Aerosol climatology using a tunable spectral variability cloud screening of AERONET data

Can cloud screening of an aerosol data set, affect the aerosol optical thickness (AOT) climatology? Aerosols, humidity and clouds are correlated. Therefore, rigorous cloud screening can systematically bias towards less cloudy conditions, underestimating the average AOT. Here, using AERONET data we show that systematic rejection of variable atmospheric optical conditions can generate such bias in the average AOT. Therefore we recommend (1) to introduce more powerful spectral variability cloud screening and (2) to change the philosophy behind present aerosol climatologies: Instead of systematically rejecting all cloud contaminations, we suggest to intentionally allow the presence of cloud contamination, estimate the statistical impact of the contamination and correct for it. The analysis, applied to 10 AERONET stations with approx. 4 years of data, shows almost no change for Rome (Italy), but up to a change in AOT of 0.12 in Beijing (PRC). Similar technique may be explored for satellite analysis, e.g. MODIS

Size resolved aerosol respiratory doses in a Mediterranean urban area: From PM10 to ultrafine particles

In the framework of the 2017 "carbonaceous aerosol in Rome and Environs" (CARE) experiment, particle number size distributions have been continuously measured on February 2017 in downtown Rome. These data have been used to estimate, through MPPD model, size and time resolved particle mass, surface area and number doses deposited into the respiratory system. Dosimetry estimates are presented for PM10, PM2.5, PM1 and Ultrafine Particles (UFPs), in relation to the aerosol sources peculiar to the Mediterranean basin and to the atmospheric conditions. Particular emphasis is focused on UFPs and their fraction deposited on the olfactory bulb, in view of their possible translocation to the brain. The site of PM10 deposition within the respiratory system considerably changes, depending on the aerosol sources and then on its different size distributions. On making associations between health endpoints and aerosol mass concentrations, the relevant coarse and fine fractions would be more properly adopted, because they have different sources, different capability of penetrating deep into the respiratory system and different toxicological implications. The separation between them should be set at 1ʵm, rather than at 2.5ʵm, because the fine fraction is considerably less affected by the contribution of the natural sources. Mass dose is a suitable metric to describe coarse aerosol events but gives a poor representation of combustion aerosol. This fraction of particles, made of UFPs and of accumulation mode particles (mainly with size below 0.2ʵm), is of high health relevance. It elicited the highest oxidative activity in the CARE experiment and is properly described by the particle surface area and by the number metrics. Such metrics are even more relevant for the UFP doses deposited on the olfactory bulb, in consideration of the role recognized to oxidative stress in the progression of neurodegenerative diseases. Such metrics would be more appropriate, rather than PMx mass concentrations, to correlate neurodegenerative pathologies with aerosol pollution

CMS physics technical design report : Addendum on high density QCD with heavy ions

Peer reviewe

Some remarks about lidar data preprocessing and different implementations of the gradient method for determining the aerosol layers

The determination of atmospheric aerosol layers from lidar returns is possible through automated algorithms. This product is useful, for example, in monitoring the Boundary Layer Height (BLH) as well as volcanic plumes. Aerosol layers are usually detected using the gradient method, i.e. by finding the inflection points of the range-corrected backscattered signal. These points can be either calculated as the minima of the numerical derivative of the signal, or by zero-order Digital Wavelet Transforms. Since for low signal-to-noise ratios the numerical derivative is very prone to noise-induced fluctuations, a moving average is often performed. We demonstrate why this procedure should be avoided in the gradient calculation. Finally, an alternative approach to the Digital Wavelet Transform is proposed, giving the same results but lowering the computational times by about one order of magnitude.</p

Bilateral Phrenic Neuropathy Responsive to Intravenous Immunoglobulin Treatment

The aetiology of phrenic neuropathy is often unknown, but immune mechanisms may play a role. In a typical case of bilateral phrenic neuropathy with paradoxical breathing (video), an inflammatory pathogenesis was suggested by prolonged distal latency of phrenic nerve compound muscle action potentials in nerve conduction studies and a clear-cut albumin-cytologic dissociation. This encouraged us to treat the patient with a standard dose of intravenous immunoglobulin. After obtaining a strong improvement at spirometry, we repeated the second cycle of intravenous immunoglobulin and observed normalization of symptoms within few weeks and no relapse after 3 years. This case suggests that lumbar puncture should be performed in the acute phase of phrenic neuropathies to detect potential responders to immunomodulatory treatment

Determination of the Optical Thickness and Effective Particle Radius of Clouds from Reflected Solar Radiation Measurements. Part 1: Theory

A method is presented for determining the optical thickness and effective particle radius of stratiform cloud layers from reflected solar radiation measurements. A detailed study is presented which shows that the cloud optical thickness (τc) and effective particle radius (re) of water clouds can be determined solely from reflection function measurements at 0.75 and 2.16 μm, provided τc ≳ 4 and re ≳ 6 μm. For optically thin clouds the retrieval becomes ambiguous, resulting in two possible solutions for the effective radius and optical thickness. Adding a third channel near 1.65 μm does not improve the situation noticeably, whereas the addition of a channel near 3.70 μm reduces the ambiguity in deriving the effective radius. The effective radius determined by the above procedure corresponds to the droplet radius at some optical depth within the cloud layer. For clouds having τc ≳ 8, the effective radius determined using the 0.75 and 2.16 μm channels can be regarded as 85%-95% of the radius at cloud top, which corresponds in turn to an optical depth 20%-40% of the total optical thickness of the cloud layer

Estimate of the Arctic Convective Boundary Layer Height from Lidar Observations: A Case Study

A new automated small size lidar system (microlidar or MULID) has been developed and employed to perform aerosol measurements since March 2010 at Ny Ålesund (78.9°N, 11.9°E), Svalbard. The lidar observations have been used to estimate the PBL height by using the gradient method based on abrupt changes in the vertical aerosol profile and monitor its temporal evolution. The scope of the present study is to compare several approaches to estimate the PBL height, by using lidar observations, meteorological measurements by radio soundings, and a zero-order one-dimensional model based on a parameterization of the turbulent kinetic energy budget within the mixing layer, under the assumptions of horizontal homogeneity, and neglecting radiation and latent heat effects. A case study is presented here for a convective PBL, observed in June 2010 in order to verify whether the Gradient Method can be applied to lidar measurements in the Arctic region to obtain the PBL height. The results obtained are in good agreement with the PBL height estimated by the analysis of thermodynamic measurements obtained from radio sounding and with the model

The Italian Automated Lidar-Ceilometer Network (ALICEnet): infrastructure, algorithms and applications

ALICEnet is a network of Automated Lidar Ceilometers (ALCs) operating across Italy. The geographical distribution of the measuring stations, extending from the north to the south of the country, allows monitoring of aerosol vertical profiles over a wide range of environmental and atmospheric conditions, dominated, for example, by anthropogenic particle production, Saharan dust transport or volcanic ash advections. The network, coordinated by CNR-ISAC and involving different institutions, is also a contributor of E-PROFILE, a EUMETNET program for surface-based profile observations. The ALICEnet infrastructure and data processing flow (including signal correction and automatic calibration procedures) are here described, together with the inversion and retrieval algorithms. These latter allow to retrieve the aerosol properties over the vertical profile, to identify different layers, and to assess the atmospheric boundary layer (ABL) characteristics, such as the ABL and mixing layer height. Based on this setup, both use of near-real time data (e.g., to monitor aerosol transport events) and long-term studies (e.g., evaluation of aerosol climatological, site-dependent characteristics) will be possible. In the present contribution, we focus on two examples of application: a case of long-range transport of Saharan dust and smoke, occurred over Rome in July 2017 during the EMERGE campaign, and the analysis of the climatological features of the mesoscale circulation between the Po Valley and the Alps. For both cases the ALICEnet retrieval procedure is validated based on independent measurements from the ground. Benefits from coupling with other remote sensing instruments, satellite radiometers, and atmospheric dispersion models are discussed