Long-term, high-quality Aura Microwave Limb Sounder (MLS) data enabled research that explains the strong seasonal and regional variations in climatically-important lower stratospheric (LS) trace gases (e.g., O3 and H2O) that are associated with the Madden-Julian Oscillation (MJO) – an eastward moving weather disturbance that traverses the tropics within 30 to 60 days, on average.
Nitrous oxide is a greenhouse gas exhibiting long-term increases in its surface and atmospheric abundance, as a result of emissions from agricultural and industrial sources.
Energetic particle precipitation (EPP) – the flux of charged solar particles into Earth’s upper atmosphere – can drive large nitrogen oxide enhancements.
Convective processes play a major role in controlling the abundances of cloud ice and water vapor in the tropical tropopause layer, which in turn strongly modulate climate. Despite their importance, these processes remain poorly represented in global climate models. Observations of the full diurnal cycle of cloud ice, closely linked to that of convection, are needed for model evaluation and refinement.
Studies associate increases in stratospheric water vapor concentrations with considerable surface warming. This study indicates that convective moisture can be transported by the monsoon circulation and yield significant, large-scale water vapor enhancements.
MLS Observations Show Relation to Overshooting Convection Diagnosed From Colocated Aqua-MODIS Data
Studying the seasonal dependence of stratospheric ozone trends in the past decades helps to understand variations and trends in the ozone layer.
An extraordinary complex of Australian fire-driven pyrocumulonimbus (pyroCb) storms at the end of 2019 (the most recent and largest of three such events in the Aura Microwave Limb Sounder, MLS, record) produced an unprecedented stratospheric plume of fire emissions that circled the globe twice.
Understanding the processes that control stratospheric water vapor, as well as the causes of observed stratospheric humidity variations, is the focus of active scientific research.
In the US, hurricane damage comes at an annual cost of $24 billion, over half the cost of all natural disasters. The National Hurricane Center (NHC) has an impressive record predicting where hurricanes might make landfall. But less successful are predictions of so-called "rapid-intensification" of the strength of landfalling hurricanes.
The Western Pacific is an accessible location that provides rich opportunities for investigating the impact of the Asian summer monsoon on global upper troposphere / lower stratosphere composition, e.g., through aircraft-based research campaigns.
Unusually prolonged cold stratospheric conditions in 2019/2020 have led to record-high chemical ozone loss and thus record-low ozone levels; only 2010/2011 came close. This behavior resembles that seen in the Antarctic, where an ozone "hole" recurs each winter.
An extraordinary complex of Australian fire-driven pyrocumulonimbus (pyroCb) storms at the end of 2019 produced an unprecedented stratospheric plume of fire emissions that circled the globe, rising from 15 to 31 km and persisting for more than two months.
What do long-term observations of ozone profiles from the Microwave Limb Sounder (MLS) aboard the Aura satellite tell us about the drivers of O3 variations near 90 km altitude (the secondary ozone maximum region), notably in relation to the 11-year solar cycle?
Aura Microwave Limb Sounder (MLS) measurements have previously shown that the easterly phase of the QBO is associated with increases in nitrogen in the Antarctic stratosphere.
Aura's MLS observes patterns of stratospheric humidity in the “Tropical Tropopause Layer” .
Aura's MLS observations of Arctic vortex-average chlorine monoxide improve the understanding of stratospheric ozone trends and their uncertainties
This study confirms the important role of monsoon regions in moistening the lower stratosphere in boreal summer using data collected from Aura's Microwave Limb Sounder (MLS) .
Depletion of gas-phase nitric acid observed by Aura's Microwave Limb Sounder (MLS)
Convective processes play a major role in controlling the abundances of cloud ice and water vapor in the tropical tropopause layer, which in turn strongly modulate climate.
Entrainment rate (λ) in convective parameterizations is one of the most sensitive, yet uncertain, parameters affecting climate sensitivity, clouds, precipitation, and trace gas distributions.
The global meridional overturning of mass in the stratosphere, generally known as the Brewer-Dobson circulation (BDC), plays a crucial role in Earth’s climate system by controlling the distributions of atmospheric constituents.
Two major modes of climate variability that affect the stratospheric circulation, and consequently trace gas distributions, are the El Niño–Southern Oscillation (ENSO) and the Quasi-Biennial Oscillation (QBO).
Conclusive verification that stratospheric ozone destruction is lessening as expected in response to international controls on anthropogenic ozone-depleting substances (ODSs) enacted under the Montreal Protocol is one of today’s atmospheric science imperatives, but robust detection of such ozone “recovery” is complicated by large natural variability.
Changes in stratospheric ozone can induce, via atmospheric radiation balance, stratospheric circulation anomalies.
How well do a free-running and “nudged” chemistry climate model reproduce global timeseries of upper atmospheric composition (biases, variability, trends)?
OMI satellite measurements reveal for the first time many key features of ozone variability inside deep convective clouds
OMI satellite measurements identify increases in tropospheric ozone over Saudi Arabia/India/Southeast Asia and other global regions
The interannual variability of tropical lower stratosphere ozone and its connections to sea surface temperatures in the equatorial Pacific are examined using a combination of chemistry climate model simulations, satellite observations, and reanalyses.
In the troposphere, ozone is both a major pollutant and a strong greenhouse gas. Although spaceborne and ground-based observations largely agree on the overall tropospheric ozone loading, estimates of decadal-scale trends vary significantly between datasets.
Variations in stratospheric water vapor are known to have a significant impact on surface climate, yet the processes controlling the long-term evolution of stratospheric humidity remain incompletely understood.
Stratospheric polar processes, such as the potential for ozone loss via heterogeneous chemical reactions, depend critically on temperature. We have assessed the temperature biases of several modern meteorological reanalysis datasets.
How well can the impacts of changes in ozone depleting substances (ODSs) and greenhouse gases (GHGs) on global ozone (O3 ) be detected and distinguished? Aura Microwave Limb Sounder (MLS) Global O3 profiles are used to detect fingerprints of ODS & GHG impacts.
The quasi-biennial oscillation (QBO) consists of alternating easterly (east-to-west) and westerly (west-to-east) directions of the wind in the tropical stratosphere with an average period of 28 months.
Ozone within deep convective clouds is controlled by several factors involving photochemical reactions and transport. Gas-phase photochemical reactions and heterogeneous surface chemical reactions involving ice, water particles, and aerosols inside the clouds all contribute to the distribution and net production and loss of ozone.
The Arctic seasonal evolution of simulated O3 and the long lived trace gas N2O from the Global Modeling Initiative Chemistry and Transport Model (GMI CTM) both closely agree with MLS observations for all years since Aura's launch in 2004.
The next three decades will see an end of the era of big ozone holes. In a new study, scientists from NASA Goddard Space Flight Center say that the ozone hole will be consistently smaller than 8 million square miles by the year 2040.
A decade of MLS Nitrous oxide reveals a remarkable transport pipeline from the midlatitude middle stratosphere to the Antarctic lower stratosphere, allowing tropical winds to modulate how much chlorine reaches the Antarctic ozone hole each year.
To quantitatively understand anthropogenic impacts to the stratospheric ozone layer, we must be able to distinguish between low ozone caused by ozone depleting substances and that caused by natural dynamical variability in the atmosphere.
MLS ClO in the 2011 Antarctic vortex was 20% lower than 2006, yet the 2011 ozone hole is very similar to the 2006 hole, the largest ever observed.
Microwave Limb Sounder (MLS) observations quantify the changes in the hydroxyl radical (OH), hydrogen dioxide (HO2), and ozone due to Solar Proton Events (SPE)
OH data from the Microwave Limb Sounder (MLS) on Aura and a ground-based FTUVS suggest a response of the OH column to the solar cycle that is significantly larger than model results using established solar forcing.
The Microwave Limb Sounder (MLS) on NASA's Aura shows weaker than usual ozone transport and strong photochemical loss
Unusually prolonged cold conditions in the spring 2011 Arctic stratosphere promoted levels of chlorine activation and chemical ozone loss never before observed in the Arctic, comparable to those in the Antarctic in some winters.
The properties of the polluted clouds indicate a warming and moistening effect on air entering the stratosphere by the pollutants in Asia.
Aura MLS observations show clear imprint of 2010 El Niño in the upper troposphere
Prolonged low temperatures in September 2006 increased by the longevity of 'active chlorine', leading to a record area and depth of the ozone hole.
OMI & MLS can estimate the tropospheric ozone residual by subtracting the MLS stratospheric ozone from OMI column ozone. These maps show pollution streaming from the U.S., Europe and China to the west in summer and pollution from biomass burning in the equatorial zone.
Cloud ice measurement will improve global circulation models used for weather and climate forecasts.
The measurements will also help quantify the upper tropospheric hydrological cycle, including water vapor feedbacks on climate change.
MLS sees cloud ice, but HIRDLS sees the clouds themselves, even clouds that are so thin that people cannot see them. Just as in the MLS cloud ice map we see large amounts of this cirrus in regions of significant cloud ice.
CO is a signature of pollution and can be transported a long way from its source. Not surprisingly, that transport can be vertical as well as horizontal. These images show how CO detected in the lower stratosphere can tell us something about where convection is occurring.
The continuous measurement of HCl in the stratosphere shows the rapid recovery of this major chlorine reservoir after polar ozone loss, and continues the long-term measurements from UARS HALOE. Monitoring HCl tells us about ozone loss processes and the recovery of the ozone layer.
The MLS measurements of OH and HO2 have provided the first tests of global stratospheric hydrogen chemistry and resolved the disagreement between model estimates of OH and earlier observations - these data suggest earlier observations are suspect.
As tropical air rises into the stratosphere it carries with it trace gases, such as CFC's that are responsible for ozone depletion.
An unprecedended suite of simultaneous measurements by MLS allows more accurate quantification of ozone destruction in the 2004-2005 Arctic winter.
These images show MLS detection of enhanced SO2 and HCI in the lower stratosphere over New Guinea on January 28, following eruption of Manam volcano on January 27.
Time-pressure sections of zonally averaged water vapor mixing ratio, shown as the deviation from the time-mean profile.
Maps of MLS HCI in the lower stratosphere (520 K, 20km) detailing the springtime breakup of the 2004 Antarctic vortex.
Aura MLS has provided first observation of this connection