Intra-seasonal rainfall variability in the Amazon basin related to large-scale circulation patterns: a focus on western Amazon-Andes transition region

2017 ◽  
Vol 38 (5) ◽  
pp. 2386-2399 ◽  
Author(s):  
Laura Paccini ◽  
Jhan Carlo Espinoza ◽  
Josyane Ronchail ◽  
Hans Segura
2011 ◽  
Vol 38 (1-2) ◽  
pp. 121-140 ◽  
Author(s):  
Jhan Carlo Espinoza ◽  
Matthieu Lengaigne ◽  
Josyane Ronchail ◽  
Serge Janicot

2020 ◽  
Author(s):  
Juan Pablo Sierra ◽  
Clementine Junquas ◽  
Jhan Carlo Epinoza ◽  
Thierry Lebel ◽  
Hans Segura

<p><span>The western Amazon and eastern flank of the Andes form what is known as the Amazon-Andes transition region. This region is characterized by the presence of the rainiest area in the Amazon basin with an average precipitation ranging from 6000 to 7000 mm per year. This rainy zone is the result of interactions between large-scale circulation and local features. However, the physical mechanisms controlling this rainfall patterns in the transition region are poorly understood. On the other hand, high precipitation values in the area, along with erosion, sediment transport and the geological mountain uplift help to explain this region as one of the most species-rich terrestrial ecosystems. Nevertheless, accelerated deforestation rates reported both in tropical Andes and central-southern Amazon threat the biodiversity hotspots and can induce alterations in land surface energy and water balances. In this context, the use of regional climate models can shed light on the possible consequences of deforestation on rainfall in the transition region. </span></p><p><span>The early results presented here are the first step in a work that seeks to gain a better understanding in the mechanisms involved in precipitation generation over the Amazon-Andes transition region, as well as the assessment of deforestation impacts on spatial and temporal rainfall variability during austral summer. The Weather Research and Forecasting (WRF) regional climate model is used with three nested domains. High resolution simulations (1km horizontal grid size) are performed over the key regions of Cuzco and Bolivian slopes. As a perspective,<span>  </span>deforestation scenarios following the land use change trajectory observed during the last decade will be used in future works. The results of this work can help to dimension the consequences of deforestation on key ecosystems such as Andean hotspots.</span></p>


2017 ◽  
Vol 102 ◽  
pp. 214-223 ◽  
Author(s):  
J.M. Correia ◽  
A. Bastos ◽  
M.C. Brito ◽  
R.M. Trigo

2020 ◽  
Vol 212 ◽  
pp. 103456
Author(s):  
Kirstin Schulz ◽  
Karline Soetaert ◽  
Christian Mohn ◽  
Laura Korte ◽  
Furu Mienis ◽  
...  

2020 ◽  
Vol 35 (2) ◽  
pp. 367-377
Author(s):  
Hyun-Ju Lee ◽  
Woo-Seop Lee ◽  
Jong Ahn Chun ◽  
Hwa Woon Lee

Abstract Forecasting extreme events is important for having more time to prepare and mitigate high-impact events because those are expected to become more frequent, intense, and persistent around the globe in the future under the warming atmosphere. This study evaluates the probabilistic predictability of the heat wave index (HWI) associated with large-scale circulation patterns for predicting heat waves over South Korea. The HWI, reflecting heat waves over South Korea, was defined as the vorticity difference at 200 hPa between the South China Sea and northeast Asia. The forecast of up to 15 days from five ensemble prediction systems and the multimodel ensemble has been used to predict the probabilistic HWI during the summers of 2011–15. The ensemble prediction systems consist of different five operational centers, and the forecast skill of the probability of heat waves occurrence was assessed using the Brier skill score (BSS), relative operating characteristics (ROC), and reliability diagram. It was found that the multimodel ensemble is capable of better predicting the large-scale circulation patterns leading to heat waves over South Korea than any other single ensemble system through all forecast lead times. We concluded that the probabilistic forecast of the HWI has promise as a tool to take appropriate and timely actions to minimize the loss of lives and properties from imminent heat waves.


2020 ◽  
Author(s):  
M. Carmen Alvarez-Castro ◽  
Silvio Gualdi ◽  
Pascal Yiou ◽  
Mathieu Vrac ◽  
Robert Vautard ◽  
...  

<p>Windstorms, extreme precipitations and instant floods seems to strike the Mediterranean area with increasing frequency. These events occur simultaneously during intense tropical-like Mediterranean cyclones. These intense Mediterranean cyclones are frequently associated with wind, heavy precipitation and changes in temperature, generating high risk situations such as flash floods and large-scale floods with significant impacts on human life and built environment. Although the dynamics of these phenomena is well understood, little is know about their climatology. It is therefore very difficult to make statements about the frequency of occurrence and its response to climate change. Thus, intense Mediterranean cyclones have many different physical aspects that can not be captured by a simple standard approach. </p><p>The first challenge of this work is to provide an extended catalogue and climatology of these phenomena by reconstructing a database of intense Mediterranean cyclones dating back up to 1969 using the satellite, the literature and reanalyses. Applying a method based on dynamical systems theory we analyse and attribute their future changes under different anthropogenic forcings by using future simulations within CMIP framework. Preliminary results show a decrease of the large-scale circulation patterns favoring intense Mediterranean cyclones in all the seasons except summer.</p>


2013 ◽  
Vol 9 (4) ◽  
pp. 3825-3870
Author(s):  
N. Merz ◽  
C. C. Raible ◽  
H. Fischer ◽  
V. Varma ◽  
M. Prange ◽  
...  

Abstract. Accumulation and aerosol chemistry records from Greenland ice cores offer the potential to reconstruct variability in Northern Hemisphere atmospheric circulation over the last millennia. However, an important prerequisite for a reconstruction is the stable relationship between local accumulation at the ice core site with the respective circulation pattern throughout the reconstruction period. We address this stability issue by using a comprehensive climate model and performing time-slice simulations for the present, the pre-industrial, the early Holocene and the last glacial maximum (LGM). The relationships between accumulation, precipitation and atmospheric circulation are investigated on on various time-scales. The analysis shows that the relationship between local accumulation on the Greenland ice sheet and the large-scale circulation undergoes a significant seasonal cycle. As the weights of the individual seasons change, annual mean accumulation variability is not necessarily related to the same atmospheric circulation patterns during the different climate states. Within a season, local Greenland accumulation variability is indeed linked to a consistent circulation pattern, which is observed for all studied climate periods, even for the LGM, however these circulation patterns are specific for different regions on the Greenland ice sheet. The simulated impact of orbital forcing and changes in the ice-sheet topography on accumulation exhibits strong spatial variability emphasizing that accumulation records from different ice core sites cannot be expected to look alike since they include a distinct local signature. Accumulation changes between different climate periods are dominated by changes in the amount of snowfall and are driven by both thermodynamic and dynamic factors. The thermodynamic impact determines the strength of the hydrological cycle, and warmer temperatures are generally accompanied by an increase in Greenland precipitation. Dynamical drivers of accumulation changes are the large-scale circulation and the local orography having a distinct influence on the local flow characteristic and hence the amount of precipitation deposited in any Greenland region.


2019 ◽  
Vol 124 (23) ◽  
pp. 12794-12809 ◽  
Author(s):  
Yang Zhao ◽  
Xiangde Xu ◽  
Jiao Li ◽  
Rong Zhang ◽  
Yanzhen Kang ◽  
...  

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