Evaluation of the performances of two rebs net radiometer designs during Nimex at a tropical site in Ile-Ife, Nigeria
In this study, the performances of two types of Radiation Energy Balance Systems (REBS) net radiometers, a domed (model Q-7.1) and domeless (model NR-LITE) against a reference, four-component net radiometer (model NR01), are evaluated during the conduct of Nigeria Micrometeorological Experiment (NIMEX) held between May 27 and June 12, 2013 at a tropical location in Ile-Ife, Nigeria. During the daytime, net radiation measurements made by NR-LITE and Q-7.1 showed good agreements with NR01, with coefficient of determination for both > 0.90. The values of the mean and standard deviation for daytime net radiation as measured by NR01, NR-LITE and Q-7.1 were 257.7 ± 174.7 W m2 , 179.6 ± 129.3 W m2 and 240.6 ± 153.1 W m2 , respectively. At nighttime, NR-LITE net radiometer responded to longwave radiation better than Q-7.1. Adjustments made by linear regression of NR-LITE and Q-7.1 datasets with NR01 produced better fit. Though costs of the two REBS type net radiometers are comparatively the same, Q-7.1 performed better than NRLITE. However, for long-term operation, the Q-7.1 type requires periodic (every 2-3 months) changing of the plastic domes due to ageing and cracking, unlike the NR-LITE. So, the NR-LITE is a preferred option to be adopted by the Weather Services in West African countries for routine measurements of net radiation because it does not require periodic changing of the plastic domes.
Keywords: Net radiation; REBS net radiometers; 4-component net radiometer; tropical location.