Measurements of Mesospheric Water Vapor From 1992 to 2021 at Three Stations From the Network for the Detection of Atmospheric Composition Change

Abstract

We present ground‐based microwave measurements of mesospheric water vapor made by the Water Vapor Millimeter‐wave Spectrometer (WVMS) instruments since the early 1990s from sites in California, Hawaii, and New Zealand. These measurements are compared with coincident measurements from the Halogen Occultation Experiment, the Aura Microwave Limb Sounder, and Sounding of the Atmosphere using Broadband Emission Radiometry; all of which combine to cover the entire time period of the ground‐based measurements. Comparisons are presented both on ∼weekly timescales in order to better identify discontinuities in the relative differences and on annual timescales in order to better study geophysical variations. The WVMS retrievals shown here are available on the Network for the Detection of Atmospheric Composition Change database. The range of WVMS trends and the differences from the satellite trends, with the latter varying over a range of ∼3%/decade, provide an estimate of how accurately it would be possible to determine multidecadal trends using ground‐based microwave instruments in a postsatellite era. This uncertainty is comparable to the trend in mesospheric water vapor that is expected to have occurred since the early 1990s.

Measurements of Stratospheric Water Vapor at Mauna Loa and the Effect of the Hunga Tonga Eruption

“…The standard WVMS measurement product is retrieved from a ∼1 week integration of the spectrum within ±30 MHz of the H 2 O emission peak at 22 GHz. Results from these retrievals from 1992 to 2021 are presented in Nedoluha et al (2022), where H 2 O vertical profiles are shown from 45 to 80 km. Unlike the standard WVMS retrievals, the retrievals for this study make use of a wider ±160 MHz spectral measurement centered around the H 2 O emission peak at 22 GHz with a much shorter integration period.…”

“…Ground‐based microwave measurements have been made at the Network for the Detection of Atmospheric Composition (NDACC) site at Mauna Loa, Hawaii (19.5°N, 204.4°E) since 1996 by a Water Vapor Millimeter‐wave Spectrometer (WVMS) instrument (Nedoluha et al., 2022). The WVMS instruments are designed primarily for mesospheric (∼50–80 km) H 2 O measurements, but no significant increase in mesospheric water vapor was detected by the WVMS instruments that could be attributed to Hunga Tonga.…”

“…Schoeberl et al (2022) discussed vertical transport of the hydrated layer, and its separation from the aerosol layer, while Coy et al (2022) discussed the response of the stratospheric circulation to the presence of the plume. Initial intrusions of H 2 O into the stratosphere as observed by radiosondes were shown in Vömel et al (2022), Khaykin et al (2022), and Sellitto et al (2022).Ground-based microwave measurements have been made at the Network for the Detection of Atmospheric Composition (NDACC) site at Mauna Loa, Hawaii (19.5°N, 204.4°E) since 1996 by a Water Vapor Millimeter-wave Spectrometer (WVMS) instrument (Nedoluha et al, 2022). The WVMS instruments are designed primarily for mesospheric (∼50-80 km) H 2 O measurements, but no significant increase in mesospheric water vapor was detected by the WVMS instruments that could be attributed to Hunga Tonga.…”

Mesospheric Water Vapor in 2022

“…The standard WVMS measurement product, which will be used in this study, is retrieved from a ∼1 week integration of the spectrum within ±30 MHz of the H 2 O emission peak at 22 GHz. Results from these retrievals from 1992 to 2021 were presented in Nedoluha et al (2022), where H 2 O vertical profiles were shown from 45 to 80 km. The vertical resolution for WVMS measurements at these altitudes is typically ∼16 km (FWHM).…”

“…Results from these retrievals from 1992 to 2021 were presented in Nedoluha et al. (2022), where H 2 O vertical profiles were shown from 45 to 80 km. The vertical resolution for WVMS measurements at these altitudes is typically ∼16 km (FWHM).…”