Surface Temperature Trend Estimation over 12 Sites in Guinea Using 57 Years of Ground-Based Data

Trend-Run model was performed to estimate the trend in surface temperatures recorded at 12 sites in Guinea from 1960 to 2016 and to examine the contribution of each climate forcing. The coefficient of determination (R2) calculated varies between 0.60 and 0.90, it provides total information about the simulation capability of the model. The decadal trend values also calculated show an upward trend (between 0.04 °C ± 0.06 °C decade−1 and 0.21 °C ± 0.06 °C decade−1). In addition, forcings’ contributions were quantified, and the annual oscillation (AO) contribution is higher for most of the stations, followed by semiannual oscillation (SAO). Among the forcings, the tropical Northern Atlantic (TNA) contribution is greater than that of the sunspot number (SSN), Niño3.4 and Atlantic Niño (AN). Moreover, the Mann-Kendall test revealed a positive significant trend for all stations except at the Macenta site. Additionally, with sequential Mann-Kendall test, trend turning points were found only for the stations of Mamou, Koundara and Macenta at different dates. The temperature anomalies depict warming episodes (1970s, 1980s, 1984 and 1990s). Since then, the temperature is consistently increasing over the country. A significant warming has been shown, which might be further investigated using these models with additional contributing factors.

The Effect of Tree Plantations on Moderating Air Temperature in Arafat, Makkah for the Period 2002-2016

Recently many studies have shown that average temperature has increased globally. However, temperature trends vary in different parts of the world due to local geographical, climatic, land usage and various socio-economic factors. This study focuses on temperature trend in Makkah and intends to investigate the effect of vegetations on temperature trend. Temperature trend is analyzed from two meteorological monitoring sties in Arafat and Waly Al-Ahd area for the period 2002-2016. The two sites have demonstrated opposite trends from each other for the above period. In Arafat area temperature has not increased and has rather decreased during the last 15 years (-0.05oC/year). The negative trend in Arafat was more evident since 2009 (-0.21oC/year). In contrast, Waly Al-Ahd area demonstrated positive significant trend (+0.14oC/year). In Arafat area mass tree plantation has taken place during the last couple of decades. Furthermore, Arafat has experienced no urbanization, as it is one of those Holy areas that are reserved for the purpose of Hajj. During the study period greenery in Arafat area has increased significantly since the plantation project was started in 1986. In contrast rapid urbanization, resulting in increase in energy use, road traffic, and change in land usage has led to temperature rise in most parts of the Makkah City including Waly Al-Ahd. This study shows how local factors, such as vegetation can affect local temperature trend. Arafat tree plantation project can be used as a good example to encourage more tree plantation in the Holy sites to cope with the increasing heat in the coming decades. Trees also provide shelter from the blazing sun, especially during Hajj season in Makkah, where temperature reaches as high as 50oC in summer months and probably will continue to rise in the future.

Natural regime of streamflow trends in Macedonia

This study investigates the annual and seasonal trends of minimum, mean and maximum streamflow, analyzed on 13 gauges/streams with natural regime, predominantly mountainous and homogeneously distributed in the studied area. The varying period of at least 40 years is used in the analysis. After the pre-whitening TFPW method was applied, the Mann-Kendall and Sen’s slope tests were used for trend testing. The analysis detects significant decreasing trends in the country (according to a = 0.1 significance level). In general, the streamflow shows levels of decrease in almost all streams with lower or higher magnitude (from 0.1 to 0.01). The results provide a unique assessment of streamflow trends in the country and the current findings are consistent with those in other regions of Europe, especially in Southern Europe. Significant trends of decrease have been found in each of the 13 streamflow gauges throughout Macedonia without a single positive significant trend. The test confirmed the general decreasing streamflow trend in the country; even the stations without any significant decreasing results are generally heading downward.