reference period
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Diversity ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 57
Marika Galanidi ◽  
Argyro Zenetos

In the present work, we analysed time series data on the introduction of new non-indigenous species (NIS) in the Mediterranean between 1970 and 2017, aiming to arrive at recommendations concerning the reference period and provisional threshold values for the NIS trend indicator. We employed regression analysis and breakpoint structural analysis. Our results confirm earlier findings that the reference conditions differ for the four Mediterranean subregions, and support a shortening of the reporting cycle from six to three years, with a two-year time lag for the ensuing assessment. Excluding Lessepsian fishes and parasites, the reference period, defined as the most recent time segment with stable mean new NIS values, was estimated as 1997–2017 for the eastern Mediterranean, 2012–2017 for the central Mediterranean, 2000–2017 for the Adriatic and 1970–2017 for the western Mediterranean. These findings are interpreted primarily on the basis of a basin scale temperature regime shift in the late 1990s, shifts in driving forces such as shellfish culture, and as a result of intensified research efforts and citizen scientist initiatives targeting NIS in the last decade. The threshold values, i.e., the three-year average new NIS values during the reference period, are indicative and will ultimately depend on the choice of species and pathways to be used in the calculations. This is discussed through the prism of target setting in alignment with specific management objectives.

2022 ◽  
Tiago Silva ◽  
Jakob Abermann ◽  
Brice Noël ◽  
Sonika Shahi ◽  
Willem Jan van de Berg ◽  

Abstract. Climate change is particularly strong in Greenland primarily as a result of changes in advection of heat and moisture fluxes from lower latitudes. The atmospheric structures involved influence the surface mass balance and their pattern are largely explained by climate oscillations which describe the internal climate variability. Based on a clustering method, we combine the Greenland Blocking Index and the North Atlantic Oscillation index with the vertically integrated water vapor to analyze inter-seasonal and regional impacts of the North Atlantic influence on the surface energy components over the Greenland Ice Sheet. In comparison to the reference period (1959–1990), the atmosphere has become warmer and moister during recent decades (1991–2020) for contrasting atmospheric circulation patterns. Particularly in the northern regions, increases in tropospheric water vapor enhance incoming longwave radiation and thus contribute to surface warming. Surface warming is most evident in winter, although its magnitude and spatial extent depend on the prevailing atmospheric configuration. Relative to the reference period, increases in sensible heat flux in the summer ablation zone are found irrespective of the atmospheric circulation pattern. Especially in the northern ablation zone, these are explained by the stronger katabatic winds which are partly driven by the larger surface pressure gradients between the ice/snow-covered surface and adjacent seas, and by the larger temperature gradient between near-surface air and the air above. Increases in net shortwave radiation are mainly connected to high-pressure systems. Whereas in the southern part of Greenland the atmosphere has gotten optical thinner, thus allowing more incoming shortwave radiation to reach the surface, in the northern part the incoming shortwave radiation flux has changed little with respect to the reference period, but the surface albedo decreased due to the expansion of the bare ice area.

Hydrology ◽  
2022 ◽  
Vol 9 (1) ◽  
pp. 12
Mouhamed Idrissou ◽  
Bernd Diekkrüger ◽  
Bernhard Tischbein ◽  
Felix Op de Hipt ◽  
Kristian Näschen ◽  

Water scarcity for smallholder farming in West Africa has led to the shift of cultivation from uplands to inland valleys. This study investigates the impacts of climate and land use/land cover (LULC) change on water resources in an intensively instrumented inland valley catchment in Southwestern Burkina Faso. An ensemble of five regional climate models (RCMs) and two climate scenarios (RCP 4.5 and RCP 8.5) was utilized to drive a physically-based hydrological model WaSiM after calibration and validation. The impact of climate change was quantified by comparing the projected period (2021–2050) and a reference period (1971–2000). The result showed a large uncertainty in the future change of runoff between the RCMs. Three models projected an increase in the total runoff from +12% to +95%, whereas two models predicted a decrease from −44% to −24%. Surface runoff was projected to show the highest relative change compared to the other runoff components. The projected LULC 2019, 2025, and 2030 were estimated based on historical LULC change (1990–2013) using the Land Change Modeler (LCM). A gradual conversion of savanna to cropland was shown, with annual rates rom 1 to 3.3%. WaSiM was used to simulate a gradual increase in runoff with time caused by this land use change. The combined climate and land use change was estimated using LULC-2013 in the reference period and LULC-2030 as future land use. The results suggest that land use change exacerbates the increase in total runoff. The increase in runoff was found to be +158% compared to the reference period but only +52% without land use change impacts. This stresses the fact that land use change impact is not negligible in this area, and climate change impact assessments without land use change analysis might be misleading. The results of this study can be used as input to water management models in order to derive strategies to cope with present and future water scarcities for smallholder farming in the investigated area.

2021 ◽  
Robi Dijk ◽  
Patricia Plaum ◽  
Stan Tummers ◽  
Frits van Osch ◽  
Dennis Barten ◽  

Background: Since the COVID-19 pandemic, there has been a decrease in emergency department(ED) utilization. Although this has been thoroughly characterized for the first wave(FW), studies during the second wave(SW) are limited. We examined the changes in ED utilization between the FW and SW, compared to 2019 reference periods. Methods: We performed a retrospective analysis of ED utilization in 3 Dutch hospitals in 2020. The FW and SW (March until June and September until December, respectively) were compared to the reference periods in 2019. ED visits were labeled as (non)COVID suspected. Findings: During the FW and SW ED visits decreased by 20.3% and 15.3%, respectively, when compared to reference periods in 2019. During both waves high urgency visits significantly increased with 3.1% and 2.1%, and admission rates (ARs) increased with 5.0% and 10.4%. Trauma related visits decreased by 5.2% and 3.4%. During the SW we observed less COVID-related visits compared to the FW (4,407 vs 3,102 patients). COVID related visits were significantly more often in higher need of urgent care and ARs where at least 24.0% higher compared to non COVID visits. Interpretation: During both COVID-19 waves ED visits were significantly reduced, with the most distinct decline during the FW. ED patients were more often triaged as high urgent and the ARs were increased compared to the reference period in 2019, reflecting a high burden on ED resources. These findings indicate the need to gain more insight into motives of patients to delay or avoid emergency care during pandemics and prepare EDs for future pandemics.

Frans Dijkstra ◽  
Rob de Vos ◽  
Jan Ruis ◽  
Marcel Crok

Abstract In 2016, the Royal Dutch Meteorological Office (KNMI) homogenized the daily temperature records for the Netherlands from 1901 to 1950 to allow a realistic comparison of the temperatures from 1901 to the present. The homogenizations for the main station De Bilt were carried out using a Percentile Matching Method (PMM) with one reference station and a 56-month reference period. In this study, it is shown that the corrections in the number of tropical days (maximum temperature ≥ 30 °C) depend strongly on the choice of the reference station and the length of the reference period. A total of 116 different variants of the homogenization of De Bilt were carried out, using all combinations of five reference stations, five reference periods, two ways to calculate percentiles, and two ways to smooth the data. The parameters used for the KNMI’s current homogenization of De Bilt result in a very sharp decrease of tropical days, which is not replicated by the majority of the 116 variants. Moreover, after homogenization, De Bilt appears to be an outlier compared to the other meteorological stations. Therefore, the current homogenized estimates of tropical days for De Bilt should be treated with considerable caution.

Water ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 3358
Patrik Sleziak ◽  
Roman Výleta ◽  
Kamila Hlavčová ◽  
Michaela Danáčová ◽  
Milica Aleksić ◽  

The changing climate is a concern with regard to sustainable water resources. Projections of the runoff in future climate conditions are needed for long-term planning of water resources and flood protection. In this study, we evaluate the possible climate change impacts on the runoff regime in eight selected basins located in the whole territory of Slovakia. The projected runoff in the basins studied for the reference period (1981–2010) and three future time horizons (2011–2040, 2041–2070, and 2071–2100) was simulated using the HBV (Hydrologiska Byråns Vattenbalansavdelning) bucket-type model (the TUW (Technische Universität Wien) model). A calibration strategy based on the selection of the most suitable decade in the observation period for the parameterization of the model was applied. The model was first calibrated using observations, and then was driven by the precipitation and air temperatures projected by the KNMI (Koninklijk Nederlands Meteorologisch Instituut) and MPI (Max Planck Institute) regional climate models (RCM) under the A1B emission scenario. The model’s performance metrics and a visual inspection showed that the simulated runoff using downscaled inputs from both RCM models for the reference period represents the simulated hydrological regimes well. An evaluation of the future, which was performed by considering the representative climate change scenarios, indicated that changes in the long-term runoff’s seasonality and extremality could be expected in the future. In the winter months, the runoff should increase, and decrease in the summer months compared to the reference period. The maximum annual daily runoff could be more extreme for the later time horizons (according to the KNMI scenario for 2071–2100). The results from this study could be useful for policymakers and river basin authorities for the optimum planning and management of water resources under a changing climate.

Atmosphere ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1549
Tomasz Turek ◽  
Ewa Diakowska ◽  
Joanna A. Kamińska

Due to the COVID-19 pandemic, there are series of negative economic consequences, however, in limiting mobility and reducing the number of vehicles, positive effects can also be observed, i.e., improvement of air quality. The paper presents an analysis of air quality measured by concentrations of NO2, NOx and PM2.5 during the most restrictive lockdown from 10 March to 31 May 2020 on the case of Wrocław. The results were compared with the reference period—2016–2019. A significant reduction in traffic volume was identified, on average by 26.3%. The greatest reduction in the concentration of NO2 and NOx was recorded at the station farthest from the city center, characterized by the lowest concentrations: 20.1% and 22.4%. Lower reduction in the average concentrations of NO2 and NOx was recorded at the municipal station (7.9% and 7.7%) and the communication station (6.7% and 10.2%). Concentrations of PMs in 2020 were on average 15% and 13.4% lower than in the reference period for the traffic station and the background station. The long-term impact of the lockdown on air quality was also examined. The analysis of the concentrations of the pollutants throughout 2020, and in the analyzed period of 2021, indicated that the reduction of concentrations and the improvement in air quality caused by the restrictions should be considered as a temporary anomaly, without affecting long-term changes and trends.

Water ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3138
Mercy Ilbay-Yupa ◽  
Franklin Ilbay ◽  
Ricardo Zubieta ◽  
Mario García-Mora ◽  
Paolo Chasi

The effects of climate change projected for 2050 to 2079 relative to the 1968–2014 reference period were evaluated using 39 CMIP5 models under the RCP8.5 emissions scenario in the Guayas River basin. The monthly normalized precipitation index (SPI) was used in this study to assess the impact of climate change for wet events and droughts from a meteorological perspective. The GR2M model was used to project changes in the streamflow of the Daule River. The climate projection was based on the four rigorously selected models to represent the climate of the study area. On average, an increase in temperature (~2 °C) and precipitation (~6%) is expected. A 7% increase in precipitation would result in a 10% increase in streamflow for flood periods, while an 8% decrease in precipitation could result in approximately a 60% reduction in flow for dry periods. The analysis of droughts shows that they will be more frequent and prolonged in the highlands (Andes) and the middle part of the basin. In the future, wet periods will be less frequent but of greater duration and intensity on the Ecuadorian coast. These results point to future problems such as water deficit in the dry season but also increased streamflow for floods during the wet season. This information should be taken into account in designing strategies for adaptation to climate change.

2021 ◽  
Vol 108 (Supplement_8) ◽  
Christos Kollatos ◽  
Ali Alhussain ◽  
Sarmad Hanna

Abstract Aim During the COVID-19 pandemic, Swedish health care centers were restructured. This was accompanied by changes in the surgical programme. The aim of this study was to determine the effects of COVID-19 on emergency and elective hernia surgeries in a Swedish health-care region. Material and Methods This was a retrospective, observational cohort study. Data from inguinal and ventral hernia surgeries were retrieved from a medical database using procedure codes from all three hospitals in Region Jönköping County from March 1, 2019 to January 31, 2021. The participants were divided into two groups: COVID-19 group (March 1, 2020 - January 31, 2021) and reference group (March 1, 2019 - January 31, 2020). The incidence rate (IR) and relative risk (RR) of operations over different time frames were analyzed. Results A total 1351 participants met the inclusion criteria. 590 were operated during the COVID-19 period and 761 during the reference period. The IR of elective operations was decreased during the COVID-19 pandemic; 146 operations/100.000 population vs 192 operations/100.000 population during the reference period. RR was 0,76 (95% CI 0.6813-0.8545, p < 0.0001). Moreover, IR of emergency operations decreased insignificantly during the COVID-19 pandemic; 17,5 operations/100.000 population vs 19,4 operations/100.000 population during the reference period. RR was 0,9 (95% CI 0.6404- 1.2649, p 0.5441). No significant variations in the emergency operations have identified when different time frames were compared. Conclusions There is no evidence to support that COVID-19 pandemic has increased emergency hernia operations during the studied period despite the significant reduction of elective operations.

2021 ◽  
Vol 22 (1) ◽  
Kamal Preet Kaur ◽  
Mavish Safdar Chaudry ◽  
Emil Loldrup Fosbøl ◽  
Lauge Østergaard ◽  
Christian Torp-Pedersen ◽  

Abstract Background Cardiovascular diseases (CVD) and infections are recognized as serious complications in patients with end stage kidney disease. However, little is known about the change over time in incidence of these complications. This study aimed to investigate temporal changes in CVD and infective diseases across more than two decades in chronic dialysis patients. Methods All patients that initiated peritoneal dialysis (PD) or hemodialysis (HD) between 1996 and 2017 were identified and followed until outcome (CVD, pneumonia, infective endocarditis (IE) or sepsis), recovery of kidney function, end of dialysis treatment, death or end of study (December 31st, 2017). The calendar time was divided into 5 periods with period 1 (1996–2000) being the reference period. Adjusted rate ratios were assessed using Poisson regression. Results In 4285 patients with PD (63.7% males) the median age increased across the calendar periods from 65 [57–73] in 1996–2000 to 69 [55–76] in 2014–2017, (p <  0.0001). In 9952 patients with HD (69.2% males), the overall median age was 71 [61–78] without any changes over time. Among PD, an overall non-significant decreasing trend in rate ratios (RR) of CVD was found, (p = 0,071). RR of pneumonia increased significantly throughout the calendar with an almost two-fold increase of the RR in 2014–2017 (RR 1.71; 95% CI 1.46–2.0), (p <  0.001), as compared to the reference period. The RR of IE decreased significantly until 2009 (RR 0.43; 95% CI 0.21–0.87), followed by a return to the reference level in 2010–2013 (RR 0.87; 95% CI 0.47–1.60 and 2014–2017 (RR 1.1; 95% CI 0.59–2.04). A highly significant (p <  0.001) increase in sepsis was revealed across the calendar periods with an almost 5-fold increase in 2014–2017 (RR 4.69 95% CI 3.69–5.96). In HD, the RR of CVD decreased significantly (p <  0.001) from 2006 to 2017 (RR 0.85; 95% CI 0.79–0.92). Compared to the reference period, the RR for pneumonia was high during all calendar periods (p <  0.05). The RR of IE was initially unchanged (p = 0.4) but increased in 2010–2013 (RR 2.02; 95% CI 1.43–2.85) and 2014–2017 (RR 3.39; 95% CI 2.42–4.75). No significant changes in sepsis were seen. Conclusion Across the two last decades the RR of CVD has shown a decreasing trend in HD and PD patients, while RR of pneumonia increased significantly, both in PD and in HD. Temporal trends of IE in HD, and particularly of sepsis in PD were upwards across the last decades.

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