Analysis of the Relationship between Surface Wind Characteristics during the Preceding Hot Season and Early Wet Rainy Seasons in Iraq

Abstract

This study investigates the potential relationship between surface wind activity and its characteristics, particularly speed and direction, with the likelihood of the onset of an early wet rainy season (wet autumn) in Iraq. Precipitation data from selected climatic stations were statistically processed to identify wet seasons and early rainy seasons based on precipitation amounts, general averages, and their relation to the standard deviation of annual totals at each station. Subsequently, a matching process was conducted between wet seasons and wet autumns, revealing a high correspondence ranging from 60% to 90% in the recurrence of wet seasons associated with wet autumns. This indicates that wet seasons are generally characterized by an early onset of rainfall.

The results also showed a strong positive correlation (up to 0.70) between wind activity during the preceding hot season and the following wet season. Two models were used for comparison and analysis: a dry season (2008–2009) and a wet season with early rainfall (2018–2019). Hourly wind direction and speed data at 10 meters’ height were processed, revealing that most stations recorded relatively higher wind speed averages during the hot season preceding the wet season compared to the hot season preceding the dry season. Wind speeds were analyzed and classified according to the Beaufort scale and represented in categories using the (WRPLOT View – Freeware) program, which analyzes hourly wind speed and direction data for the selected months. The analysis showed an increase in wind speed categories near or above 7 m/s during wet seasons, with clear recurrence, in contrast to the hot season preceding the dry 2008–2009 season.