Recent observations show anomalously high methane growth in 2020, which has been attributed to increased wetland emissions and decreased OH from lower COVID-19 nitrogen oxide (NO x ) emissions. NO x is not the only species that affects OH—isoprene, the most significant non-methane hydrocarbon by total emissions, is oxidized by OH, which can deplete OH during periods of high emissions. Using satellite isoprene retrievals from the Cross-track infrared sounder (CrIS), we find anomalously high isoprene columns during 2020, coincident with high methane growth. Isoprene's oxidation produces carbon monoxide, which can be transported over longer distances and decrease OH outside of isoprene source regions. Elevated isoprene concentrations may have contributed 13% (bounds: 10%–28%) of 2020's methane growth if we assume no change in NO x emissions in 2020. Since COVID-19 decreased anthropogenic NO x emissions, this estimate is an upper-limit and may depend on whether isoprene or NO emissions drove this isoprene anomaly.

The Madden Julian Oscillation (MJO) consists of a tropical convective region that propagates eastward through the Indo-Pacific warm pool. Decadal climate variability alters sea surface temperature patterns, affecting the MJO's basic state. This investigation examines the impact of projected SST and moisture pattern changes over the 21st Century on MJO precipitation and zonal wind amplitude changes in 80 members of the Community Earth System Model 2 Large Ensemble in the SSP370 radiative forcing scenario, each with its unique representation of decadal variability. Ensemble members with strongest MJO precipitation change in a given 20-year period have a more El Niño-like east Pacific warming pattern. MJO amplitude increases for east Pacific warming because of a strengthened meridional moisture gradient that supports MJO eastward propagation. A stronger vertical moisture gradient also exists for ensemble members with preferential east Pacific warming, which supports a stronger MJO under moisture mode theory.

We present the first sulfur dioxide (SO2) retrievals from Tropospheric Emissions: Monitoring of Pollution (TEMPO), the first geostationary atmospheric composition sensor to cover North America, along with some potential applications of TEMPO SO2 data. We show that high resolution (∼10 km2) TEMPO measurements can be used to produce good quality SO2 retrievals with relatively small noise and biases. We demonstrate that hourly TEMPO data are useful for monitoring volcanic hazards, by providing frequent updates on the plume location and additional information on the plume height or winds. With the large number of measurements from TEMPO, it is also feasible to monitor diurnal changes in SO2 for relatively large sources such as the Cantarell oil field. We also show that high-cadence TEMPO measurements allow estimates of SO2 degassing from Popocatépetl volcano on sub-daily timescales. Overall, our results suggest that TEMPO can significantly enhance space-based SO2 detection and monitoring over North America.

Accurate observations of maritime low clouds are important for air and sea transportation, understanding boundary layer processes, and measuring Earth's radiation budget. The nighttime maritime low cloud extent is often determined in meteorological satellite imagery using the brightness-temperature difference between the longwave infrared (e.g., 11 μm) and shortwave infrared (e.g., 3.9 μm) window bands. However, this nighttime low-cloud detection has been previously shown to be contaminated by clear-sky false low cloud (FLC) signals associated with warm and moist air over cold regions of water. We use numerical model data and radiative transfer to quantitatively estimate the global extent and intensity of FLC signals. Insights from this research can help forecasters and researchers determine which regions and conditions are prone to nighttime FLCs and thus may require either refinement of detection algorithms or independent sensor assessments.

Previous studies have demonstrated that signals originating from the South Pacific can improve the El Niño-Southern Oscillation (ENSO) prediction at various lead times. In this study, it is found that sea surface height anomalies in the off-equatorial South Pacific (SP SSH), potentially improves ENSO prediction with lead times exceeding 9 months. Using linear inverse models, we find that SP SSH anomalies and the associated accumulation of warm water result from continuous easterly winds over the tropical central Pacific that force downwelling Rossby waves in the off-equatorial South Pacific. These downwelling Rossby waves reflect into equatorial downwelling Kelvin waves that propagate into the central and eastern Pacific, ultimately leading to an El Niño event in the following winter.

Observations from the Juno spacecraft near the M-shells of the Galilean moons have identified alternating enhancements and reductions of particle fluxes at discrete energies. These banded structures were previously attributed to bounce resonance between particles and standing Alfvén waves generated by moon-magnetospheric interactions. Here, we show that this explanation is inconsistent with key observational features, and propose an alternative interpretation: the bands are remote signatures of particle absorption at the moons. In this scenario, whether a particle encounters the moon before reaching Juno depends on the number of bounce cycles it undergoes within a fixed drift segment determined by the moon-spacecraft separation. Therefore, the absorption bands are expected to appear at discrete, equally-spaced velocities. This is largely consistent with the observations, though discrepancies remain, possibly due to spacecraft charging and/or finite data resolution. This finding improves our understanding of moon-plasma interactions and may help constrain Jovian magnetospheric models.