Recent trends and anomalies in mean seasonal and annual temperatures over Sudan

Elagib, Nadir Ahmed; Mansell, M. G.

doi:10.1006/jare.2000.0639

Cited by 56 publications

(51 citation statements)

References 43 publications

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“…1, were selected to cover the four main regions of the country, i.e. the southern region (south of 10°N), the central region (10-16°N), the northern region (north of 16°N) and the coastal region of the Red Sea in the north-east (Elagib and Mansell 2000a). Available data since the 1940s on mean monthly maximum and minimum temperatures for these stations were acquired from the Sudan Meteorological Authority.…”

Section: Methodsmentioning

confidence: 99%

“…The seasonal MEANs show that most of the warming is identified in the summer and fall. Using MEAN data, Elagib and Mansell (2000a) showed significant trends in wet-and hot-season series for Sudanese stations located south of latitude 16°N for the period since the 1940s to 1996, with the rising trends in the former series being higher and more significant. Aguilar et al (2009) found a decrease in cold extremes and an increase in warm extremes over western central Africa, Guinea Conakry and Zimbabwe.…”

Section: Introductionmentioning

confidence: 98%

“…Both for the transient and double CO 2 climate simulations, the results showed that the temperature variability tends to decrease in the warmer climate (Rind et al 1989). In the light of the increasing awareness of the importance of the study of climate variability (Katz and Brown 1992), a number of investigators examined the long-term temperature observations (Karl et al 1995;Przybylak 1997;Michaels et al 1998;Elagib and Mansell 2000a;Pal and Al-Tabbaa 2009) in a search for changing variability in a changing climate.…”

Section: Introductionmentioning

confidence: 99%

“…Adequate knowledge of the spatial distribution of changes and variability of temperature extremes is insufficient. In this study, further analysis of recent temperature trends and variability is performed for Sudan over that conducted by Elagib and Mansell (2000a) by updating the time series to the year 2005 and including, in addition to MEAN, the records on MAX, MIN and DTR. The paper also expands upon Karl et al's (1993) study which considered the nationwide MAX, MIN andDTR series during 1951-1987.…”

Section: Introductionmentioning

confidence: 99%

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Trends in Intra- and Inter-Annual Temperature Variabilities Across Sudan

Elagib

2010

AMBIO

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Four mean temperature variables, namely maximum (MAX), minimum (MIN), mean (MEAN) and diurnal temperature range (DTR), were considered for 14 selected observational stations throughout Sudan. The objectives were to investigate the seasonal and annual regimes, the seasonal and annual trends, the intra-annual variability (IAV) by the coefficient of variation (CV), and the interrelationships between the temperature variables and percent of possible sunshine. A mounting evidence of daytime and nighttime warming since the 1940s until 2005 is presented. The exception is the dry season which is dominated by daytime cooling attributable to the damping effect of dust haze/storms. Apparently, the progressive drought across inland locations has raised the MAXs, and to a lesser extent the MINs, of the wet season over those for the hot season. Accordingly, maximum rates of 0.451 and 0.336°C decade -1 were found for the nighttime and daytime temperatures, respectively. The extreme eastern and western locations have been frequently dominated by the warmest trend rates obtained nationwide. The prevalence of significant decreases (increases) of DTR is more apparent in the dry, hot and annual series (wet series). Depending on the temperature variable under consideration, many stations possessed significant trends toward either increased or decreased variability of the within-year monthly values, i.e. IAV. The correlation between the time series of annual CV and extreme values for each of the four temperature variables shows generally that warmer climate in Sudan is associated with higher intra-annual temperature variability and vise versa, i.e. the CV is directly correlated with the highest value within the year, but inversely correlated with the lowest one. The findings of this investigation also indicate that the DTR is directly related to percent of possible sunshine, but the relationship of the latter parameter is not so clear with MAX, MIN and MEAN.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Trends in Intra- and Inter-Annual Temperature Variabilities Across Sudan

Elagib

2010

AMBIO

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“…In particular, two main climatic parameters, namely rainfall and temperature, are studied in detail for the Arabian Peninsula as well as for Saudi Arabia because these two variables are important measures of climate in a region (Elagib and Mansell, 2000;Lazaro et al, 2001;Moonen et al, 2002;Islam et al, 2010). Rainfall is important for the natural replenishment of aquifers for fresh renewable water.…”

Section: Introductionmentioning

confidence: 99%

Recent climate change in the Arabian Peninsula: annual rainfall and temperature analysis of Saudi Arabia for 1978–2009

Almazroui

Islam

Athar

et al. 2012

Intl Journal of Climatology

271

204

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ABSTRACT:The rainfall and temperature climatology over the Arabian Peninsula are analysed on an annual basis using various gridded datasets. For Saudi Arabia, the area of which represents almost 80% of the Peninsula, the climatic datasets from its 27 ground observations are analysed for the period 1978-2009, with additional gridded datasets used to describe the observed state and change of the present climate. The gridded datasets represent well the very dry (40-80 mm) area over the world's largest sand desert (Rub Al-Khali), the dry (80-150 mm) area over middle-to-north of Saudi Arabia, and the wettest (>150 mm) region in the southwest of the Peninsula. The annual temperature is relatively high (24-27°C) in the middle-to-south of the Peninsula and low (<21°C) in the northwest and southwest. The highest temperature (>27°C) is obtained over the Rub Al-Khali. Over Saudi Arabia, the observed annual rainfall showed a significant decreasing trend (47.8 mm per decade) in the last half of the analysis period, with a relatively large interannual variability, while the maximum, mean and minimum temperatures have increased significantly at a rate of 0.71, 0.60, and 0.48°C per decade, respectively. This information is invaluable to consider in any climate impact assessment studies in Saudi Arabia.

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Correcting Hargreaves‐Samani formula using geographical coordinates and rainfall over different timescales

Elagib

Musa

2023

Hydrological Processes

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The United Nations Food and Agricultural Organization (FAO) approved the Hargreaves-Samani formula (HAR-85) as an alternative to the standard Penman-Monteith method (FAO-PM) for estimating grass reference evapotranspiration (ETo).With much less data demand, HAR-85 is unequivocally useful where meteorological variables are often scarce, incomplete or unavailable. Herein, we evaluate HAR-85 against FAO-PM across 2.505 million km 2 , representing Sudan and South Sudan and encompassing wide hydroclimate domains including the Nile River. We further propose simple year-round and seasonal adjustment models to correcting HAR-85 across the entire study area. The models express HAR-85's error in multiple linear regressions in terms of latitude, longitude, altitude and/or monthly rainfall. Varying data periods, including odd, even and all years, are used in the evaluation and the adjustment models development and validation processes to investigate the influence of changing data period. A suit of eight performance indicators shows dependency of the original bias of HAR-85 on the geographical location, monthly rainfall amount, season of the year and data period. All error indicators amplify southward from the hyper-arid region to the dry sub-humid zone. For example, the mean bias error (MBE) ranges from À0.51 to 1.29 mm/day, respectively. Study area-wide, HAR-85 least represents FAO-PM during the hottest month and the transitional month (between the wet and dry-cool seasons) with MBE of 0.65 and 0.70 mm/day, respectively. Conversely, it represents FAO-PM the most in the wettest month, with smallest MBE of 0.32 mm/day. Beholding this spatiotemporal trait, the final yearly and seasonal adjustment models developed herein enormously moderate the predominant overestimation of the original HAR-85. The former model explains 46.7% of the error variance whereas 36.9% to 62.3% of the variation in the error is explainable by the latter models. These adjustment models narrow the monthly MBE among the stations from À0.71-2.17 to À0.80-1.20 and À0.65-0.99 mm/day, respectively. Without undermining the accuracy, the year-round adjustment model can still be feasibly recommended for general use across the study area.

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Recent trends and anomalies in mean seasonal and annual temperatures over Sudan

Cited by 56 publications

References 43 publications

Trends in Intra- and Inter-Annual Temperature Variabilities Across Sudan

Trends in Intra- and Inter-Annual Temperature Variabilities Across Sudan

Recent climate change in the Arabian Peninsula: annual rainfall and temperature analysis of Saudi Arabia for 1978–2009

Correcting Hargreaves‐Samani formula using geographical coordinates and rainfall over different timescales

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