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[en] A climate network of extreme rainfall over eastern Asia is constructed for the period of 1971–2000, employing the tools of complex networks and a measure of nonlinear correlation called event synchronization (ES). Using this network, we predict the extreme rainfall for several cases without delay and with n-day delay (1 ≤ n ≤ 10). The prediction accuracy can reach 58% without delay, 21% with 1-day delay, and 12% with n-day delay (2 ≤ n ≤ 10). The results reveal that the prediction accuracy is low in years of a weak east Asia summer monsoon (EASM) or 1 year later and high in years of a strong EASM or 1 year later. Furthermore, the prediction accuracy is higher due to the many more links that represent correlations between different grid points and a higher extreme rainfall rate during strong EASM years. (geophysics, astronomy, and astrophysics)
[en] Most disaster researchers believe that collective resources can help recovery, but there has been little quantitative research because data are scarce. We investigate the contribution of civic engagement and social networks to repopulation in New Orleans after Hurricane Katrina (2005), also taking into account storm damage and individual resources like income, race, female-headed households, and age. We conducted a large (N = 5729) representative survey in Greater New Orleans after Hurricane Katrina that contains extensive measures of collective resources. We aggregated these data to the census tract level and merged them with government data on repopulation and demographic factors. Our analyses show that civic engagement encouraged repopulation, though its effects faded over time. Social networks had an effect at the zero order, but were insignificant when damage was controlled. Damage had the largest, negative, effect on repopulation. Individual resources affected repopulation at the zero order, but when damage was controlled, only income and age had an effect.
[en] In the aftermath of large-scale disasters, the public's dependency on federal and state agencies for information about public safety and environmental risk is acute. While formal rules and procedures are in place to guide policy decisions in environmental risk assessment of spatially concentrated hazards such as regulated waste sites or vacant city lots, standard procedures for risk assessment seem potentially less well-suited for urban-scale disaster zones where environmental hazards may be widely dispersed and widely varying. In this paper we offer a new approach for the social assessment of regulatory science in response to large-scale disaster, illustrating our methodology through a socio-spatial analysis of the U.S. Environmental Protection Agency's (EPA) hazard assessment in New Orleans, Louisiana, following Hurricane Katrina in 2005. We find that the agency's commitment of epistemic resources or 'knowledge investments' varied considerably across the flood-impacted portion of the city, concentrating in poorer and disproportionately African American neighborhoods previously known to be heavily contaminated. We address some of the study's social and policy implications, noting the multidimensionality and interactive nature of knowledge investments and the prospects for deepening and extending this approach through comparative research
[en] Public awareness of civil infrastructure performance has increased considerably in recent years as a result of repeated natural disasters. Risks from natural hazards may increase dramatically in the future, given current patterns of urbanization and population growth in hazard-prone areas. Risk assessments for infrastructure with expected service periods of a century or more are highly uncertain, and there is compelling evidence that climatology will evolve over such intervals. Thus, current natural hazard and risk assessment models, which are based on a presumption of stationarity in hazard occurrence and intensity, may not be adequate to assess the potential risks from hazards occurring in the distant future. This paper addresses two significant intergenerational elements – the potential impact of non-stationarity in hazard due to climate change and intergenerational discounting practices – that are essential to provide an improved decision support framework that accommodates the needs and values of future generations. The framework so developed is tested through two benchmark problems involving buildings exposed to hurricanes. - Highlights: • Difficulties of conventional life-cycle engineering decision-making over multiple generations are clearly elaborated. • Two intergenerational elements are proposed to reflect equitable allocations of risk between generations. • A data-based approach to forecast future hurricanes is provided to bridge the gap between models at large and local scales. • The feasibility and practicability of a refined framework are examined through two lifecycle cost assessment examples. • The two intergenerational elements suggested in this study have a wide range of applicability.
[en] This study investigates the transition from East Asian winter monsoon (EAWM) to following summer monsoon (EASM) under two types of El Niño and La Niña events. A robust out-of-phase transition from weak EAWM to strong EASM is related to El Niño events, which is more distinct in eastern Pacific (EP) El Niño than that in central Pacific (CP) El Niño due to the stronger and wider western North Pacific (WNP) anticyclone (WNPAC) as a persistent atmospheric bridge. The WNPAC differences result from the combined impacts of the warming over northern Indian Ocean (NIO) remotely, the dipolar sea surface temperature (SST) anomalies and the anomalous sinking motion over WNP locally. In terms of La Niña, the out-of-phase strong EAWM to weak EASM transition exists only for CP La Niña. Moreover, this connection is weaker compared to that for El Niño events because of a weaker WNP cyclone (WNPC). Conversely, when EP La Niña occurs, an in-phase transition is detected with a strong EAWM evolving into a strong EASM due to the emergence of WNPAC in summer. For CP and EP La Niña, the cooling SST anomalies over NIO and WNP play opposite roles in affecting WNP summertime circulation anomalies. Observational and model results suggest that the WNPC (WNPAC) is dominated by remote (local) cooling in NIO (WNP) in the summer following CP (EP) La Niña. In addition, the local rising (sinking) flow also contributes to the WNPC (WNPAC) associated with CP (EP) La Niña.
[en] A network of 9-m-tall surface flux measurement stations were deployed at eight sparsely vegetated sites during the Monsoon '90 experiment to measure net radiation, Q, soil heat flux, G, sensible heat flux, H (using eddy correlation), and latent heat flux, E (using the energy balance equation). At four of these sites, 2-m-tall eddy correlation systems were used to measure all four fluxes directly. Also a 2-m-tall Bowen ratio system was deployed at one site. Magnitudes of the energy balance closure (Q + G + H + E) increased as the complexity of terrain increased. The daytime Bowen ratio decreased from about 10 before the monsoon season to about 0.3 during the monsoons. Source areas of the measurements are developed and compared to scales of heterogeneity arising from the sparse vegetation and the topography. There was very good agreement among simultaneous measurements of Q with the same model sensor at different heights (representing different source areas), but poor agreement among different brands of sensors. Comparisons of simultaneous measurements of G suggest that because of the extremely small source area, extreme care in sensor deployment is necessary for accurate measurement in sparse canopies. A recently published model to estimate fetch is used to interpret measurements of H at the 2 m and 9 m heights. Three sites were characterized by undulating topography, with ridgetops separated by about 200-600 m. At these sites, sensors were located on ridgetops, and the 9-m fetch included the adjacent valley, whereas the 2-m fetch was limited to the immediate ridgetop and hillside. Before the monsoons began, vegetation was mostly dormant, the watershed was uniformly hot and dry, and the two measurements of H were in close agreement. After the monsoons began and vegetation fully matured, the 2-m measurements of H were significantly greater than the 9-m measurements, presumably because the vegetation in the valleys was denser and cooler than on the ridgetops
[en] A case of deep and rapid cyclo genesis over the Gulf of Genoa and its impact on a limited area energy budget are examined in this paper. Energy components, including boundary and generation terms, are calculated for the period 18-21 November 1999 over a limited region in which this disturbance is the major synoptic-scale feature. The energy contents and their changes through the studied atmospheric volume are discussed in the course of the cyclone's development. The combined boundary pressure work and dissipation terms of the zonal and eddy kinetic energies, as well as generation terms of zonal and eddy available energies, are computed as residuals. Data of ALADIN/LACE model are used as input fields for calculations. Formation of the cyclone under study initiated in the upper atmospheric levels. At the initial stage of its development, energy conversion C(KZ,KE) was intense. Thus, zonal flow acted as a source of eddy kinetic energy. The disturbance was induced by a very strong wind shear and the progress of the vortex toward the lower atmospheric layers was associated with downward eddy kinetic energy transport (from the jet stream level toward the surface). Simultaneously, the upward transport of both zonal and eddy available energies (from the lower and middle troposphere toward the upper levels) was present. The disturbance was a consequence of very strong wind shear and it was evident how it progressed toward the lower atmospheric layers. As the vortex reached the ground, energy conditions allowed its possible further growth there. In spite of that, the surface cyclone lifetime was very short due to dynamical conditions that attenuated cyclone development
[en] The study found that deforestation causes more monsoon moisture to be retained in the mid-troposphere, thereby reducing the northward transport of moisture needed for rainfall over West Africa. Hence, deforestation has dynamical impacts on the West African monsoon and rainfall.