ABSTRACT
Stability indices evaluate the atmospheric instability which is a basic and precursor ingredient needed for storms to develop. In this study, we evaluated changes of some atmospheric ...stability indices, namely Convective Available Potential Energy (CAPE), Deep‐Layer Wind Shear (SHR06) and Severe Weather Threat (SWEAT), for the Iberian Peninsula, for a future climate scenario (2081–2100), considering the greenhouse gases emission scenario RCP8.5, relative to a historical period (1986–2005). The Weather Research and Forecasting (WRF) was forced by ERA‐Interim, for validation purposes, and by the Max Planck Institute (MPI) Earth System Model. The novelty of this approach is the study of extreme weather events through the evaluation of conditions favourable to their development instead of directly studying them. The latter approach may be problematic since these phenomena are known to be poorly reproduced by models due to their relatively low resolution and parametrization processes such as clouds and precipitation. Our approach uses stability indices obtained from simulated variables, such as temperature and winds, which are, generally, much better simulated by models. The WRF‐MPI model was validated against WRF‐ERA. Overall, the WRF‐MPI simulates well the three indices considered here, particularly CAPE, when compared to WRF‐ERA. Their spatial patterns were similar, although there is a systematic positive bias in the WRF‐MPI. This is minimized when we evaluate climate change by computing differences of WRF‐MPI simulations between the future climate scenario and the historical period.
In the future, it is estimated a significant increase of CAPE and SWEAT intensity, mainly in summer and autumn. It is also expected a decrease of SHR06 intensity in summer and autumn and an increase in the remaining seasons. Therefore, we may anticipate an increase of the probability of occurrence of environments favourable to the development of severe weather, mainly in the Mediterranean, mostly associated to higher CAPE values.
Seasonal normalized distribution of environments for various CAPE and SHR06 bins, simulated by WRF‐MPI for the recent‐past period (1986–2005) for (a) summer (June through August). The solid black line represents the discriminant between favourable conditions for the development of severe and non‐severe environments (CAPE × SHR06 = 10 000 m3 s−3). Seasonal difference between the long future (2081–2100) and the recent past (1986–2005) for (b) summer. Statistical significant differences (t‐test) at 5% significance level are represented by black dots. Notice that we used a logarithmic scale in both the horizontal and vertical axes and the scales of both figures are different.
In this work, bioclimatic parameters and indices relevant to the grapevine are estimated for the years 2000 (recent-pat), 2049 (medium-term future) and 2097 (long-term future), based on very high ...resolution (1 km × 1 km) MPI-WRF RCP8.5 climate simulations. The selected parameters and indices are the mean temperature during the grapevine growing season period (April to October, Tgs), the cumulative rainfall during the grapevine growing season period (Pgs), the Winkler index (WI), the Huglin heliothermic index (HI), the night cold index (CI) and the dryness index (DI). In general, a significant increase in mean temperature during the grapevine growing season period is observed, together with a significant decrease in precipitation. The recent-past WI is associated with the production of high-quality wines; the higher values predicted for the future represent intensive production of wines of intermediate quality. The HI shows the passage of a grapevine growing region considered as temperate-warm to a warm category of higher helio-thermicity. The recent-past CI indicates very cool conditions (associated with quality wines), while in the future there is a tendency for temperate or warmer nights. Finally, DI indicates an increase in water stress considered already high under the recent-past climate conditions. These results point to an increased climatic stress on the Douro region wine production and increased vulnerability of its vine varieties, providing evidence to support strategies aimed to preserve the high-quality wines in the region and their typicality in a sustainable way.
Recently, a significant increase in the atmospheric moisture
content has been documented over the Arctic, where both local contributions
and poleward moisture transport from lower latitudes can play ...a role. This
study focuses on the anomalous moisture transport events confined to long
and narrow corridors, known as atmospheric rivers (ARs), which are expected
to have a strong influence on Arctic moisture amounts, precipitation, and
the energy budget. During two concerted intensive measurement campaigns –
Arctic CLoud Observations Using airborne measurements during polar Day
(ACLOUD) and the Physical feedbacks of Arctic planetary boundary layer, Sea
ice, Cloud and AerosoL (PASCAL) – that took place at and near Svalbard,
three high-water-vapour-transport events were identified as ARs, based on
two tracking algorithms: the 30 May event, the 6 June event, and the 9 June 2017 event. We explore
the temporal and spatial evolution of the events identified as ARs and the
associated precipitation patterns in detail using measurements from the French (Polar
Institute Paul Emile Victor) and German (Alfred Wegener Institute for Polar
and Marine Research) Arctic Research Base (AWIPEV) in Ny-Ålesund,
satellite-borne measurements, several reanalysis products (the European Centre for
Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA) Interim
(ERA-Interim); the ERA5 reanalysis; the Modern-Era Retrospective
analysis for Research and Applications, version 2 (MERRA-2); the
Climate Forecast System version 2 (CFSv2); and the Japanese 55-Year
Reanalysis (JRA-55)), and the HIRHAM regional climate model version 5 (HIRHAM5).
Results show that the tracking algorithms detected the events differently, which is
partly due to differences in the spatial and temporal resolution as well as differences in the
criteria used in the tracking algorithms. The first event extended from
western Siberia to Svalbard, caused mixed-phase precipitation, and was
associated with a retreat of the sea-ice edge. The second event, 1 week later,
had a similar trajectory, and most precipitation occurred as rain, although mixed-phase precipitation or only snowfall occurred in some areas, mainly
over the coast of north-eastern Greenland and the north-east of Iceland, and no
differences were noted in the sea-ice edge. The third event showed a
different pathway extending from the north-eastern Atlantic towards Greenland
before turning south-eastward and reaching Svalbard. This last AR caused high
precipitation amounts on the east coast of Greenland in the form of rain and
snow and showed no precipitation in the Svalbard region. The vertical profiles
of specific humidity show layers of enhanced moisture that were concurrent with
dry layers during the first two events and that were not captured by all of the
reanalysis datasets, whereas the HIRHAM5 model misrepresented humidity at all vertical levels. There was an increase in wind speed with height during the first
and last events, whereas there were no major changes
in the wind speed during the second event. The accuracy of the representation of wind speed by the
reanalyses and the model depended on the event. The objective of this
paper was to build knowledge from detailed AR case studies, with the
purpose of performing long-term analysis. Thus, we adapted a regional AR
detection algorithm to the Arctic and analysed how well it identified
ARs, we used different datasets (observational, reanalyses, and model) and
identified the most suitable dataset, and we analysed the evolution of the ARs
and their impacts in terms of precipitation. This study shows the importance
of the Atlantic and Siberian pathways of ARs during spring and
beginning of summer in the Arctic; the significance of the AR-associated strong heat increase, moisture
increase, and precipitation phase transition; and the requirement for
high-spatio-temporal-resolution datasets when studying these intense short-duration events.
The Arctic is warming faster than the global average and any other region of a similar size. One important factor in this is the poleward atmospheric transport of heat and moisture, which contributes ...directly to the surface and air warming. In this case study, the atmospheric circulation and spatio-temporal structure of a moisture intrusion event is assessed, which occurred from 5 to 7 June 2017 over the Nordic seas during an intensive measurement campaign over Svalbard. This analysis focuses on high-spatial-resolution simulations with the ICON (ICOsahedral Non-hydrostatic) model which is put in context with coarser-resolution runs as well the ERA5 reanalysis. A variety of observations including passive microwave satellite measurements is used for evaluation. The global operational ICON forecasts from the Deutscher Wetterdienst (DWD) at 13 km horizontal resolution are used to drive high-resolution Limited-Area Mode (LAM) ICON simulations over the Arctic with 6 and 3 km horizontal resolutions. The results show the skilful capacity of the ICON-LAM model to represent the observed spatio-temporal structure of the selected moisture intrusion event and its signature in the temperature, humidity and wind profiles, and surface radiation. In several aspects, the high-resolution simulations offer a higher accuracy than the global simulations and the ERA5 reanalysis when evaluated against observations. One feature where the high-resolution simulations demonstrated an advanced skill is the representation of the changing vertical structure of specific humidity and wind associated with the moisture intrusion passing Ny-Ålesund (western Svalbard); the humidity increase at 1–2 km height topped by a dry layer and the development of a low-level wind jet are best represented by the 3 km simulation. The study also demonstrates that such moisture intrusions can have a strong impact on the radiative and turbulent heat fluxes at the surface. A drastic decrease in downward shortwave radiation by ca. 500 W m−2 as well as an increase in downward longwave radiation by ca. 100 W m−2 within 3 h have been determined. These results highlight the importance of both moisture and clouds associated with this event for the surface energy budget.
Ozone is the most damaging phytotoxic air pollutant to crop yield quantity and quality. This study presents the validation of a simulation with the WRF-CHIMERE modelling system in order to assess the ...risk of phytotoxicity by tropospheric ozone for an important and characteristic Mediterranean crop, i.e. the grapevine. The study region was the Douro wine region in Portugal, which is characterized by a rugged relief and a Mediterranean climate. The simulation covered a reference grapevine growing season in the Northern Hemisphere (from April to September 2017), during which a particular measuring campaign was also carried out. The validation of the meteorological simulations on a daily and hourly time resolution was performed based on data from three weather stations, namely on temperature, global solar radiation, relative humidity, wind speed and direction values. The ozone phytotoxicity was assessed with data from two measuring stations. A specific grapevine growth parameter based on monitored phenological observations was introduced for ozone stomatal uptake assessment. Concerning meteorology, validation statistics were acceptable and within the range of what has been found in other regional climate modelling simulations. Ground-level ozone-based values were calculated for a better assessment of the phytotoxic risk, in particular cumulative standards for vegetation protection. Stomatal flux estimates were within the range of those measured for the local cultivars in the field campaign when there was not severe water stress limitation. Both field and statistically adjusted model values indicate that considerable areas in the Demarcated Douro Region of Portugal can exceed the critical exposure values for vegetation according to current European legislation standards. Moreover, measured and simulated results indicate an ozone impact on grapevine yield and quality in the target region because the exposure- and flux-based indices exceed the criteria based on current open-top-chamber experimental knowledge.
Meteorological and ground-level O3 patterns were successfully replicated in complex terrain under Mediterranean conditions by RCM. Without a soil water limiting factor, grapevine O3 stomatal uptake simulations were closer to those present in the study area under less water limited conditions. Current ground-level O3 can already pose a potential threat for a renowned wine producing region such as the Demarcated Douro Region in Portugal. Ground-level O3 extremes should also be considered along heatwaves and drought as compromising factors for grapevine yield and quality. Display omitted
•Meteorological and ground-level O3 patterns were successfully replicated in Mediterranean complex terrain by RCM.•Grapevine O3 stomatal uptake simulations were closer to those present under less water limited conditions.•Current ground-level O3 can already pose a potential threat for a wine producing area such as the Douro Region in Portugal.•Ground-level O3 extremes should also be considered along heatwaves and drought as compromising factors for the grapevine.
The two concerted field campaigns, Arctic CLoud Observations Using airborne measurements during polar Day (ACLOUD) and the Physical feedbacks of Arctic planetary boundary level Sea ice, Cloud and ...AerosoL (PASCAL), took place near Svalbard from 23 May to 26 June 2017. They were focused on studying Arctic mixed-phase clouds and involved observations from two airplanes (ACLOUD), an icebreaker (PASCAL) and a tethered balloon, as well as ground-based stations. Here, we present the synoptic development during the 35-day period of the campaigns, using near-surface and upper-air meteorological observations, as well as operational satellite, analysis, and reanalysis data. Over the campaign period, short-term synoptic variability was substantial, dominating over the seasonal cycle. During the first campaign week, cold and dry Arctic air from the north persisted, with a distinct but seasonally unusual cold air outbreak. Cloudy conditions with mostly low-level clouds prevailed. The subsequent 2 weeks were characterized by warm and moist maritime air from the south and east, which included two events of warm air advection. These synoptical disturbances caused lower cloud cover fractions and higher-reaching cloud systems. In the final 2 weeks, adiabatically warmed air from the west dominated, with cloud properties strongly varying within the range of the two other periods. Results presented here provide synoptic information needed to analyze and interpret data of upcoming studies from ACLOUD/PASCAL, while also offering unprecedented measurements in a sparsely observed region.
Water vapor is an important component in the water and energy cycle of the Arctic. Especially in light of Arctic amplification, changes in water vapor are of high interest but are difficult to ...observe due to the data sparsity of the region. The ACLOUD/PASCAL campaigns performed in May/June 2017 in the Arctic North Atlantic sector offers the opportunity to investigate the quality of various satellite and reanalysis products. Compared to reference measurements at R/V Polarstern frozen into the ice (around 82∘ N, 10∘ E) and at Ny-Ålesund, the integrated water vapor (IWV) from Infrared Atmospheric Sounding Interferometer (IASI) L2PPFv6 shows the best performance among all satellite products. Using all radiosonde stations within the region indicates some differences that might relate to different radiosonde types used. Atmospheric river events can cause rapid IWV changes by more than a factor of 2 in the Arctic. Despite the relatively dense sampling by polar-orbiting satellites, daily means can deviate by up to 50 % due to strong spatio-temporal IWV variability. For monthly mean values, this weather-induced variability cancels out, but systematic differences dominate, which particularly appear over different surface types, e.g., ocean and sea ice. In the data-sparse central Arctic north of 84∘ N, strong differences of 30 % in IWV monthly means between satellite products occur in the month of June, which likely result from the difficulties in considering the complex and changing surface characteristics of the melting ice within the retrieval algorithms. There is hope that the detailed surface characterization performed as part of the recently finished Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) will foster the improvement of future retrieval algorithms.
Heat waves are large-scale atmospheric phenomena that may cause heat stress in ecosystems and socio-economic activities. In cities, morbidity and mortality may increase during a heat wave, ...overloading health and emergency services. In the face of climate change and associated warming, cities need to adapt and mitigate the effects of heat waves. This study suggests a new method to evaluate heat waves’ impacts on cities by considering some aspects of heat waves that are not usually considered in other similar studies. The method devises heat wave quantities that are easy to calculate; it is relevant to assessing their impacts and permits the development of adaptation measures. This study applies the suggested method to quantify various aspects of heat waves in Lisbon for future climate projections considering future mid-term (2046–2065) and long-term (2081–2100) climates under the RCP8.5 greenhouse emission scenario. This is achieved through the analysis of various regional climate simulations performed with the WRF model and an ensemble of EURO-CORDEX models. This allows an estimation of uncertainty and confidence of the projections. To evaluate the climate change properties of heat waves, statistics for future climates are compared to those for a reference recent climate. Simulated temperatures are first bias corrected to minimize the model systematic errors relative to observations. The temperature for mid and long-term futures is expected to increase relative to the present by 1.6 °C and 3.6 °C, respectively, with late summer months registering the highest increases. The number of heat wave days per year will increase on average from 10, in the present climate, to 38 and 63 in mid and long-term climates, respectively. Heat wave duration, intensity, average maximum temperature, and accumulated temperature during a heat wave will also increase. Heat waves account for an annual average of accumulated temperature of 358 °C·day in the present climate, while in the mid and long-term, future climates account for 1270 °C·day and 2078 °C·day, respectively. The largest increases are expected to occur from July to October. Extreme intensity and long-duration heat waves with an average maximum temperature of more than 40 °C are expected to occur in the future climates.
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