Decadal changes in mean annual rainfall drive long-term changes in bush-encroached southern African savannas

2016 ◽  
Vol 41 (6) ◽  
pp. 690-700 ◽  
Author(s):  
Munyaradzi D. Shekede ◽  
Amon Murwira ◽  
Mhosisi Masocha ◽  
Fadzai M. Zengeya
Keyword(s):  
Annual Rainfall ◽  
Mean Annual Rainfall ◽  
Long Term Changes

Evaluating climate effects over long-term salts accumulation in hyperarid soils using stochastic modeling

2021 ◽  
Author(s):  
Lior Siman-Tov ◽  
Onn Crouvi ◽  
Efrat Morin ◽  
Rivka Amit ◽  
Yehouda Enzel ◽  
...  
Keyword(s):  
Late Pleistocene ◽  
Alluvial Fan ◽  
Sensitivity Analyses ◽  
Annual Rainfall ◽  
Soil Profiles ◽  
Sulfate Concentration ◽  
Climate Scenarios ◽  
Mean Annual Rainfall ◽  
Dust Flux

<p>Hyperarid (< 80 mm yr<sup>-1</sup>) soils in hot deserts are characterized by accumulations of soluble salts (gypsum and halite) in diagnostic horizons as a result of limited moisture availability. In most desert terrains, the source for pedogenic gypsum and halite is atmospheric dust and rainwater. The interplay between climatic properties such as frequency and intensity of rain events, rainfall composition, dust flux, and evaporation rates, govern the depth and concentration of these salts. Better understanding of these relationships can improve our estimation of regional paleoenvironmental and paleoclimate conditions. Up to date, only empirical correlations between annual rainfall and pedogenic salt horizons are available.</p><p>The goals of this study are to: 1) quantify rates of pedogenic gypsum accumulation with time and the role of controlling climatic conditions that govern its accumulation, 2) estimate the most likely climatic scenarios that led to the formation of the diagnostic gypsic horizon developed in late Pleistocene (~ 60 ka) abandoned alluvial fan surfaces in the hyperarid Negev desert,  southern Israel. To achieve these goals, we constructed a compartment model that simulates gypsum accumulation in soil and tests its sensitivity to various changes in the long-term climate properties. The model predicts gypsum content and depth of accumulation in the soil profile over thousands of years and more. The input parameters are stochastically simulated rainstorms, evaporation, dust flux, and sulfate concentration in rainwater, at daily time steps. The model was tested and calibrated using data of Holocene (< 11 ka) soil profiles developed on stable alluvial fans in the hyperarid Negev. With the assumption that the climate during the Holocene was not much different than today (i.e., mean annual rainfall < 50 mm). Sensitivity analyses indicate that gypsum accumulation is highly sensitive to mean annual rainfall and sulfate concentration in rainwater. Synthetic gypsum profiles were calculated using different climate scenarios and compared to late Pleistocene soils. Our results suggest that: (a) gypsum accumulation in late Pleistocene soils cannot occur simply by extending current climate conditions for a much longer duration. (b) The plausible climate scenarios for the late Pleistocene must include additional rain input (1.5 – 2.0 times than mean annual rainfall today) and increased sulfate concentration in rainwater (2.0 – 2.5 times than today) to successfully reconstruct the observed accumulated gypsum in mature (60 – 12 Ka) soil profiles.</p>

Long-term changes in annual rainfall patterns in southern Israel

1994 ◽  
Vol 49 (2) ◽  
pp. 59-67 ◽  
Author(s):  
T. Ben-Gai ◽  
A. Bitan ◽  
A. Manes ◽  
P. Alpert
Keyword(s):  
Annual Rainfall ◽  
Long Term Changes ◽  
Rainfall Patterns

scholarly journals Long-Term Changes of Aquatic Invasive Plants and Implications for Future Distribution: A Case Study Using a Tank Cascade System in Sri Lanka

Climate ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 31
Author(s):  
Champika S. Kariyawasam ◽  
Lalit Kumar ◽  
Benjamin Kipkemboi Kogo ◽  
Sujith S. Ratnayake
Keyword(s):  
Sri Lanka ◽  
Climate Variability ◽  
Annual Rainfall ◽  
Trend Test ◽  
P Value ◽  
Positive Trend ◽  
Cascade System ◽  
Landsat Images ◽  
Long Term Changes

Climate variability can influence the dynamics of aquatic invasive alien plants (AIAPs) that exert tremendous pressure on aquatic systems, leading to loss of biodiversity, agricultural wealth, and ecosystem services. However, the magnitude of these impacts remains poorly known. The current study aims to analyse the long-term changes in the spatio-temporal distribution of AIAPs under the influence of climate variability in a heavily infested tank cascade system (TCS) in Sri Lanka. The changes in coverage of various features in the TCS were analysed using the supervised maximum likelihood classification of ten Landsat images over a 27-year period, from 1992 to 2019 using ENVI remote sensing software. The non-parametric Mann–Kendall trend test and Sen’s slope estimate were used to analyse the trend of annual rainfall and temperature. We observed a positive trend of temperature that was statistically significant (p value < 0.05) and a positive trend of rainfall that was not statistically significant (p values > 0.05) over the time period. Our results showed fluctuations in the distribution of AIAPs in the short term; however, the coverage of AIAPs showed an increasing trend in the study area over the longer term. Thus, this study suggests that the AIAPs are likely to increase under climate variability in the study area.

scholarly journals Farmers’ Perceptions of Climate Change, Long-term Variability and Trends in Rainfall in Apac District, Northern Uganda

2021 ◽  
Author(s):  
Francis Atube ◽  
Geoffrey M. Malinga ◽  
Martine Nyeko ◽  
Daniel M. Okello ◽  
Basil Mugonola ◽  
...  
Keyword(s):  
Climate Change ◽  
Abrupt Change ◽  
Smallholder Farmers ◽  
Change Points ◽  
Annual Rainfall ◽  
The Past ◽  
Rainfall Trends ◽  
Long Term Changes ◽  
Cropping Seasons

Abstract Background: Climate change poses a serious threat to agricultural livelihoods and food security of smallholder farmers in Sub Saharan Africa. Understanding long-term rainfall trends of variability and extremes at local scales and perceptions regarding long-term changes in climate variables is important in planning appropriate adaptation measures to climate change. This paper examines the perception of farmers in Apac district regarding long-term changes in climate variables and analyzes the trend of occurrence in seasonal and annual rainfall in Apac district, northern Uganda. A cross-sectional survey design was employed to collect data on perception of farmers regarding long-term changes in climate from 260 randomly selected small-holder farmers’ households across two sub-counties in Apac district by the administration of semi-structured questionnaires in February 2018. Monthly rainfall data sets from the Uganda Meteorological Authority (UMA) for the period 1980 to 2019 for the Apac district were also used to analyze trends of occurrences in seasonal and annual rainfall in the study area. The nonparametric Sequential Mann-Kendall (SMK) and Sequential SMK tests were employed at a 5% significance level to detect trends and abrupt change points in mean seasonal rainfall. Results: The majority of the respondents (87%) perceived a decrease in precipitation over the past 39 years. The plot of forward regression u(ti) values and backward regression u’(ti) values showed interactions indicating rainfall trends: rainfall lower and upper limits and abrupt change points in the different cropping seasons. Analysis of historical series of mean monthly and annual rainfall showed an abrupt change in rainfall in March, April, May (MAM) season in 1982. Although the September, October and November (SON) season did not show an abrupt significant change, there was a significant (p<0.05) increase in rainfall above the upper limit from 1994 to date. Conclusion: The mean seasonal rainfall for MAM and SON cropping seasons in the Apac district were highly variable from different time points within the past 39 years (1980-2019), while JJA did not realize a significant change in rainfall within the same study period. Thus, the two cropping seasons (MAM and SON) in the district experienced remarkable variations in rainfall. This, therefore, provides a basis for Government to strengthen the provision of an effective climate tailored agricultural advisory service to aid farmers’ adaptation planning at the local level and to assist smallholder farmers and land-use managers in developing effective adaptation management strategies to the effects of climate change.

Long-term climatic change in the western Indian Ocean

1979 ◽  
Vol 286 (1011) ◽  
pp. 11-23 ◽  
Keyword(s):  
Indian Ocean ◽  
Climatic Change ◽  
Western Indian Ocean ◽  
Annual Rainfall ◽  
Historical Records ◽  
The Past ◽  
Mean Annual Rainfall

Analysis of rainfall records for stations on Mahé (Seychelles), Mauritius, Minicoy and Amini Divi (Laccadives), and other western Indian Ocean stations, shows substantial fluctuations in mean annual rainfall over the past 100 years, with high rainfalls at the beginning of this century, at about 1930, and at the present day, with troughs during 1915-20 and 1940-50. Overlapping series of more recent records for Aldabra, Assumption and the Iles Glorieuses also suggest substantial variations, and the existence of these is supported by episodic historical records. The consequences of such changes for the land biota of Aldabra, especially for the giant tortoises, are discussed, and brief reference is made to other types of evidence for climatic change on the atoll.

scholarly journals Differential Signal of Change Among Multiple Components of West African Rainfall

2021 ◽  
Author(s):  
Omon Aigbovboise Obarein ◽  
Cameron C. Lee
Keyword(s):  
Rainfall Intensity ◽  
Climate Models ◽  
Grid Point ◽  
Congo Basin ◽  
Annual Rainfall ◽  
Reanalysis Dataset ◽  
Rainfall Frequency ◽  
Hourly Rainfall ◽  
Long Term Changes

Abstract Rainfall components likely differ in the magnitude and direction of their long-term changes for any given location, and some rainfall components may carry a greater regional signal of change than rainfall totals. This study evaluates the magnitude of change of multiple rainfall components relative to other components, and the greatest regions of change across all rainfall components in West Africa. Hourly rainfall data from the ERA5 reanalysis dataset was used to derive twelve rainfall components, which were evaluated for long-term means, interannual variability, and long-term changes. For rainfall totals and rainfall intensity, the central Sahel is witnessing increasing trends while the western Sahel is experiencing significant decreasing trends. In general, decreasing trends predominate in the study domain, especially in the northwestern Congo Basin, where annual rainfall is decreasing by 120mm per decade. Importantly, rainfall frequency accounts for 49% of all significant grid-point trends for the whole domain. In contrast, rainfall totals account for 26% of all combined significant trends across the domain, while rainfall intensity (12.6%), rainy season length (9.5%), and seasonality (3.3%) account for the remaining signals of change. Most of the changes among the rainfall components are in the Tropical Wet and Dry regions (59% of all significant trends); the Saharan and Equatorial regions account for the least changes. This study finds evidence that rainfall frequency is changing more across the regions compared to rainfall totals and should be explored as rainfall inputs in climate models to potentially improve regional predictions of future rainfall.

scholarly journals Analysis of changes in climatological condition: a perspective from Barguna district of Bangladesh

2017 ◽  
Vol 5 (2) ◽  
pp. 133
Author(s):  
Tapos Kormoker ◽  
Ram Proshad ◽  
Mohammed Mahmud Khan ◽  
Bidhan Chandra Saha
Keyword(s):  
Missing Values ◽  
Small Time ◽  
Annual Rainfall ◽  
Measured Temperature ◽  
Secondary Sources ◽  
Average Maximum ◽  
Macro Scale ◽  
Long Term Changes ◽  
Significant Change

This study investigated the long-term changes in climatological condition, such as temperature, rainfall, humidity, storms, and tidal surge and flooding in Barguna district of Bangladesh. The BMD (Bangladesh Meteorological Department) data were used for temperature, rainfall, and humidity. The data for storms have been collected from secondary sources i.e. various journals, website and various records. This study applied the time series statistical test to examine the long-term changes in climatological condition, such as temperatures (1970-2015), rainfall (1975-2013), humidity (1975-2013), and storms (1987-2007). A parametric technique of trend analysis was used in this study for its inclusive use and simplicity. Data screening and filling missing values were also done before the analyses. The analyses of measured temperature indices that the annual average maximum and minimum mean temperature has increased 1.16°C and 0.56°C respectively at the end of 2015 since 1982 indicating that the weather has been becoming hotter. The analysis of the last 30 years rainfall data of Barguna was compared with national total annual rainfall and no significant change observed. The number of wetter days has been increasing over the time and more rainfall has been happening within small time. There is also a significant change in relative humidity. A total of thirty-five depressions, storms and cyclones hit Barguna district during the last 130 years among which hard hit severe cyclones have occurred in 1935, 1965, 1970 and the most recent cyclone SIDR in 2007 was notable. The study found that storm surge level and surge induced coastal flooding reached from the outfall of Baleshwar River up to 50 km upstream at Morrelganj with high surge level. Therefore, this study will provide a condensed view in further studies in advanced statistical modeling in combination with future scenario analysis for micro and macro scale climate variable changes in Bangladesh.

Improved long-term mean annual rainfall fields for Colombia

2010 ◽  
Vol 31 (14) ◽  
pp. 2194-2212 ◽  
Author(s):  
Oscar David Álvarez-Villa ◽  
Jaime Ignacio Vélez ◽  
Germán Poveda
Keyword(s):  
Annual Rainfall ◽  
Mean Annual Rainfall
Sign in / Sign up

Export Citation Format

Share Document