This in-depth review covers recent developments in the area of metal dipyrrinato complexes based on dipyrrins, a unique class of compounds which have fascinated the scientific community due to their ...ease of syntheses, interesting photophysical properties, and diverse architectures arising from self-assembly. Dipyrrins can form stable, highly crystalline and neutral complexes with a various metal ions however underdeveloped photochemistry and photophysics of these compounds have limited their technological applications. Recently, the area of metal dipyrrin complexes has witnessed a large surge due to their promising use in the development of bright and stable emitters which find wide applications in sensing, materials science, generation of infinite architecture through self-assembly, and catalysis. In the present review, Section 2 describes syntheses of dipyrrins and their analogues; Section 3 covers the geometrical consideration of metal-dipyrrin complexes. Section 4 focuses on synthesis, while Section 5 includes properties of metal-dipyrrin complexes and their applications in sensing, supra-molecular assembly, coordination polymers, anticancer agents, nanotechnology and catalysis.
During August 25-30, 2017, Hurricane Harvey stalled over Texas and caused extreme precipitation, particularly over Houston and the surrounding area on August 26-28. This resulted in extensive ...flooding with over 80 fatalities and large economic costs. It was an extremely rare event: the return period of the highest observed three-day precipitation amount, 1043.4 mm 3dy−1 at Baytown, is more than 9000 years (97.5% one-sided confidence interval) and return periods exceeded 1000 yr (750 mm 3dy−1) over a large area in the current climate. Observations since 1880 over the region show a clear positive trend in the intensity of extreme precipitation of between 12% and 22%, roughly two times the increase of the moisture holding capacity of the atmosphere expected for 1 °C warming according to the Clausius-Clapeyron (CC) relation. This would indicate that the moisture flux was increased by both the moisture content and stronger winds or updrafts driven by the heat of condensation of the moisture. We also analysed extreme rainfall in the Houston area in three ensembles of 25 km resolution models. The first also shows 2 × CC scaling, the second 1 × CC scaling and the third did not have a realistic representation of extreme rainfall on the Gulf Coast. Extrapolating these results to the 2017 event, we conclude that global warming made the precipitation about 15% (8%-19%) more intense, or equivalently made such an event three (1.5-5) times more likely. This analysis makes clear that extreme rainfall events along the Gulf Coast are on the rise. And while fortifying Houston to fully withstand the impact of an event as extreme as Hurricane Harvey may not be economically feasible, it is critical that information regarding the increasing risk of extreme rainfall events in general should be part of the discussion about future improvements to Houston's flood protection system.
In the period 2015-2017, the Western Cape region has suffered from three consecutive years of below average rainfall-leading to a prolonged drought and acute water shortages, most prominently in the ...city of Cape Town. After testing that the precipitation deficit is the primary driver behind the reduced surface water availability, we undertake a multi-method attribution analysis for the meteorological drought, defined in terms of a deficit in the 3 years running mean precipitation averaged over the Western Cape area. The exact estimate of the return time of the event is sensitive to the number of stations whose data is incorporated in the analysis but the rarity of the event is unquestionable, with a return time of more than a hundred years. Synthesising the results from five different large model ensembles as well as observed data gives a significant increase by a factor of three (95% confidence interval 1.5-6) of such a drought to occur because of anthropogenic climate change. All the model results further suggest that this trend will continue with future global warming. These results are in line with physical understanding of the effect of climate change at these latitudes and highlights that measures to improve Cape Town's resilience to future droughts are an adaptation priority.
Defining El Niño indices in a warming climate van Oldenborgh, Geert Jan; Hendon, Harry; Stockdale, Timothy ...
Environmental research letters,
04/2021, Letnik:
16, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Abstract
Extreme weather and climate events associated with El Niño and La Niña cause massive societal impacts. Therefore, observations and forecasts are used around the world to prepare for such ...events. However, global warming has caused warm El Niño events to seem bigger than they are, while cold La Niña events seem smaller, in the commonly used Niño3.4 index (sea surface temperature (SST) anomalies over 5
∘
S–5
∘
N, 120–170
∘
W). We propose a simple and elegant adjustment, defining a relative Niño3.4 index as the difference between the original SST anomaly and the anomaly over all tropical oceans (20
∘
S–20
∘
N). This relative index describes the onset of convection better, is not contaminated by global warming and can be monitored and forecast in real-time. We show that the relative Niño3.4 index is better in line with effects on rainfall and would be more useful for preparedness for El Niño and La Niña in a changing climate and for El Niño—Southern Oscillation research.
Dhanalakshmi, S. and Kankara, R.S., 2020. Assessment on shoreline retreat in response to sea level rise – Chennai coast. In: Sheela Nair, L.; Prakash, T.N.; Padmalal, D., and Kumar Seelam, J. (eds.), ...Oceanic and Coastal Processes of the Indian Seas. Journal of Coastal Research, Special Issue No. 89, pp. 145-149. Coconut Creek (Florida), ISSN 0749-0208. In the present condition, the rise in sea level due to climate change is a serious threat for the environment. Global average sea levels are predicted as 1.8 mm/y during 1870-2009 and nearly 2.8 mm/y along the Indian Coast by Intergovernmental Panel on Climate change (IPCC). Impacts of rise in sea-level will be the loss of land in coastal areas through erosion, submergence of the coastal landscape and the threat of inundation. Shore erosion causes the shoreline to retreat and this leads to affecting the erosion zone by moving the shoreline inland. In this study, the attempt is made to demarcate the impact of sea level rise along the Chennai coast (Tamil Nadu) located along the southeast coast of India. This area experiences threat from many disasters such as storm, cyclone, flood, tsunami and long-term sea level rise. The shoreline has been extracted and using DSAS tool in ArcGIS, long-term (1990-2012, 1990-2013, 1990-2014, 1990-2015 and 1990-2016) were analyzed using Linear regression Rate and Weighted Linear Regression. 36.7% of the coast was seen with eroding condition. Overall long-term analysis trend suggest that more than 60% of the region falls in stable to low accretion. Projection of climate change-induced SLR at different RCPs (2.6, 4.5, 6, 8.5) of IPCC AR5 on different time scale (2025, 2050, 2075, 2100) for the coasts of Chennai. The values range from 7.1 cm to 36.87 cm for RCP 2.6; 7.37 cm to 49.84 cm for RCP 4.5; 7.16 cm to 51.75 cm for RCP 6; 7.38 cm to 77.88 cm for RCP 8.5. Shoreline retreat to an increase in local sea level was mapped using the Bruun Rule. Since the Bruun Rule (BR) has some limitations, the modified Bruun rule was used to analyze the inundation factor. The area of horizontal inundation is estimated as ∼1.6 km (Bruun rule) and ∼1.1 km (Modified Bruun Rule). The required data was processed using GIS environment. Since we adhere to the fact that the coastal change is not a periodical accumulation per year, but that it entraps a value of future crisis assessment and gives a literal warning about the shore to be persevered.
Noujas, V. and Kankara, R.S., 2020. Shoreline evolution along Vengurla, south Maharashtra coast using a numerical model. In: Sheela Nair, L.; Prakash, T.N.; Padmalal, D., and Kumar Seelam, J. (eds.), ...Oceanic and Coastal Processes of the Indian Seas. Journal of Coastal Research, Special Issue No. 89, pp. 105-110. Coconut Creek (Florida), ISSN 0749-0208. Shoreline are very dynamic and undergo changes due to natural and various human interventions. Shoreline evolution models are very useful tools to understand the shoreline change behaviour over a period of time. In this study, a shoreline evolution model is implemented along Vengurla, west coast of India. Major inputs required for estimation of shoreline evolution are nearshore wave climate, bathymetry, sediment characteristics and initial coastline. Nearshore wave climate at a depth of 15 m were collected using wave rider buoy during the year 2015. Bathymetry, nearshore sediments and shoreline information were also collected during the same year. Initially shoreline evolution model was set up for one year and the results were verified with field data. Model results showed a good comparison with the measured data, except the extreme northern boundary of the study region. Further model run continued for 10 years with calibrated model. The result indicates approximately 20-30 m beach advancement in the southern boundary of the study region. Erosion of about 65 m was observed in the extreme northern boundary in the first year which reduced during the subsequent years and finally stopped after 5 years as the shoreline attained equilibrium. The result of this study can be used by coastal managers for suggesting suitable management plans along the sector.
In July 2021 extreme rainfall across Western Europe caused severe flooding and substantial impacts, including over 200 fatalities and extensive infrastructure damage within Germany and the Benelux ...countries. After the event, a hydrological assessment and a probabilistic event attribution analysis of rainfall data were initiated and complemented by discussing the vulnerability and exposure context. The global mean surface temperature (GMST) served as a covariate in a generalised extreme value distribution fitted to observational and model data, exploiting the dependence on GMST to estimate how anthropogenic climate change affects the likelihood and severity of extreme events. Rainfall accumulations in Ahr/Erft and the Belgian Meuse catchment vastly exceeded previous observed records. In regions of that limited size the robust estimation of return values and the detection and attribution of rainfall trends are challenging. However, for the larger Western European region it was found that, under current climate conditions, on average one rainfall event of this magnitude can be expected every 400 years at any given location. Consequently, within the entire region, events of similar magnitude are expected to occur more frequently than once in 400 years. Anthropogenic climate change has already increased the intensity of the maximum 1-day rainfall event in the summer season by 3–19 %. The likelihood of such an event to occur today compared to a 1.2
∘
C cooler climate has increased by a factor of 1.2–9. Models indicate that intensity and frequency of such events will further increase with future global warming. While attribution of small-scale events remains challenging, this study shows that there is a robust increase in the likelihood and severity of rainfall events such as the ones causing extreme impacts in July 2021 when considering a larger region.
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