Papers publicados por HEMERA
https://repositorio.umayor.cl/xmlui/handle/sibum/8003
Contiene los artículos/papers publicados por HEMERA en revistas nacionales e internacionales2024-03-28T11:15:53ZClimate variability of the southern Amazon inferred by a multi-proxy tree-ring approach using Cedrelafissilis Vell
https://repositorio.umayor.cl/xmlui/handle/sibum/9508
Climate variability of the southern Amazon inferred by a multi-proxy tree-ring approach using Cedrelafissilis Vell
Ortega Rodríguez, Daigard Ricardo; Sánchez-Salguero, Rail; Hevia, Andrea; Granato-Souza, Daniela; Cintra, Bruno B. L.; Hornink, Bruna; Andreu-Hayles, Laia; Assis-Pereira, Gabriel; Roig, Fidel A. [Univ Mayor, Escuela Ingn Forestal, Fac Ciencias, Hemera Ctr Observac Tierra, Chile]; Tomazello-Filho, Mario
The analysis of climate variability and development of reconstructions based on tree-ring records in tropical forests have been increasing in recent decades. In the Amazon region, ring width and stable isotope long-term chronologies have been used for climatic studies, however little is known about the potential of wood traits such as density and chemical concentrations. In this study, we used well-dated rings of Cedrela fissilis Vell. from the drought-prone southern Amazon basin to assess the potential of using inter-annual variations of annually-resolved ring width, wood density, stable oxygen isotope (818OTR) measured in tree-ring cellulose and concentration of Sulfur (STR) and Calcium (CaTR) in xylem cells to study climate variability. During wet years, Cedrela fissilis produced wider and denser rings with higher CaTR and lower STR, as well as depleted 818OTR values. During dry years, a wider range of responses was ob-served in growth, density and STR, while lower CaTR and enriched 818OTR values were found. The annual centennial chronologies spanning from 1835 to 2018 showed good calibration skills for reconstructing local precipitation, evapo-transpiration (P-PET), Amazon-wide rainfall, as well as climate modes related to sea surface temperature (SST) anom-alies such as El Nino South Oscillation (ENSO), Tropical Northern Atlantic (TNA), and the Western Hemisphere Warm Pool (WHWP) oscillations. CaTR explained 42 % of the variance of local precipitation (1975-2018), RW explained 30 % of the P-PET variance (1975-2018), while 818OTR explained 60 % and 57 % of the variance of Amazon rainfall (1960-2018) and El Nino 3.4 (1920-2018), respectively. Our results show that a multi-proxy tropical tree-ring ap-proach can be used for high-reliable reconstructions of climate variability over Amazon basin at inter-annual and multidecadal time scales.
2023-02-01T00:00:00ZWeakening of the Summer Monsoon Over the Past 150 Years Shown by a Tree-Ring Record From Shandong, Eastern China, and the Potential Role of North Atlantic Climate
https://repositorio.umayor.cl/xmlui/handle/sibum/9482
Weakening of the Summer Monsoon Over the Past 150 Years Shown by a Tree-Ring Record From Shandong, Eastern China, and the Potential Role of North Atlantic Climate
Chen, Qiaomei; Zhang, Xiaojian; Chen, Feng; Zhang, Heli; Yuan, Yujiang; Yu, Shulong; Hadad, Martin A.; Roig, FA [Univ Mayor, Escuela Ingn Forestal, Fac Ciencias, Hemera Ctr Observac Tierra, Huechuraba, Chile]
The causes of the decreased intensity of the East Asian summer monsoon (EASM) over the past 150 years are still not fully understood, although several studies have linked the monsoon weakening to the warming of tropical oceans. Here, we use pine tree-rings to reconstruct the precipitation total for April-August from 1810 to 2018, in south-central Shandong Province, in the EASM region. The reconstruction accounts for 41.8% of the instrumental precipitation variance during 1965-2018. The EASM precipitation reconstruction shows extreme pluvial conditions in 1832, 1833, 1886, and 1998, and extreme droughts in 1878, 1901, and 1910, which correspond precisely to extreme climatic events recorded in historical documents. The reconstructed precipitation reveals a drying trend since the 1870s, which matches well with the decreasing trend of the EASM inferred from stalagmite oxygen isotope (d(18)O) records and climate simulations. The trend of decreasing precipitation since the 1870s, indicated by our reconstruction, is significantly correlated with the spring sea surface temperature (SST) of the North Atlantic Ocean, which suggests that the EASM weakening was linked to North Atlantic SST variations during the past 150 years. This potential role of North Atlantic SST variability is supported by climate sensitivity simulations of the Community Earth System Model. North Atlantic SST variability induces two teleconnections of Rossby-like wave propagation from the North Atlantic into East Asia, resulting in anomalous precipitation in this region.
2023-03-01T00:00:00ZSeasonal precipitation in south-central Chile: Trends in extreme events since 1900
https://repositorio.umayor.cl/xmlui/handle/sibum/9164
Seasonal precipitation in south-central Chile: Trends in extreme events since 1900
González-Reyes, Alvaro [Univ Mayor, Fac Ciencias, Escuela Ing Forestal, Hemera Ctr Observat Tierra, Chile]; Jacques-Coper, Martin; Muñoz, Ariel A.
We study a regional precipitation time series built upon seven meteorological records from south-central Chile (SCC; 37 degrees-42 degrees S), which altogether cover the period 1900-2019. As a first objective, we investigated changes in the return period (RP) of dry ( P20) and wet ( P80) seasonal extreme events of precipitation (SEE) for each season. We observed a reduction in the RP of wet SEE during 1900-1950 in all seasons. Moreover, the dry SEE RP shows a reduction from 1950 to the present in all seasons. This phenomenon is noteworthy since 1900 for summer and winter, and since 1930 for autumn. Spring registers a constant RP value from 1990 onwards. As a second objective, we study possible relationships between seasonal precipitation variability and climate modes, such as the Southern Annular Mode (SAM) and the Tripole Index (TPI) of sea surface temperature (SST) over the Pacific Ocean. Summer and autumn precipitation showed a significant negative correlation with SAM activity at interannual and decadal scales, while winter and spring precipitation recorded a significant positive correlation with SST variability over multiple regions of the Pacific Ocean (including the tropics and New Zealand) and the Southern Ocean (Amundsen-Bellingshausen Sea). Finally, we confirm that SAM strongly modulates precipitation in SCC, especially in autumn, and that SEE variability in SCC is considerably associated with climate modes of tropical and extra-tropical origin.
2021-09-01T00:00:00ZTree-ring-based hydroclimatic reconstruction for the northwest Argentine Patagonia since 1055 CE and its teleconnection to large-scale atmospheric circulation
https://repositorio.umayor.cl/xmlui/handle/sibum/9163
Tree-ring-based hydroclimatic reconstruction for the northwest Argentine Patagonia since 1055 CE and its teleconnection to large-scale atmospheric circulation
Hadad, Martin A.; González-Reyes, Alvaro [Univ Mayor, Hemera Ctr Observac Tierra, Escuela Ing Forestal, Fac Ciencias, Chile]; Roig, Fidel A. [Univ Mayor, Hemera Ctr Observac Tierra, Escuela Ingn Forestal, Fac Ciencias, Chile]; Matskovsky, Vladimir; Cherubini, Paolo
State-of-the-art climate models project droughts of stronger intensity and longer persistence in many arid and semi-arid regions such as northern Patagonia, which constitutes a serious concern worldwide. Moisture availability has a significant influence on the dynamic, stability and function of terrestrial ecosystems. In this study, we used wood samples from 260 Austrocedrus chilensis trees growing in northwestern Patagonia to reconstruct the Standardized Precipitation Evapotranspiration Index (SPEI) for the last millennium (1055-2014). Our reconstruction explained 41.6% of the variance contained in the November-December SPEI at a 1-month scale for the period 1930-2013. The SPEI reconstruction has provided a long record of extreme pluvial (1060s, 1090s, 1200s, 1300s, 1360s, 1390s, 1400s, 1550s, 1580s, 1580s, 1630s, 1940s, 1960s, and 2000s) and drought events (1070s, 1150s, 1170s, 1180s, 1270s, 1310s, 1430s, 1450s, 1570s, 1600s, 1620s, and 1950s) for northwest Argentine Patagonia. Although the SPEI reconstruction indicates that the frequency of extreme events has increased since 1950, our record indicates that current levels have not exceeded those previously reached, particularly when compared to those recorded around the suggested periods for the Medieval Warm and towards the end of the Little Ice Age. The spatial and temporal relationships associated with the South Annular Mode and the Pacific Sea Surface Temperature variability as expressed by the Tripole Index indicated that the temporal variability observed in the SPEI reconstruction is modulated by hemispheric-scale atmospheric circulation dynamics. These climate forcings are likely responsible for the intensity and the rate of occurrence of extreme weather events in northwestern Patagonia. Furthermore, the SPEI reconstruction showed a spatial and temporal pattern similar to that observed in previous PDSI-based reconstructions. This study provides robust evidence of hydroclimatic variations for extratropical sectors of South America, improving our knowledge of the climate dynamics during the last millennium and allowing us to review the recently observed increase in wet and dry events in a long-term historical context.
2021-07-01T00:00:00Z