The Anomalous Change in the QBO in 2015-2016

The quasi-biennial oscillation (QBO) is a tropical lower stratospheric, downward propagating zonal wind variation, with an average period of approximately 28 months. The QBO has been constantly documented since 1953. Here we describe the evolution of the QBO during the Northern Hemisphere winter of 2015-16 using radiosonde observations and meteorological reanalyses. Normally, the QBO would show a steady downward propagation of the westerly phase. In 2015-16, there was an anomalous upward displacement of this westerly phase from approximately30 hPa to 15 hPa. These westerlies impinge on, or cut-off the normal downward propagation of the easterly phase. In addition, easterly winds develop at 40 hPa. Comparisons to tropical wind statistics for the 1953-present record demonstrate that this 2015-16 QBO disruption is unprecedented

A review of the Match technique as applied to AASE-2/EASOE and SOLVE/THESEO 2000

International audienceWe apply the NASA Goddard Trajectory Model to data from a series of ozonesondes to derive ozone loss rates in the lower stratosphere for the AASE-2/EASOE mission (January-March 1992) and for the SOLVE/THESEO 2000 mission (January-March 2000) in an approach similar to Match. Ozone loss rates are computed by comparing the ozone concentrations provided by ozonesondes launched at the beginning and end of the trajectories connecting the launches. We investigate the sensitivity of the Match results to the various parameters used to reject potential matches in the original Match technique. While these filters effectively eliminate from consideration 80% of the matched sonde pairs and >99% of matched observations in our study, we conclude that only a filter based on potential vorticity changes along the calculated back trajectories seems warranted. Our study also demonstrates that the ozone loss rates estimated in Match can vary by up to a factor of two depending upon the precise trajectory paths calculated for each trajectory. As a result, the statistical uncertainties published with previous Match results might need to be augmented by an additional systematic error. The sensitivity to the trajectory path is particularly pronounced in the month of January, for which the largest ozone loss rate discrepancies between photochemical models and Match are found. For most of the two study periods, our ozone loss rates agree with those previously published. Notable exceptions are found for January 1992 at 475K and late February/early March 2000 at 450K, both periods during which we generally find smaller loss rates than the previous Match studies. Integrated ozone loss rates estimated by Match in both of those years compare well with those found in numerous other studies and in a potential vorticity/potential temperature approach shown previously and in this paper. Finally, we suggest an alternate approach to Match using trajectory mapping. This approach uses information from all matched observations without filtering and uses a two-parameter fit to the data to produce robust ozone loss rate estimates. As compared to loss rates from our version of Match, the trajectory mapping approach produces generally smaller loss rates, frequently not statistically significantly different from zero, calling into question the efficacy of the Match approach

Chance Encounter with a Stratospheric Kerosene Rocket Plume from Russia over California

During a routine ER-2 aircraft high-altitude test flight on April 18, 1997, an unusual aerosol cloud was detected at 20 km altitude near the California coast at about 370 degrees N latitude. Not visually observed by the ER-2 pilot, the cloud was characterized bv high concentration of soot and sulfate aerosol in a region over 100 km in horizontal extent indicating that the source of the plume was a large hydrocarbon fueled vehicle, most likely a launch vehicle powered only by rocket motors burning liquid oxygen and kerosene. Two Russian Soyuz rockets could conceivably have produced the plume. The first was launched from the Baikonur Cosmodrome, Kazakhstan on April 6th; the second was launched from Plesetsk, Russia on April 9. Air parcel trajectory calculations and long-lived tracer gas concentrations in the cloud indicate that the Baikonur rocket launch is the most probable source of the plume. The parcel trajectory calculations do not unambiguously trace the transport of the Soyuz plume from Asia to North America, illustrating serious flaws in the point-to-point trajectory calculations. This chance encounter represents the only measurement of the stratospheric effects of emissions from a rocket powered exclusively with hydrocarbon fuel

Forecasting carbon monoxide on a global scale for the ATom-1 aircraft mission: insights from airborne and satellite observations and modeling

The first phase of the Atmospheric Tomography Mission (ATom-1) took place in July–August 2016 and included flights above the remote Pacific and Atlantic oceans. Sampling of atmospheric constituents during these flights is designed to provide new insights into the chemical reactivity and processes of the remote atmosphere and how these processes are affected by anthropogenic emissions. Model simulations provide a valuable tool for interpreting these measurements and understanding the origin of the observed trace gases and aerosols, so it is important to quantify model performance. Goddard Earth Observing System Model version 5 (GEOS-5) forecasts and analyses show considerable skill in predicting and simulating the CO distribution and the timing of CO enhancements observed during the ATom-1 aircraft mission. We use GEOS-5's tagged tracers for CO to assess the contribution of different emission sources to the regions sampled by ATom-1 to elucidate the dominant anthropogenic influences on different parts of the remote atmosphere. We find a dominant contribution from non-biomass-burning sources along the ATom transects except over the tropical Atlantic, where African biomass burning makes a large contribution to the CO concentration. One of the goals of ATom is to provide a chemical climatology over the oceans, so it is important to consider whether August 2016 was representative of typical boreal summer conditions. Using satellite observations of 700&thinsp;hPa and column CO from the Measurement of Pollution in the Troposphere (MOPITT) instrument, 215&thinsp;hPa&thinsp;CO from the Microwave Limb Sounder (MLS), and aerosol optical thickness from the Moderate Resolution Imaging Spectroradiometer (MODIS), we find that CO concentrations and aerosol optical thickness in August 2016 were within the observed range of the satellite observations but below the decadal median for many of the regions sampled. This suggests that the ATom-1 measurements may represent relatively clean but not exceptional conditions for lower-tropospheric CO.</p

Partitioning of the reactive nitrogen reservoir in the lower sratosphere of the southern hemisphere: Observations and modeling

Measurements of nitric oxide (NO), nitrogen dioxide (NO2), and total reactive nitrogen (NOy = NO + NO2 + NO3 + HNO3 + ClONO2 + 2N2O5 + ...) were made during austral fall, winter, and spring 1994 as part of the NASA Airborne Southern Hemisphere Ozone Experiment/Measurements for Assessing the Effects of Stratospheric Aircraft mission. Comparisons between measured NO2 values and those calculated using a steady state (SS) approximation are presented for flights at mid and high latitudes. The SS results agree with the measurements to within 8%, suggesting that the kinetic rate coefficients and calculated NO2 photolysis rate used in the SS approximation are reasonably accurate for conditions in the lower stratosphere. However, NO2 values observed in the Concorde exhaust plume were significantly less than SS values. Calculated NO2 photolysis rates showed good agreement with values inferred from solar flux measurements, indicating a strong self-consistency in our understanding of UV radiation transmission in the lower stratosphere. Model comparisons using a full diurnal, photochemical steady state model also show good agreement with the NO and NO2 measurements, suggesting that the reactions affecting the partitioning of the NO2 reservoir are well understood in the lower stratosphere

Inorganic chlorine partitioning in the summer lower stratosphere: Modeled and measured [ClONO_2]/[HCl] during POLARIS

We examine inorganic chlorine (Cl_y,) partitioning in the summer lower stratosphere using in situ ER-2 aircraft observations made during the Photochemistry of Ozone Loss in the Arctic Region in Summer (POLARIS) campaign. New steady state and numerical models estimate [ClONO_2]/[HCl] using currently accepted photochemistry. These models are tightly constrained by observations with OH (parameterized as a function of solar zenith angle) substituting for modeled HO_2 chemistry. We find that inorganic chlorine photochemistry alone overestimates observed [ClONO_2]/[HCl] by approximately 55–60% at mid and high latitudes. On the basis of POLARIS studies of the inorganic chlorine budget, [ClO]/[ClONO_2], and an intercomparison with balloon observations, the most direct explanation for the model-measurement discrepancy in Cl_y, partitioning is an error in the reactions, rate constants, and measured species concentrations linking HCl and ClO (simulated [ClO]/[HCl] too high) in combination with a possible systematic error in the ER-2 ClONO_2 measurement (too low). The high precision of our simulation (±15% 1σ for [ClONO_2]/[HCl], which is compared with observations) increases confidence in the observations, photolysis calculations, and laboratory rate constants. These results, along with other findings, should lead to improvements in both the accuracy and precision of stratospheric photochemical models

Comparison of modeled and observed values of NO_2 and JNO_2 during the Photochemistry of Ozone Loss in the Arctic Region in Summer (POLARIS) mission

Stratospheric measurements of NO, NO_(2), O_(3), ClO, and HO_(2) were made during spring, early summer, and late summer in the Arctic region during 1997 as part of the Photochemistry of Ozone Loss in the Arctic Region in Summer (POLARIS) field campaign. In the sunlit atmosphere, NO_(2) and NO are in steady state through NO2 photolysis and reactions involving O_(3), ClO, BrO, and HO_(2). By combining observations of O_(3), ClO, and HO_(2), observed and modeled values of the NO_(2) photolysis rate coefficient (JNO_(2)), and model estimates of BrO, several comparisons are made between steady state and measured values of both NO_(2) and JNO_(2). An apparent seasonal dependence in discrepancies between calculated and measured values was found; however, a source for this dependence could not be identified. Overall, the mean linear fits in the various comparisons show agreement within 19%, well within the combined uncertainties (±50 to 70%). These results suggest that photochemistry controlling the NO_(2)/NO abundance ratio is well represented throughout much of the sunlit lower stratosphere. A reduction in the uncertainty of laboratory determinations of the rate coefficient of NO + O_(3) → NO_(2) + O_(2) would aid future analyses of these or similar atmospheric observations

Comparison between DC-8 and ER-2 species measurements in the tropical middle troposphere: NO, NO\u3csub\u3ey\u3c/sub\u3e, O\u3csub\u3e3\u3c/sub\u3e, CO\u3csub\u3e2\u3c/sub\u3e, CH\u3csub\u3e4\u3c/sub\u3e, and N\u3csub\u3e2\u3c/sub\u3eO

We compare measurements of six species taken aboard NASA DC-8 and ER-2 aircraft during two flight legs in the tropical middle troposphere near Hawaii. NO, NOy, O3, CH4, and N2O measurements agree to within the limits set by the known systematic errors. For CO2, which can be measured with better relative precision than the other five species, differences in measured values from the two platforms are slightly larger than expected if the air masses sampled by the two aircraft were indeed similar in CO2 composition to better than 0.08%. Copyright 1998 by the American Geophysical Union

Randomised controlled trial of exercise to prevent shoulder problems in women undergoing breast cancer treatment: Study protocol for the prevention of shoulder problems trial (UK PROSPER)

Musculoskeletal shoulder problems are common after breast cancer treatment. Early postoperative exercises targeting the upper limb may improve shoulder function. This protocol describes a National Institute for Health Research-funded randomised controlled trial (RCT) to evaluate the clinical and cost-effectiveness of an early supervised structured exercise programme compared with usual care, for women at high risk of developing shoulder problems after breast cancer surgery. Methods This pragmatic two-armed, multicentre RCT is underway within secondary care in the UK. PRevention Of Shoulder ProblEms tRial (PROSPER) aims to recruit 350 women from approximately 15 UK centres with follow-up at 6 weeks, 6 and 12 months after randomisation. Recruitment processes and intervention development were optimised through qualitative research during a 6-month internal pilot phase. Participants are randomised to the PROSPER intervention or best practice usual care only. The PROSPER intervention is delivered by physiotherapists and incorporates three main components: shoulder-specific exercises targeting range of movement and strength; general physical activity and behavioural strategies to encourage adherence and support exercise behaviour. The primary outcome is upper arm function assessed using the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire at 12 months postrandomisation. Secondary outcomes include DASH subscales, acute and chronic pain, complications, health-related quality of life and healthcare resource use. We will interview a subsample of 20 participants to explore their experiences of the trial interventions. Discussion The PROSPER study is the first multicentre UK clinical trial to investigate the clinical and cost-effectiveness of supported exercise in the prevention of shoulder problems in high-risk women undergoing breast cancer surgery. The findings will inform future clinical practice and provide valuable insight into the role of physiotherapy-supported exercise in breast cancer rehabilitation. Protocol version Version 2.1; dated 11 January 2017 Trial registration number ISRCTN35358984; Pre-results