Engineering topics

G Taha

Publications and source records attributed to G Taha.

5 records

NASA NTRS2024

Evolution of the Climate Forcing During the Two Years after the Hunga Tonga-Hunga Ha’apai Eruption

We calculate the climate forcing for the 2 ys after the 15 January 2022, Hunga Tonga-Hunga Ha'apai (Hunga) eruption. We use satellite observations of stratospheric aerosols, trace gases and temperatures to compute the tropopause radiative flux changes relative to climatology. Overall, the net downward radiative flux decreased compared to climatology. The Hunga stratospheric water vapor anomaly initially increases the downward infrared radiative flux, but this forcing diminishes as the anomaly disperses. The Hunga aerosols cause a solar flux reduction that dominates the net flux change over most of the 2 yrs period. Hunga induced temperature changes produce a decrease in downward long-wave flux. Hunga induced ozone reduction increases the short-wave downward flux creating small sub-tropical increase in total flux from mid-2022 to 2023. By the end of 2023, most of the Hunga induced radiative forcing changes have disappeared. There is some disagreement in the satellite measured stratospheric aerosol optical depth (SAOD) observations which we view as a measure of the uncertainty; however, the SAOD uncertainty does not alter our conclusion that, overall, aerosols dominate the radiative flux changes.

M R Schoeberl↗

NASA NTRS2023

The Cross Equatorial Transport of the Hunga Tonga-Hunga Ha'apai Eruption Plume

On 15 January 2022, the Hunga Tonga-Hunga Ha'apai (HT) eruption injected SO 2 and water into the middle stratosphere. Shortly after the eruption, the water vapor anomaly moved northward toward and across the equator. This northward movement appears to be due to equatorial Rossby waves forced by the excessive infrared water vapor cooling. Following the early eruption stage, persistent mid-stratospheric water vapor and aerosol layers were mostly confined to Southern Hemisphere tropics (Eq. to 30°S). However, during the spring of 2022, the westerly phase of the tropical quasi-biennial oscillation (QBO) descended through the tropics. The HT water vapor and aerosol anomalies were observed to again move across the equator coincident with the shift in the Brewer-Dobson circulation and the descent of the QBO shear zone.

water↗

NASA NTRS2022

Analysis and Impact of the Hunga Tonga-Hunga Ha’apai Stratospheric Water Vapor Plume

On Jan. 15, 2022, the Hunga Tonga-Hunga Ha’apai eruption injected SO2 and H2O into the 31 middle stratosphere. The eruption produced a persistent mid-stratospheric sulfate aerosol and H2O layer mostly confined to Southern Hemisphere (SH) tropics (Eq. to 30°S). These layers are still present in the tropics 5 ½ months after the eruption. The SH tropical confinement is simulated using a trajectory model. Measurements following the eruption show that the H2O layer is slowly rising while the aerosol layer is descending. The H2O layer’s upward movement is consistent with the residual vertical velocity. Gravitationally settling explains the descent of the aerosol layer. A -4K temperature anomaly coincident with the H2O enhancement is observed and is caused by thermal adjustment to the additional H2O IR cooling. A simple model of volcanic water injection at the time of the eruption simulates the observed vertical distribution H2O.

Atmospheric science↗

NASA NTRS2022

Tracking the 2022 Hunga Tonga-Hunga Ha'Apai Aerosol Cloud in the Upper and Middle Stratosphere Using Space-Based Observations

On 15 January 2022, the submarine Hunga Tonga volcanic eruption lofted materials high into the upper stratosphere, reaching a record-breaking altitude of ~58 km, unprecedented in the satellite observations era. Within two weeks, the bulk of the injected material circulated the globe between 20 – 30 km altitude, as observed by satellite instruments. We estimate that the stratospheric aerosol optical depth (sAOD) is the largest since the Pinatubo eruption and is at least twice as great as the sAOD after the 2015 Calbubo eruption despite the similar SO 2 injection from that eruption. We use space-based observations to monitor the Hunga-Tonga volcanic plume evolution and transport at different altitudes as it circulates the globe. While the main aerosol layer remains trapped in the tropical pipe, small parts have already made it to both the northern and southern hemisphere poles by April, which is almost certain to influence this year's ozone hole.

Atmospheric science↗

NASA NTRSDate not supplied

TPSAS-NF1676L-32668-DND

The Stratospheric Aerosol and Gas Experiment (SAGE) III is a solar occultation instrument installed on the International Space Station (ISS) that has been providing vertically resolved measurements of aerosol extinction, ozone concentrations, and other trace gases. With a legacy going back to the late 1970s, SAGE ozone measurements have been a vital contributor to international ozone assessments and analyses on stratospheric ozone trends. As the newest SAGE instrument, SAGE III/ISS will continue to provide high precision profiles of ozone that will help determine if the Montreal Protocol has been successful in enabling the recovery of the ozone layer. However, as is a necessary step for all new instruments, a rigorous validation of the data quality is required to determine if the data is sufficient for incorporation into trend analyses. Herein we discuss an initial evaluation of the data quality of vertical profiles of ozone with a focus on internal consistency for the first validation version (v5.1) derived from SAGE III/ISS measurements.

R Damadeo↗