169 research outputs found
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Seasonal cycles and variability of O3 and H2O in the UT/LMS during SPURT
Airborne high resolution in situ measurements of a large set of trace gases including ozone (O3) and total water (H2O) in the upper troposphere and the lowermost stratosphere (UT/LMS) have been performed above Europe within the SPURT project. SPURT provides an extensive data coverage of the UT/LMS in each season within the time period between November 2001 and July 2003.
In the LMS a distinct spring maximum and autumn minimum is observed in O3, whereas its annual cycle in the UT is shifted by 2â3 months later towards the end of the year. The more variable H2O measurements reveal a maximum during summer and a minimum during autumn/winter with no phase shift between the two atmospheric compartments.
For a comprehensive insight into trace gas composition and variability in the UT/LMS several statistical methods are applied using chemical, thermal and dynamical vertical coordinates. In particular, 2-dimensional probability distribution functions serve as a tool to transform localised aircraft data to a more comprehensive view of the probed atmospheric region. It appears that both trace gases, O3 and H2O, reveal the most compact arrangement and are best correlated in the view of potential vorticity (PV) and distance to the local tropopause, indicating an advanced mixing state on these surfaces. Thus, strong gradients of PV seem to act as a transport barrier both in the vertical and the horizontal direction. The alignment of trace gas isopleths reflects the existence of a year-round extra-tropical tropopause transition layer. The SPURT measurements reveal that this layer is mainly affected by stratospheric air during winter/spring and by tropospheric air during autumn/summer.
Normalised mixing entropy values for O3 and H2O in the LMS appear to be maximal during spring and summer, respectively, indicating highest variability of these trace gases during the respective seasons
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Tracing troposphere-to-stratosphere transport above a mid-latitude deep convective system
Within the project SPURT (trace gas measurements in the tropopause region) a variety of trace gases have been measured in situ in order to investigate the role of dynamical and chemical processes in the extra-tropical tropopause region. In this paper we report on a flight on 10 November 2001 leading from Hohn, Germany (52ïżœN) to Faro, Portugal (37ïżœN) through a strongly developed deep stratospheric intrusion. This streamer was associated with a large convective system over the western Mediterranean with potentially significant troposphere-to-stratosphere transport. Along major parts of the flight we measured unexpectedly high NOy mixing ratios. Also H2O mixing ratios were significantly higher than stratospheric background levels confirming the extraordinary chemical signature of the probed air masses in the interior of the streamer. Backward trajectories encompassing the streamer enable to analyze the origin and physical characteristics of the air masses and to trace troposphere-to-stratosphere transport. Near the western flank of the streamer features caused by long range transport, such as tropospheric filaments characterized by sudden drops in the O3 and NOy mixing ratios and enhanced CO and H2O can be reconstructed in great detail using the reverse domain filling technique. These filaments indicate a high potential for subsequent mixing with the stratospheric air. At the south-western edge of the streamer a strong gradient in the NOy and the O3 mixing ratios coincides very well with a sharp gradient in potential vorticity in the ECMWF fields. In contrast, in the interior of the streamer the observed highly elevated NOy and H2O mixing ratios up to a potential temperature level of 365K and potential vorticity values of maximum 10 PVU cannot be explained in terms of resolved troposphere-to-stratosphere transport along the backward trajectories. Also mesoscale simulations with a High Resolution Model reveal no direct evidence for convective H2O injection up to this level. Elevated H2O mixing ratios in the ECMWF and HRM are seen only up to about tropopause height at 340 hPa and 270 hPa, respectively, well below flight altitude of about 200 hPa. However, forward tracing of the convective influence as identified by satellite brightness temperature measurements and counts of lightning strokes shows that during this part of the flight the aircraft was closely following the border of an air mass which was heavily impacted by convective activity over Spain and Algeria. This is evidence that deep convection at mid-latitudes may have a large impact on the tracer distribution of the lowermost stratosphere reaching well above the thunderstorms anvils as claimed by recent studies using cloud-resolving models
Long-range transport pathways of tropospheric source gases originating in Asia into the northern lower stratosphere during the Asian monsoon season 2012
Global simulations with the Chemical Lagrangian Model of the Stratosphere (CLaMS) using artificial tracers of air mass origin are used to analyze transport mechanisms from the Asian monsoon region into the lower stratosphere. In a case study, the transport of air masses from the Asian monsoon anticyclone originating in India/China by an eastward-migrating anticyclone which broke off from the main anticyclone on 20 September 2012 and filaments separated at the northeastern flank of the anticyclone are analyzed. Enhanced contributions of young air masses (younger than 5 months) are found within the separated anticyclone confined at the top by the thermal tropopause. Further, these air masses are confined by the anticyclonic circulation and, on the polar side, by the subtropical jet such that the vertical structure resembles a bubble within the upper troposphere. Subsequently, these air masses are transported eastwards along the subtropical jet and enter the lower stratosphere by quasi-horizontal transport in a region of double tropopauses most likely associated with Rossby wave breaking events. As a result, thin filaments with enhanced signatures of tropospheric trace gases were measured in the lower stratosphere over Europe during the TACTS/ESMVal campaign in September 2012 in very good agreement with CLaMS simulations. Our simulations demonstrate that source regions in Asia and in the Pacific Ocean have a significant impact on the chemical composition of the lower stratosphere of the Northern Hemisphere. Young, moist air masses, in particular at the end of the monsoon season in September/October 2012, flooded the extratropical lower stratosphere in the Northern Hemisphere with contributions of up to â30% at 380K (with the remaining fraction being aged air). In contrast, the contribution of young air masses to the Southern Hemisphere is much lower. At the end of October 2012, approximately 1.5 ppmv HO is found in the lower Northern Hemisphere stratosphere (at 380 K) from source regions both in Asia and in the tropical Pacific compared to a mean water vapor content of â5 ppmv. In addition to this main transport pathway from the Asian monsoon anticyclone to the east along the subtropical jet and subsequent transport into the northern lower stratosphere, a second horizontal transport pathway out of the anticyclone to the west into the tropics (TTL) is found in agreement with MIPAS HCFC-22 measurements
Ice particle sampling from aircraft â influence of the probing position on the ice water content
The ice water content (IWC) of cirrus clouds is an
essential
parameter determining their radiative properties and thus is
important for climate simulations. Therefore, for a reliable
measurement of IWC on board research aircraft, it is important to
carefully design the ice crystal sampling and measuring devices.
During the ML-CIRRUS field campaign in 2014 with the German
Gulfstream GV HALO (High Altitude and Long Range Research Aircraft),
IWC was recorded by three closed-path total water together with one
gas-phase water instrument. The hygrometers were supplied by inlets
mounted on the roof of the aircraft fuselage. Simultaneously, the
IWC is determined by a cloud particle spectrometer attached under an
aircraft wing. Two more examples of simultaneous IWC measurements by
hygrometers and cloud spectrometers are presented, but the inlets of
the hygrometers were mounted at the fuselage side (M-55 Geophysica,
StratoClim campaign 2017) and bottom (NASA WB57, MacPex campaign 2011).
This combination of instruments and inlet positions provides the
opportunity to experimentally study the influence of the ice
particle sampling position on the IWC with the approach of
comparative measurements. As expected from theory and shown by
computational fluid dynamics (CFD) calculations, we found that the
IWCs provided by the roof inlets deviate from those measured under
the aircraft wing. As a result of the inlet position in the shadow zone
behind the aircraft cockpit, ice particle populations with mean
mass sizes larger than about 25âŻÂ”m radius are subject to
losses, which lead to strongly underestimated IWCs. On the other
hand, cloud populations with mean mass sizes smaller than about 12âŻÂ”m are dominated by particle enrichment and thus
overestimated IWCs. In the range of mean mass sizes between 12 and
25âŻÂ”m, both enrichment and losses of ice crystals can occur,
depending on whether the ice crystal mass peak of the size distribution â in these
cases bimodal â is on the smaller or larger mass
mode.
The resulting deviations of the IWC reach factors of up to 10 or
even more for losses as well as for enrichment. Since the mean mass
size of ice crystals increases with temperature, losses are more
pronounced at higher temperatures, while at lower temperatures IWC is
more affected by enrichment.
In contrast, in the cases where the hygrometer inlets were mounted
at the fuselage side or bottom, the agreement of IWCs is most
frequently within a factor of 2.5 or better â due to
less disturbed ice particle sampling, as expected from theory â independently of the
mean ice crystal sizes. The rather large scatter between IWC
measurements reflects, for example, cirrus cloud inhomogeneities and
instrument uncertainties as well as slight sampling biases which
might also occur on the side or bottom of the fuselage and under the
wing. However, this scatter is in the range of other studies and
represent the current best possible IWC recording on fast-flying
aircraft.</p
UTLS water vapour from SCIAMACHY limb measurements V3.01 (2002-2012)
The SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) aboard the Envisat satellite provided measurements from August 2002 until April 2012. SCIAMACHY measured the scattered or direct sunlight using different observation geometries. The limb viewing geometry allows the retrieval of water vapour at about 10â25 km height from the near-infrared spectral range (1353â1410 nm). These data cover the upper troposphere and lower stratosphere (UTLS), a region in the atmosphere which is of special interest for a variety of dynamical and chemical processes as well as for the radiative forcing. Here, the latest data version of water vapour (V3.01) from SCIAMACHY limb measurements is presented and validated by comparisons with data sets from other satellite and in situ measurements. Considering retrieval tests and the results of these comparisons, the V3.01 data are reliable from about 11 to 23 km and the best results are found in the middle of the profiles between about 14 and 20 km. Above 20 km in the extra tropics V3.01 is drier than all other data sets. Additionally, for altitudes above about 19 km, the vertical resolution of the retrieved profile is not sufficient to resolve signals with a short vertical structure like the tape recorder. Below 14 km, SCIAMACHY water vapour V3.01 is wetter than most collocated data sets, but the high variability of water vapour in the troposphere complicates the comparison. For 14â20 km height, the expected errors from the retrieval and simulations and the mean differences to collocated data sets are usually smaller than 10% when the resolution of the SCIAMACHY data is taken into account. In general, the temporal changes agree well with collocated data sets except for the Northern Hemisphere extratropical stratosphere, where larger differences are observed. This indicates a possible drift in V3.01 most probably caused by the incomplete treatment of volcanic aerosols in the retrieval. In all other regions a good temporal stability is shown. In the tropical stratosphere an increase in water vapour is found between 2002 and 2012, which is in agreement with other satellite data sets for overlapping time periods
Cancer and heart attack survivorsâ expectations of employment status: results from the English Longitudinal Study of Ageing
Background: Sociodemographic, health- and work-related factors have been found to influence return to work in cancer survivors. It is feasible though that behavioural factors, such as expectation of being at work, could also affect work-related outcomes. Therefore, the effect of earlier identified factors and expectation of being at work on future employment status in cancer survivors was explored. To assess the degree to which these factors specifically concern cancer survivors, a comparison with heart attack survivors was made. Methods: Data from the English Longitudinal Study of Ageing were used. Cancer and heart attack survivors of working age in the UK were included and followed up for 2 years. Baseline characteristics of both cancer and heart attack survivors were compared regarding employment status. Univariate and multivariate regression analyses were performed in survivors at work, and the interaction between independent variables and diagnose group was assessed. Results: In cancer survivors at work (N = 159), alcohol consumption, participating in moderate or vigorous sport activities, general health and participation were univariate associated with employment status at two-year followup. Only fair general health (compared to very good general health) remained statistically significant in the multivariate model (OR 0.31; 95% CI 0.13â0.76; p = 0.010). In heart attack survivors at work (N = 78), gender, general health and expectation of being at work were univariate associated with employment status at follow-up. Female gender (OR 0.03; 95% CI 0.00â0.57; p = 0.018) and high expectation of being at work (OR 10.68; 95% CI 1.23â93.92; p = 0.033) remained significant in the multivariate model. The influence of gender (p = 0.066) and general health (p = 0.020) regarding employment status was found to differ significantly between cancer and heart attack survivors. Conclusions: When predicting future employment status in cancer survivors in the UK, general health is the most relevant factor to consider. While expectation of being at work did not show any significant influence in cancer survivors, in heart attack survivors, it should not be disregarded though, when developing interventions to affect their employment status. Future research should focus on more specific measures for expectation, and additional behavioural factors, such as self-efficacy, and their effect on employment status
Usefulness and engagement with a guided workbook intervention (WorkPlan) to support work related goals among cancer survivors
Background: Returning to work after cancer is associated with improved physical and psychological functioning, but managing this return can be a challenging process. A workbook based intervention (WorkPlan) was developed to support return-to-work among cancer survivors. The aim of this study was to explore how participants using the workbook engaged with the intervention and utilised the content of the intervention in their plan to return-to-work. Methods: As part of a feasibility randomised controlled trial, 23 participants from the intervention group were interviewed 4-weeks post intervention. Interviews focussed on intervention delivery and data was analysed using Framework analysis. Results: Participants revealed a sense of empowerment and changes in their outlook as they transitioned from patient to employee, citing the act of writing as a medium for creating their own return-to-work narrative. Participants found the generation of a return-to-work plan useful for identifying potential problems and solutions, which also served as a tool for aiding discussion with the employer on return-to-work. Additionally, participants reported feeling less uncertain and anxious about returning to work. Timing of the intervention in coordination with ongoing cancer treatments was crucial to perceived effectiveness; participants identified the sole or final treatment as the ideal time to receive the intervention. Conclusions: The self-guided workbook supports people diagnosed with cancer to build their communication and planning skills to successfully manage their return-to-work. Further research could examine how writing plays a role in this process
Return to work of breast cancer survivors: a systematic review of intervention studies
<p>Abstract</p> <p>Background</p> <p>Breast cancer management has improved dramatically in the past three decades and as a result, a population of working age women is breast cancer survivor. Interventions for breast cancer survivors have shown improvements in quality of life and in physical and psychological states. In contrast, efforts aimed at stimulating re-employment and return-to-work interventions for breast cancer survivors have not kept pace. The objective of this review was to study the effects and characteristics of intervention studies on breast cancer survivors in which the outcome was return to work.</p> <p>Methods</p> <p>The Cochrane Controlled Trials Register (The Cochrane Library, Issue 4, 2006), Medline, Ovid, EMBASE and PsychInfo were systematically searched for studies conducted between 1970 to February 2007. Intervention studies for female breast cancer survivors that were focused on return to work were included.</p> <p>Results</p> <p>Our search strategy identified 5219 studies. Four studies out of 100 potentially relevant abstracts were selected and included 46â317 employed women who had had mastectomy, adjuvant therapy and rehabilitation, with the outcome return to work. The intervention programs focused on improvement of physical, psychological and social recovery. Although a substantial percentage (between 75% to 85%) of patients included in these studies returned to work after rehabilitation, it is not clear whether this proportion would have been lower for patients without counseling or exercise, or any other interventions, as three out of four studies did not include a comparison group.</p> <p>Conclusion</p> <p>The most important finding of this review is the lack of methodologically sound intervention studies on breast cancer survivors with the outcome return to work. Using evidence from qualitative and observational studies on cancer and the good results of intervention studies on return to work programs and vocational rehabilitation, return to work interventions for breast cancer survivors should be further developed and evaluated.</p
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