scholarly journals Tropical–North Pacific Climate Linkages over the Past Four Centuries*

2005 ◽  
Vol 18 (24) ◽  
pp. 5253-5265 ◽  
Author(s):  
Rosanne D’Arrigo ◽  
Rob Wilson ◽  
Clara Deser ◽  
Gregory Wiles ◽  
Edward Cook ◽  
...  
Keyword(s):  
Twentieth Century ◽  
Tree Ring ◽  
North Pacific ◽  
Climatic Variability ◽  
Regime Shifts ◽  
Climate Index ◽  
Climate Indices ◽  
Supporting Evidence ◽  
The Past ◽  
Decadal Scale

Abstract Analyses of instrumental data demonstrate robust linkages between decadal-scale North Pacific and tropical Indo-Pacific climatic variability. These linkages encompass common regime shifts, including the noteworthy 1976 transition in Pacific climate. However, information on Pacific decadal variability and the tropical high-latitude climate connection is limited prior to the twentieth century. Herein tree-ring analysis is employed to extend the understanding of North Pacific climatic variability and related tropical linkages over the past four centuries. To this end, a tree-ring reconstruction of the December–May North Pacific index (NPI)—an index of the atmospheric circulation related to the Aleutian low pressure cell—is presented (1600–1983). The NPI reconstruction shows evidence for the three regime shifts seen in the instrumental NPI data, and for seven events in prior centuries. It correlates significantly with both instrumental tropical climate indices and a coral-based reconstruction of an optimal tropical Indo-Pacific climate index, supporting evidence for a tropical–North Pacific link extending as far west as the western Indian Ocean. The coral-based reconstruction (1781–1993) shows the twentieth-century regime shifts evident in the instrumental NPI and instrumental tropical Indo-Pacific climate index, and three previous shifts. Changes in the strength of correlation between the reconstructions over time, and the different identified shifts in both series prior to the twentieth century, suggest a varying tropical influence on North Pacific climate, with greater influence in the twentieth century. One likely mechanism is the low-frequency variability of the El Niño–Southern Oscillation (ENSO) and its varying impact on Indo-Pacific climate.

scholarly journals North Pacific twentieth century decadal-scale variability is unique for the past 342 years

2017 ◽  
Vol 44 (8) ◽  
pp. 3761-3769 ◽  
Author(s):  
B. Williams ◽  
J. Halfar ◽  
K. L. Delong ◽  
E. Smith ◽  
R. Steneck ◽  
...  
Keyword(s):  
Twentieth Century ◽  
North Pacific ◽  
The Past ◽  
Decadal Scale

scholarly journals Supporting Restoration Decisions through Integration of Tree-Ring and Modeling Data: Reconstructing Flow and Salinity in the San Francisco Estuary over the Past Millennium

Water ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2139
Author(s):  
Paul H. Hutton ◽  
David M. Meko ◽  
Sujoy B. Roy
Keyword(s):  
San Francisco ◽  
Tree Ring ◽  
San Francisco Estuary ◽  
Salinity Intrusion ◽  
Estuarine Ecosystem ◽  
Freshwater Flow ◽  
The Past ◽  
Decadal Scale ◽  
Tree Ring Data ◽  
Past Millennium

This work presents updated reconstructions of watershed runoff to San Francisco Estuary from tree-ring data to AD 903, coupled with models relating runoff to freshwater flow to the estuary and salinity intrusion. We characterize pre-development freshwater flow and salinity conditions in the estuary over the past millennium and compare this characterization with contemporary conditions to better understand the magnitude and seasonality of changes over this time. This work shows that the instrumented flow record spans the range of runoff patterns over the past millennium (averaged over 5, 10, 20 and 100 years), and thus serves as a reasonable basis for planning-level evaluations of historical hydrologic conditions in the estuary. Over annual timescales we show that, although median freshwater flow to the estuary has not changed significantly, it has been more variable over the past century compared to pre-development flow conditions. We further show that the contemporary period is generally associated with greater spring salinity intrusion and lesser summer–fall salinity intrusion relative to the pre-development period. Thus, salinity intrusion in summer and fall months was a common occurrence under pre-development conditions and has been moderated in the contemporary period due to the operations of upstream reservoirs, which were designed to hold winter and spring runoff for release in summer and fall. This work also confirms a dramatic decadal-scale hydrologic shift in the watershed from very wet to very dry conditions during the late 19th and early 20th centuries; while not unprecedented, these shifts have been seen only a few times in the past millennium. This shift resulted in an increase in salinity intrusion in the first three decades of the 20th century, as documented through early records. Population growth and extensive watershed modification during this period exacerbated this underlying hydrologic shift. Putting this shift in the context of other anthropogenic drivers is important in understanding the historical response of the estuary and in setting salinity targets for estuarine restoration. By characterizing the long-term behavior of San Francisco Estuary, this work supports decision-making in the State of California related to flow and salinity management for restoration of the estuarine ecosystem.

scholarly journals Supporting Restoration Decisions through Integration of Tree-Ring and Modeling Data: Reconstructing Flow and Salinity in the San Francisco Estuary over the Past Millennium

2021 ◽  
Author(s):  
Paul H Hutton ◽  
David M Meko ◽  
Sujoy B Roy
Keyword(s):  
San Francisco ◽  
Tree Ring ◽  
San Francisco Estuary ◽  
Salinity Intrusion ◽  
Estuarine Ecosystem ◽  
Freshwater Flow ◽  
The Past ◽  
Decadal Scale ◽  
Tree Ring Data ◽  
Past Millennium

This work presents updated reconstructions of watershed runoff to San Francisco Estuary from tree-ring data to AD 903, coupled with models relating runoff to freshwater flow to the estuary and salinity intrusion. We characterize pre-development freshwater flow and salinity conditions in the estuary over the past millennium and compare this characterization with contemporary conditions to better understand the magnitude and seasonality of changes over this time. This work shows that the instrumented flow record spans the range of runoff patterns over the past millennium (averaged over five, ten, twenty and one hundred years), and thus serves as a reasonable basis for planning-level evaluations of historical hydrologic conditions in the estuary. Over annual timescales we show that, although median freshwater flow to the estuary has not changed significantly, it has been more variable over the past century compared to pre-development flow conditions. We further show that the contemporary period is generally associated with greater spring salinity intrusion and lesser summer-fall salinity intrusion relative to the pre-development period. Thus, salinity intrusion in summer and fall months was a common occurrence under pre-development conditions and has been moderated in the contemporary period due to the operations of upstream reservoirs, which were designed to hold winter and spring runoff for release in summer and fall. This work also confirms a dramatic decadal-scale hydrologic shift in the watershed from very wet to very dry conditions during the late 19th and early 20th centuries; while not unprecedented, these shifts have been seen only a few times in the past millennium. This shift resulted in an increase in salinity intrusion in the first three decades of the 20th century, as documented through early records. Population growth and extensive watershed modification during this period exacerbated this underlying hydrologic shift. Putting this shift in the context of other anthropogenic drivers is important in understanding the historical response of the estuary and in setting salinity targets for estuarine restoration. By characterizing the long-term behavior of San Francisco Estuary, this work supports decision-making in the State of California related to flow and salinity management for restoration of the estuarine ecosystem.

scholarly journals Precipitation reconstruction based on tree-ring width over the past 270 years in the central Lesser Khingan Mountains, Northeast China

2020 ◽  
Author(s):  
Mingqi Li ◽  
Guofu Deng ◽  
Xuemei Shao ◽  
Zhi-Yong Yin
Keyword(s):  
Tree Ring ◽  
Northeast China ◽  
Large Scale ◽  
Ring Width ◽  
The Arctic ◽  
Pinus Koraiensis ◽  
Tree Ring Width ◽  
Precipitation Reconstruction ◽  
The Past ◽  
Decadal Scale

Abstract. Inter-annual variations in precipitation play important roles in management of forest ecosystems and agricultural production in Northeast China. This study presents a 270-year precipitation reconstruction of winter to early growing season for the central Lesser Khingan Mountains, Northeast China based on tree-ring width data from 99 tree-ring cores of Pinus koraiensis Sieb. et Zucc. from two sampling sites near Yichun. The reconstruction explained 43.9 % of the variance in precipitation from the previous October to current June during the calibration period 1956–2017. At the decadal scale, we identified four dry periods that occurred during AD 1748–1759, 1774–1786, 1881–1886 and 1918–1924, and four wet periods occurring during AD 1790–1795, 1818–1824, 1852–1859 and 2008–2017, and the period AD 2008–2017 was the wettest in the past 270 years. Power spectral analysis and wavelet analysis revealed cyclic patterns on the inter-annual (2–3 years) and inter-decadal (~11 and ~32–60 years) timescales in the reconstructed series, which may be associated with the large-scale circulation patterns such as the Arctic Oscillation and North Atlantic Oscillation through their impacts on the Asian polar vortex intensity, as well as the solar activity.

Seasonal and regional temperature differences in subtropical China during the past 200 years

2020 ◽  
Author(s):  
Qiufang Cai ◽  
Yu Liu
Keyword(s):  
Tree Ring ◽  
Eastern China ◽  
Temperature Series ◽  
Seasonal Temperature ◽  
Subtropical China ◽  
The Past ◽  
Winter Half ◽  
Decadal Scale ◽  
Reconstructed Temperature ◽  
Summer Time

<p>Tree ring plays an important role in deciphering the paleoclimatic signals over the past 100-10000 years. However, tree-ring studies from tropical to subtropical regions are rarer than that from extratropical regions, which greatly limit our understanding of some critical climate change issues. Based on tree-ring-width chronologies in different area of Subtropical China (SC), seasonal temperature history of different seasons over the past 200 years were reconstructed. In addition to the warm and cold fluctuations in the reconstructed temperature series, main conclusions are drawn in the following two aspects: 1) Winter-half year temperature had good agreement with summer-time temperature variation in SC at decadal scale, while the winter-half year warming in recent decades was more evident than summer-time. 2) Comparison of the tree-ring based temperature series indicated that the start time of the recent warming in eastern China was regional different. It delayed gradually from north to south, starting at least around 1940 AD in the north part, around 1970 AD in the central part and around 1980s in the south part.</p>

scholarly journals Synoptic-Scale Atmospheric Circulation and Boreal Canada Summer Drought Variability of the Past Three Centuries

2006 ◽  
Vol 19 (10) ◽  
pp. 1922-1947 ◽  
Author(s):  
Martin-Philippe Girardin ◽  
Jacques C. Tardif ◽  
Mike D. Flannigan ◽  
Yves Bergeron
Keyword(s):  
Atmospheric Circulation ◽  
North Pacific ◽  
Land Surface ◽  
Fire Regimes ◽  
Global Ocean ◽  
Summer Drought ◽  
Eastern Canada ◽  
Meridional Component ◽  
The Past ◽  
Decadal Scale

Abstract Five independent multicentury reconstructions of the July Canadian Drought Code and one reconstruction of the mean July–August temperature were developed using a network of 120 well-replicated tree-ring chronologies covering the area of the eastern Boreal Plains to the eastern Boreal Shield of Canada. The reconstructions were performed using 54 time-varying reconstruction submodels that explained up to 50% of the regional drought variance during the period of 1919–84. Spatial correlation fields on the six reconstructions revealed that the meridional component of the climate system from central to eastern Canada increased since the mid–nineteenth century. The most obvious change was observed in the decadal scale of variability. Using 500-hPa geopotential height and wind composites, this zonal to meridional transition was interpreted as a response to an amplification of long waves flowing over the eastern North Pacific into boreal Canada, from approximately 1851 to 1940. Composites with NOAA Extended Reconstructed SSTs indicated a coupling between the meridional component and tropical and North Pacific SST for a period covering at least the past 150 yr, supporting previous findings of a summertime global ocean–atmosphere–land surface coupling. This change in the global atmospheric circulation could be a key element toward understanding the observed temporal changes in the Canadian boreal forest fire regimes over the past 150 yr.

scholarly journals The changing physical and ecological meanings of North Pacific Ocean climate indices

2020 ◽  
Vol 117 (14) ◽  
pp. 7665-7671 ◽  
Author(s):  
Michael A. Litzow ◽  
Mary E. Hunsicker ◽  
Nicholas A. Bond ◽  
Brian J. Burke ◽  
Curry J. Cunningham ◽  
...  
Keyword(s):  
Climate Change ◽  
Climate Variability ◽  
North Pacific ◽  
North Pacific Ocean ◽  
Historical Record ◽  
Climate Index ◽  
Climate Indices ◽  
Northeast Pacific ◽  
Temporal Variance ◽  
Basin Scale

Climate change is likely to change the relationships between commonly used climate indices and underlying patterns of climate variability, but this complexity is rarely considered in studies using climate indices. Here, we show that the physical and ecological conditions mapping onto the Pacific Decadal Oscillation (PDO) index and North Pacific Gyre Oscillation (NPGO) index have changed over multidecadal timescales. These changes apparently began around a 1988/1989 North Pacific climate shift that was marked by abrupt northeast Pacific warming, declining temporal variance in the Aleutian Low (a leading atmospheric driver of the PDO), and increasing correlation between the PDO and NPGO patterns. Sea level pressure and surface temperature patterns associated with each climate index changed after 1988/1989, indicating that identical index values reflect different states of basin-scale climate over time. The PDO and NPGO also show time-dependent skill as indices of regional northeast Pacific ecosystem variability. Since the late 1980s, both indices have become less relevant to physical–ecological variability in regional ecosystems from the Bering Sea to the southern California Current. Users of these climate indices should be aware of nonstationary relationships with underlying climate variability within the historical record, and the potential for further nonstationarity with ongoing climate change.

scholarly journals Pycnocline Variations in the Eastern Tropical and North Pacific, 1958–2008

2013 ◽  
Vol 26 (2) ◽  
pp. 583-599 ◽  
Author(s):  
Paul C. Fiedler ◽  
Roy Mendelssohn ◽  
Daniel M. Palacios ◽  
Steven J. Bograd
Keyword(s):  
North Pacific ◽  
Global Climate ◽  
Mixed Layer Depth ◽  
Climatic Variability ◽  
Low Frequency ◽  
Ocean Data Assimilation ◽  
Ecosystem Effects ◽  
Eastern Equatorial Pacific ◽  
Decadal Scale ◽  
The Tropics

Abstract Climatic variability of the pycnocline in the eastern tropical and North Pacific has oceanographic and ecological implications. Gridded monthly profiles of temperature and salinity from the Simple Ocean Data Assimilation (SODA) reanalysis, 1958–2008, were used to derive estimates of four variables related to the density structure of the upper-ocean water column: surface temperature, pycnocline depth, mixed layer depth, and stratification (potential energy anomaly). The pycnocline is primarily a thermal gradient in this region, except in subarctic waters at the northern extreme of the study area, where salinity becomes more important than temperature in determining stratification. Spatial patterns of mean and standard deviation of the four pycnocline variables are presented. Partitioning of variance between seasonal and interannual scales shows the predominance of interannual variability in the tropics and seasonal variability at higher latitudes. Low-frequency variations (trends) in the pycnocline variables were derived by state-space analysis of time series averaged in 5° squares. Regionally coherent trends were either monotonic over 50 years or had decadal-scale changes in sign (±5–10-m depth, ±5%–10% of stratification). For example, in the eastern equatorial Pacific, the pycnocline shoaled by 10 m and weakened by 5% over the 50 years, while in the California Current the pycnocline deepened by ~5 m but showed little net change in stratification, which weakened by 5% to the mid-1970s, strengthened by 8% to the mid-1990s, and then weakened by 4% to 2008. These observed changes in the pycnocline, and future changes resulting from global climate change, may have important biological and ecosystem effects.

scholarly journals Evidence for Using Lagged Climate Indices to Forecast Australian Seasonal Rainfall

2012 ◽  
Vol 25 (4) ◽  
pp. 1230-1246 ◽  
Author(s):  
Andrew Schepen ◽  
Q. J. Wang ◽  
David Robertson
Keyword(s):  
Cross Validation ◽  
Sea Surface ◽  
Seasonal Rainfall ◽  
Climate Index ◽  
Climate Indices ◽  
Supporting Evidence ◽  
Pacific Region ◽  
The Pacific ◽  
Sea Surface Temperature Anomalies ◽  
Predictive Densities

Abstract Lagged oceanic and atmospheric climate indices are potentially useful predictors of seasonal rainfall totals. A rigorous Bayesian joint probability modeling approach is applied to find the cross-validation predictive densities of gridded Australian seasonal rainfall totals using lagged climate indices as predictors over the period of 1950–2009. The evidence supporting the use of each climate index as a predictor of seasonal rainfall is quantified by the pseudo-Bayes factor based on cross-validation predictive densities. The evidence strongly supports the use of climate indices from the Pacific region with weaker, but positive, evidence for the use of climate indices from the Indian region and the extratropical region. The spatial structure and seasonal variation of the evidence for each climate index is mapped and compared. Spatially, the strongest supporting evidence is found for forecasting in northern and eastern Australia. Seasonally, the strongest evidence is found from August–October to November–January and the weakest evidence is found from March–May to May–July. In some regions and seasons, there is little evidence supporting the use of climate indices for forecasting seasonal rainfall. Climate indices derived from sea surface temperature anomalies in the Pacific region show stronger persistence in the relationship with Australian seasonal rainfall totals than climate indices derived from sea surface temperature anomalies in the Indian region. Climate indices derived from atmospheric variables are also strongly supported, provided they represent the large-scale circulation. Many climate indices are found to show similar supporting evidence for forecasting Australian seasonal rainfall, leading to the prospect of combining climate indices in multiple predictor models and/or model averaging.

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