Subscribe Now Subscribe Today
Science Alert
 
Blue
   
Curve Top
Asian Journal of Applied Sciences
  Year: 2017 | Volume: 10 | Issue: 1 | Page No.: 10-17
DOI: 10.3923/ajaps.2017.10.17
 
Facebook Twitter Digg Reddit Linkedin StumbleUpon E-mail

Parameterization of the Downward Long Wave Radiation under Clear-sky Condition in Baghdad, Iraq

Alaa M. AL-Lami, Ali M. AL-Salihi and Yaseen K. AL-Timimi

Abstract:
Objective: The purpose of this study is to evaluate the performance of seven downward long wave radiation models under clear-sky condition and to propose a locally modified equation. Methodology: The observed vapor pressure and air temperature data, downward long wave radiation and the atmospheric parameters were measured within the period, from 1st October, 2014 to 31st September, 2015 at a solar radiation station installed at the experimental site in Baghdad, Iraq. Results: The comparative statistics for the performance of the downward long wave radiation model calculations during day-time and night-time have shown that the parameterizations have the best results compared to the measured data. The locally proposed equation showed errors not greater than 1.1%, in comparison with the measured values, the models were used for estimating the apparent emissivity of the locally calibrated atmosphere. The percentage mean relative error and the root square errors obtained from calibrated equations were equal to 5.9 and 1.4%, 28.3 and 7.3 W m–2 for Idso and Jackson, Sugita and Brutsaert equations, respectively. Conclusion: It was found that the errors obtained basically reduced with the standardization performed and those calculations of the downward long wave radiation with the same output results are far more accurate than those made with the calibrations originally proposed. Finally, the locally examined equation can be used to estimate downward long wave energy, needed as input to most agricultural and hydrological models in some regions of Iraq, where this parameter is not measured.
PDF Fulltext XML References Citation Report Citation
How to cite this article:

Alaa M. AL-Lami, Ali M. AL-Salihi and Yaseen K. AL-Timimi, 2017. Parameterization of the Downward Long Wave Radiation under Clear-sky Condition in Baghdad, Iraq. Asian Journal of Applied Sciences, 10: 10-17.

DOI: 10.3923/ajaps.2017.10.17

URL: https://scialert.net/abstract/?doi=ajaps.2017.10.17

COMMENT ON THIS PAPER
 
 
 

 

 
 
 
 
 
 
 
 
 

 
 
 
 
 
 
 

Curve Bottom