Campus Units

Geological and Atmospheric Sciences

Document Type

Article

Publication Version

Accepted Manuscript

Publication Date

12-4-2018

Journal or Book Title

Theoretical and Applied Climatology

DOI

10.1007/s00704-018-2713-0

Abstract

The impact on society of extreme temperature events is enormous. This study examines the temporal evolution and trends in mean temperatures (minimum temperature, TN and maximum temperature, TX) and warm extremes in Nigeria as well as in three regions in Nigeria (Guinea, Savanna, and Sahel) using homogenized daily TN and TX for the period 1971–2012. Warm extremes are defined as days with TX > 35 °C (HotD) and nights with TN > 20°C (TropN). The modified Mann-Kendall test is used to calculate and assess the statistical significance of trends in the indices. The results at annual and seasonal (JFM, AMJ, JAS, and OND) timescales indicate a significant positive increase in temperatures in Nigeria. The warming in annual and seasonal TN is greater than in TX. The temporal evolution in warm extremes is similar to those of the mean temperatures, with trends in TropN greater than those of the HotD. In all the regions, the temporal patterns of trends in mean temperatures and warm extremes are similar. The indices are characterized by positive trends, with the exception of HotD in Guinea with no data during JAS. Analysis of large-scale atmospheric fields during warm extreme days when both TX and TN exceed their respective 90th percentile thresholds shows that warm extreme days are associated with mid-tropospheric subsidence motion in vertical velocity anomaly that is connected with the core of the thermal low and the net convergent flow. These features are accompanied by positive surface shortwave radiation anomaly coupled with cloud cover reduction.

Comments

This is a manuscript of an article published as Abatan, Abayomi A., Babatunde J. Abiodun, Elijah A. Adefisan, and William J. Gutowski. "Hot days and tropical nights in Nigeria: trends and associated large-scale features." Theoretical and Applied Climatology (2018). doi: 10.1007/s00704-018-2713-0. Posted with permission.

Copyright Owner

Springer-Verlag GmbH Austria, part of Springer Nature 2018

Language

en

File Format

application/pdf

Published Version

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