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[1] We investigate the uncertainties in the carbon dioxide (CO2) mixing ratio and inferred surface flux associated with boundary layer processes and advection by using mixed-layer theory. By extending the previous analysis presented by Pino et al. (2012), new analytical expressions are derived to quantify the uncertainty of CO2 mixing ratio or surface flux associated to, among others, boundary layer depth, early morning CO2 mixing ratio at the mixed layer or at the free atmosphere; or CO2 advection. We identify and calculate two sorts of uncertainties associated to the CO2 mixing ratio and surface flux: instantaneous and past (due to advection). The numerical experiments are guided and constrained by meteorological and CO2 observations taken at the Cabauw 213 m tower. We select 2 days (25 September 2003 and 12 March 2004) with a well-defined convective boundary layer but different CO2 advection contributions. Our sensitivity analysis shows that uncertainty of the CO2 advection in the boundary layer due to instantaneous uncertainties represents at 1600 LT on 12 March 2004 a contribution of 2¿ppm and 0.072 mg m-2s-1 in the uncertainty of the CO2 mixing ratio and inferred surface flux, respectively. Taking into account that the monthly averaged minimum CO2 surface flux for March 2004 was -0.55 mg m-2s-1, the error on the surface flux is on the order of 10%. By including CO2 advection in the analytical expressions, we demonstrate that the uncertainty of the CO2 mixing ratio or surface flux also depends on the past uncertainties of the boundary layer depth.

Guided and constrained by a complete data set of surface and upper-air observations taken during the fifth Intensive Observational Period (IOP-05, 25th June 2011) of the Boundary Layer Late Afternoon and Sunset Turbulence (BLLAST) experiment, we reconstruct the evolution of the atmospheric boundary layer (ABL) using mixed-layer theory. The model results are corroborated by UHF radar and multiple profiles done by unmanned and manned aircraft platforms as well as by radiosondes. During the first morning hours, the ABL is mainly controlled by surface forcing, reaching a depth between 500 and 600 meter. At these levels, large-scale subsidence motions become similar in magnitude to the entrainment velocity and the ABL-growth becomes nearly zero. This equilibrium is maintained until the afternoon transition where mixed-layer model results and observations show a decrease of the boundary layer depth in spite of well mixed observed vertical profiles of heat and moisture. We discuss potential explanations to the development of subsidence motions associated to mesoscale flows driven by the proximity of the Pyrenees mountain range and to large-scale forcing. The heat and moisture budgets are also further analyzed with the mixed layer model. We find strong indications of the active role of heat and moisture advection required to reproduce the observed diurnal variability in temperature and specific humidity. By quantifying the budget terms, we are able to obtain a first estimation of the contribution of advection to the heat and moisture budgets. To complete the analysis, we extend the study to examine the turbulent characteristics of the ABL by using aircraft measurements combined with large-eddy simulations. In so doing, we are able to study the role of wind (directional) shear in the development and maintenance of the ABL. IOP05 was characterized by easterly flows within the ABL and westerly winds aloft. Our findings stress the important role of large scale forcing in understanding the ABL development at various stages during BLLAST. The proposed method can also be very useful to support the further interpretation of observations and mesoscale model experiments.

Mixed-layer theory and large-eddy simulations are used to analyze the dynamics of the boundary layer on two intensive operational periods during the Boundary Layer Late Afternoon and Sunset Turbulence (BLLAST) campaign: 1st and 2nd of July 2011, when convective boundary layers (CBLs) were observed. Continuous measurements made by several remote sensing and in situ instruments in combination with radiosoundings, and measurements done by unmanned aerial vehicles and an aircraft probed the vertical structure and the temporal evolution of the boundary layer. Mixed layer theory (Tennekes and Driedonks, 1981) and the Dutch Atmospheric Large-Eddy Simulation model (DALES, Heus et al., 2011) are set to reproduce and analyze the dynamics of the atmosphere during these two days. The initial vertical profiles of potential temperature, specific humidity and wind, and the temporal evolution of the surface heat and moisture fluxes prescribed in the model runs are inspired by the observations taken at the two supersites that concentrated most of the instrumentation during the campaign. For DALES the initial profile (at 7 UTC on 1st July and 5 UTC on 2nd July) takes into account the existence of a residual layer above the nocturnal stable layer observed during the early morning. The mixed layer model is initialized when a well-developed convective boundary layer was observed, from 10 UTC. Due to the surface heterogeneity of the area, the models were run separately to analyze the boundary layer conditions at the two different supersites. First, the research focuses on the role-played by the residual layer (RL) on the evolution of the boundary layer. By using DALES, we show the importance of the dynamics of the boundary layer during the previous night to the development of the boundary layer at the morning. DALES, which takes into account the residual layer, is capable to model the observed sudden increase of the boundary layer depth and of the potential temperature occurred during the morning transition. There are different sources, which can be the responsible of the overshooting for instance surface and entrainment fluxes or large-scale phenomena. Analyzing the entrainment buoyancy heat flux, a large increase is obtained by the simulation when the residual layer is incorporated in the mixed layer by the growing convective boundary layer. Consequently, a precise definition of the characteristics of the residual layer is fundamental even though it is complex because the evolution of the main variables in the residual layer during the previous night depends on different factors such as radiation divergence or advection. Once the boundary layer is fully developed around midday, both models are used to study the dynamics of the boundary layer during the studied days. The models are able to reproduce the evolution of the boundary layer depth, potential temperature and specific humidity from late morning. They are also used to analyze the role played by subsidence and large-scale advection during the afternoon transition. During 1st of July, heat and moisture advection are negligible contributions to the heat or moisture budget, respectively, but subsidence plays an important role in the turbulence decay during the afternoon when a clear decrease of boundary layer depth was observed. On 2nd of July the main boundary layer variables follow similar evolution to the previous day, but with a lower maximum of the boundary layer depth. However, in the last part of the day, a front was approaching advecting moisture over the area and increasing the cloud cover. To summarize, the residual layer and large-scale phenomena play a crucial role in the development of the boundary layer during some days of the BLLAST campaign.

Goal of this study is to quantify the effect of wind shear on the turbulent transport in the dry Convective Boundary Layer (CBL). Questions addressed include the effect of wind shear on the depth of the mixed layer, the effect of wind shear on the depth and structure of the capping inversion, and the effect of wind shear on the entrainment of free tropospheric air into the mixed layer. Following previous research, we use numerical experiments performed with the DALES LES-model varying both the strength and vertical profile of the geostrophic wind. In contrast to previous investigations, the effect of wind shear is analysed using a General Structure Model (GSM), instead of a more traditional zero-order or first order approach. We have selected the GSM framework because it allows for a more detailed assessment of the vertical structure of the capping inversion. Concepts derived within this framework can therefore be more easily transfered to global and meso-scale models turbulent transport parameterizations, as especially in conditions with high wind shear the capping inversion is often of such thickness that it can comprises multiple model layers in state-of-the art meso-scale and Numerical Weather Prediction (NWP) models. The effect of wind shear on the parameterized turbulence transport in NWP and meso-scale models is examined using the Eddy Diffusivity Mass-Flux (EDMF) approach. In contrast with traditional approaches based on K-theory, the EDMF framework acknowledges that turbulent transfer in the CBL can be decomposed into transport due to vertical advection by confined updrafts and diffusive transport (K-theory) within the updrafts and the environmental air. The DALES LES-model results are used to evaluate the effect of wind shear on the different parameters of the EDMF approach. Parameters include the release height and the excess temperature of a parcel that is employed to monitor the updrafts, the vertical velocity of an updraft parcel as it rises through the CBL and penetrates into the capping inversion, and the fraction of air occupied by the updrafts. This study thus extends previous research showing the performance of the EDMF approach in representing turbulent transfer in both clear and cloud-topped boundary layers without wind shear.

BLLAST (Boundary Layer Late Afternoon and Sunset Turbulence) aims at better understanding the thermodynamical processes that occur during the late afternoon in the lower troposphere. In direct contact with the Earth surface, the atmospheric boundary layer is governed by buoyant and mechanical turbulence, with a strong diurnal cycle. The late afternoon transition, from the daytime dry convection to the night-time stable boundary layer, still raises a lot of issues and is poorly represented in the meteorological models. Yet, it plays an important role in the transport and diffusion of trace gases, like water vapour, carbon dioxide, pollutants, dusts... How does the afternoon decay in the lower troposphere happen, when the surface sensible heat flux start to sharply decrease ? How do the scales of the motions and transfers change ? What is the impact on the chemical closure and transport of trace gases and aerosols ? How to properly represent those processes in the meteorological models ? An international group is working on those issues by use of observations and numerical simulations, in order to improve our understanding and representation of the turbulent processes of the boundary-layer late afternoon transition. The roles of surface heterogeneity, entrainment at the boundary layer top, large scale subsidence, radiative effects, advection and gravity waves are studied. Due to the large lack of observations during this phase, a field campaign was organized in the vicinity of a 60-m instrumented tower of Laboratoire d'Aérologie, near the Pyrenees ridge in Southwest France, from 14 June to 8 July 2011. This experiment puts together complementary observation resources, in order to obtain an exhaustive description of the boundary-layer dynamical processes, its vertical structure, and the spatial variability related to surface heterogeneity. Continuous measurements (UHF radar and sodar wind profilers, lidars, ground stations), and intensive observations with aircraft, unmanned aerial vehicles, tethered balloons and radiosoundings were used. Particular emphasis was placed to bridge the different spatial scales with an integrated analysis of the observations and a complete numerical model hierarchy. This presentation will give an overview of the field experiment, with an emphasis on specific and innovative instrumental aspects, and with some preliminary results, introducing various contributions of BLLAST participants that will be shown along the 20th BLT conference.

International audience; Oxygen minimum zones (OMZs), known as suboxic layers which are mainly localized in the Eastern Boundary Upwelling Systems, have been expanding since the 20th "high CO2" century, probably due to global warming. OMZs are also known to significantly contribute to the oceanic production of N2O, a greenhouse gas (GHG) more efficient than CO2. However, the contribution of the OMZs on the oceanic sources and sinks budget of CO2, the main GHG, still remains to be established. We present here the dissolved inorganic carbon (DIC) structure, associated locally with the Chilean OMZ and globally with the main most intense OMZs (O2-1) in the open ocean. To achieve this, we examine simultaneous DIC and O2 data collected off Chile during 4 cruises (2000-2002) and a monthly monitoring (2000-2001) in one of the shallowest OMZs, along with international DIC and O2 databases and climatology for other OMZs. High DIC concentrations (>2225 μmol kg-1, up to 2350 μmol kg-1) have been reported over the whole OMZ thickness, allowing the definition for all studied OMZs a Carbon Maximum Zone (CMZ). Locally off Chile, the shallow cores of the OMZ and CMZ are spatially and temporally collocated at 21° S, 30° S and 36° S despite different cross-shore, long-shore and seasonal configurations. Globally, the mean state of the main OMZs also corresponds to the largest carbon reserves of the ocean in subsurface waters. The CMZs-OMZs could then induce a positive feedback for the atmosphere during upwelling activity, as potential direct local sources of CO2. The CMZ paradoxically presents a slight "carbon deficit" in its core (~10%), meaning a DIC increase from the oxygenated ocean to the OMZ lower than the corresponding O2 decrease (assuming classical C/O molar ratios). This "carbon deficit" would be related to regional thermal mechanisms affecting faster O2 than DIC (due to the carbonate buffer effect) and occurring upstream in warm waters (e.g., in the Equatorial Divergence), where the CMZ-OMZ core originates. The "carbon deficit" in the CMZ core would be mainly compensated locally at the oxycline, by a "carbon excess" induced by a specific remineralization. Indeed, a possible co-existence of bacterial heterotrophic and autotrophic processes usually occurring at different depths could stimulate an intense aerobic-anaerobic remineralization, inducing the deviation of C/O molar ratios from the canonical Redfield ratios. Further studies to confirm these results for all OMZs are required to understand the OMZ effects on both climatic feedback mechanisms and marine ecosystem perturbations.

The current version of the Dutch Atmospheric Large-Eddy Simulation (DALES) is presented. DALES is a large-eddy simulation code designed for studies of the physics of the atmospheric boundary layer, including convective and stable boundary layers as well as cloudy boundary layers. In addition, DALES can be used for studies of more specific cases, such as flow over sloping or heterogeneous terrain, and dispersion of inert and chemically active species. This paper contains an extensive description of the physical and numerical formulation of the code, and gives an overview of its applications and accomplishments in recent years.

International audience

Dry convective boundary layers characterized by a significant wind shear on the surface and at the inversion zone are studied by means of the mixed layer theory. Two different representations of the entrainment zone, each of which has a different closure of the entrainment heat flux, are considered. The simplest of the two is based on a sharp discontinuity at the inversion (zeroth--order jump), whereas the second one prescribes a finite depth of the inversion zone (first--order jump). By using scaling arguments, we parameterize the entrainment heat flux by analyzing each term of the Turbulent Kinetic Energy equation. This parameterization is implemented in the mixed layer model. Large-eddy simulation data is used to provide the initial conditions for the mixed layer models, and to verify their results. Two different atmospheric boundary layers with different stratification in the free atmosphere are analyzed. We show that, in spite of the simplicity of the zeroth--order jump model, it provides similar results to the first--order jump model, and can reproduce the evolution of the mixed layer variables obtained by the large--eddy simulations in sheared convective boundary layers. The mixed layer model with both closures compares better with the large--eddy simulation results in the atmospheric boundary layer characterized by a moderate wind shear and a weak temperature inversion

We evaluated risk factors for functional ovarian cysts using data from a case-control study conducted in Milan. Cases were 68 women with histologically confirmed functional cysts. Controls were 272 women admitted to hospital for acute conditions. Compared with women who were 11 years of age or younger at menarche, women who experienced menarche at 12-13 years or at 14 years or later had odds ratios (ORs) of 0.9 [95% confidence interval (CI) = 0.5-1.6] and 0.4 (95% CI = 0.2-0.9). In comparison with women reporting menstrual cycles lasting less than 26 days, the OR was 1.8 (95% CI = 0.7-5.0) in women reporting cycles lasting 26-30 days, 1.8 (95% CI = 0.4-7.4) in those reporting cycles greater than 30 days, and 1.9 (95% CI = 0.4-7.7) in those with totally irregular cycles. Body mass was inversely related to the risk of functional ovarian cysts: compared with women with a Quetelet index below 20, the OR was 0.9 (95% CI = 0.5-1.7) in those with an index in the range from 20-24 and 0.5 (95% CI = 0.2-1.2) in those with an index of 25 or more. We found little relation between the risk of functional ovarian cysts and education, smoking, marital status, or age at first marriage. For oral contraceptive use, we found an OR of 1.3 (95% CI = 0.7-2.6).

Objective To describe the clinical characteristics of a combination of midazolam and ketamine for procedural sedation and analgesia in adult emergency department (ED) patients. Methods This was a prospective, observational trial, conducted in the ED of an urban level II trauma center. Patients > or = 18 years of age requiring procedural sedation and analgesia were eligible, and enrolled patients received 0.07 mg/kg of intravenous midazolam followed by 2 mg/kg of intravenous ketamine. Vital signs were recorded at regular intervals. The adequacy of sedation, adverse effects, patient satisfaction, and time to reach discharge alertness were determined. Descriptive statistics were calculated using statistical analysis software. Results Seventy-seven patients were enrolled. Three were excluded due to protocol violations, three due to lack of documentation, and one due to subcutaneous infiltration of ketamine, leaving 70 patients for analysis. The average age was 31 years, and 41 (59%) were female. Indications for procedural sedation and analgesia included abscess incision and drainage (66%), fracture/joint reduction (26%), and other (8%). The mean dose of midazolam was 5.6 +/- 1.4 mg and the mean dose of ketamine was 159 +/- 42 mg. The mean time to achieve discharge criteria was 64 +/- 24 minutes. Five patients experienced mild emergence reactions, but there were no episodes of hallucinations, delirium, or other serious emergence reactions. Eighteen (25%) patients recalled dreaming while sedated; twelve (17%) were described as pleasant, two (3%) unpleasant, three (4%) both pleasant and unpleasant, and one (1%) neither pleasant nor unpleasant. There were four (6%) cases of respiratory compromise, two (3%) episodes of emesis, and one (1%) case of myoclonia. All of these were transient and did not result in a change in the patient's disposition. Only one (1%) patient indicated that she was not satisfied with the sedation regimen. Conclusions The combination of midazolam and ketamine provides effective procedural sedation and analgesia in adult ED patients, and appears to be safe.