Search

Since a trend towards aridification is expected in Algeria, as in the countries of the Maghreb and the Mediterranean basin, changes in precipitation and temperature can have a significant impact on various water and energy balance processes and, consequently, on surface soil moisture (SSM). The latter is an important measure for monitoring and even forecasting meteorological and hydrological droughts, as well as irrigation for water resource optimization. This study examines the spatiotemporal sensitivity of SSM to variations in precipitation and temperature in different climatic zones of the Cheliff basin. The monthly mean data from four datasets of SSM, extracted from two reanalysis products (ERA-Land and ERA5), active and passive microwave satellite observations (ESA CCI SM), GLEAM model, along with precipitation and temperature records over the period from 1980 to 2018 from 104 weather stations, were analyzed by using the Modified Mann–Kendall test (MMK) and canonical correlation; the study revealed that (1) SSM generally increased from September to December or March, depending on the dataset; (2) monthly precipitation increased from September to November; (3) SSM decreased from June to August, coinciding with rising temperatures; (4) the results of the canonical analysis revealed that monthly SSM is positively correlated with delayed precipitation from 1 to 3 months, depending on the climatic zone; (5) SSM is negatively correlated with temperatures over the previous 2 months for the stations in Csa and Bsk climate zones and with temperatures over the previous 1 and 2 months for the stations in Bsh climate zone from 1 to 2 months prior, also depending on the climatic zone. These results highlight the crucial role of SSM in monitoring and forecasting weather events such as droughts and provide insights for irrigation strategies aiming to optimize water resources. [ABSTRACT FROM AUTHOR]

The frequency of drought events in the Mediterranean region has increased significantly in recent years, along with a substantial increase in their spatial and temporal extent. These events are associated with high temperatures and low precipitation. Our study presents a vision on the impact of temperature on agricultural drought frequency, severity, and temporal extent under future scenarios over seven vast plains located in the semi-arid region of the Mediterranean basin. A multivariate frequency analysis of both meteorological and agricultural drought characteristics is based using the copula theory. The return periods of past and future drought events are determined using the two drought indices standardized precipitation index and standardized precipitation evapotranspiration index. The projected drought events are determined based on climate simulations (monthly precipitations and temperatures) from the RCA4-MPI-ESM-LR model, and the projection period was forced by the two representative concentration pathway scenarios RCP4.5 and RCP8.5. Results showed that the frequency of drought events is much higher if only precipitation (SPI) is taken into account than if overall climate (precipitation and temperature, SPEI) is considered while their severity and duration are more intense using SPEI. The risk of drought is best estimated by multivariate frequency analysis where the unvaried return periods, considering the duration or severity, underestimate the recurrence of events. Drought events in the plains are likely to be more severe and to last longer, particularly during the hot season (between May and September) between 2021 and 2071 according to the two future scenarios. In addition, agricultural production is threatened by a spring agricultural drought (between February and April) between 2050 and 2100 under the RCP4.5 scenario, which can have serious consequences on agricultural income as well as food security. [ABSTRACT FROM AUTHOR]

This study investigates the effect of autocorrelation on temporal trends and step change on a monthly, seasonal and annual temperatures of six meteorological stations over the North of Algeria. Afterwards, links between the general atmospheric circulation, via six climate indices, and temperature data are examined. The trends in temperatures are analysed using six different versions of the Mann-Kendall approach while, the step changes of the time series are defined using the original Pettitt test and the modified-Pettitt. The Statistical tests have shown an increase in annual temperatures from 0.8 to 0.9°C since the 1980s in the coastal regions and the 1990s on the highlands. This warming most often exceeds 1°C on a seasonal scale, particularly in summer; however, no significant trend is observed in the winter. On a monthly scale, the increase in temperatures is marked between April and October. The analysis of the relationships between six climate indices and average temperatures has shown that the inter-annual temperature variability is most often associated with the East Atlantic oscillation for the entire study area. The winter temperatures are influenced by the Mediterranean oscillation as well as the North Atlantic oscillation. The East Atlantic oscillation is the dominant mode of circulation in spring and summer, whereas in autumn, the temperatures are strongly linked to the West Mediterranean oscillation. However, no significant correlations have been observed between temperatures and the Arctic oscillation and El Nino southern oscillation. [ABSTRACT FROM AUTHOR]