55°S, 175.4°W) erupted twice, sending material high into the stratosphere. The first volcanic plume on 13 January reached an altitude between 18 and 20 km. On 15 January, a second and more powerful series of explosions started at 4:10 UTC and lasted 11 hr, generating airborne shockwaves and oceanic tsunami waves that traveled around the globe (https://www.nesdis. noaa.gov/news/the-hunga-tonga-hunga-haapai-eruption-multi-hazard-event). The eruption lofted material high in the upper stratosphere, reaching an altitude of 55-58 km (Carr et al., 2022;Proud et al., 2022), the highest observed by space-based measurements, creating an umbrella cloud with radius ∼ 500 km. Until this year, the 1991 eruption of Mount Pinatubo, Philippines, had the highest altitude volcanic injection recorded in the satellite era, which reached 40 km (Holasek et al., 1996). It is unlikely that this eruption will have significant aerosol-driven climate effects because of the relatively low SO 2 injection, 400,000 tonnes compared to 20 million tonnes for Pinatubo (Witze, 2022). Millán et al. (2022 estimated that this eruption injected 146 Tg (1 Tg = 1 million tonnes) of water into the stratosphere and predicted that it would result in surface warming rather than surface cooling expected from the sulfate aerosol alone. Thus, because of the extraordinary nature of the eruption, it is essential that we monitor the initial impact and transport of the volcanic plume as it circulates the globe to understand the long-term effect of this eruption. We expect it to influence Earth's radiative balance and affect the chemical and dynamical processes related to ozone destruction in the stratosphere.

Abstract. The OMPS Limb Profiler (LP) instrument is designed to provide high-vertical-resolution ozone and aerosol profiles from measurements of the scattered solar radiation in the 290–1000 nm spectral range. It collected its first Earth limb measurement on 10 January 2012 and continues to provide daily global measurements of ozone and aerosol profiles from the cloud top up to 60 and 40 km, respectively. The relatively high vertical and spatial sampling allow detection and tracking of sporadic events when aerosol particles are injected into the stratosphere, such as volcanic eruptions or pyrocumulonimbus (PyroCb) events. In this paper we discuss the newly released Version 2.0 OMPS multi-wavelength aerosol extinction coefficient retrieval algorithm. The algorithm now produces aerosol extinction profiles at 510, 600, 674, 745, 869 and 997 nm wavelengths. The OMPS LP Version 2.0 data products are compared to the SAGE III/ISS, OSIRIS and CALIPSO missions and shown to be of good quality and suitable for scientific studies. The comparison shows significant improvements in the OMPS LP retrieval performance in the Southern Hemisphere (SH) and at lower altitudes. These improvements arise from use of the longer wavelengths, in contrast with the V1.0 and V1.5 OMPS aerosol retrieval algorithms, which used radiances only at 675 nm and therefore had limited sensitivity in those regions. In particular, the extinction coefficients at 745, 869 and 997 nm are shown to be the most accurate, with relative accuracies and precisions close to 10 % and 15 %, respectively, while the 675 nm relative accuracy and precision are on the order of 20 %. The 510 nm extinction coefficient is shown to have limited accuracy in the SH and is only recommended for use between 20–24 km and only in the Northern Hemisphere. The V2.0 retrieval algorithm has been applied to the complete set of OMPS LP measurements, and the new dataset is publicly available.

No abstract

[1] This study compares the limb scattered radiances calculated by six radiative transfer models for a variety of viewing conditions. Atmospheres that include molecular scattering, aerosol scattering, and ozone absorption are considered. All models treat single scattering accurately in full spherical geometry. Two ''approximate spherical'' models (CDI and LIMBTRAN) rely on the plane-parallel atmosphere approximation to calculate the diffuse radiance field; the remaining four ''spherical'' models (Siro, MCC++, GSLS, and CDIPI) treat multiple scattering in a spherical atmosphere. Only three of the models (Siro, MCC++, and GSLS) have vector treatment with polarization. A brief comparison of vector radiances with the limb scattered radiances measured by the SOLSE and LORE instruments demonstrates agreement usually within 15% and always within 30%. The inclusion of polarization appears to have little effect on the level of agreement among the models (which agree to within 2% for this sample case). A more general comparison among calculated scalar radiances follows, including four solar zenith angles (20°, 60°, 80°, and 90°), three relative azimuth angles (20°, 90°, and 160°), and two surface albedos (0 and 0.95). The single scattered radiances agree to within 1% for almost every case. Comparisons of the total radiance show larger differences, with 2-4% spread among the results of the spherical models. The approximate spherical models show a positive radiance difference relative to the other models that increases with tangent height, reaching as much as 8% at 60 km. The rule used to divide the model atmosphere into discrete layers is shown to affect the calculated radiance, causing a height-dependent difference of up to 1% for 1 km layer thickness.