Estimation and Correlation of Surface Water Vapour Density in Benin, Nigeria
M. I. Iliyasu
Department of Science Laboratory Technology, Physics Unit, Ummaru Ali Shinkafi Polytechnic Sokoto, Nigeria.
D. O. Akpootu *
Department of Physics, Usmanu Danfodiyo University, Sokoto, Nigeria.
M. Momoh
Department of Physics, Usmanu Danfodiyo University, Sokoto, Nigeria.
Z. Abdullahi
Department of Physics, Adamu Augie College of Education, Kebbi State, Nigeria.
A. Yusuf
Department of Science Education, Ibrahim Badamasi Babangida University, Lapai, Nigeria.
N. Muhammad
Department of Physical and Health Education, Shehu Shagari College of Education Sokoto, Nigeria.
S. A. Sidi
Department of Mathematics and Statistics, Ummaru Ali Shinkafi Polytechnic Sokoto, Nigeria.
S. Aruna
Department of Physics, Usmanu Danfodiyo University, Sokoto, Nigeria.
M. Umar
Department of Physics, Usmanu Danfodiyo University, Sokoto, Nigeria.
M. Y. Sani
Department of Science Laboratory Technology, Biology Unit, Ummaru Ali Shinkafi Polytechnic Sokoto, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
The present study investigated the monthly average daily mean temperature, relative humidity, surface pressure, cloud cover, and sunshine hours associated with monthly variations in surface water vapour density (SWVD) for the period extending from 1979 to 2016 for Benin (Latitude 6.320N, Longitude 5.100E). The daily variation of SWVD for the dry season (November to March) and rainy season (April to October) for the year 2014 was examined. Statistical indices of coefficient of determination (R2), mean bias error (MBE), root mean square error (RMSE), mean percentage error (MPE), Nash-Sutcliffe equation (NSE), and index of agreement (IA) were used to compare and evaluate the generated two variable SWVD-based models. The findings revealed that the level of SWVD varied throughout the investigation period on each day of the month. The SWVD is higher during the wet season than it is during the dry season, based to the monthly average daily values. The average SWVD was found to be at its highest point in the month of August during the rainy season and its lowest point in the month of December during the dry season (21.1448 gm-3). The greatest amount of SWVD was observed on 23rd May, 2014 with 27.5731gm-3 and the lowest on 26th December, 2014 with 9.6567 gm-3. Pressure and precipitable water vapour are related to each other using a multivariate correlation regression model that was constructed with R2 = 100%, MBE = -0.0204 gm-3, RMSE = 0.0206 gm-3, MPE = 0.1105 %, NSE = 99.9897% and IA = 99.9974% was better appropriate for SWVD estimation with the best fitting and therefore can be used for estimating SWVD in Benin.
Keywords: Correlation models, dry season, ECMWF, rainy season, SWVD