Erratum: Uranus in Northern Mid-spring: Persistent atmospheric temperatures and circulations inferred from thermal imaging (Astronomical Journal (2020) 159 (45) DOI: 10.3847/1538-3881/ab5dc7)

Due to a flaw in our generation of ranked absorption coefficient (k) distributions from line-by-line calculations used to model the gaseous opacity of acetylene, there was a systematic error in the retrieved acetylene abundances and stratospheric temperatures as published. This flaw resulted from insufficient sampling of the narrow Doppler-broadened lines at low pressures in our underlying line-by-line model, prior to re-organization for generating k distributions. While the measured brightness temperatures, modeled emissions, trends with latitude and time, and conclusions drawn therefrom remain unchanged, the precise values of retrieved acetylene and temperatures have changed. The revised values are now provided in Figure 1, correcting Figures 10 and 11 of the original manuscript. The numbers and evaluations provided here should supersede all equivalent values reported in Sections 4.3 and 5.2 of the original text. The revised acetylene abundances are roughly one-third of our previously reported values. Significantly, when integrated over the entire disk, these acetylene abundances are now consistent with the nominal 1D acetylene profile inferred from Spitzer disk-integrated observations (Orton et al. 2014b), despite the abundances spanning a factor of ~10 difference between the equatorial minimum and midlatitude maximum. The images provide little constraint on the vertical distribution, but by scaling of the nominal vertical profile of acetylene (Orton et al. 2014b) to reproduce the observed radiances, we find this corresponds to peak volume mixing ratios of 9.5+4.7/-3.5×10-7 in 2009 and 9.3+7.1/-4.7×10-7 in 2018 at 43 N latitude at 0.2mbar (roughly where the acetylene VMR and the contribution functions reach their maximum, see Figure 1). Minimum values drop to 9.4+2.6/-2.4×10-8 and 7.7+3.5/-2.9×10-8 near the equator in 2009 and 2018, respectively. All retrieved values at 0.2mbar are 20%-25% greater if, instead of scaling the prior of (Orton et al. 2014b), the acetylene profiles are constrained to only vary near the peak of the contribution function. The retrieved maximum mixing ratios are now roughly consistent with values predicted by the photochemical seasonal models of Moses et al. (2018) at this altitude, although their equatorial values and latitudinal variation are significantly different. Similarly, if variation in the stratospheric emission is attributed to latitudinal temperature gradients, we find a range of nearly 16 K at 0.2 mbar, ranging from a mid-latitude maximum of 121 K (121.2 +2.4/-2.8 K in 2009 and 121.3 +3.4/-4.4 K in 2018) to an equatorial minimum of ~106 K (106.7 +1.6/-2.0 K in 2009 and 105.7 +2.3/-2.8 K in 2018) with errors again dominated by systematic uncertainties in the flux calibration. As a consequence of these changes, the computed vertical velocity difference (?w) in Section 5.2 would increase to ~3.5?×?10-5?m?s-1-six times greater in magnitude than what Flasar et al. (1987) computed for the tropospheric vertical velocity. {figure presented}. Finally, we have corrected the 13.0 μ m contribution functions and acetylene profile depicted in Figure 14 of the Appendix. The contribution functions changed slightly as a result of the revised k-tables, while the VMR axis was originally scaled incorrectly. The original caption also erroneously equated the acetylene profiles of Orton et al. (2014b) and Moses et al. (2018); the latter profile is has a significantly greater VMR at 0.2 mbar.