气候变化领域集成服务门户(CCPortal): Investigation and amelioration of long-term instrumental drifts in water vapor and nitrous oxide measurements from the Aura Microwave Limb Sounder (MLS) and their implications for studies of variability and trends

CCPortal

DOI	10.5194/acp-21-15409-2021
	Investigation and amelioration of long-term instrumental drifts in water vapor and nitrous oxide measurements from the Aura Microwave Limb Sounder (MLS) and their implications for studies of variability and trends
	Livesey N.J.; Read W.G.; Froidevaux L.; Lambert A.; Santee M.L.; Schwartz M.J.; Millán L.F.; Jarnot R.F.; Wagner P.A.; Hurst D.F.; Walker K.A.; Sheese P.E.; Nedoluha G.E.
发表日期	2021
ISSN	1680-7316
起始页码	15409
结束页码	15430
卷号	21 期号:20
英文摘要	The Microwave Limb Sounder (MLS), launched on NASA's Aura spacecraft in 2004, measures vertical profiles of the abundances of key atmospheric species from the upper troposphere to the mesosphere with daily near-global coverage. We review the first 15 years of the record of H2O and N2O measurements from the MLS 190gGHz subsystem (along with other 190gGHz information), with a focus on their long-term stability, largely based on comparisons with measurements from other sensors. These comparisons generally show signs of an increasing drift in the MLS "version 4"(v4) H2O record starting around 2010. Specifically, comparisons with v4.1 measurements from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) indicate a g1/4g2g%-3g% per decade drift over much of the stratosphere, increasing to as much as g1/4g7g% per decade around 46ghPa. Larger drifts, of around 7g%-11g% per decade, are seen in comparisons to balloon-borne frost point hygrometer measurements in the lower stratosphere. Microphysical calculations considering the formation of polar stratospheric clouds in the Antarctic winter stratosphere corroborate a drift in MLS v4 water vapor measurements in that region and season. In contrast, comparisons with the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on NASA's Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) mission, and with ground-based Water Vapor Millimeter-wave Spectrometer (WVMS) instruments, do not show statistically significant drifts. However, the uncertainty in these comparisons is large enough to encompass most of the drifts identified in other comparisons. In parallel, the MLS v4 N2O product is shown to be generally decreasing over the same period (when an increase in stratospheric N2O is expected, reflecting a secular growth in emissions), with a more pronounced drift in the lower stratosphere than that found for H2O. Comparisons to ACE-FTS and to MLS N2O observations in a different spectral region, with the latter available from 2004 to 2013, indicate an altitude-dependent drift, growing from 5g% per decade or less in the mid-stratosphere to as much as 15g% per decade in the lower stratosphere. Detailed investigations of the behavior of the MLS 190gGHz subsystem reveal a drift in its "sideband fraction"(the relative sensitivity of the 190gGHz receiver to the two different parts of the microwave spectrum that it observes). Our studies indicate that sideband fraction drift accounts for much of the observed changes in the MLS H2O product and some portion of the changes seen in N2O. The 190gGHz sideband fraction drift has been corrected in the new "version 5"(v5) MLS algorithms, which have now been used to reprocess the entire MLS record. As a result of this correction, the MLS v5 H2O record shows no statistically significant drifts compared to ACE-FTS. However, statistically significant drifts remain between MLS v5 and frost point measurements, although they are reduced. Drifts in v5 N2O are about half the size of those in v4 but remain statistically significant. Scientists are advised to use MLS v5 data in all future studies. Quantification of interregional and seasonal to annual changes in MLS H2O and N2O will not be affected by the drift. However, caution is advised in studies using the MLS record to examine long-term (multiyear) variability and trends in either of these species, especially N2O; such studies should only be undertaken in consultation with the MLS team. Importantly, this drift does not affect any of the MLS observations made in other spectral regions such as O3, HCl, CO, ClO, or temperature. © Copyright:
语种	英语
scopus关键词	cloud microphysics; microwave limb sounder; nitrous oxide; stratosphere; trend analysis; vertical profile; water vapor
来源期刊	ATMOSPHERIC CHEMISTRY AND PHYSICS
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/246500
作者单位	Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States; Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, United States; NOAA Global Monitoring Laboratory, Boulder, CO, United States; Department of Physics, University of Toronto, Ontario, Canada; Remote Sensing Division, Naval Research Laboratory, Washington, DC, United States
推荐引用方式 GB/T 7714	Livesey N.J.,Read W.G.,Froidevaux L.,et al. Investigation and amelioration of long-term instrumental drifts in water vapor and nitrous oxide measurements from the Aura Microwave Limb Sounder (MLS) and their implications for studies of variability and trends[J],2021,21(20).
APA	Livesey N.J..,Read W.G..,Froidevaux L..,Lambert A..,Santee M.L..,...&Nedoluha G.E..(2021).Investigation and amelioration of long-term instrumental drifts in water vapor and nitrous oxide measurements from the Aura Microwave Limb Sounder (MLS) and their implications for studies of variability and trends.ATMOSPHERIC CHEMISTRY AND PHYSICS,21(20).
MLA	Livesey N.J.,et al."Investigation and amelioration of long-term instrumental drifts in water vapor and nitrous oxide measurements from the Aura Microwave Limb Sounder (MLS) and their implications for studies of variability and trends".ATMOSPHERIC CHEMISTRY AND PHYSICS 21.20(2021).