In this work, analysis of the variability of total column ozone (TCO) over the Kingdom of Saudi Arabia (KSA) has been conducted during the 1979–2020 period based on the ECMWF-ERA5 dataset. It is found that the highest values of TCO appear in the spring and winter months especially over north KSA, while the lowest values of TCO occur in the autumn months. The highest values of the coefficient of variation (COV) for TCO occur in winter and spring as they gradually decrease southward, while the lowest COV values appear in summer and autumn. The Mann–Kendall test indicates that the positive trend values are dominant for the annual and seasonal TCO values over KSA, and they gradually increase southward. The study of long-term variability of annual TCO at KSA stations shows negative trend values are the dominant behavior during the 1979–2004 period, while positive trend values are the dominant behavior during the 2004–2020 period. The Mann–Whitney test assessed the abrupt change of the annual TCO time series at 28 stations in KSA and confirmed that there is an abrupt change towards increasing values around 2000, 2005, and 2014. The climatological monthly mean of the ozone mass mixing ratio (OMR) is studied at three stations representing the north, middle, and south of KSA. The highest values of OMR are found in the layer between 20 and 4 hPa with the maximum in summer and early autumn, while the lowest values are found below 100 hPa.

Ozone variation during a case of cyclogenesis

This paper aimed to study the variation in the total ozone column amount (TOC) during the life cycle of the tropical cyclone (TC) that occurred over the northwest Indian Ocean in October 2008. The characteristics of TC tilts with vertically varying background flows were inspected preliminarily also in the current study. The vertical wind shear (VWS) was estimated as one of the most important dynamical parameters of the large-scale environment related to TC formation, structure, and intensity changes. It is found that the magnitude of VWS increased during the growth period, meanwhile, VWS weakened during the decay period. Anomalies of daily TOC have been calculated and found related to the strengthening of the cyclonic system. During the development of the tropical cyclone, an outflow develops in the upper levels with high velocities that can extend beyond tropopause up to the lower stratosphere. As a result, the lowest value of TOC during the tropical cyclone was owing to a large amount of injected water vapor from the troposphere into the stratosphere through the convection processes which was mostly photo-dissociated into OH plus atomic O by deep solar radiation in the upper and lower stratosphere leading to severe reduction of stratospheric ozone

The variability of ozone over Egypt has been studied in this work. Higher values of coefficient of variation (COV) at eight stations occur at winter while lowest values occur at summer. The COV is function of latitude in annual, winter and spring where it decreases gradually from the north to south of Egypt. The trend analysis of ozone over the eight stations indicates negative trends over northern stations for both annual and seasonal time series with the greatest one at winter. The horizontal distribution of ozone trend values is negative over all Egypt in winter while it positive over middle and south Egypt in the other seasons. The long-term variability of the behavior of the annual ozone shows positive trend values in ozone are the dominant features during the period 1979- 1989 at the most stations. Negative trend values in ozone are the dominant features during the period 1990- 2014 at all stations. The Mann–Kendall test confirms that there is an abrupt change towards decreasing of ozone occurs in 1981, 1984, 2012, 1999, 2000, 1998 and 2010, while a change towards increasing of ozone appears in 2006, 2014, 1993 and 1989.

The COVID-19 pandemic disease affects us all and get the world into an enormous crisis. Temperature is an important factor in infectivity reduction of viral disease. The current study screens the probable association between the extreme temperature events and COVID-19 outbreak. The most recent heatwave that hit Egypt in May 2020 selected as a case study. We studied the daily progression and current situation of COVID-19 morbidity in Egypt. The concurrent heatwave was identified and synoptically explained in deep. Considering the incubation-induced lag time between heatwave intensities and COVID-19 confirmed cases, visual interpretation of line graphs discovered an interesting identical connection between the real-time thermal intensities and the 14-day retreated infected cases during the heatwave days. The 5-day heatwave with thermal intensities 6.1–7.8 °C led to a 5-day fall in COVID-19 morbidity. The thermal intensity peak of the heatwave caused the greatest decline in COVID-19 confirmed cases by about onethird. The 2nd order polynomial regression model for the relationship suggested that heatwave intensity of 5.5 °C is the critical thermal threshold at which COVID-19 morbidity begins to be reduced, and 10.7 °C as a threshold of COVID-19 outbreak pause. It is concluded that heatwave of late spring can effectively restrict COVID-19 pandemic outbreak in warm arid environments like Egypt. COVID-19 is also highly expected to be restricted as the temperatures increase with the advance of summer season. It is recommended that lag time resulted from the virus incubation period must be considered in COVID-19 mortality and morbidity researches.

The aim of this work was to study the variation in the total ozone column amount (TOC) during the life cycle of the tropical cyclone (TC) that occurred over the northwest Indian Ocean from 14 to 25 October 2008. This goal was achieved through examining the behavior of the tropical cyclone tilt under vertically varying background flows in association with the cyclone development. Thus, the vertical wind shear (VWS) was estimated as one of the most important dynamical parameters related to TC formation and intensity changes. Moreover, we estimated the variations in the daily values of TOC during the period of cyclone activity. We found that the magnitude of VWS increased during the growth period, and VWS weakened during the decay period. Anomalies of daily TOC were found to reduce steadily before and during the cyclone formation, followed by an increasing trend after the dissipation of cyclone. It was also found that during the development of the tropical cyclone, an outflow developed in the upper levels, having high velocities that extended beyond the tropopause up to the lower stratosphere. As a result, the lowest value of TOC during the tropical cyclone was due to a large amount of injected water vapor from the troposphere into the stratosphere through the convection processes. This was mostly photo-dissociated into OH and atomic O by deep solar radiation in the upper and lower stratosphere, leading to a severe reduction in stratospheric ozone.