of EP,and provide a theoretical basis for deriving precipitation disaster chains and construction of disaster cluster characteristics.

Spatial and Temporal Evolution Characteristics of Extreme Precipitation and Isohyets in Ningxia

The multi-scale spatial and temporal evolution characteristics of extreme precipitation and isohyets in Ningxia were studied using daily,monthly,and annual precipitation data from 20 meteorological stations in Ningxia over the last 60 years.The results revealed that the intensity of rainstorms in Ningxia had decreased slightly over the previous 60 years,with the intensity of rainstorms in southern and central Ningxia being higher than in northern areas.Ningxia's annual and seasonal precipitation varied regionally,declining from the southeast to the northwest.Annual,spring and autumn precipitation exhibited a significantly declining trend from 1960 to the early 21^(st)century;summer precipitation displayed a slightly decreasing trend;and winter precipitation showed a significantly increasing trend.Nevertheless,there was a noticeable increase in annual and seasonal precipitation after 2005.From the 1960s to the 2000s,the 200 mm isohyet moved slowly southward,while the 400 mm isohyet jumped southward twice in the 1970s and 2000s before jumping considerably northward in the 2010s to reach their northernmost region.

Characteristics of Spatial Structural Patterns and Temporal Variability of Annual Precipitation in Ningxia

[Objective] The aim was to study the characteristics of the spatial structural patterns and temporal variability of annual precipitation in Ningxia.[Method] Using rotated empirical orthogonal function,the precipitation concentration index,wavelet analysis and Mann-Kendall rank statistic method,the characteristics of precipitation on the spatial-temporal variability and trend were analyzed by the monthly precipitation series in Ningxia during 1951-2008.[Result] In Ningxia,the spatial structural patterns of annual precipitation appeared 'North-south type' and 'North-center-south type'.It increased from north to south,the changes of interannual precipitation decreased from north to south.Precipitation changed significantly in month and distributed differently in the Yellow River irrigation area.But it was conversely steady in central arid zone and mountainous area of southern Ningxia.The probability of single abundant precipitation year was higher than single short precipitation year and the continuous short precipitation year was higher than continuous abundant precipitation year.The main cycles were 3a,6a and 10a approximately.In the mid arid zone and the mountainous area of southern Ningxia,the probability of precipitation reduction was about 75% and the Yellow river irrigation area,71.4%,respectively.The reduction in the entire area was about 73.3%.The annual precipitation in the middle arid area and irrigation area was increasing.The variability would change slowly for the intra-annual distribution of precipitation.Especially,the reduction tendency rate in the middle arid area reached 100.0%.[Conclusion] The study provided references for the effective utilization of the local precipitation,and the coordinated development of the regional social economy and ecological environment.

The Influence of Climate Change and Variability on Spatio-Temporal Rainfall and Temperature Distribution in Zanzibar

Climate change has resulted in serious social-economic ramifications and extremely catastrophic weather events in the world, Tanzania and Zanzibar in particular, with adaptation being the only option to reduce impacts. The study focuses on the influence of climate change and variability on spatio-temporal rainfall and temperature variability and distribution in Zanzibar. The station observation datasets of rainfall, Tmax and Tmin acquired from Tanzania Meteorological Authority (TMA) and the Coordinated Regional Climate Downscaling Experiment program (CORDEX) projected datasets from the Regional climate model HIRHAM5 under driving model ICHEC-EC-EARH, for the three periods of 1991-2020 used as baseline (HS), 2021-2050 as near future (NF) and 2051-2080 far future (FF), under two representative concentration pathways (RCP) of 4.5 and 8.5, were used. The long-term observed Tmax and Tmin were used to produce time series for observing the nature and trends, while the observed rainfall data was used for understanding wet and dry periods, trends and slope (at p ≤ 0.05) using the Standardized Precipitation Index (SPI) and the Mann Kendall test (MK). Moreover, the Quantum Geographic Information System (QGIS) under the Inverse Distance Weighting (IDW) interpolation techniques were used for mapping the three decades of 1991-2000 (hereafter D1), 2001-2010 (hereafter D2) and 2011-2020 (hereafter D3) to analyze periodical spatial rainfall distribution in Zanzibar. As for the projected datasets the Climate Data Operator Commands (CDO), python scripts and Grid analysis and Display System (GrADS) soft-wares were used to process and display the results of the projected datasets of rainfall, Tmax and Tmin for the HS, NF and FF, respectively. The results show that the observed Tmax increased by the rates of 0.035℃ yr-1 and 0.0169℃ yr-1, while the Tmin was increased by a rate of 0.064℃ yr-1 and 0.104℃ yr-1 for Unguja and Pemba, respectively. The temporal distribution of wetness and dryness indices showed a climate shift from near normal to moderate wet during 2005 at Zanzibar Airport, while normal to moderately dry conditions, were observed in Pemba at Matangatuani. The decadal rainfall variability and distributions revealed higher rainfall intensity with an increasing trend and good spatial distribution in D3 from March to May (MAM) and October to December (OND). The projected results for Tmax during MAM and OND depicted higher values ranging from 1.7℃ - 1.8℃ to 1.9℃ - 2.0℃ and 1.5℃ to 2.0℃ in FF compared to NF under both RCPs. Also, higher Tmin values of 1.12℃ - 1.16℃ was projected in FF for MAM and OND under both RCPs. Besides, the rainfall projection generally revealed increased rainfall intensity in the range of 0 - 25 mm for Pemba and declined rainfall in the range of 25 - 50 mm in Unguja under both RCPs in perspectives of both NF and FF. Conclusively the study has shown that the undergoing climate change has posed a significant impact on both rainfall and temperature spatial and temporal distributions in Zanzibar (Unguja and Pemba), with Unguja being projected to have higher rainfall deficits while increasing rainfall strengths in Pemba. Thus, the study calls for more studies and formulation of effective adaptation, strategies and resilience mechanisms to combat the projected climate change impacts especially in the agricultural sector, water and food security.

The Spatial-Temporal Change of Extreme Precipitation in the Southwest Region of Zhejiang Province during 1953-2022

Based on the daily precipitation from 17 meteorological stations in the southwest of Zhejiang from 1953 to 2022, 11 extreme precipitation indices were calculated, and the temporal-spatial characteristic of extreme precipitation were analyzed. The results indicate that 1) Except for the number of consecutive dry days (CDD), all the other extreme precipitation indices had low values in the northeast of the study area and high value around Liuchun Lake;2) CDD had a decreasing trend in most part of study area, while the other indices were on the rise, especially at Suichang (SC) and Tonglu (TL) stations, the change was significant (p 0.05);3) The annual variation showed that CDD declined with the trend of 0.83 d/10a, however, all the other indices increased, especially after 2000, the increase was more obvious. In general, the extreme precipitation mount, the extreme precipitation days showed an increasing trend, drought was less likely to happen, and the possibility of heavy precipitation is less, however, at some individual station such as SC, heavy precipitation and storm is much more likely to occur.

Temporal and spatial variations of δ^18O in precipitation of the Yarlung Zangbo River Basin

This paper reveals the temporal and spatial variations of stable isotope in precipitation of the Yarlung Zangbo River Basin based on the variations of δ^18O in precipitation at four stations （Lhaze, Nugesha, Yangcun and Nuxia） in 2005. The results show that δ^18O of precipitation has distinct seasonal changes in the Yarlung Zangbo River Basin. The higher value of δ^18O occurs in spring prior to monsoon precipitation, and the lower value occurs during monsoon precipitation. From the spatial variations, with the altitude-effect and rainout process during moisture transport along the Yarlung Zangbo River Valley, δ^18O of precipitation is gradually depleted. Thus, δ^18O of precipitation decreases gradually from the downstream to the upstream, and the lapse rate of δ^18O in precipitation is approximately 0.34‰/100m and 0.7%J‰/100km for the two reasons. During monsoon precipitation, spatial variation of δ^18O in precipitation is dominated by the amount effect in the large scale synoptic condition.

SPATIAL AND TEMPORAL VARIABILITY OF NORTHWEST PACIFIC TROPICAL CYCLONE ACTIVITY IN A GLOBAL WARMING SCENARIO

Utilizing the Joint Typhoon Warning Center(JTWC) and Tokyo-Typhoon Center of the Japan Meteorological Agency(JMA RSMC TOKYO) best-track tropical cyclone(TC) data for the period 1951-2014,variations in spatial and temporal characteristics of Northwest Pacific TC activity for a global warming scenario are discussed.The results suggest that since the early 1960 s,there has been an overall decreasing trend in the frequency of occurrence,intensity,peak intensity,length of movement,and lifetime of TCs.However,global wanning has led to a linearly increasing trend in TC activity in eastern Asia,which indicates that Northwest Pacific TC activity decreases,but the frequency of landfalls and intensity are likely strengthened.Therefore,the threat of TCs towards eastern Asia is enhanced.The increase in TC activity in eastern Asia is likely the result of a strengthened Walker circulation due to an increasing temperature gradient between the northwest Pacific Ocean and the central and eastern Pacific Ocean.The strengthening Walker circulation could increase the magnitude of the vertical wind shear,relative vorticity,and meridional wind shear of low-level easterlies near the equator in the tropical Northwest Pacific,which affects the spatial and temporal variations of TC activity in the Northwest Pacific.

Spatial and Temporal Variability of N, P and K Balances for Agroecosystems in China

Nitrogen, phosphorus, and potassium balances for agroecosystems in China from 1993 to 2001 were calculated at national and provincial levels using statistical data and related parameters, and their spatial and temporal variabilities were analyzed with GIS to estimate the potential impacts of nutrient N, P and K surpluses or deficits to soil, water and air. At the national scale, the N and P balances from 1993 to 2001 showed a surplus, with the nitrogen surplus remaining relatively stable from 1997—2001. Although during this period the P surplus pattern was similar to N, it had smaller values and kept increasing as the use of phosphate fertilizer increased year by year. However, K was deficient from 1993 to 2001 even though from 1999 to 2001 the K deficit decreased. The spatial analysis revealed higher N surpluses in the more developed southeastern provinces and lowest in the western and northern provinces where there was less chemical fertilizer input. The serious K deficit mainly occurred in Shanghai and Beijing municipalities, Jiangsu, Zhejiang and Hubei provinces, and Xinjiang autonomous regions. For the years 1992, 1996 and 2001, N surpluses and K deficits had significant positive spatial correlations with per capita gross domestic product (GDP), per capita gross industrial output value, and per capita net income of rural households. This showed that the level of economic development played an important role on nutrient balances in the agroecosystems.

Spatial and temporal distribution of precipitation based on corrected TRMM data around the Hexi Corridor,China

Accurate rainfall distribution is difficult to acquire based on limited meteorological stations, especially in remote areas like high mountains and deserts. The Hexi Corridor and its adjacent regions （including the Qilian Mountains and the Alxa Plateau） are typical districts where there are only 30 available rain gauges. Tropical Rainfall Measuring Mission （TRMM） data provide a possible solution. After precision analysis of monthly 0.25 degree resolution TRMM 3B43 data from 1998 to 2012, we find that the correlations between TRMM 3B43 estimates and rain gauge precipitation are significant overall and in each station around the Hexi Corridor; however, the biases of annual precipitation differ in different stations and are seriously overestimated in most of the sites. Thus, Inverse Distance Weighting （IDW） interpolation method was used to rectify TRMM data based on the difference between TRMM 3B43 estimates and rain gauge observations. The results show that rectified TRMM data present more details than rain gauges in remote areas where there are few stations, alt- hough they show high coherence of distribution. Precipitation decreases from southeast to northwest on an annual and seasonal scale. There are three rainfall centers （〉500 mm） including Menyuan, Qilian and Toson Lake, and two low rain- fall centers （〈50 mm） including Dunhuang and Ejin Banner. Meanwhile, precipitation in most of the study area presents an increasing trend; especially in northern Qilian Mountains （〉5 mm/a）, Badain Jaran Desert （〉2 mm/a）, Toson Lake （〉20 mm/a） and Qingtu Lake （〉20 ram/a） which shows a significant increasing trend, while precipitation in Hala Lake （〈-2 mm/a） and Tengger Desert （〈-3 mm/a） demonstrates a decreasing trend.

Spatial and Temporal Variability of Soil Moisture

The characterization of temporal and spatial variability of soil moisture is highly relevant for understanding the many hydrological processes, to model the processes better and to apply them to conservation planning. Considerable variability in space and time coupled with inadequate and uneven distribution of irrigation water results in uneven yield in an area Spatial and temporal variability highly affect the heterogeneity of soil water, solute transport and leaching of chemicals to ground water. Spatial variability of soil moisture helps in mapping soil properties across the field and variability in irrigation requirement. While the temporal variability of water content and infiltration helps in irrigation management, the temporal correlation structure helps in forecasting next irrigation. Kriging is a geostatistical technique for interpolation that takes into account the spatial auto-correlation of a variable to produce the best linear unbiased estimate. The same has been used for data interpolation for the C. T. A. E. Udaipur India. These interpolated data were plotted against distance to show variability between the krigged value and observed value. The range of krigged soil moisture values was smaller than the observed one. The goal of this study was to map layer-wise soil moisture up to 60 cm depth which is useful for irrigation planning.

Delineation of Site-Specific Management Zones Based on Temporal and Spatial Variability of Soil Electrical Conductivity

A coastal saline field of 10.5 ha was selected as the study site and 122 bulk electrical conductivity (ECb) measurements were performed thrice in situ in the topsoil (0-20 cm) across the field using a hand held device to assess the spatial variability and temporal stability of the distribution of soil electrical conductivity (EC), to identify the management zones using cluster analysis based on the spatiotemporal variability of soil EC, and to evaluate the probable potential for site-specific management in coastal regions with conventional statistics and geostatistical techniques. The results indicated high coefficients of variation for topsoil salinity over all the three samplings. The spatial structure of the salinity variability remained relatively stable with time. Kriged contour maps, drawn on the basis of spatial variance structure of the data, showed the spatial trend of the salinity distribution and revealed areas of consistently high or consistently low salinity, while a temporal stability map indicated stable and unstable regions. On the basis of the spatiotemporal characteristics, cluster analysis divided the site into three potential management zones, each with different characteristics that could have an impact on the way the field was managed. On the basis of the clearly defined management zones it was concluded that coastal saline land could be managed in a site-specific way.

The Analysis on the Temporal and Spatial Variation of Strong Precipitation Caused Flood and Agricultural Disaster Loss in Huaihe River Basin of Anhui Province during Meiyu Period of 2007

[Objective] The research aimed to analyze temporal and spatial variation of strong precipitation caused flood and agricultural disaster loss in Huaihe River basin of Anhui Province during Meiyu period of 2007.[Method] On the basis of rainfalls of each station in Huaihe River basin of Anhui,rainfall data during Meiyu period of 2007 and flood disaster data in the same period,the temporal and spatial distribution characteristics of strong precipitation caused flood during Meiyu period of 2007 and its harm on agriculture were analyzed.The variation rule,distribution characteristics of strong precipitation during Meiyu period in Huaihe River basin of Anhui and its relationship with agricultural disaster loss were discussed.[Result] During Meiyu period of 2007 in Huaihe River basin of Anhui,the rainstorm was more,and the rainfall was large.The precipitation variation showed 'three-peak' trend.Rainfall in Huaihe River basin during Meiyu period of 2007 was greatly more than that homochronously in Yangtze River basin.The rain area over 400.0 mm during Meiyu period mainly located in Huaihe River basin,and the rain area over 600.0 mm mainly located from area along Huaihe River to central Huaibei.The rainfall during Meiyu period gradually decreased toward south and north by the north bank of Huaihe River as the symmetry axis.The rainfall in area along Huaihe River showed wavy distribution in east-west direction.The flood disaster loss index and disaster area of crops in Huaihe River basin of Anhui both increased as rainfall in Meiyu period.[Conclusion] The research provided theoretical basis for flood prevention,disaster reduction and agricultural flood-avoiding development in Huaihe River basin.

Analysis on Temporal and Spatial Variation Characteristics of the Precipitation in Hexi Corridor in Recent 58 Years

[ Objective] The research aimed to analyze temporal and spatial variation characteristics of the precipitation in Hexi Corridor in the past 58 years. [Method] Based on monthly rainfall data in Hexi Corridor from 1951 to 2008, by using moving average, wavelet analysis and climate trend coefficient, variation rule of the precipitation in Hexi Corridor in the past 58 years was analyzed. [ Result] Average rainfall in Hexi Corridor in the past 58 years was 130.4 mm. Precipitation mainly concentrated in summer, occupying 59.08% of the annual rainfall. From June to September, it occupied 72.57% of the annual precipitation. Interdecadal change of the precipitation in Hexi Corridor wasn＇t severe. Average rainfall in each dec- ade was from 120.8 to 139.0 mm. The precipitation series had periods of the 5, 10, 21 and 32 years in Hexi Corridor from 1951 to 2008. in the fu- ture, annual, spring, summer and winter precipitation would have small increase tendency. Increase amplitude of the annual precipitation in Shule River basin was the biggest （5.231 -0.062 mm/10 a）. The increase amplitude in the south and southeast of the Heihe River basin was bigger than that in the northwest. The smallest increase amplitude of the annual precipitation was 3.280 -0.098 mm/10 a in Shiyang River basin. [ Conclusion] This research could provide beneficial reference for coordinated development between local social economy and ecological environment.

Spatial and Temporal Variability of Water Vapor Content during 1961-2011 in Tianshan Mountains,China

Based on the climate factors data and surface vapor pressure(SVP) data of 44 weather stations in Tianshan Mountains during the years 1961-2011, this paper establishes a water vapor content(WVC) estimation model according to the relationship between monthly WVC of radiosonde and corresponding SVP and analyzes the spatial and temporal variability of WVC and their causes. The results show that the WVC is linearly and negatively related to the elevation and longitude(Vertical zonality and Longitude zonality), while it was not linearly related to the latitude. The westerly wind, geographical situation and sea level elevation composed complex surface conditions to influence the spatial distribution of WVC in the Tianshan Mountains. The Mann-Kendall(M-K) statistical test shows a significant increasing trend in the mean annual WVC in Tianshan Mountains during 1961-2011(P < 0.001), with a rate of 0.23 mm/decade, and indicates an abrupt turning point in 1985(P < 0.001). Correlation analysis shows that the WVC are significantly correlated to the temperature, especially during the winter, but the summer WVC are significantly correlated to the precipitation. In addition, the North Atlantic Oscillation Index(NAOI)and the Arctic Oscillation Index(AOI) are significantly correlated to the winter WVC in the Tianshan Mountains. As a new Microwave radiometric profilers(MWRPs) instrument, the MP-3000 A provides continuous, real-time and high temporal resolution atmospheric profiles up to 10 km. In order to monitor water vapor and atmosphere profiles in Tianshan Mountains, an MP-3000 A was established in Urumqi(43.8°N, 87.58°N) in May 2008. The results indicated that the MP-3000 A was applicable to this area, and the evolutionary process of water vapor and the WVC peak values of MP-3000 A were a strong signal for rainstorm and flood forecasts for Urumqi and the Tianshan Mountains.

Analysis on Spatial and Temporal Changes of Extreme Precipitation Events in Ningxia in Recent 50 Years

[ Objective] The aim was to study the spatial and temporal changes of extreme precipitation events in Ningxia in recent 50 years. [ Method] Using dally precipitation data at 20 stations in Ningxia from 1961 to 2010, and defining the threshold value of extreme precipitation in each sta- tion by percentage method, choosing indicators such as precipitation, frequency and intensity of extreme precipitation events, the characteristics of the spatial and temporal distribution and linear trend of extreme precipitation events in Ningxia were analyzed based on linear regression and M-K non-parameter statistical test method. [ Result] The percentage method suggested the threshold value of average extreme precipitation in Ningxia in recent 50 years decreased from south to north. The large threshold value was in southern Haiyuan, Tongxin and northern Yancheng, which was similar to the distribution of mean annual precipitation in Ningxia. In recent 50 years, extreme precipitation frequency and extreme precipitation de- creased in most part of Ningxia but the intensity tended to strengthen. Study of extreme precipitation in Mahuang Mountain and Liupan Mountain in- dicated that precipitation frequency, intensity and extreme precipitation reduced. Annual extreme precipitation frequency narrowed and then in- creased after 1994 and had mutation in 2003. Annual extreme precipitation intensity enhanced since 1984. Mutation took place in 1984. Intensity in Liupan Mountain had weakened since 1978. [ Conclusion] The study provided theoretical basis for the mutation of climate in Ningxia.

Spatial-Temporal Variations in January Precipitation over the Period of 1950-2000 in Pakistan and Possible Links with Global Teleconnections: Geographical Perspective

Empirical Orthogonal Function (EOF) was performed to investigate spatial variation in January precipitation over Pakistan using ground observed mean monthly precipitation data from 1950-2000 with a combination of gridded reanalysis data of sea level pressure (SLP) and 500 hPa geopotential height. The leading EOF mode captures 37.51% of the total variance and the spatial-temporal variability of January precipitation was consistent in the study area. The temporal changes explicate non-periodic interannual variability and some tacit interdecadal variation. The anomalous condition is more prominent along the western bordering mountains and northern high mountainous region than any other region of Pakistan. Based on results the study reveals spatial-temporal variation in January precipitation and possible links with global teleconnections located both in the proximity as well as in the remote areas from the study locus.

Spatial-temporal variability of throughfall in a subtropical deciduous forest from the hilly regions of eastern China

Throughfall variability plays a crucial role in regulating hydrological and biogeochemical processes in forest ecosystems. However, throughfall variability and its potential influencing factors remain unclear in the subtropical deciduous forest because of its complex canopy and meteorological conditions. Here, the spatial variability and temporal stability of throughfall were investigated from October 2016 to December 2017 within a deciduous forest in the subtropical hilly regions of eastern China, and the effects of meteorological variables and distance from nearest tree trunk on throughfall variability were systematically evaluated. Throughfall variability during the leafed period was slightly higher than that during the leafless period inferred from the coefficient of variation of throughfall amounts(CVTF), with 13.2%-40.9% and 18.7%-31.9%, respectively. The multiple regression model analysis suggested that the controlling factors of throughfall variability were different in studied periods: Maximum 10-min rainfall intensity, wind speed and air temperature were the dominant influencing factors on throughfall variability during the leafed period, with the relative contribution ratio(RCR) of 25.9%, 18.7% and 8.9%, respectively. By contrast, throughfall variability was affected mainly by the mean rainfall intensity(RCR=40.8%) during the leafless period. The temporal stability plots and geostatistical analysis indicated that spatial patterns of throughfall were stable and similar among rainfall events. Our findings highlight the important role of various meteorological factors in throughfall variability and are expected to contribute to the accurate assessment of throughfall, soil water and runoff within the subtropical forests.

Temporal-Spatial Variability of Soil Organic Carbon Stocks in a Rehabilitating Ecosystem

In global change research, changes of soil organic carbon (SOC) reservoirs in tropical and subtropical regions are still unknown. The temporal-spatial variability of SOC stocks was determined in a basin of over 579 km2 in subtropical China from 1981 to 2002. ArcGIS8.1 software was utilized for spatial analysis of semivariance, ordinary kriging (OK),and probability kriging (PK). Grid and hierarchical approaches were employed for the sampling scenario in 2002 with 106Global Position System (GPS) established spots sampled. Bulk topsoil samples (0-30 cm) were collected at three random sites on each spot. The SOC content for 1981 came from the SOC map of the Second National Soil Survey. Geostatistical results of the nugget to sill ratio (0.215-0.640) in the rehabilitating ecosystem indicated a moderate spatial dependence for SOC on this large scale. The range of SOC changed from 2.04 km in 1981 to 7.15 km in 2002. The mean topsoil SOC increased by 4.6% from 10.63 g kg-1 (1981) to 11.12 g kg-1 (2002). However, during this 21-year period 25.2%of the total basin area experienced a decrease in SOC. Also, the probability kriging results showed that the geometric mean probabilities of SOC ≤ 6.0 g kg-1, ≤ 11.0 g kg-1 and ＞ 15.0 g kg-1 were 0.188, 0.534 and 0.378, respectively in 2002, comparing to 0.234, 0.416 and 0.234 in that order in 1981, respectively. The SOC storage in the topsoil increased by 17.0% during this time with the main increase occurring in forests and cultivated land, which amounted to 82.5% and 17.0% of the total increase, respectively.

On the Variability of Charleston South Carolina Winds, Atmospheric Temperatures, Water Levels, Waves and Precipitation

Atmospheric winds, air temperatures, water levels, precipitation and oceanic waves in the Charleston South Carolina (SC) coastal zone are evaluated for their intrinsic, internal variability over temporal scales ranging from hours to multi-decades. The purpose of this study was to bring together a plethora of atmospheric and coastal ocean state variable data in a specific locale, to assess temporal variabilities and possible relationships between variables. The questions addressed relate to the concepts of weather and climate. Data comprise the basis of this study. The overall distributions of atmospheric and coastal oceanic state variable variability, including wind speed, direction and kinematic distributions and state variable amplitudes over a variety of time scales are assessed. Annual variability is shown to be highly variable from year to year, making arithmetic means mathematically tractable but physically meaningless. Employing empirical and statistical methodologies, data analyses indicate the same number of intrinsic, internal modes of temporal variability in atmospheric temperatures, coastal wind and coastal water level time series, ranging from hours to days to weeks to seasons, sub-seasons, annual, multi-year, decades, and centennial time scales. This finding demonstrates that the atmosphere and coastal ocean in a southeastern U.S. coastal city are characterized by a set of similar frequency and amplitude modulated phenomena. Kinematic hodograph descriptors of atmospheric winds reveal coherent rotating and rectilinear particle motions. A mathematical statistics-based wind to wave-to-wave algorithm is developed and applied to offshore marine buoy data to create an hour-by-hour forecast capability from 1 to 24 hours;with confidence levels put forward. This affects a different approach to the conventional deterministic model forecasting of waves.