scholarly journals Incorporating Pacific Ocean climate information to enhance the tree-ring-based streamflow reconstruction skill

2020 ◽  
Author(s):  
Saria Bukhary ◽  
Ajay Kalra ◽  
Sajjad Ahmad
Keyword(s):  
Pacific Ocean ◽  
River Basin ◽  
Tree Ring ◽  
Cross Validation ◽  
Southern Oscillation ◽  
Low Flow ◽  
Tree Ring Chronology ◽  
Streamflow Reconstruction ◽  
Current Scenario ◽  
Instrumental Records

Abstract The Sacramento River Basin (SRB) and the San Joaquin River Basin (JRB) have a history of recurring droughts. Both are important for California, being the crucial source of water supply. The available instrumental records may not depict the long-term hydrologic variability encompassing the duration and frequency of the historic low flow events. Thus, streamflow reconstruction becomes important in the current scenario of climatic alteration, escalating population and growing water needs. Studies have shown that Pacific Decadal Oscillation (PDO), Southern Oscillation Index (SOI), and Pacific Ocean sea surface temperature (SST) influence the precipitation and streamflow volumes of southwestern United States, particularly California. The focus of this study is to enhance the traditional tree-ring chronology (TRC)-based streamflow reconstruction approach by incorporating the predictors of SST, PDO, and SOI together with TRC, in a stepwise linear regression (SLR) model. The methodology was successfully applied to selected gages located in the SRB and the JRB using five SLR models (SLR 1–5), and reconstructions were developed from 1801 to 1980 with an overlap period of 1933–1980. An improved reconstruction skill was demonstrated by using SST in combination with TRC (SLR-3 and SLR-5) (calibration r2 = 0.6–0.91 and cross-validation r² = 0.44–0.74) compared with using TRC only (SLR-1), or TRC along with SOI and PDO (SLR-2; calibration r2 = 0.51–0.78 and cross-validation r² = 0.41–0.68).

scholarly journals Juniper Tree-Ring Data from the Kuramin Range (Northern Tajikistan) Reveals Changing Summer Drought Signals in Western Central Asia

Forests ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 505 ◽  
Author(s):  
Feng Chen ◽  
Tongwen Zhang ◽  
Andrea Seim ◽  
Shulong Yu ◽  
Ruibo Zhang ◽  
...  
Keyword(s):  
Central Asia ◽  
Tree Ring ◽  
Large Scale ◽  
Southern Oscillation ◽  
Severity Index ◽  
Drought Severity ◽  
Summer Drought ◽  
Tree Ring Chronology ◽  
Tree Ring Data ◽  
June July

Coniferous forests cover the mountains in many parts of Central Asia and provide large potentials for dendroclimatic studies of past climate variability. However, to date, only a few tree-ring based climate reconstructions exist from this region. Here, we present a regional tree-ring chronology from the moisture-sensitive Zeravshan juniper (Juniperus seravschanica Kom.) from the Kuramin Range (Tajikistan) in western Central Asia, which is used to reveal past summer drought variability from 1650 to 2015 Common Era (CE). The chronology accounts for 40.5% of the variance of the June–July self-calibrating Palmer Drought Severity Index (scPDSI) during the instrumental period (1901 to 2012). Seven dry periods, including 1659–1696, 1705–1722, 1731–1741, 1758–1790, 1800–1842, 1860–1875, and 1931–1987, and five wet periods, including 1742–1752, 1843–1859, 1876–1913, 1921–1930, and 1988–2015, were identified. Good agreements between drought records from western and eastern Central Asia suggest that the PDSI records retain common drought signals and capture the regional dry/wet periods of Central Asia. Moreover, the spectral analysis indicates the existence of centennial (128 years), decadal (24.3 and 11.4 years), and interannual (8.0, 3.6, 2.9, and 2.0 years) cycles, which may be linked with climate forces, such as solar activity and El Niño-Southern Oscillation (ENSO). The analysis between the scPDSI reconstruction and large-scale atmospheric circulations during the reconstructed extreme dry and wet years can provide information about the linkages of extremes in our scPDSI record with the large-scale ocean–atmosphere–land circulation systems.

scholarly journals A 431-Yr Reconstruction of Western Colorado Snowpack from Tree Rings

2003 ◽  
Vol 16 (10) ◽  
pp. 1551-1561 ◽  
Author(s):  
Connie A. Woodhouse
Keyword(s):  
Twentieth Century ◽  
River Basin ◽  
Tree Ring ◽  
Snow Water Equivalent ◽  
Southern Oscillation ◽  
Strong Relationship ◽  
Transitional Zone ◽  
Winter Precipitation ◽  
Winter Climate ◽  
Western Colorado

Abstract A tree-ring-based reconstruction for 1 April snow water equivalent (SWE) is generated for the Gunnison River basin region in western Colorado. The reconstruction explains 63% of the variance in the instrumental record and extends from 1569 to 1999. When the twentieth-century part of the record is compared to the full record, the variability and extremes in the twentieth century appear representative of the long-term record. However, years of extreme SWE (low and high) and persistent low SWE events are not evenly distributed throughout the record. The twentieth century is notable for several periods that lack extreme years, and along with the nineteenth century and the second half of the eighteenth century, contains many fewer persistent low SWE events than the first half of the reconstruction. Low SWE in the western United States is associated with several circulation patterns, including the Pacific–North American (PNA) pattern and those related to El Niño–Southern Oscillation (ENSO), but the Gunnison River basin is on the edge of the area with a strong relationship to the PNA and is generally in a transitional zone with respect to regional ENSO influences. Tree-ring chronologies from Oregon and New Mexico, regions impacted by ENSO, were used as rough proxies of northwestern and southwestern U.S. winter precipitation to explore possible associations between Gunnison SWE and winter climate in these two regions over the past four centuries.

scholarly journals Long-term reliability of the Athabasca River (Alberta, Canada) as the water source for oil sands mining

2015 ◽  
Vol 112 (41) ◽  
pp. 12621-12626 ◽  
Author(s):  
David J. Sauchyn ◽  
Jeannine-Marie St-Jacques ◽  
Brian H. Luckman
Keyword(s):  
Surface Water ◽  
Tree Ring ◽  
Water Allocation ◽  
Oil Sands ◽  
Low Flow ◽  
Athabasca River ◽  
Decadal Scale ◽  
Alberta Oil Sands ◽  
Instrumental Records

Exploitation of the Alberta oil sands, the world’s third-largest crude oil reserve, requires fresh water from the Athabasca River, an allocation of 4.4% of the mean annual flow. This allocation takes into account seasonal fluctuations but not long-term climatic variability and change. This paper examines the decadal-scale variability in river discharge in the Athabasca River Basin (ARB) with (i) a generalized least-squares (GLS) regression analysis of the trend and variability in gauged flow and (ii) a 900-y tree-ring reconstruction of the water-year flow of the Athabasca River at Athabasca, Alberta. The GLS analysis removes confounding transient trends related to the Pacific Decadal Oscillation (PDO) and Pacific North American mode (PNA). It shows long-term declining flows throughout the ARB. The tree-ring record reveals a larger range of flows and severity of hydrologic deficits than those captured by the instrumental records that are the basis for surface water allocation. It includes periods of sustained low flow of multiple decades in duration, suggesting the influence of the PDO and PNA teleconnections. These results together demonstrate that low-frequency variability must be considered in ARB water allocation, which has not been the case. We show that the current and projected surface water allocations from the Athabasca River for the exploitation of the Alberta oil sands are based on an untenable assumption of the representativeness of the short instrumental record.

scholarly journals Investigating links between rainfall variations in the Ogooué River basin and ENSO in the Pacific Ocean over the period 1940–1999

2021 ◽  
Vol 384 ◽  
pp. 181-186
Author(s):  
Sakaros Bogning ◽  
Frédéric Frappart ◽  
Gil Mahé ◽  
Adrien Paris ◽  
Raphael Onguene ◽  
...  
Keyword(s):  
Time Series ◽  
Pacific Ocean ◽  
River Basin ◽  
Southern Oscillation ◽  
Rainfall Variability ◽  
The Pacific ◽  
Basin Scale ◽  
The Pacific Ocean ◽  
Wavelet Coherence Analysis ◽  
Enso Index

Abstract. This paper investigates links between rainfall variability in the Ogooué River Basin (ORB) and El Niño Southern Oscillation (ENSO) in the Pacific Ocean. Recent hydroclimatology studies of the ORB and surrounding areas resulting in contrasting conclusions about links between rainfall variability and ENSO. Thus, to make the issue clearer, this study investigates the links between ENSO and rainfall in the ORB over the period 1940–1999. The principal component analysis of monthly rainfall in the ORB was done. The temporal mode of the first component corresponds to the interannual variations of rainfall on the ORB. Also, the pattern of the spatial mode of the first component shows that the ORB is a homogeneous hydroclimatic zone. However, no leading mode is significantly correlated to the ENSO index. A cross-wavelet analysis of the time series of basin-scale rainfall and the ENSO index was therefore carried out. The result is a set of periodogram structures corresponding to some ENSO episodes recorded over the study period. And wavelet coherence analysis of both time series confirms that there are significant links between ENSO and rainfall in the ORB.

scholarly journals Large scale climate signals of a European oxygen isotope network from tree-rings – predominantly caused by ENSO teleconnections?

2020 ◽  
Author(s):  
Daniel F. Balting ◽  
Monica Ionita ◽  
Martin Wegmann ◽  
Gerhard Helle ◽  
Gerhard H. Schleser ◽  
...  
Keyword(s):  
Atmospheric Circulation ◽  
Tree Ring ◽  
Tree Rings ◽  
Large Scale ◽  
Southern Oscillation ◽  
Circulation Pattern ◽  
Isotopic Signature ◽  
Atmospheric Circulation Patterns ◽  
Climate Signals ◽  
Instrumental Records

Abstract. We investigate the annual variability of δ18O tree ring records from sites distributed all over Europe covering the last 400 years. An Empirical Orthogonal Function (EOF) analysis reveals two distinct modes of variability on the basis of the existing δ18O tree ring records. The first mode of δ18O variability is associated with anomaly patterns of the El Niño-Southern Oscillation (ENSO) and reflects a multi-seasonal climatic signal. The ENSO signal is visible for the last 130 years, but is found weak during the period 1600 to 1850 suggesting that the relationship between ENSO and the European climate may not stable over time. The second mode of δ18O variability, which captures an out-of-phase variability between northwestern and southeastern European δ18O tree ring records, is related to a regional summer atmospheric circulation pattern revealing a pronounced centre over the North Sea. Locally, the δ18O anomalies associated with this mode show the same (opposite) sign with temperature (precipitation). We infer that the investigation of large-scale atmospheric circulation patterns and related teleconnections far beyond instrumental records can be done with oxygen isotopic signature derived from tree rings. However, the European δ18Ocel tree network needs to be consolidated and updated, as well as additional research on the stationarity of reconstructed climate signals and the stationarity of teleconnections is advisable.

scholarly journals A Tree-Ring-Based Reconstruction of Delaware River Basin Streamflow Using Hierarchical Bayesian Regression

2013 ◽  
Vol 26 (12) ◽  
pp. 4357-4374 ◽  
Author(s):  
Naresh Devineni ◽  
Upmanu Lall ◽  
Neil Pederson ◽  
Edward Cook
Keyword(s):  
River Basin ◽  
Tree Ring ◽  
Parameter Uncertainty ◽  
Bayesian Regression ◽  
Regression Coefficients ◽  
Hierarchical Bayesian ◽  
Tree Ring Chronology ◽  
Unknown Parameters ◽  
Delaware River ◽  
Posterior Probability Distribution

Abstract A hierarchical Bayesian regression model is presented for reconstructing the average summer streamflow at five gauges in the Delaware River basin using eight regional tree-ring chronologies. The model provides estimates of the posterior probability distribution of each reconstructed streamflow series considering parameter uncertainty. The vectors of regression coefficients are modeled as draws from a common multivariate normal distribution with unknown parameters estimated as part of the analysis. This leads to a multilevel structure. The covariance structure of the streamflow residuals across sites is explicitly modeled. The resulting partial pooling of information across multiple stations leads to a reduction in parameter uncertainty. The effect of no pooling and full pooling of station information, as end points of the method, is explored. The no-pooling model considers independent estimation of the regression coefficients for each streamflow gauge with respect to each tree-ring chronology. The full-pooling model considers that the same regression coefficients apply across all streamflow sites for a particular tree-ring chronology. The cross-site correlation of residuals is modeled in all cases. Performance on metrics typically used by tree-ring reconstruction experts, such as reduction of error, coefficient of efficiency, and coverage rates under credible intervals is comparable to, or better, for the partial-pooling model relative to the no-pooling model, and streamflow estimation uncertainty is reduced. Long record simulations from reconstructions are used to develop estimates of the probability of duration and severity of droughts in the region. Analysis of monotonic trends in the reconstructed drought events do not reject the null hypothesis of no trend at the 90% significance over 1754–2000.

scholarly journals Two Centuries-Long Streamflow Reconstruction Inferred from Tree Rings for the Middle Reaches of the Weihe River in Central China

Forests ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 208 ◽  
Author(s):  
Na Liu ◽  
Guang Bao ◽  
Yu Liu ◽  
Hans W. Linderholm
Keyword(s):  
River Basin ◽  
Tree Ring ◽  
El Niño ◽  
El Nino ◽  
Central China ◽  
Streamflow Reconstruction ◽  
Weihe River ◽  
June July ◽  
Weihe River Basin

Water source is one of the most important concerns for regional society and economy development, especially in the Weihe River basin which is located in the marginal zone of the Asian summer monsoon. Due to the weakness of short instrumental records, the variations of streamflow during the long-term natural background are difficult to access. Herein, the average June–July streamflow variability in the middle reaches of the Weihe River was identified based on tree-ring width indices of Chines pine (Pinus tabulaeformis Carr.) from the northern slope of the Qinling Mountains in central China. Our model could explain the variance of 39.3% in the observed streamflow period from 1940 to 1970 AD. There were 30 extremely low years and 26 high years which occurred in our reconstruction for the effective span of 1820 to 2005. Several common dryness and wetness periods appeared in this reconstructed streamflow, and other tree-ring precipitation series suggested the coherence of hydroclimate fluctuation over the Weihe River basin. Some significant peaks in cycles implied the linkages of natural forcing on the average June–July streamflow of the Weihe River, such as the Pacific Decadal Oscillation (PDO) and El Niño-Southern Oscillation (ENSO) activities. Spatial correlation results between streamflow and sea surface temperature in the northern Pacific Ocean, as well as extremely low/high years responding to the El Niño/La Nina events, supported the teleconnections. The current 186-year streamflow reconstruction placed regional twentieth-century drought and moisture events in a long-term perspective in the Weihe River basin, and provided useful information for regional water resource safety and forest management, particularly under climate warming conditions.

scholarly journals Millennial Minimum Temperature Variations in the Qilian Mountains, China: evidence from Tree rings

2014 ◽  
Vol 10 (1) ◽  
pp. 341-380 ◽  
Author(s):  
Y. Zhang ◽  
X. Shao ◽  
Z.-Y. Yin ◽  
Y. Wang
Keyword(s):  
Tibetan Plateau ◽  
Tree Ring ◽  
Minimum Temperature ◽  
Southern Oscillation ◽  
Volcanic Eruptions ◽  
Qilian Mountains ◽  
Eastern Tibetan Plateau ◽  
Tree Ring Chronology ◽  
The North ◽  
North Eastern

Abstract. A 1342 yr-long tree-ring chronology was developed from Qilian junipers in the central Qilian Mountains of the north-eastern Tibetan Plateau, China. The climatic implications of this chronology were investigated using simple correlation, partial correlation and response function analyses. The chronology was significantly positively correlated with temperature variables during the pre- and current growing seasons, especially with minimum temperature. The variability of the mean minimum temperature from January to August since 670 AD was then reconstructed based on the tree-ring chronology. The reconstruction explained 58.5% of the variance in the instrumental temperature records during the calibration period (1960–2011) and captured the variation patterns in minimum temperature at the annual to centennial time scales over the past millennium. The most recent 50 yr were the warmest period, while 1690–1880 was the coldest period since 670 AD. Comparisons with other temperature series from neighbouring regions and for the Northern Hemisphere as a whole supported the validity of our reconstruction and suggested that it provided a good regional representation of temperature change in the north-eastern Tibetan Plateau. The results of multi-taper spectral analysis showed the occurrence of significant quasi-periodic behaviour at a number of periods (2–3, 28.8–66.2, 113.6–169.5, and 500 yr), which were consistent with those associated with El Niño-Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO) and solar activity. Some reconstructed cold events may have close relationship with the volcanic eruptions.

scholarly journals Variation in Climate Signals in Teak Tree-Ring Chronologies in Two Different Growth Areas

Forests ◽  
2018 ◽  
Vol 9 (12) ◽  
pp. 772 ◽  
Author(s):  
Sineenart Preechamart ◽  
Nathsuda Pumijumnong ◽  
Paramate Payomrat ◽  
Supaporn Buajan
Keyword(s):  
Tree Ring ◽  
Southern Oscillation ◽  
Monsoon Season ◽  
Ring Width ◽  
Tectona Grandis ◽  
Ring Structure ◽  
Limiting Factor ◽  
Tree Ring Chronology ◽  
Teak Tree ◽  
Northwestern Thailand

We developed two tree-ring chronologies of teak (Tectona grandis L.f.) from Mae Tuen (462-year, 1555–2016) and Umphang (165-year, 1852–2016) in Tak province, northwestern Thailand. The chronologies were based on 67 and 71 living teak trees, respectively. We used crossdating methods to check and verify the tree-ring width data and tree-ring chronology construction using the ARSTAN program. In this study, the two teak tree-ring chronologies from two different growth areas could not be crossdated. The relationship among these chronologies is, thus, relatively low (r = 0.33, n = 165, p < 0.01). This result shows that the growth of tree-ring structure from two sites can be affected by a variety of non-climatic patterns due to site variation, such as topography, nutrient, light, and internal factors. However, these chronologies have a significant positive correlation with rainfall, during the pre-monsoon season (April to May). As demonstrated by the spatial correlation patterns, these chronologies represent April to May rainfall, which was a limiting factor of teak growth from northwestern Thailand. While the difference in surface temperatures of the Indian Ocean Dipole (IOD) might not be affected by rainfall, its unstable relationship with the El Niño-Southern Oscillation (ENSO) was noted to have occurred.

scholarly journals Large-scale climate signals of a European oxygen isotope network from tree rings

2021 ◽  
Vol 17 (3) ◽  
pp. 1005-1023
Author(s):  
Daniel F. Balting ◽  
Monica Ionita ◽  
Martin Wegmann ◽  
Gerhard Helle ◽  
Gerhard H. Schleser ◽  
...  
Keyword(s):  
Atmospheric Circulation ◽  
Tree Ring ◽  
Tree Rings ◽  
Large Scale ◽  
Southern Oscillation ◽  
Circulation Pattern ◽  
Isotopic Signature ◽  
Atmospheric Circulation Patterns ◽  
The North ◽  
Instrumental Records

Abstract. We investigate the climate signature of δ18O tree-ring records from sites distributed all over Europe covering the last 400 years. An empirical orthogonal function (EOF) analysis reveals two distinct modes of variability on the basis of the existing δ18O tree-ring records. The first mode is associated with anomaly patterns projecting onto the El Niño–Southern Oscillation (ENSO) and reflects a multi-seasonal climatic signal. The ENSO link is pronounced for the last 130 years, but it is found to be weak over the period from 1600 to 1850, suggesting that the relationship between ENSO and the European climate may not be stable over time. The second mode of δ18O variability, which captures a north–south dipole in the European δ18O tree-ring records, is related to a regional summer atmospheric circulation pattern, revealing a pronounced centre over the North Sea. Locally, the δ18O anomalies associated with this mode show the same (opposite) sign with temperature (precipitation). Based on the oxygen isotopic signature derived from tree rings, we argue that the prevailing large-scale atmospheric circulation patterns and the related teleconnections can be analysed beyond instrumental records.

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