The circulation of the lower Capibaribe Estuary (Brazil) and its implications for the transport of scalars

The Capibaribe Estuary is a water body that crosses the Recife Metropolitan Area (RMA), one of the largest population centers in Brazil, and causes large pollutant loads and poor water quality. The fresh water inflow of wastewater from the RMA can account for three times the volume of the river discharge during the low discharge period. This article assesses the hydrodynamics and potential transport of particulate and dissolved scalars in this estuary. A field experiment was conducted to record the water level, current velocity, salinity, temperature and suspended particulate matter (SPM) contents during a full semi-diurnal tidal cycle. This experiment was performed during low river discharge and spring tide conditions. The estuary showed a partially mixed circulation pattern. The residual transport of water and salt were up estuary, while the SPM residual transport was down estuary. The former were understood as the effect of the residual circulation around the islands, while the latter was interpreted as a morphological factor inducing greater resuspension during the ebb, despite the symmetrical ebb and flood currents. This mechanism may transport SPM to the inner shelf, even under tide-dominated conditions when the opposite would be expected.O estuário do Rio Capibaribe é um corpo de água que atravessa a Região Metropolitana de Recife (RMR), um dos maiores centros populacionais do Brasil, o que causa grande quantidade de carga de poluentes e baixa qualidade da água. A entrada de água doce a partir das águas residuais da RMR pode contabilizar mais de três vezes a contribuição fluvial durante o período de baixa descarga. Este artigo investiga a hidrodinâmica e o potencial transporte de escalares particulados e dissolvidos neste estuário. Um experimento de campo foi realizado para registrar nível da água, velocidade de corrente, salinidade, temperatura e material particulado em suspensão (MPS) durante um ciclo de maré semidiurno completo. O experimento foi realizado em condições de baixa descarga e em condições de maré de sizígia. O estuário apresentou padrão de circulação parcialmente estratificado. O transporte residual de água e sal foi estuário acima, enquanto que o transporte residual de MPS foi estuário abaixo. Os primeiros são entendidos como o efeito da complexa circulação ao redor das ilhas que formam o baixo estuário, enquanto que o último foi interpretado como devido a efeitos morfológicos que induzem à ressuspensão durante a vazante, a despeito da simetria entre correntes de enchente e vazante. Este mecanismo pode produzir transporte para a plataforma adjacente, mesmo durante períodos dominados pela maré, quando o oposto seria esperado

State of the climate in 2018

In 2018, the dominant greenhouse gases released into Earth’s atmosphere—carbon dioxide, methane, and nitrous oxide—continued their increase. The annual global average carbon dioxide concentration at Earth’s surface was 407.4 ± 0.1 ppm, the highest in the modern instrumental record and in ice core records dating back 800 000 years. Combined, greenhouse gases and several halogenated gases contribute just over 3 W m−2 to radiative forcing and represent a nearly 43% increase since 1990. Carbon dioxide is responsible for about 65% of this radiative forcing. With a weak La Niña in early 2018 transitioning to a weak El Niño by the year’s end, the global surface (land and ocean) temperature was the fourth highest on record, with only 2015 through 2017 being warmer. Several European countries reported record high annual temperatures. There were also more high, and fewer low, temperature extremes than in nearly all of the 68-year extremes record. Madagascar recorded a record daily temperature of 40.5°C in Morondava in March, while South Korea set its record high of 41.0°C in August in Hongcheon. Nawabshah, Pakistan, recorded its highest temperature of 50.2°C, which may be a new daily world record for April. Globally, the annual lower troposphere temperature was third to seventh highest, depending on the dataset analyzed. The lower stratospheric temperature was approximately fifth lowest. The 2018 Arctic land surface temperature was 1.2°C above the 1981–2010 average, tying for third highest in the 118-year record, following 2016 and 2017. June’s Arctic snow cover extent was almost half of what it was 35 years ago. Across Greenland, however, regional summer temperatures were generally below or near average. Additionally, a satellite survey of 47 glaciers in Greenland indicated a net increase in area for the first time since records began in 1999. Increasing permafrost temperatures were reported at most observation sites in the Arctic, with the overall increase of 0.1°–0.2°C between 2017 and 2018 being comparable to the highest rate of warming ever observed in the region. On 17 March, Arctic sea ice extent marked the second smallest annual maximum in the 38-year record, larger than only 2017. The minimum extent in 2018 was reached on 19 September and again on 23 September, tying 2008 and 2010 for the sixth lowest extent on record. The 23 September date tied 1997 as the latest sea ice minimum date on record. First-year ice now dominates the ice cover, comprising 77% of the March 2018 ice pack compared to 55% during the 1980s. Because thinner, younger ice is more vulnerable to melting out in summer, this shift in sea ice age has contributed to the decreasing trend in minimum ice extent. Regionally, Bering Sea ice extent was at record lows for almost the entire 2017/18 ice season. For the Antarctic continent as a whole, 2018 was warmer than average. On the highest points of the Antarctic Plateau, the automatic weather station Relay (74°S) broke or tied six monthly temperature records throughout the year, with August breaking its record by nearly 8°C. However, cool conditions in the western Bellingshausen Sea and Amundsen Sea sector contributed to a low melt season overall for 2017/18. High SSTs contributed to low summer sea ice extent in the Ross and Weddell Seas in 2018, underpinning the second lowest Antarctic summer minimum sea ice extent on record. Despite conducive conditions for its formation, the ozone hole at its maximum extent in September was near the 2000–18 mean, likely due to an ongoing slow decline in stratospheric chlorine monoxide concentration. Across the oceans, globally averaged SST decreased slightly since the record El Niño year of 2016 but was still far above the climatological mean. On average, SST is increasing at a rate of 0.10° ± 0.01°C decade−1 since 1950. The warming appeared largest in the tropical Indian Ocean and smallest in the North Pacific. The deeper ocean continues to warm year after year. For the seventh consecutive year, global annual mean sea level became the highest in the 26-year record, rising to 81 mm above the 1993 average. As anticipated in a warming climate, the hydrological cycle over the ocean is accelerating: dry regions are becoming drier and wet regions rainier. Closer to the equator, 95 named tropical storms were observed during 2018, well above the 1981–2010 average of 82. Eleven tropical cyclones reached Saffir–Simpson scale Category 5 intensity. North Atlantic Major Hurricane Michael’s landfall intensity of 140 kt was the fourth strongest for any continental U.S. hurricane landfall in the 168-year record. Michael caused more than 30 fatalities and $25 billion (U.S. dollars) in damages. In the western North Pacific, Super Typhoon Mangkhut led to 160 fatalities and$6 billion (U.S. dollars) in damages across the Philippines, Hong Kong, Macau, mainland China, Guam, and the Northern Mariana Islands. Tropical Storm Son-Tinh was responsible for 170 fatalities in Vietnam and Laos. Nearly all the islands of Micronesia experienced at least moderate impacts from various tropical cyclones. Across land, many areas around the globe received copious precipitation, notable at different time scales. Rodrigues and Réunion Island near southern Africa each reported their third wettest year on record. In Hawaii, 1262 mm precipitation at Waipā Gardens (Kauai) on 14–15 April set a new U.S. record for 24-h precipitation. In Brazil, the city of Belo Horizonte received nearly 75 mm of rain in just 20 minutes, nearly half its monthly average. Globally, fire activity during 2018 was the lowest since the start of the record in 1997, with a combined burned area of about 500 million hectares. This reinforced the long-term downward trend in fire emissions driven by changes in land use in frequently burning savannas. However, wildfires burned 3.5 million hectares across the United States, well above the 2000–10 average of 2.7 million hectares. Combined, U.S. wildfire damages for the 2017 and 2018 wildfire seasons exceeded $40 billion (U.S. dollars)

Circulation and suspended sediment transport in a sediment starving ria: the Itapessoca

The Itapessoca estuary is part of the Itamaracá-Itapessoca Estuarine System, a ria-type estuary located on the northeastBrazilian shore, in the state of Pernambuco. Here we present an assessment of the estuarine circulation, suspended sedimentdynamics, and its main transport mechanisms. We carried out a field survey where water level, currents, salinity, temperature,and suspended sediment concentration (SSC) were recorded at 10-minute intervals during two complete semi-diurnal tidalcycles under spring tide conditions. The field survey was conducted in September (2012), which is a transitional period betweenwet and dry seasons. The water level displayed symmetrical ebb-flood phases; however, currents were ebb-dominated. Thefreshwater contribution was negligible, and the mean salinity was ~35 g/kg, which is slightly lower than the adjacent shelfvalues (36.5 g/kg). The SSC transport was driven by the ebb-dominated tidal currents, with the highest values of ~30 mg/loccurring during the peak current during the ebb. The source of the suspended sediment was the erosion from the bottom,and the concentration was much lower than other similar estuaries (e.g., Caravelas). This observation suggests this system is a‘sediment starved system’ in the sense that it presents a low concentration of suspended sediment

The circulation of the lower Capibaribe Estuary (Brazil) and its implications for the transport of scalars

Abstract The Capibaribe Estuary is a water body that crosses the Recife Metropolitan Area (RMA), one of the largest population centers in Brazil, and causes large pollutant loads and poor water quality. The fresh water inflow of wastewater from the RMA can account for three times the volume of the river discharge during the low discharge period. This article assesses the hydrodynamics and potential transport of particulate and dissolved scalars in this estuary. A field experiment was conducted to record the water level, current velocity, salinity, temperature and suspended particulate matter (SPM) contents during a full semi-diurnal tidal cycle. This experiment was performed during low river discharge and spring tide conditions. The estuary showed a partially mixed circulation pattern. The residual transport of water and salt were up estuary, while the SPM residual transport was down estuary. The former were understood as the effect of the residual circulation around the islands, while the latter was interpreted as a morphological factor inducing greater resuspension during the ebb, despite the symmetrical ebb and flood currents. This mechanism may transport SPM to the inner shelf, even under tide-dominated conditions when the opposite would be expected

A cidadania sob o signo do desvio: Para uma crítica da "tese de excepcionalidade brasileira"

O propósito central do artigo consiste em realizar uma consideração crítica do que denominamos de "tese da excepcionalidade normativa brasileira". As duas principais questões orientadoras são: em primeiro lugar, haveria alguma desvantagem, do ponto de vista analítico, em manter-se orientado pela noção conforme a qual a experiência da cidadania no Brasil é algo particular em relação ao "centro da modernidade"? Em segundo lugar, é possível vislumbrar outra maneira profícua de refletir a respeito da experiência da cidadania no Brasil para além da "tese da excepcionalidade normativa"?<br>This article aims at carrying out a critique of the so-called "thesis of the Brazilian normative exceptionality". The two driving questions are: first and foremost, is there any disadvantage, from an analytical point of view, in remaining oriented by the notion according to which the experience of citizenship in Brazil is something peculiar as compared to the "nucleus of modernity"? Secondly, is it possible to envisage another fruitful way of framing such an experience which goes beyond the "exceptionality thesis"