Thornton, Philip K. · CGSPace A Repository of Agricultural Research Outputs (Consultative Group for International Agricultural Research) · 2014
In Africa, where most agriculture is rainfed, crop growth is limited by water availability. Rainfall variability during a growing season generally translates into variability in crop production. While the seasonality of rainfall in the drier rangelands can play a significant role in productivity, rain-use efficiency (RUE)—the amount of biomass produced (in kilograms of dry matter per hectare) per millimeter of rainfall—also drives production.
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Thornton, Philip K. · IFPRI E-brary (International Food Policy Research Institute) · 2014
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Pierre Camberlin · HAL (Le Centre pour la Communication Scientifique Directe) · 2006
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Laban Ogallo · Monthly Weather Review · 1979
Time series of annual rainfall for 69 stations in Africa were analyzed for trends and periodicities. Trend analysis showed that most of the annual series indicate some forms of oscillations rather than any particular trend. Use of binomial coefficients to smooth the series indicated positive or negative trends in recent years in 20 series, but only four of these were statistically significant judging by the Spearman rank correlation test. These four stations were geographically distributed within those showing no significant trends. Assuming the generating process to be purely random, the prominent cycles revealed by the spectral analysis were 2.0–2.5 years and 2.7–3.3 years. In general, the larger observed cycles (3.5–4.4 years, 5.0 years, 6.0–6.5 years, 7.0–8.0 years and 10.0 years) were weak at the 0.05 significance level.
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Lei Lan · 1936
The factors that influence the rate of growth, length of life, fecundity, abundance, death rate, or time of appearance of vegetation are obviously climatic. And the rainfall and temperature conditions are the most important factors in defining the large areas of crop distribution and plant varieties. For example, rice cultivation flouristes where the rainfall is 30 inches or more and there is at least eight months of growing season. Wheat is densely centered in the yellow river delta and the Wei Ho valley where winter is the dry season. Kaoliang and millet, owing to their peculier ability of suspending growth
activities in periods of drought, are the dominant summer crops in the part of North
China where the rainfall is highly unreliable. These are long established adjustments between climatic conditions and crop cultivation, But it is important to realize that the important feature that governs the success of crop growth and maturity is variability/or reliability.
The frequent droughts in certain parts of tell that rainfall is more reliable in-some parts of the country than other parts. Fig. 1 is an approximation to a quantitative representation of this variation. It is derived after Professor Griffith Taylor's method by averaging departures. The annual rainfall of all years available in ''The rainfall of China by the Institute of Meteorology of 1935. are considered. Their departures, ignoring sign, from the normal obtained in each year are then averaged and the result is expressed as a percentage of the total rainfall. Thus at Kiukiang the average rainfall for 46 years is 1413 mm. The average departure is 260 mm. or 18. 4%. This means that in Kiukiang, in every one hundred years, for eighteen years the rainfall distribution is not successful. This last figure is plotted on the chart.
It is interesting to note that the most reliable rainfall occurs in South where the visitations of extratropical cyclones have the highest frequency. A narrow fringe of the Fukien coast is comparatively less reliable. The 20 per cent isoplebh runs westward from northern Kiangsu parallel to the Tsingling range. The 25 per cent isopleth has a striking bulge south into southern Honan, and then the line turns toward the north a little.From the norrow belt of eastern Shantung to the province of Heilungkiang the departure is about 30 per cent.
The isopleths of greater variability, run concentric- to the least favored region of the loess plateau where a variation of over 30 per cent is the rule, and in places it is well over 40 per cent. The 20 per cent isopleth is found to go closely with the 30 inches isohyet. The isopleths of great variability lie in the region of the least rain, where the rainfall is the least it is also the least reliable. This is true also both of semi-arid United States and Australia. Fig. 2 shows the deficiencies and excesses of rain in Tsinan, andNanking. Nanking shows a higher correlation between the summer and spring variation-This is important to the different crop cultivation of China.
Poor crops are resulted from many kinds of factors. Here we are only concerned with the factor of rainfall. Besides those caused by excess and deficiency of rainfall, variability is another problem of much importance and must be fully considered in agricultural work.
(1) When the total rainfall is the same but the variability is not the same. At Taiyuan, Shansi, the annual mean for sixteen years is 388m.m. For the year 1934 the annual total was 46. 3m.m. Quantitatively speaking, the year 1934 obviously has a positive departure of 77. 3m.m. over that of the mean. It should be a fat year. But in fact 1934 was a poor year for Taiyuan, The reason is because the year was commenced by a deficient rainfall in the spring. Crops were not able to be planted and developed on time. Then came an excess of rain which is harmful to the growth of plants. Finally the crops were ruined by killing frast before reached maturity. The region has suffered loss both from deficiency and excess of rainfall while the annual varia
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Vincent Moron, Andrew W. Robertson, Michael Ghil · 2011
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Kenny Thiam Choy Lim Kam Sian, Brian Ayugi, Charles Onyutha et al. · Elsevier eBooks · 2025
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M. Rajeevan, Parthasarathi Mukhopadhyay, Arindam Chakraborty · Elsevier eBooks · 2025
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E. Fukui · Geographical Review of Japan · 1934
The annual precipitation in Japan, generally speaking, is not constant as one would expect, but fluctuates within a wide range from year to year, which fact is important not only from the climatological point of view but from the industrial and economic as well. The writer calculated the rainfall variability for ninety six stations in Japan and neighbourhood after Maurer's scheme. The geographical distribution of the variability as represented on a map (Fig. 1), when studied, give very interesting results. In the Japanese Islands, the pacific side has greater variability compared with the Japan Sea side and the variability increases from south to north. Hokkaido, Karahuto (Sakhalin), and Tyôsen (Korea) have relatively high variabilities. These numerical values are shown in tables.
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Chen, Mengting · SHAREOK (University of Oklahoma; Oklahoma State University; Central Oklahoma University) · 2025
Rainfall erosivity (R-factor) is an essential input dataset used in soil erosion models such as USLE, RUSLE, and RUSLE2, as it quantifies the combined effects of rainfall and runoff in causing soil erosion. Accurate estimation of rainfall erosivity is critical for predicting soil loss, evaluate the risk of water pollution from construction sites, and supporting land management decisions under changing climate conditions. However, the determination of erosivity depends on rainfall data, and due to changing precipitation patterns, erosivity datasets must be updated periodically. The main objectives of this dissertation are to:(1) evaluate the applicability of published regression equations for estimating annual rainfall erosivity based on annual precipitation in EPA Region 6; (2) estimate monthly rainfall erosivity using high-temporal-resolution (5-minute interval) data from a dense gauge network in Oklahoma; (3) assess the performance of gridded precipitation datasets when applied in the erosivity density approach to estimate rainfall erosivity; (4) quantify discrepancies between the estimates generated in this dissertation and those from published global datasets (GloREDa 1.2 and GloRESatE); and (5) identify changes in rainfall erosivity and erosivity density with variations in rainfall through trend analysis from 1995 to 2023. The results demonstrate that commonly used regression equations introduce substantial bias, highlighting the need for region-specific models. High-resolution gauge observations revealed significant spatial and seasonal variability in erosivity across Oklahoma, with increasing trends particularly evident in the eastern regions. Comparisons with global datasets uncovered considerable discrepancies, underscoring the need to update these products. Additionally, significant upward trends in both erosivity and erosivity density were observed, indicating intensifying rainfall events. This dissertation emphasizes the need to revise existing rainfall erosivity databases in response to changing climate conditions. There is a critical need for robust estimation approaches that integrate gridded precipitation data and leverage machine learning techniques. Gauge-derived erosivity estimates are essential for training and evaluating these emerging methods.
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P. Driver · Open University of Cape Town (University of Cape Town) · 2014
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C. D. Hall · The Ballarat naturalist. · 2003
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Vishwambhar Prasad Sati · Earth and environmental sciences library · 2026
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Mekonen Ayana, Banchiamlak Kebede · 2010
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James W. Wilson, Marshall A. Atwater · Journal of Geophysical Research Atmospheres · 1972
Storm rainfall variability over Connecticut was investigated by using data from the 66 cooperative rain gages of the National Weather Service supplemented by 70 volunteer stations. The analyses concentrated on large-scale stratiform type rainstorms. Much of the observed rainfall variability within storms can best be explained by variations in terrain. A minimum in rainfall generally occurs in the Connecticut River valley and along the coastal plain and a maximum on the windward side of the hills. The wind direction at hilltop level is an important factor in explaining differences in the rainfall pattern between storms. More upper-air stations and more frequent soundings would be needed to assess the importance of other atmospheric variables in influencing the effectiveness of topography as a modifier of precipitation patterns. The results of this study emphasize the importance of topography, even in regions with small elevation differences, when attempts are being made to evaluate man's planned or inadvertent modification of precipitation.
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Carneiro, Renato Quinderé · LA Referencia (Red Federada de Repositorios Institucionales de Publicaciones Científicas) · 2021
Climate variability knowledge is key information in water resources planning. This information, however, could be misleading if based only on observed series since these usually are not long enough to represent the variability in its full range. Climate reconstitution by a proxy variable is very successful in extending these series, but it finds difficulties when dealing with tropical regions such as NEB. The approach adopted in this study is to use Paleoclimatic model output from PMIP´s last millennium experiment to assess Climate variability, which leads to the problem of assessing the model´s ability to represent the climate of the studied region. In its first part, this study proposes a method for model evaluation which decomposes the series in seasonal and pluriannual components and compares the result to observed series using measures from Information Theory. The model ranking was obtained by TOPSIS in three different scenarios. In the second part, the top-ranked models for the pluriannual variability scenario were assessed through the distribution-free CUSUM test and Wavelet analysis to detect change points and oscillatory modes. Models were also compared to each other and to both solar irradiation and volcanic forcing to assess whether the detected modes were due to internal variability or to external forcings. Model comparison simulations in the seasonality scenario showed that CSIRO-Mk3L-1-2, bcc-csm1-1, and CCSM4 were the models with the best adherence to the observed series, while simulations in the pluriannual scenario showed that HadCM3, MPI-ESM-P, and EC-Earth3-Veg-LR were the models with the best adherence. In the third scenario, the best performance was due to models bcc-csm1-1, MRI-ESM2-0, and HadCM3. In the second part, no change point was detected in the series with a confidence level of 95%., while in Wavelet Analysis modes with a period range of 4 to 8 years, 16 to 32 years, and 128 to 256 years were detected. Comparisons between models and external forcings analysis led to evidence that the mode with a period range of 128 to 256 years could be caused by external forcings.
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Matthias Steiner, James A. Smith, Remko Uijlenhoet et al. · 2015
Rainfall is highly variable in space and time, depending on synoptic, mesoscale or topographic forcing. This variability affects our capability to measure rainfall from an in-situ as well as remote-
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R Akhila, S. K. Pramada · Water Resources Management · 2025
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Kenneth Okechukwu Ekpetere · SSRN Electronic Journal · 2024
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CentAUR (University of Reading) · 2018
The Sahel-Soudano zone that spans North Africa, from Senegal to Ethiopia, has experienced pronounced climatic variability (and conflicts) for millennia. This home to 250 million people—one quarter of Africa’s population—is a fragile transition zone in environmental and human terms. From south-to-north, rainfall decreases from around 30 inches per year on average to essentially nothing. Back-to-back contrasting rain years (deficits in 2011, floods in 2012) left over 18 million people in the West African Sahel threatened by food shortages between 2012 and 2013, highlighting yet again the strong the dependence between livelihoods on rainfall in the region. Ironically (tragically, even), the stakeholders within the Sahel have less access to, and therefore use less, instrumental rainfall information for planning and management than almost anywhere else in the world. Furthermore, short-term weather and seasonal climate forecasting have limited skill for West Africa. Whilst many of the National Hydrological and Meteorological agencies are making impressive efforts to produce tailored climate forecasts for their stakeholders, most appear to be country specific. \n \nRecognizing these constraints, this Special Issue presents the latest understanding of African rainfall variability and on-going efforts to translate this into useable information through knowledge co-production and dissemination, to assure content relevance and accuracy for intended purposes. Stakeholders must establish practical innovations to anticipate impending crises and work collaboratively across the region to share information and strengthen supporting infrastructure. Within this framework, timely access to user-relevant climate information, access to relevant and reliable forecasts, and the ability of stakeholders to act on that information through effective strategic partnerships will prove the difference between coping proactively with emerging climate challenges and perpetuating the cycle of climate triggers and crisis.
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