Global model studies on the distribution and composition of potential atmospheric ice nuclei

Black carbon (BC) and mineral dust particles are among the most important atmospheric aerosol types forming ice crystals by heterogeneous nucleation, the so called potential ice nuclei (PIN). When emitted, most BC and dust particles are externally mixed with other aerosol compounds. Through coagulation with other particles and condensation of gases, externally mixed particles gain a liquid coating and are, therefore, transferred to an internal mixture. This ageing process is essential for the direct and indirect effect of BC and dust particles on the climate, since the coating changes their radiative and hygroscopic properties and consequently their cloud activation ability and lifetime. Moreover, laboratory studies have shown that a liquid coating influences the freezing properties of the particles and hence their behavior as ice nuclei. Due to large computational resources required, global climate models mostly parameterize the particle ageing by using estimated turnover times rather than simulating the ageing processes explicitly. In the present study the population of PIN in the global upper troposphere and lowermost stratosphere (UTLS) is characterized. To reach this goal the new aerosol model ECHAM5/MESSy-MADEsoot is developed. The aerosol module MADEsoot is able to simulate separately BC and dust particles in their different states of mixing (internally or externally mixed) and BC and dust free aerosols, as well as the relevant ageing processes of externally mixed particles. MADEsoot is implemented in the global climate model ECHAM5/MESSY. The resulting system is evaluated with aircraft and surface measurements and performs well both in the boundary layer and in the UTLS. ECHAM5/MESSy-MADEsoot (E5/M-MADEsoot) is the only existing model able to resolve the mixing state of BC and dust particles while giving a reliable representation of the UTLS. E5/M-MADEsoot is applied to characterize the PIN through their number and mass concentration, composition and mixing state. The results of this study show that PIN contribute only up to 0.7% to the total aerosol number concentration in the UTLS. At surface level PIN contribute between 10% and 50% to the total aerosol number concentration, where the highest values are reached over the major emission areas. Nearly all PIN in the UTLS are internally mixed with soluble material, while only up to the 3% of PIN is externally mixed. E5/M-MADEsoot allows also for the investigation of the ageing process of BC and dust particles and for the determination of its timescale, showing that the ageing process is mainly driven by the condensation of vapor. The timescale of the ageing process is calculated with E5/M-MADEsoot to be around some hours at surface level and some days in the UTLS, but shows a high geographical variability, especially in the boundary layer and in the lower troposphere. The timescale of the ageing process shows also a less pronounced seasonality, with higher values in winter and lower in summer

Differences in the Vertical and Microphysical Evolution of Volcanic and Pyrocumulonimbus Stratospheric Aerosol Plumes as Observed by CALIOP and CATS Satellite Lidar

For some time, volcanic eruptions have been thought to be the only significant direct injectors of aerosols in the stratosphere. However, recent fire seasons have featured fire events resulting in large volcanic-sized pyrocumulonimbus plumes of smoke aerosols reaching many kilometers into the lower stratosphere. To understand and model the effects of these pyrocumulonimbus events on stratospheric composition and climate, a natural analogy lies with better studied volcanic events; however, differences in plume composition may limit this comparison. Using satellite lidar from both CATS and CALIOP, we show that the stratospheric aerosol plumes from the record-setting Pacific Northwest pyrocumulonimbus event of 2017 and the Calbuco volcanic eruption of 2015 evolve differently both vertically and microphysically. Specifically, depolarization ratios indicate that this pyrocumulonimbus events aerosol particles became more irregularly shaped over time in contrast to volcanic aerosols which become more spherical over time. Accounting for these changes in aerosol properties may be significant in assessing the effects of pyrocumulonimbus events on the Earths radiative balance and aid in refining stratospheric aerosol typing algorithms to differentiate volcanic from pyrocumulonimbus plumes

Influence of Aerosol Heating on the Stratospheric Transport of the Mt. Pinatubo Eruption

On June 15th, 1991 the eruption of Mt. Pinatubo (15.1 deg. N, 120.3 Deg. E) in the Philippines injected about 20 Tg of sulfur dioxide in the stratosphere, which was transformed into sulfuric acid aerosol. The large perturbation of the background aerosol caused an increase in temperature in the lower stratosphere of 2-3 K. Even though stratospheric winds climatological]y tend to hinder the air mixing between the two hemispheres, observations have shown that a large part of the SO2 emitted by Mt. Pinatubo have been transported from the Northern to the Southern Hemisphere. We simulate the eruption of Mt. Pinatubo with the Goddard Earth Observing System (GEOS) version 5 global climate model, coupled to the aerosol module GOCART and the stratospheric chemistry module StratChem, to investigate the influence of the eruption of Mt. Pinatubo on the stratospheric transport pattern. We perform two ensembles of simulations: the first ensemble consists of runs without coupling between aerosol and radiation. In these simulations the plume of aerosols is treated as a passive tracer and the atmosphere is unperturbed. In the second ensemble of simulations aerosols and radiation are coupled. We show that the set of runs with interactive aerosol produces a larger cross-equatorial transport of the Pinatubo cloud. In our simulations the local heating perturbation caused by the sudden injection of volcanic aerosol changes the pattern of the stratospheric winds causing more intrusion of air from the Northern into the Southern Hemisphere. Furthermore, we perform simulations changing the injection height of the cloud, and study the transport of the plume resulting from the different scenarios. Comparisons of model results with SAGE II and AVHRR satellite observations will be shown

Impacts of the Mount Pinatubo eruption on ENSO in the GEOS seasonal-to-subseasonal forecasting system

The eruption of Mount Pinatubo in June 1991 introduced a perturbation of the Earth's global energy budget by increasing the stratospheric aerosol loading by an order of magnitude, with effects on the global climate. In this presentation we analyze the effects of the Mt. Pinatubo eruption on the seasonal forecast performed with Goddard Earth Observing System Seasonal-to Subseasonal (GEOS-S2S) system, an Earth System Model that includes an interactive ocean and a bulk aerosol model coupled to radiation. We performed 10-member ensembles for the year after the eruption (June 1991-May 1992) at ~0.5 horizontal resolution, with and without the inclusion of the Mt. Pinatubo eruption. In GEOS-S2S, the eruption leads to ta strengthening of El Nino peaking in January 1992. The strengthening is mainly due to the weakening of the trade winds, which is caused by a attening of the temperature gradient across the Pacic due to a differential response to the volcanic forcing between the central and eastern Pacic (ocean-dynamical thermostat). This response largely depends on the assumed size for the volcanic aerosols. Indeed, we performed simulations assuming a volcanic aerosol effective radius of 0.35 m (similar to tropospheric aerosol, and the default in GEOS) and 0.6 m (closer to observations of volcanic aerosol from Pinatubo-sized eruptions). We nd that in the latter case the tropical radiative forcing is lower, since smaller aerosols scatter shortwave radiation more eciently than larger ones. Accordingly, the impact on ENSO is not statistically signicant when a larger and more realistic particle radius is assumed

Mt. Pinatubo's Impacts on the GEOS Forecasting System

The eruption of Mount Pinatubo in June 1991 had dramatic effects on the global climate, introducing a sudden and extreme forcing on the radiative budget. In this presentation we analyze the effects of the Mt. Pinatubo eruption on the seasonal forecast performed with Goddard Earth Observing System (GEOS), an Earth System Model that includes a bulk aerosol model coupled to radiation and an interactive ocean.We performed three ten-member ensembles of 12-month simulations (June 1991-May 1992). These simulations were performed with a 0.5 longitude by 0.5 latitude horizontal resolution. Out of the three ensembles, one excludes the eruption, representing the control experiment. The other two ensembles include the eruption of Mt. Pinatubo, varying in the effective radius of the volcanic sulfate: one assumed the effective radius to be equal to 0.35 micron (as for tropospheric aerosol) and the other has the effective radius set to 0.6 micron (closer to natural observation). Through the analysis of the aerosol forcing results derived from the two assumptions, we can show how this forcing acts on the seasonal forecast system. In particular, we will focus on the impacts to the surface and ocean temperatures and precipitation

Macrophage Autophagy and Oxidative Stress: An Ultrastructural and Immunoelectron Microscopical Study

The word autophagy broadly refers to the cellular catabolic processes that lead to the removal of damaged cytosolic proteins or cell organelles through lysosomes. Although autophagy is often observed during programmed cell death, it may also serve as a cell survival mechanism. Accumulation of reactive oxygen species within tissues and cells induces various defense mechanisms or programmed cell death. It has been shown that, besides inducing apoptosis, oxidative stress can also induce autophagy. To date, however, the regulation of autophagy in response to oxidative stress remains largely elusive and poorly understood. Therefore, the present study was designed to examine the ratio between oxidative stress and autophagy in macrophages after oxidant exposure (AAPH) and to investigate the ultrastructural localization of beclin-1, a protein essential for autophagy, under basal and stressful conditions. Our data provide evidence that oxidative stress induces autophagy in macrophages. We demonstrate, for the first time by immunoelectron microscopy, the subcellular localization of beclin-1 in autophagic cells

The Response of Ozone and Nitrogen Dioxide to the Eruption of Mount Pinatubo

Observations have shown that the global mass of nitrogen dioxide decreased in both hemispheres in the year following the eruption of Mt. Pinatubo, indicating an enhanced heterogeneous chemistry. In contrast, the observed ozone response was largely asymmetrical with respect to the equator, with a decrease in the northern hemisphere and little change in the southern hemisphere. Simulations including enhanced heterogeneous chemistry due to the presence of the volcanic aerosol reproduce a decrease of ozone in the northern hemisphere, but also produce a comparable ozone decrease in the southern hemisphere, contrary to observations. Our simulations show that the heating due to the volcanic aerosol enhanced both the tropical upwelling and the extratropical downwelling. The enhanced extratropical downwelling, combined with the time of the eruption relative to the phase of the Brewer-Dobson circulation, increased the ozone in the southern hemisphere and counteracted the ozone depletion due to heterogeneous chemistry on volcanic aerosol

The Response of Ozone and Nitrogen Dioxide to the Eruption of Mt. Pinatubo

Observations have shown that the global mass of nitrogen dioxide decreased in both hemispheres in the year following the eruption of Mt. Pinatubo. In contrast, the observed ozone response was largely asymmetrical with respect to the equator, with a decrease in the northern hemisphere and little change and even a small increase in the southern hemisphere. Simulations including enhanced heterogeneous chemistry due to the presence of the volcanic aerosol reproduce a decrease of ozone in the northern hemisphere, but also produce a comparable ozone decrease in the southern hemisphere, contrary to observations. Our simulations show that the heating due to the volcanic aerosol enhanced both the tropical upwelling and the extratropical downwelling. The enhanced extratropical downwelling, combined with the time of the eruption relative to the phase of the Brewer-Dobson circulation, increased the ozone in the southern hemisphere and counteracted the ozone depletion due to heterogeneous chemistry on volcanic aerosol

Dispersion of the Volcanic Sulfate Cloud from the Mount Pinatubo Eruption

We simulate the transport of the volcanic cloud from the 1991 eruption of Mount Pinatubo with the GEOS-5 general circulation model. Our simulations are in good agreement with observational data. We tested the importance of initial condition corresponding to the specific meteorological situation at the time of the eruption by employing reanalysis from MERRA. We found no significant difference in the transport of the cloud. We show how the inclusion of the interaction between volcanic sulfate aerosol and radiation is essential for a reliable simulation of the transport of the volcanic cloud. The absorption of long wave radiation by the volcanic sulfate induces a rising of the volcanic cloud up to the middle stratosphere, combined with divergent motion from the latitude of the eruption to the tropics. Our simulations indicate that the cloud diffuses to the northern hemisphere through a lower stratospheric pathway, and to mid- and high latitudes of the southern hemisphere through a middle stratospheric pathway, centered at about 30 hPa. The direction of the middle stratospheric pathway depends on the season. We did not detect any significant change of the mixing between tropics and mid- and high latitudes in the southern hemisphere

The reduced content of estrogen and progesterone receptors in varicocele sperm may be indicative of the clinical surgery in the testicular varicocele

The enigma of testicular varicocele has always attracted the researcher’s attention as attested by the consistent literature, although conflicting data are reported (1). The detrimental role of varicocele in fertility is supported by the presence of an higher frequency of affected men in the infertile population (2). Varicocele influences male fertility in a variety of ways: spermatogenesis, semen quality and gamete biology. However, the mechanism/s by which the pathology impairs sperm production and activity, are not known yet. In spite of active interest, our knowledge about sperm molecular anatomy is very limited. Instead, it is important to fully elucidate the molecular sperm architecture, in order to clarify clinical cases of idiopathic infertility since not all the apparently normal sperm are able to fertilize. The presence of steroid/steroid receptor systems was demonstrated in human sperm, suggesting that both systemic and local steroids through sperm receptors, may influence male fertility. From our data, it emerged that varicocele causes a damage in the gamete at molecular level which includes a significant reduction of estrogen and progesterone receptors, opening a new chapter in the already multifaceted physiopathology of the disease. By the time of ovulation, estradiol and progesterone are almost everywhere in the egg microenvironment affecting ability of sperm to fertilize the oocyte. Therefore, the reduced responsiveness to these hormones as we observed in varicocele sperm, impedes their goal. Altogether, these studies constrain the need of further researches on the molecular anatomy of human male gamete both in healthy and in pathological conditions related the male genital apparatus, considering the high couple infertility linked to the male. The translation of these new researches in the clinic surgery of testicular varicocele needs to be taken into account since the reduction of steroid receptors in sperm implies a decline in the acquisition of fertilizing ability