The role of surface wind on fog occurrence at Jomo Kenyatta international airport, Nairobi, Kenya.

Abstract

Meteorology involve delivery of timely and real weather information as a warning that helps people or establishments exposed to likely weather threats to take precaution that avoids or reduces their exposure to risks. In order to improve on fog forecasting, this study seeks to examine the influence of surface wind on fog occurrence at Jomo Kenyatta International Airport, especially the diurnal and annual wind variation. Few studies have been conducted in this regard. Surface wind is one of the key weather elements that influence a number of weather events. For example at Jomo Kenyatta International Airport and its surrounding, surface wind influences both temporal and spatial distribution of fog. The major problem that can be posed by fog is the closing down of airports and the consequent disruptions that occur such as deviations of airplanes already nearing their terminus. Extensive fog may murky ground features so that pictorial enroute navigation is lessened, but the chief problem is its effect on landing and takeoff. The influence of surface wind on fog occurrence from the year 2011 to 2015 at JKIA was analyzed. The data used in this study was obtained from the Kenya Meteorological department. These data include hourly fog and wind observations from Jomo Kenyatta International Airport. The results shows that high frequency of fog occurrence is associated southerly wind direction, especially during winter months. The months with the highest frequency were June, July and August. Rainy months also registered substantial fog frequencies, unlike dry months. Hourly fog occurrence was frequent in the early morning between 03UTC to 05UTC. The onset of hourly fog was as from 20UTC up to 07UTC the following day. From 08UTC to 20UTC fog occurrence was not registered. Monthly and hourly fog occurrences were both registered with weak wind speeds, of about 6KT and below. The results denote an inverse relation between wind speed and fog occurrence, with an increasing trend towards the 2015 year.