Assessment of GNSS zenith tropospheric delay responses to atmospheric variables derived from ERA5 data over Nigeria

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Table 5 Coefficients and performance evaluations of LRM for fitting ERA5-AWVC and GNSS-ZWD data

GNSS stations	ERA5-AWVC data	Model coefficients (with 95% confidence bounds)		Goodness of fit		Degree of freedom (DF)\(n = 2\)
		\(a_{1}\)	\(a_{2}\)	\(R^{2}\)	RMS (mm)
ABUZ	RH	2.178 ± 0.028	76.18 ± 1.72	0.6553	46.9539	12,088
	SH	12,550.0 ± 120	50.02 ± 1.485	0.7838	37.1837
	DPT	7.708 ± 0.077	− 2022 ± 22	0.7614	39.0678
	PWV	5.87 ± 0.0275	13.59 ± 0.905	0.9361	20.2188
BJCO	RH	3.295 ± 0.07	22.14 ± 6.01	0.2554	46.5323	24,687
	SH	10,970.0 ± 350	109.2 ± 6.25	0.1326	50.2251
	DPT	11.42 ± 0.42	− 3089 ± 125	0.1027	51.0816
	PWV	6.149 ± 0.0275	− 3.259 ± 1.386	0.8865	18.1709
BKFP	RH	2.889 ± 0.029	82.47 ± 1.355	0.7097	48.8334	15,488
	SH	13,360.0 ± 90	59.87 ± 1.075	0.8408	36.1681
	DPT	7.834 ± 0.062	− 2047 ± 18	0.7972	40.8157
	PWV	5.757 ± 0.0205	16.26 ± 0.705	0.9517	19.9201
FUTY	RH	3.07 ± 0.0315	86.52 ± 1.66	0.6950	52.8728	16,164
	SH	15,840.0 ± 105	46.59 ± 1.325	0.8457	37.6068
	DPT	10.25 ± 0.075	− 2729 ± 21.5	0.8183	40.8057
	PWV	5.977 ± 0.024	14.76 ± 0.95	0.9343	24.5464
OSGF	RH	2.315 ± 0.04	88.32 ± 2.48	0.6856	42.5332	5866
	SH	14,460.0 ± 200	39.97 ± 2.635	0.7716	36.2556
	DPT	9.933 ± 0.1765	− 2665 ± 51	0.6765	43.1457
	PWV	6.082 ± 0.0445	6.51 ± 1.622	0.9252	20.7529
UNEC	RH	1.807 ± 0.0455	157.4 ± 3.5	0.3599	51.1786	10,986
	SH	14,630.0 ± 280	55.42 ± 4.575	0.4910	45.6383
	DPT	10.76 ± 0.215	− 2882 ± 64	0.4625	46.8961
	PWV	6.141 ± 0.0415	3.304 ± 2.0015	0.8834	21.8449
Average	RH	2.5923 ± 0.0407	85.5050 ± 2.7875	0.5602	48.1507
	SH	13,635 ± 190.835	60.17833 ± 2.89084	0.6442	40.5129
	DPT	9.6508 ± 0.1709	− 2572.33 ± 50.25	0.6031	43.6354
	PWV	5.9960 ± 0.0309	8.5275 ± 1.2616	0.9195	20.9090