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Added value of amateur observational network for high-resolution climatological analysis: a case study in the aterno valley, abruzzo, Italy
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Atti del Convegno Evidenze del Cambiamento climatico: dalla scala globale a quella locale
No full textAn important fingerprint of wildfires on the European aerosol load
No full textWildland fires represent the major source of fine aerosols, i.e., atmospheric particles with diameters <1 mu m. The largest numbers of these fires occur in Africa, Asia and South America, but a not negligible fraction also occurs in Eastern Europe and former USSR countries, particularly in the Russian Federation, Ukraine and Kazakhstan. Besides the impact of large forest fires, recent studies also highlighted the crucial role played by routine agricultural fires in Eastern Europe and Russia on the Arctic atmosphere. An evaluation of the impact of these fires over Europe is currently not available. The assessment of the relative contribution of fires to the European aerosol burden is hampered by the complex mixing of natural and anthropogenic particle types across the continent. In this study we use long term (20022007) satellite-based fires and aerosol data coupled to atmospheric trajectory modelling in the attempt to estimate the wildfires contribution to the European aerosol optical thickness (AOT). Based on this dataset, we provide evidence that fires-related aerosols play a major role in shaping the AOT yearly cycle at the continental scale. In general, the regions most impacted by wildfires emissions and/or transport are Eastern and Central Europe as well as Scandinavia. Conversely, a minor impact is found in Western Europe and in the Western Mediterranean. We estimate that in spring 5 to 35% of the European fine fraction AOT (FFAOT) is attributable to wildland fires. The estimated impact maximizes in April (20-35%) in Eastern and Central Europe as well as in Scandinavia and in the Central Mediterranean. An important contribution of wildfires to the FFAOT is also found in summer over most of the continent, particularly in August over Eastern Europe (28%) and the Mediterranean regions, from Turkey (34%) to the Western Mediterranean (25%). Although preliminary, our results suggest that this fires-related, continent-wide haze plays a not negligible role on the European radiation budget, and possibly, on the European air quality, therefore representing a clear target for mitigation
Analysis of Radon Near-Surface Measurements, Using Co-Located Ozone Data, Radio-Sounding Vertical Profiles, Sensible Heat Flux and Back-Trajectory Calculation
Full text linkSimultaneous and co-located observations of nearsurface
Radon-222, ozone and meteorological parameters in a
central Italy observation site operated by the University of
L’Aquila (Italy), are used to study the physical drivers of the radon
abundance during night-time hours. The knowledge of the potential
temperature vertical gradient in the surface layer of nocturnal
thermal inversion is made possible using co-located radio-sounding
vertical profiles of pressure and temperature, thus making possible
to indirectly infer the local surface flux of atmospheric radon
(16 ± 6 mBq m-2 s-1). The dynamical removal due to turbulent
convective motions is found to be the dominant controlling process,
determining large differences in the near-surface radon abundance
between stable and unstable conditions of the nocturnal Planetary
Boundary Layer (PBL). Usual unstable PBL conditions during
daytime hours induce an effective dynamical vertical dilution of
surface radon, which rapidly reaches a quasi-steady-state abundance
during mid-day and afternoon hours, with very low
concentration values (5.1 ± 2.0 Bq m-3). Using back-trajectory
reanalyses, estimates of local radon fluxes and vertical mixing
efficiencies inside the PBL along the air mass latitudinal-longitudinal
path and finally the irreversible radon loss due to radioactive
decay, we have explored the fraction of daytime radon
attributable to long-range advection in the continental nearmountain
measurement site of L’Aquila (44 ± 18%)
Building a High‐Resolution Climate Gridded Dataset in Complex Terrain: Validating Different Methods in the Abruzzo Region in Italy
No full textPresent-day radiative effect from radiation-absorbing aerosols in snow
Full text linkBlack carbon (BC), brown carbon (BrC), and
soil dust are the most important radiation-absorbing aerosols
(RAAs). When RAAs are deposited on the snowpack, they
lower the snow albedo, causing an increase in the solar radiation
absorption. The climatic impact associated with the
snow darkening induced by RAAs is highly uncertain. The
Intergovernmental Panel on Climate Change (IPCC) Special
Report on the Ocean and Cryosphere in a Changing Climate
(SROCC) attributes low and medium confidence to radiative
forcing (RF) from BrC and dust in snow, respectively. Therefore,
the contribution of anthropogenic sources and carbonaceous
aerosols to RAA RF in snow is not clear. Moreover, the
snow albedo perturbation induced by a single RAA species
depends on the presence of other light-absorbing impurities
contained in the snowpack. In this work, we calculated the
present-day RF of RAAs in snow starting from the deposition
fields from a 5-year simulation with the GEOS-Chem global
chemistry and transport model. RF was estimated taking into
account the presence of BC, BrC, and mineral soil dust in
snow, simultaneously. Modeled BC and black carbon equivalent
(BCE) mixing ratios in snow and the fraction of light absorption
due to non-BC compounds (fnon-BC) were compared
with worldwide observations.We showed that BC, BCE, and
fnon-BC, obtained from deposition and precipitation fluxes,
reproduce the regional variability and order of magnitude
of the observations. Global-average all-sky total RAA-, BC-
, BrC-, and dust-snow RF were 0.068, 0.033, 0.0066, and
0.012Wm2, respectively. At a global scale, non-BC compounds
accounted for 40% of RAA-snow RF, while anthropogenic RAAs contributed to the forcing for 56 %. With regard
to non-BC compounds, the largest impact of BrC has
been found during summer in the Arctic (C0.13Wm2).
In the middle latitudes of Asia, the forcing from dust in
spring accounted for 50% (C0.24Wm2) of the total RAA
RF. Uncertainties in absorbing optical properties, RAA mixing
ratio in snow, snow grain dimension, and snow cover
fraction resulted in an overall uncertainty of 50 %/C61 %,
57 %/C183 %, 63 %/C112 %, and 49 %/C77% in BC-
, BrC-, dust-, and total RAA-snow RF, respectively. Uncertainty
upper bounds of BrC and dust were about 2 and 3 times
larger than the upper bounds associated with BC. Higher BrC
and dust uncertainties were mainly due to the presence of
multiple absorbing impurities in the snow. Our results highlight
that an improvement of the representation of RAAs in
snow is desirable, given the potential high efficacy of this
forcing
First Implementation of the WRF-CHIMERE-EDGAR Modeling System Over Argentina
No full textAir quality monitoring and research have been gaining importance in Argentina and Latin America, mainly in megacities where pollution reaches critical levels as in other places of the world. This work is a first attempt at simulating pollution levels at the country scale, in order to support air quality management and forecasting activities. We implemented the global scale inventory of anthropogenic emissions EDGAR v4.2 into the CHIMERE chemistry-transport model, driven by WRF meteorological fields, at a resolution of about 50 km, a performance evaluation of the modeling system is presented by the use of ground-based and satellite data. The lack of monitoring stations in the country constrained the evaluation to the March-May 2009 time period in three cities. We obtain a generally large underestimation of nitrogen oxides and particulate matter, but a good simulation of the daily cycles. The magnitude of pollution levels is underestimated probably because of the misrepresentation of the monitoring stations (sites heavily affected by local traffic) and of the coarse resolution of the model. Nitrogen dioxide tropospheric column obtained by the OMI sensor (onboard Aura/NASA) was used to evaluate spatial correspondence with the simulation outputs, revealing that spatial features are broadly captured by the model. Further work would imply an emission inventory refinement and the use of other satellite data available considering other periods of time; however, a more dense and representative air quality monitoring network throughout the country is very much needed
Analysis of Rainfall Erosivity Trends 1980–2018 in a Complex Terrain Region (Abruzzo, Central Italy) from Rain Gauges and Gridded Datasets
Full text linkThe erosive capacity of precipitation depends on its intensity, volume, and duration. The rainfall erosivity factor (R) of the Universal Soil Loss Equation (USLE) requires high frequency (subhourly) data. When these are not available, R can be estimated from simplified indices such as the Modified Fournier Index (MFI), the Precipitation Concentration Index (PCI), and the Seasonality Index (SI), which are computed from monthly precipitation. We calculated these indices for 34 stations in the complex terrain Abruzzo region (central Italy) during 1980–2018, based on both gauge (point) and grid datasets. Using 30-min rainfall data of 14 stations, we verified that MFI and PCI are reliable predictors of R (R2 = 0.91, RMSE = 163.6 MJ mm ha−1 h−1 year−1). For MFI, grid data do not capture the peaks in high-altitude stations and the low values in some inland areas, detected by the point dataset. Grid data show significant MFI positive trends in 74% of the stations, while the point data display significant positive trends in only 26% of stations and significant negative trends in four stations in the inland areas. The grid data complex orography requires preliminary validation work
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