The low-lying negative parity states in the 133Ba nucleus have been investigated using the 124Sn(13C, 4nγ)133Ba reaction at Elab = 48 MeV. With the addition of new γ-transitions, nω=0,1,2 wobbling ...bands were identified in this nucleus. The angular correlations and linear polarization measurements have been performed to confirm the spin and parity of the states. Predominant E2 character was obtained for the inter-linking ΔI=1 transitions between the successive phonon (Δnω=1) wobbling bands. The transverse nature of the wobbling bands is concluded on the basis of observed decreasing behavior of the wobbling frequency with increasing spin. The quasiparticle triaxial rotor model calculations are found to be in agreement with the experimentally determined wobbling frequency and the transition probability ratios. This letter reports the first observation of transverse wobbling mode associated with a hole-like quasiparticle.
Top‐down constraints on global sulfur dioxide (SO2) emissions are inferred through inverse modeling using SO2 column observations from two satellite instruments (SCIAMACHY and OMI). We first ...evaluated the SO2 column observations with surface SO2 measurements by applying local scaling factors from a global chemical transport model (GEOS‐Chem) to SO2 columns retrieved from the satellite instruments. The resulting annual mean surface SO2 mixing ratios for 2006 exhibit a significant spatial correlation (r = 0.86, slope = 0.91 for SCIAMACHY and r = 0.80, slope = 0.79 for OMI) with coincident in situ measurements from monitoring networks throughout the United States and Canada. We evaluate the GEOS‐Chem simulation of the SO2 lifetime with that inferred from in situ measurements to verify the applicability of GEOS‐Chem for inversion of SO2 columns to emissions. The seasonal mean SO2 lifetime calculated with the GEOS‐Chem model over the eastern United States is 13 h in summer and 48 h in winter, compared to lifetimes inferred from in situ measurements of 19 ± 7 h in summer and 58 ± 20 h in winter. We apply SO2 columns from SCIAMACHY and OMI to derive a top‐down anthropogenic SO2 emission inventory over land by using the local GEOS‐Chem relationship between SO2 columns and emissions. There is little seasonal variation in the top‐down emissions (<15%) over most major industrial regions providing some confidence in the method. Our global estimate for annual land surface anthropogenic SO2 emissions (52.4 Tg S yr−1 from SCIAMACHY and 49.9 Tg S yr−1 from OMI) closely agrees with the bottom‐up emissions (54.6 Tg S yr−1) in the GEOS‐Chem model and exhibits consistency in global distributions with the bottom‐up emissions (r = 0.78 for SCIAMACHY, and r = 0.77 for OMI). However, there are significant regional differences.
In the Antarctic ozone hole, ozone mixing ratios have been decreasing to extremely low values of 0.01–0.1 ppm in nearly all spring seasons since the late 1980s, corresponding to 95–99% local chemical ...loss. In contrast, Arctic ozone loss has been much more limited and mixing ratios have never before fallen below 0.5 ppm. In Arctic spring 2020, however, ozonesonde measurements in the most depleted parts of the polar vortex show a highly depleted layer, with ozone loss averaged over sondes peaking at 93% at 18 km. Typical minimum mixing ratios of 0.2 ppm were observed, with individual profiles showing values as low as 0.13 ppm (96% loss). The reason for the unprecedented chemical loss was an unusually strong, long‐lasting, and cold polar vortex, showing that for individual winters the effect of the slow decline of ozone‐depleting substances on ozone depletion may be counteracted by low temperatures.
Plain Language Summary
The severe stratospheric chemical ozone loss in the Antarctic ozone hole and its impact on human health and climate have generated widespread public, political, and scientific interest. In contrast, Arctic stratospheric ozone reduction has been much more limited because of higher temperatures and higher transport variability in the Northern Hemisphere (lower temperatures lead to more chemical loss, and more transport can increase ozone values). In the Arctic spring 2020, however, observations of balloon sondes and satellites show that locally, absolute values of ozone (measured in mixing ratios, i.e., molecules of ozone per molecules of air) are significantly lower than in any previous year and are comparable to typical local values in the Antarctic ozone hole, albeit over a much narrower vertical layer. Locally, the chemical loss of ozone peaked at 93% in the Arctic spring of 2020, compared to values of 95–99% in the Antarctic in most winters since the late 1980s. The reason for the unprecedented loss was unusually cold and stable conditions in the Arctic stratosphere.
Key Points
Local minimum ozone mixing ratios of 0.1–0.2 ppm observed by sondes in Arctic spring 2020 are significantly lower than in any previous year
Local ozone loss (93%) and low mixing ratios are comparable to typical values in the Antarctic ozone hole (95–99%, 0.01–0.1 ppm)
The reason for the unprecedented chemical loss was an unusually strong, long‐lasting, and record cold polar vortex
The nucleus 180Hf is one of the most primary examples of an axially symmetric prolate rotor. Combined with the presence of high-K isomers, spectroscopic studies can provide important information on ...the nature of its single-particle levels. Precise measurements are essential for constraining nuclear models and interpreting the nature of such isomeric states. In this work, the nucleus 180Hf was populated using the proton pick-up reaction 181Ta(11B,12C)180Hf at beam energy of 47 MeV at Horia Hulubei National Institute of Nuclear Physics and Engineering (IFIN-HH). The spin of the 1374 keV state and the mixing ratio of the 1066 keV transition have been measured, the latter with an increased precision compared to the previous value from literature. The presently measured spin of the 1374 keV state, currently assigned a tentative value of (41−), favors one of the two different values that were previously reported. The particular state constitutes the band-head of a rotational band in 180Hf. The measured multipolarity mixing ratio of the inter-band transition 1374→309 keV can provide important information for the testing and constraining of theoretical nuclear models used for the study of the intrinsic properties of 180Hf, as well as its neighboring isotopes.
Stratospheric ozone and water vapour are key components of the Earth system, and past and future changes to both have important impacts on global and
regional climate. Here, we evaluate long-term ...changes in these species from the pre-industrial period (1850) to the end of the 21st century
in Coupled Model Intercomparison Project phase 6 (CMIP6)
models under a range of future emissions scenarios. There is good agreement between the CMIP multi-model mean and observations for total column
ozone (TCO), although there is substantial variation between the individual CMIP6 models. For the CMIP6 multi-model mean, global mean TCO has
increased from ∼ 300 DU in 1850 to ∼ 305 DU in 1960, before rapidly declining in the 1970s and 1980s following the
use and emission of halogenated ozone-depleting substances (ODSs). TCO is projected to return to 1960s values by the middle of the 21st century
under the SSP2-4.5, SSP3-7.0, SSP4-3.4, SSP4-6.0, and SSP5-8.5 scenarios, and under the SSP3-7.0 and SSP5-8.5 scenarios TCO values are projected to
be ∼ 10 DU higher than the 1960s values by 2100. However, under the SSP1-1.9 and SSP1-1.6 scenarios, TCO is not projected to
return to the 1960s values despite reductions in halogenated ODSs due to decreases in tropospheric ozone mixing ratios. This global pattern is
similar to regional patterns, except in the tropics where TCO under most scenarios is not projected to return to 1960s values, either through
reductions in tropospheric ozone under SSP1-1.9 and SSP1-2.6, or through reductions in lower stratospheric ozone resulting from an acceleration of
the Brewer–Dobson circulation under other Shared Socioeconomic Pathways (SSPs). In contrast to TCO, there is poorer agreement between the
CMIP6 multi-model mean and observed lower
stratospheric water vapour mixing ratios, with the CMIP6 multi-model mean underestimating observed water vapour mixing ratios by
∼ 0.5 ppmv at 70 hPa. CMIP6 multi-model mean stratospheric water vapour mixing ratios in the tropical lower stratosphere have
increased by ∼ 0.5 ppmv from the pre-industrial to the present-day period and are projected to increase further by the end of the 21st
century. The largest increases (∼ 2 ppmv) are simulated under the future scenarios with the highest assumed forcing pathway
(e.g. SSP5-8.5). Tropical lower stratospheric water vapour, and to a lesser extent TCO, shows large variations following explosive volcanic eruptions.
Light‐emitting chiral carbonized polymer dots (Ch‐CPDs) are attracting great interest because of their extraordinary photonic properties, but modulating their band‐gap emission, especially at long ...wavelength, and maintaining their chiral structure to achieve multicolor, high‐emission Ch‐CPDs remains challenging. Reported here for the first time is the synthesis of red‐ and multicolor‐emitting Ch‐CPDs using the common precursors L‐/D‐tryptophan and o‐phenylenediamine, and a solvothermal approach at one temperature. The quantum yield of the Ch‐CPDs was between 31 % and 54 %. Supramolecular self‐assembly provided multicolor‐emitting Ch‐CPDs showing novel circularly polarized luminescence, with the highest dissymmetric factor (glum) of 1×10−2. Importantly, circularly polarized white‐emitting CPDs were fabricated for the first time by tuning the mixing ratio of the three colored Ch‐CPDs in a gel. This strategy affords exciting opportunities for designing functional chiroptical materials.
The synthesis of red‐ and multicolor‐emitting chiral carbonized polymer dots (Ch‐CPDs) is reported for the first time. The quantum yield of the Ch‐CPDs is between 31 % and 54 %. Furthermore, these Ch‐CPDs were combined with chiral gels through supramolecular self‐assembly, thereby yielding their multicolor and white circularly polarized luminescence.
In this study, the boreal sudden stratospheric warming (SSW) event of 2013 and the austral SSW event of 2019 are considered to investigate the influence of the SSW events on the polar and antipodal ...upper mesosphere and lower thermosphere (UMLT) regions using ground‐based, space‐borne, reanalysis and model data sets. During the SSW events, the solar semi‐diurnal tidal (SDT) amplitudes are much larger than the lunar amplitudes in both UMLT regions. Besides, the solar SDT shows an increase in its amplitude in both the polar UMLT heights during the SSW events. However, the lunar tides show enhancement in its amplitude in the boreal polar UMLT region during both the SSW events. In the antipodal UMLT region, a peak enhancement in solar SDT amplitude is observed a few days after the onset of the boreal SSW and near to the onset time of the austral SSW. No concurrent stratospheric ozone volume mixing ratio (vmr) increase is observed which indicates that the SDT peak can be unlikely due to the underlying stratospheric ozone vmr changes. However, similar periodicity in the UMLT zonal winds of both poles indicates the possibility of cross equatorial propagation of planetary wave (PW). As the SDT amplitude also reveal similar planetary wave periodicity as observed in zonal wind, it is suggested that the PW modulation of the SDT could be the reason for the enhancement of SDT in the opposite polar UMLT region.
Plain Language Summary
This work provides an observational evidence of the cross equatorial propagation of PWs associated with the SSW events that affect the UMLT region extending up to the next pole. Using ground‐based, space‐borne, reanalysis and model outputs, the tidal and PW activity during two SSWs (2013 and 2019) are studied simultaneously over both the poles. The meteor radar observation reveals the dominance of solar SDT in the polar UMLT region compared to the lunar tides and its amplitude increases around the SSW onset days. A peak in the antipodal SDT is observed in the UMLT region with no simultaneous increase in the stratospheric ozone. It is suggested that a cross equatorial propagation of PW periodicity associated with the SSW events may modulate the solar SDT in the antipodal UMLT region and result in its increased amplitude after the SSW events.
Key Points
Solar semi‐diurnal tide enhances in both polar mesosphere during sudden stratospheric warming but at no relation with stratospheric ozone
Solar tides are relatively stronger than lunar tides with the enhancement of the latter observed only in the boreal polar mesosphere
Similar planetary waves in both polar mesosphere and their modulation of solar tides in antipode show their cross equatorial propagation
Surface ozone is a secondary air pollutant produced during the atmospheric photochemical degradation of emitted volatile organic compounds (VOCs) in the presence of sunlight and nitrogen oxides ...(NOx). Temperature directly influences ozone production through speeding up the rates of chemical reactions and increasing the emissions of VOCs, such as isoprene, from vegetation. In this study, we used an idealised box model with different chemical mechanisms (Master Chemical Mechanism, MCMv3.2; Common Representative Intermediates, CRIv2; Model for OZone and Related Chemical Tracers, MOZART-4; Regional Acid Deposition Model, RADM2; Carbon Bond Mechanism, CB05) to examine the non-linear relationship between ozone, NOx and temperature, and we compared this to previous observational studies. Under high-NOx conditions, an increase in ozone from 20 to 40°C of up to 20ppbv was due to faster reaction rates, while increased isoprene emissions added up to a further 11ppbv of ozone. The largest inter-mechanism differences were obtained at high temperatures and high-NOx emissions. CB05 and RADM2 simulated more NOx-sensitive chemistry than MCMv3.2, CRIv2 and MOZART-4, which could lead to different mitigation strategies being proposed depending on the chemical mechanism. The increased oxidation rate of emitted VOC with temperature controlled the rate of Ox production; the net influence of peroxy nitrates increased net Ox production per molecule of emitted VOC oxidised. The rate of increase in ozone mixing ratios with temperature from our box model simulations was about half the rate of increase in ozone with temperature observed over central Europe or simulated by a regional chemistry transport model. Modifying the box model set-up to approximate stagnant meteorological conditions increased the rate of increase of ozone with temperature as the accumulation of oxidants enhanced ozone production through the increased production of peroxy radicals from the secondary degradation of emitted VOCs. The box model simulations approximating stagnant conditions and the maximal ozone production chemical regime reproduced the 2ppbv increase in ozone per degree Celsius from the observational and regional model data over central Europe. The simulated ozone-temperature relationship was more sensitive to mixing than the choice of chemical mechanism. Our analysis suggests that reductions in NOx emissions would be required to offset the additional ozone production due to an increase in temperature in the future.
We explore the minimum distance from a host star where an exoplanet could potentially be habitable in order not to discard close-in rocky exoplanets for follow-up observations. We find that the inner ...edge of the Habitable Zone for hot desert worlds can be as close as 0.38 AU around a solar-like star, if the greenhouse effect is reduced (~1% relative humidity) and the surface albedo is increased. We consider a wide range of atmospheric and planetary parameters such as the mixing ratios of greenhouse gases (water vapor and CO sub(2)), surface albedo, pressure, and gravity. Intermediate surface pressure (~1-10 bars) is necessary to limit water loss and to simultaneously sustain an active water cycle. We additionally find that the water loss timescale is influenced by the atmospheric CO sub(2) level, because it indirectly influences the stratospheric water mixing ratio. If the CO sub(2) mixing ratio of dry planets at the inner edge is smaller than 10 super(-4), the water loss timescale is ~1 billion years, which is considered here too short for life to evolve. We also show that the expected transmission spectra of hot desert worlds are similar to an Earth-like planet. Therefore, an instrument designed to identify biosignature gases in an Earth-like atmosphere can also identify similarly abundant gases in the atmospheres of dry planets. Our inner edge limit is closer to the host star than previous estimates. As a consequence, the occurrence rate of potentially habitable planets is larger than previously thought.
The emissions of BVOCs from oilseed rape (Brassica napus), both when the plant is exposed to clean air and when it is fumigated with ozone at environmentally-relevant mixing ratios (ca. 135 ppbv), ...were measured under controlled laboratory conditions. Emissions of BVOCs were recorded from combined leaf and root chambers using a recently developed Selective Reagent Ionisation-Time of Flight-Mass Spectrometer (SRI-ToF-MS) enabling BVOC detection with high time and mass resolution, together with the ability to identify certain molecular functionality. Emissions of BVOCs from below-ground were found to be dominated by sulfur compounds including methanethiol, dimethyl disulfide and dimethyl sulfide, and these emissions did not change following fumigation of the plant with ozone. Emissions from above-ground plant organs exposed to clean air were dominated by methanol, monoterpenes, 4-oxopentanal and methanethiol. Ozone fumigation of the plants caused a rapid decrease in monoterpene and sesquiterpene concentrations in the leaf chamber and increased concentrations of ca. 20 oxygenated species, almost doubling the total carbon lost by the plant leaves as volatiles. The drop in sesquiterpenes concentrations was attributed to ozonolysis occurring to a major extent on the leaf surface. The drop in monoterpene concentrations was attributed to gas phase reactions with OH radicals deriving from ozonolysis reactions. As plant-emitted terpenoids have been shown to play a role in plant-plant and plant-insect signalling, the rapid loss of these species in the air surrounding the plants during photochemical pollution episodes may have a significant impact on plant-plant and plant-insect communications.
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