京都大学 · 環境科学
Sridhara Nayak教授の研究室は、気候変動が極端な気象現象に与える影響を、主に気候モデルと観測データを統合して解明しています。特に、温暖化に伴う水蒸気の増加が極端な降雨に与える影響(Clausius-Clapeyron関係)や、台風の強化、陸上利用変化が気温に与える影響を、地域的・季節的スケールで分析しています。日本や南アジアを対象に、高解像度気候モデルを用いたダウンスケーリング手法を駆使し、気象災害の予測とリスク評価を進めています。
Figures are computed from collected data and may differ slightly.
Recent studies have revealed that an increase in surface air temperature elevates the intensity of extreme precipitation associated with the increase of water vapor in the atmosphere, according to the principle of the Clausius–Clapeyron (CC) relationship. In this study, (1) we have verified the dependence of extreme precipitation intensity on temperature (CC relationship) under current climate and (2) investigated the projected changes of the CC relationship over Japan by using multi-model ensem
Typhoons are considered as one of the most powerful disaster-spawning weather phenomena. Recent studies have revealed that typhoons will be stronger and more powerful in a future warmer climate and be a threat to lives and properties. In this study, we conduct downscaling experiments of an extreme rain-producing typhoon, Typhoon Lionrock (2016), to assess the impacts of climate change on resulting hazards by assuming pseudo global warming (PGW) conditions. The downscaled precipitations over the
This study explores the influence of land-use and land cover (LULC) changes on the temperature over North India (NI) and North-Eastern India (NEI) during 1981–2006 by subtracting the reanalysis temperature from the observed temperature (observation minus reanalysis (OMR) method). The normalized difference vegetation index (NDVI) data of the AVHRR satellite for the period 1981–2006 were analyzed to understand the type of LULC changes during this period and their linkage with the temperature chang
Informes recientes del IPCC sugieren que el mundo se est calentando. Como resultado, la concentracin atmosfrica de vapor de agua, que determina el agua precipitable, est aumentando de manera considerable en concordancia con la relacin Clausius-Clapeyron (cc), la cual establece que el vapor de agua en la atmsfera se incrementa a razn de 7% por cada grado centgrado de calentamiento. En este estudio se explora la relacin entre eventos extremos de agua precipitable y la temperatura a nivel global, e
The occurrence of extreme precipitation events is now a serious concern in recent years in Japan. This study explores the atmospheric driving mechanisms of two extreme precipitation events occurred during 5–6 July 2017 and 5–8 July 2018 over western Japan. We identified that the atmospheric transport of large amounts of moisture and wind streams with wind speed of minimum 15 m s−1 from south of Japan towards north on the days before these torrential precipitation events are mainly responsible fo
The climate change scenarios, especially global warming, have raised significant concerns, and the Himalayan regions such as Uttarakhand are highly vulnerable to such climatic shifts. Considering 10 Coordinated Regional Climate Downscaling Experiments in South Asia (CORDEX-SA), experiments with 3 regional climate models (RCMs), driven by 13 global climate models, historical estimates and future projections are analyzed from the mid-century (MC) i.e., from 2021–2050 to the end of the century (EC)
Abstract In August 2016, northern Japan was stuck by apparently unusual occurrence of the landfall of four typhoons and experienced record-breaking heavy precipitations. This study analyzed the extreme precipitations carried out by these four typhoons to understand their internal structure over northern Japan by computing the probability distributions of precipitation durations with their peak intensities exceeding a range of percentile thresholds starting from 70 to 99%. The main focus was on t
Abstract In August 2016, an unusual occurrence of the landfall of four typhoons in northern Japan caused severe and widespread damage by excessive rainfall and high wind. This study examines the characteristics and structure of these typhoons and the responses to the global warming climate to explore the robust features of typhoon hazards in northern Japan in a future warming climate. By obtaining similar typhoon tracks under the 2016 conditions and a pseudo global warming (PGW) climate, we foun
Recent studies have argued that extreme precipitation intensities are increased in many regions across the globe due to atmospheric warming. This argument is based on the principle of the Clausius-Clapeyron (CC) relationship, which states that the atmosphere can hold more moisture in warmer air temperatures (~7%°C–1). In this study, we investigate the future changes of extreme precipitation intensities associated with temperature over Japan, by analyzing multimodel ensemble downscaling experimen
The usefulness of Clausius–Clapeyron (CC) scaling in explaining extremely heavy precipitations is explored in the present-day climate and in pseudo-global-warming (PGW) conditions. This is analyzed by conducting regional-scale numerical simulations at 1-km grid resolution for two recent extreme rainfall events that occurred in Japan: the case in northern Kyushu during 5–6 July 2017 and the case in Shikoku Island during 5–8 July 2018. The Weather Research and Forecasting (WRF) model was used for
Many recent studies have argued that tropical cyclones will become severer in future warming climate and may cause various catastrophic damages to human life and economy. This study explores the impact of climate change on Typhoon Chanthu (2016) by performing a high-resolution (1 km) simulation for current and future climate. We focused on the typhoon intensity, size, heat fluxes, associated precipitation and wind speed over northern Japan under global warming with different initial times at 6-h
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