1,721,025 research outputs found
Author Correction: Human fingerprint in global weather
No full textIn the version of this News & Views originally published, the ref. 5 author surnames Meihnausen, Fisher and Szekely were spelled incorrectly; they should have been spelled Meinshausen, Fischer and Székely, respectively. This has now been corrected. © 2020, Springer Nature Limited.11Nsciessciscopu
Multi-model ensemble projections of extreme ocean wave heights over the Indian ocean
No full textExtreme ocean waves can have devastating impacts on many populous coastal regions or offshore islands. Yet, knowledge of how ocean waves are likely to respond to future climate change remains limited. To assess potential increases in risk associated with extreme ocean waves, future changes in seasonal mean and extreme significant wave height (SWH) are examined over the Indian Ocean (IO) using 18 Coupled Model Intercomparison Project Phase 5 (CMIP5) models forced with representative concentration pathway (RCP) 4.5 and 8.5 scenarios. The seasonal maxima are fit to the generalized extreme value (GEV) distribution and corresponding 10-year return values are estimated for the present-day (1981–2010) and future periods (2070–2099). Overall, projected changes in IO SWH exhibit noticeable seasonality. Under the high emissions RCP8.5 scenarios, mean and extreme SWH in the Arabian Sea (AS) and Bay of Bengal (BOB) are projected to increase during all seasons except December–February (DJF). In the western tropical IO (TIO), mean and extreme SWHs are projected to increase during June–August (JJA) and September–November (SON) in line with the projected circulation changes toward an Indian Ocean Dipole (IOD) positive phase-like mean state. Southern IO (SIO) SWHs exhibit a strong zonal shift, with large increases over high-latitudes and decreases over mid-latitudes, which is related to future changes in the Southern Annular Mode (SAM) toward its positive phase. Interestingly, some regions like the western TIO show significantly less increases in SWH under the lower emissions RCP4.5 scenarios, highlighting avoidable future risk through global warming mitigation efforts. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.11Nsciescopu
CMIP5 model evaluation for extreme ocean wave height responses to ENSO
No full textThe El Niño-Southern Oscillation (ENSO) exerts significant influences on extreme significant wave height (SWH) but climate model capabilities in reproducing the observed ENSO impact on SWH have not been evaluated. This study assesses the performances of the Coupled Model Intercomparison Project phase 5 (CMIP5) models in term of extreme SWH responses to ENSO over the Indo-Pacific Ocean focusing on December-February (DJF). 18 CMIP5 models are evaluated using their historical simulations for 1950–2005 in view of the ERA-20C reanalysis. A non-stationary generalized extreme value (GEV) analysis is employed to fit DJF maxima of 6-hourly SWHs and obtain the extreme SWH response patterns to ENSO by incorporating Niño3.4 index as a covariate. Results show that CMIP5 models can on average capture the major observed mean and extreme SWH responses to ENSO, including the increased SWH over the northeastern North Pacific (NENP) and the decreased SWH over the Maritime Continent (MC) during El Niño. The inter-model relations between ENSO characteristics and SWH responses are further examined for the two hotspot regions (NENP and MC). It is found that ENSO intensity is a dominant factor determining simulated SWH over the NENP such that models with stronger ENSO simulate stronger SWH responses. In contrast, for the MC, the sea level pressure teleconnection pattern significantly affects the inter-model spread in SWH responses, also explaining the systematic underestimation of SWH responses over the region. Implication is that ENSO intensity and atmospheric teleconnection patterns need to be considered for better simulations and reliable predictions of extreme SWH variability. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.11Nsciescopu
Multi-RCM near-term projections of summer climate extremes over East Asia
No full textA first systematic analysis was conducted to assess near-term future changes in climate extremes over East Asia during the summer season (June-August) using five regional climate model (RCM) simulations participating in the CORDEX-East Asia project (HadGEM3-RA, RegCM4, SNU-MM5, SNU-WRF, and YSU-RSM). The 20-year return values of extreme temperature and precipitation were compared between the present (1979-2005) and near-term future (2024-2049) periods, which were estimated using the generalized extreme value (GEV) analysis. Multi-RCM mean results show that temperature and precipitation will increase in both means and extremes and that the increase in precipitation extreme will follow the enhanced moisture availability with warming (similar to 7%degrees C-1, Clausius-Clapeyron relation). It was found that the increases in GEV location parameter (mean intensity) and scale parameter (inter-annual variability) contribute dominantly to the increase in extremes of temperature and precipitation, respectively. Robust inter-RCM relations were observed between mean and extreme projections over East Asia and even on grid scales, more strongly for temperature. Model biases and future projections exhibit a significant relationship for temperature such that RCMs with warmer biases tend to predict stronger warming and vice versa. Results from three sub-regions (South Korea, Southern China, and Mongolia and northern China) consistently indicate that temperature increase involves an overall shift of the daily temperature distribution toward warmer conditions while precipitation increases are due to dominant increases in moderate-heavy rainfall events. Our multi-RCM assessment provides new insights to the uncertainty in future climate extremes over East Asia
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Determining the Anthropogenic Greenhouse Gas Contribution to the Observed Intensification of Extreme Precipitation
No full textThis study conducts a detection and attribution analysis of the observed changes in extreme precipitation during 1951-2015. Observed and CMIP6 multimodel simulated changes in annual maximum daily and consecutive 5-day precipitation are compared using an optimal fingerprinting technique for different spatial scales from global land, Northern Hemisphere extratropics, tropics, three continental regions (North America and western and eastern Eurasia), and global "dry" and "wet" land areas (as defined by their average extreme precipitation intensities). Results indicate that anthropogenic greenhouse gas influence is robustly detected in the observed intensification of extreme precipitation over the global land and most of the subregions considered, all with clear separation from natural and anthropogenic aerosol forcings. Also, the human-induced greenhouse gas increases are found to be a dominant contributor to the observed increase in extreme precipitation intensity, which largely follows the increased moisture availability under global warming. Plain Language Summary Human influences have been identified in the observed intensification of extreme precipitation at global and continental scales, but quantifying the contribution of greenhouse gas increases remains challenging. Here, we isolate anthropogenic greenhouse gas impacts on the observed intensification of extreme precipitation during 1951-2015 by comparing observations with CMIP6 individual forcing experiments. Results show that greenhouse gas influences are detected over the global land, Northern Hemisphere extratropics, western and eastern Eurasia, and global "dry" and "wet" regions, which are separable from other external forcings such as solar and volcanic activities and anthropogenic aerosols. The human-induced greenhouse gas increases are also found to explain most of the observed changes in extreme precipitation intensity, which are consistent with the increased moisture availability with warming. Our results provide the first quantitative evidence for the dominant influence of human-made greenhouse gases on extreme precipitation increase.11Nsciescopu
Contrasting factors on the trends in hot days and warm nights over Northern Hemisphere land during summer
No full textThe authors examined the contrasting factors behind the distinct increases in hot days (HDs, daytime hot extremes) and warm nights (WNs, nighttime hot extremes) over land in the Northern Hemisphere during the boreal summers (June to August) of 1980?2018. While the occurrence of HDs has increased gradually since 1980, that of WNs increased abruptly during the late 1990s and has changed little since then. This sudden increase observed in the occurrence of WNs was found to be related to the low frequency variability in sea surface temperature, including the Pacific Decadal Oscillation/Interdecadal Pacific Oscillation. Comparisons of observational data with historical simulations by CMIP5 climate models under different forcings suggest that the increasing trend in observed HDs was largely due to anthropogenic forcing, but that the observed regime shift-like increase in WNs could not be reproduced by external forcing alone. Unlike the observations, the CMIP5 models exhibited accelerated increasing trends in both HDs and WNs, indicating distinct factors controlling the observed trends in HDs and WNs. ? 202111Ysciescopu
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Possible impact of the diabatic heating over the Indian subcontinent on heat waves in South Korea
No full textWe investigate the impact of the diabatic heating (Q1) over the Indian subcontinent and Tibetan Plateau (TP) sensible heat on the heat waves in South Korea in July and August over a recent 42-year period. In particular, we emphasize the role of the convective activity across the region from northeastern Pakistan to northwestern India (PWI) induced by the heat from the TP, especially over the western and eastern TP. A composite analysis indicates that the composite differences between the heat-wave summers (HWS) and non-heat-wave summers (NHWS) resemble the circum-global teleconnection (CGT) pattern, which generates a high-pressure anomaly over the Korean Peninsula, producing favourable conditions for heat waves in South Korea. The first coupled mode of the geopotential height at 250 hPa with the daily maximum temperature (TM) for July and August in South Korea is consistent with the composite pattern, suggesting that the diabatic heating over the Indian subcontinent induces a high-pressure anomaly over the Korean Peninsula through a CGT-like mechanism. The regression analysis of the wind vectors in the upper troposphere also indicates that the diabatic heating over the PWI region and associated TP sensible heating generates the strong convection over the PWI region, which corresponds to the anomalous anticyclonic circulation at 250 hPa over the western TP and the cyclonic circulation at 850 hPa over the PWI region. Moreover, the correlation patterns of the 250-hPa geopotential height with the normalized rainfall amount index (IMRI) over the PWI region and the wave activity flux pattern confirm that the strong convective activity over the PWI region contributes to the anomalous high pressure and heat waves over the Korean Peninsula.11Nsciescopu
- …
