Table 3.

Measured NEB wave properties

Date	Latitude (graphic)	Latitude Extent (°)	λ (°)	Velocity, c (m/s)	Phase Speed, c-u (m/s)
1979–06-26 to 1979–07-03	17.1 ± 0.3	2.2 ± 0.2	1.2 ± 0.2	−24.7 ± 5	−5.2 ± 8
2012–09-20	17.2 ± 0.8	2.5 ± 0.2	1.2 ± 0.3	inconclusive
2015–01-19	16.1 ± 0.6	2.4 ± 0.6	1.1 ± 0.1	inconclusive
2016–02-09	16.9 ± 0.4	2.4 ± 0.2	1.1 ± 0.1	−17.5 ± 10	−2.5 ± 10
2016–12-11	16.1 ± 0.1	2.3 ± 0.3	1.1 ± 0.1	inconclusive
2017–01-11	16.5 ± 0.3	2.6 ± 0.5	1.2 ± 0.1	−14.2 ± 10	−4.2 ± 10
2017–02-01	16.5 ± 0.3	2.4 ± 0.3	1.1 ± 0.1	Inconclusive
2017–04-03	16.3 ± 0.2	2.9 ± 0.5	1.2 ± 0.2	−15 ± 15	−3 ± 15
2017–05-19	16.5 ± 0.5	2.4 ± 0.3	1.1 ± 0.1	---
2017–07-11	16.2 ± 0.2	2.8 ± 0.4	1.1 ± 0.1	---
2018–02-06	16.2 ± 0.2	2.8 ± 0.3	1.3 ± 0.2	---
2018–04-01	16.5 ± 0.7	4.3 ± 1.2	1.2 ± 0.2	---
2018–04-16	16.0 ± 0.3	2.5 ± 0.5	1.1 ± 0.1	Inconclusive

Note: Negative phase speeds indicate westward motion. For consistency, wave phase speeds are computed with respect to the zonal wind profiles previously measured for those dates (Simon-Miller and Gierasch 2010 for 1979, Tollefson et al. 2017 for 2016, Johnson et al. 2018 for 2017).