Low-frequency divergence of tree-ring d18O variations on both sides of climatic boundary mountain of eastern China since 1980s

2020 ◽  
Author(s):  
Qiang Li ◽  
Yu Liu ◽  
Huiming Song
Keyword(s):  
Relative Humidity ◽  
Tree Ring ◽  
Time Scale ◽  
Eastern China ◽  
Sampling Site ◽  
Low Frequency ◽  
Mountain Range ◽  
Decadal Time Scale ◽  
Qinling Mountain ◽  
Significant Divergence

<p>The Qinling Mountain is the most important mountain range in eastern China, and is the geographical boundary and the climatic boundary. We investigated tree-ring d18O variations in South and North Slope of the Qinling Mountain, and found that the variations of tree-ring  d18O were significantly correlated over the past two and a half centuries (r=0.641, n=247, p<0.001). And they are negatively correlated with relative humidity and precipitation, and positively correlated with temperature. Compared with the various hydroclimate-related time series in the surrounding area, it is found that both can represent the region's long-term hydroclimate change. The consistent changes in the interannual time scale may be due to the common modulation of ENSO. However, on the decadal time scale, there have been significant divergence between the two tree-ring  d18O series since 1981 and the divergence may be caused by changes in relative humidity at the sampling site, suggesting that in the context of global warming, although the warming range is the same, but the triggered relative humidity changes are not consistent. In addition, changes in PDO may be another cause of low-frequency difference.</p>

scholarly journals Influence of Decadal Ocean Signals on Meteorological Conditions Associated With the Winter Haze Over Eastern China

2021 ◽  
Vol 9 ◽  
Author(s):  
Wen Zhang ◽  
Xiao Dong ◽  
Zhenxin Liu ◽  
Renping Lin ◽  
Hao Luo
Keyword(s):  
Time Scale ◽  
Wave Train ◽  
Eastern China ◽  
Meteorological Conditions ◽  
Positive Phase ◽  
Decadal Time Scale ◽  
Near Surface ◽  
The Pacific ◽  
Decadal Scale ◽  
Central Eastern

The possible influence of the Atlantic multidecadal oscillation (AMO) and the Pacific decadal oscillation (PDO) on the meteorological conditions associated with haze over central eastern China at decadal time scale was investigated using reanalysis and observational dataset for 1979–2018. Four indices, including Siberian high (SH) strength and position indices (SHI/SHPI), a normalized near-surface wind-speed index (WSI) and a potential air temperature gradient index (ATGI), are adopted to denote the meteorological conditions associated with haze. Results shown that the AMO and PDO are both highly correlated with the fluctuation of meteorological factors associated with haze on decadal scale. Although AMO and PDO were in opposite phases during the whole period, since 1997, they both changed phases (AMO shifted to a positive phase and PDO changed to negative) and became favorable for an anomalous dipole-type SLP pattern in the middle-high latitudes of East Asia. The AMO has played a leading role in decadal variation of the large-scale circulation system, while the PDO has had a closer relationship with the lower ventilation condition in eastern China. On the decadal time scale, the AMO stimulates a zonal teleconnection wave train (the AMO northern Hemisphere pattern, ANH) that originates from the North Atlantic Ocean and passes through central Europe, the northern Ural Mountains, Lake Balkhash-Baikal, and central eastern China. During the positive phase of AMO, the ANH induces a stronger and westward shifted SH, with the central eastern China controlled by the anomalous high pressure. In addition, affected by the cyclone (anticyclone) anomaly over Hetao region and North China (the Sea of Japan), southerly wind anomalies dominate over central eastern China. Compared with the AMO, the wave train generated by the negative (positive) PDO phase mainly propagates in the Pacific region, and there is a strong anticyclonic (cyclonic) anomaly over the Northeast Pacific, guiding the air flow southward (northward) along the East Asian coast and thus suppressing (encouraging) the dispersion of pollutants and resulting in above (below)-normal haze episodes.

Assessing Bjerknes Compensation for Climate Variability and Its Time-Scale Dependence

2016 ◽  
Vol 29 (15) ◽  
pp. 5501-5512 ◽  
Author(s):  
Yingying Zhao ◽  
Haijun Yang ◽  
Zhengyu Liu
Keyword(s):  
Climate Variability ◽  
Heat Transport ◽  
Phase Difference ◽  
Time Scale ◽  
Theoretical Perspective ◽  
Low Frequency ◽  
Box Model ◽  
Climate Feedback ◽  
Decadal Time Scale ◽  
New Approach

Abstract The Bjerknes compensation (BJC) refers to the tendency for changes in the atmosphere heat transport (AHT) and ocean heat transport (OHT) to compensate each other. However, the nature of this compensation varies with the time scale of changes. In this study, a new approach was developed to diagnose BJC for climate variability by considering the correlation between AHT and OHT and their relative magnitudes. The correlation is equivalent to the cosine of phase difference between AHT and OHT. For high-frequency climate variability, AHT lags or leads OHT by π/2, the correlation is zero, and BJC does not occur concurrently. For low-frequency climate variability, AHT lags or leads OHT by π, the correlation is −1, and BJC is concurrent. With increasing time scale, the phase difference between AHT and OHT changes from π/2 to π, and the BJC reaches equilibrium. A coupled box model is used to justify the approach and to understand the temporal change of BJC from a theoretical perspective. The correlation and BJC rate derived from theory and from the box model exhibit similar transient behaviors, approaching equilibrium monotonically with increasing time scale. The equilibrium BJC is established at decadal time scale. Since the BJC is closely related to climate feedback, a proper identification of BJC processes in climate variability can reveal the nature of dominant climate feedback processes at different time scales.

scholarly journals Radiocarbon Calibration and Application to Geophysics, Solar Physics, and Astrophysics

Radiocarbon ◽  
2000 ◽  
Vol 42 (1) ◽  
pp. 137-150 ◽  
Author(s):  
Paul E Damon ◽  
Alexei N Peristykh
Keyword(s):  
Tree Ring ◽  
Time Scale ◽  
Thermohaline Circulation ◽  
Second Harmonic ◽  
Piecewise Linear ◽  
Solar Physics ◽  
Piecewise Linear Approximation ◽  
Decadal Time Scale ◽  
Fundamental Frequencies ◽  
History Of

This paper includes a brief history of the calibration of the radiocarbon time scale from the first recognition of the necessity of calibration in 1962 to INTCAL98. Thirty-six years of effort by dendrochronologists and the 14C community have pushed the tree-ring calibration back to 11,854 yr BP. All of this part of the calibration has been done by high-precision beta counting. Uranium-thorium (U-Th) dating of coral samples coupled with accelerator mass spectrometry (AMS) measurement of 14C has extended a fairly detailed calibration back beyond the Bølling warm episode to 15,000 BP. Earlier than 15,000 BP, piecewise linear approximation extends INTCAL98 calibration to 24,200 BP.Blending 1-, 2-, 3-, 10-, and 20-yr tree-ring samples containing regional and data offsets into a decadal time scale does not make an ideal error and bias free δ14C record. Nevertheless, spectral analysis reveals some statistically significant fundamental frequencies as well as interesting “beat” frequencies and the second harmonic of the around 208-yr cycle that is considered to be solar in origin. Although, some very prominent peaks such as the 88-yr (Gleissberg) are clearly solar in origin, some of the lower frequencies such as of the 512-yr period may have an origin in thermohaline circulation. Thus, INTCAL98 provides useful data for geophysical and solar physics research. Lastly, single year δ14C analysis would be useful for revealing invaluable information for solar physics, astrophysics and geophysics not accessible by decadal data. We provide several examples.

scholarly journals Locally and Remotely Forced Subtropical AMOC Variability: A Matter of Time Scales

2020 ◽  
Vol 33 (12) ◽  
pp. 5155-5172
Author(s):  
Quentin Jamet ◽  
William K. Dewar ◽  
Nicolas Wienders ◽  
Bruno Deremble ◽  
Sally Close ◽  
...  
Keyword(s):  
Time Series ◽  
Time Scales ◽  
North Atlantic ◽  
Time Scale ◽  
Low Frequency ◽  
Meridional Overturning Circulation ◽  
Open Boundary ◽  
Overturning Circulation ◽  
Decadal Scale ◽  
Meridional Overturning

AbstractMechanisms driving the North Atlantic meridional overturning circulation (AMOC) variability at low frequency are of central interest for accurate climate predictions. Although the subpolar gyre region has been identified as a preferred place for generating climate time-scale signals, their southward propagation remains under consideration, complicating the interpretation of the observed time series provided by the Rapid Climate Change–Meridional Overturning Circulation and Heatflux Array–Western Boundary Time Series (RAPID–MOCHA–WBTS) program. In this study, we aim at disentangling the respective contribution of the local atmospheric forcing from signals of remote origin for the subtropical low-frequency AMOC variability. We analyze for this a set of four ensembles of a regional (20°S–55°N), eddy-resolving (1/12°) North Atlantic oceanic configuration, where surface forcing and open boundary conditions are alternatively permuted from fully varying (realistic) to yearly repeating signals. Their analysis reveals the predominance of local, atmospherically forced signal at interannual time scales (2–10 years), whereas signals imposed by the boundaries are responsible for the decadal (10–30 years) part of the spectrum. Due to this marked time-scale separation, we show that, although the intergyre region exhibits peculiarities, most of the subtropical AMOC variability can be understood as a linear superposition of these two signals. Finally, we find that the decadal-scale, boundary-forced AMOC variability has both northern and southern origins, although the former dominates over the latter, including at the site of the RAPID array (26.5°N).

Fire history on a desert mountain range: Rincon Mountain Wilderness, Arizona, U.S.A.

1990 ◽  
Vol 20 (10) ◽  
pp. 1559-1569 ◽  
Author(s):  
Christopher H. Baisan ◽  
Thomas W. Swetnam
Keyword(s):  
Tree Ring ◽  
Large Scale ◽  
Fire History ◽  
Fire Regime ◽  
Forest Type ◽  
Drought Severity ◽  
Mountain Range ◽  
Mixed Conifer ◽  
The Mean ◽  
Mean Fire Interval

Modern fire records and fire-scarred remnant material collected from logs, snags, and stumps were used to reconstruct and analyze fire history in the mixed-conifer and pine forest above 2300 m within the Rincon Mountain Wilderness of Saguaro National Monument, Arizona, United States. Cross-dating of the remnant material allowed dating of fire events to the calendar year. Estimates of seasonal occurrence were compiled for larger fires. It was determined that the fire regime was dominated by large scale (> 200 ha), early-season (May–July) surface fires. The mean fire interval over the Mica Mountain study area for the period 1657–1893 was 6.1 years with a range of 1–13 years for larger fires. The mean fire interval for the mixed-conifer forest type (1748–1886) was 9.9 years with a range of 3–19 years. Thirty-five major fire years between 1700 and 1900 were compared with a tree-ring reconstruction of the Palmer drought severity index (PDSI). Mean July PDSI for 2 years prior to fires was higher (wetter) than average, while mean fire year PDSI was near average. This 490-year record of fire occurrence demonstrates the value of high-resolution (annual and seasonal) tree-ring analyses for documenting and interpreting temporal and spatial patterns of past fire regimes.

Frequency-Weighted Variable-Length Controllers Using Anytime Control Strategies

2011 ◽  
Author(s):  
Gundula B. Runge ◽  
Al Ferri ◽  
Bonnie Ferri
Keyword(s):  
Time Scale ◽  
Weighting Function ◽  
Control Strategies ◽  
Low Frequency ◽  
Low Frequencies ◽  
High Frequencies ◽  
Frequency Components ◽  
Computational Resources ◽  
Weighted Variable ◽  
Selection Of

This paper considers an anytime strategy to implement controllers that react to changing computational resources. The anytime controllers developed in this paper are suitable for cases when the time scale of switching is in the order of the task execution time, that is, on the time scale found commonly with sporadically missed deadlines. This paper extends the prior work by developing frequency-weighted anytime controllers. The selection of the weighting function is driven by the expectation of the situations that would require anytime operation. For example, if the anytime operation is due to occasional and isolated missed deadlines, then the weighting on high frequencies should be larger than that for low frequencies. Low frequency components will have a smaller change over one sample time, so failing to update these components for one sample period will have less effect than with the high frequency components. An example will be included that applies the anytime control strategy to a model of a DC motor with deadzone and saturation nonlinearities.

scholarly journals A 40,000-Year Varve Chronology from Lake Suigetsu, Japan: Extension of the 14C Calibration Curve

Radiocarbon ◽  
1997 ◽  
Vol 40 (1) ◽  
pp. 505-515 ◽  
Author(s):  
Hiroyuki Kitagawa ◽  
Johannes Van Der Plicht
Keyword(s):  
Tree Ring ◽  
Calibration Curve ◽  
Time Scale ◽  
Mass Spectrometric ◽  
Laminated Sediments ◽  
Varve Chronology ◽  
Total Range ◽  
Dating Method ◽  
Annually Laminated Sediments ◽  
Potential Tool

A sequence of annually laminated sediments is a potential tool for calibrating the radiocarbon time scale beyond the range of the absolute tree-ring calibration (11 ka). We performed accelerator mass spectrometric (AMS) 14C measurements on >250 terrestrial macrofossil samples from a 40,000-yr varve sequence from Lake Suigetsu, Japan. The results yield the first calibration curve for the total range of the 14C dating method.

scholarly journals Tree-ring-based spring precipitation reconstruction in the Sikhote-Alin' Mountain range

2021 ◽  
Vol 17 (2) ◽  
pp. 951-967
Author(s):  
Olga Ukhvatkina ◽  
Alexander Omelko ◽  
Dmitriy Kislov ◽  
Alexander Zhmerenetsky ◽  
Tatyana Epifanova ◽  
...  
Keyword(s):  
Climate Variability ◽  
Tree Ring ◽  
Southern Oscillation ◽  
Russian Far East ◽  
Pinus Koraiensis ◽  
Mountain Range ◽  
Korean Pine ◽  
Sikhote Alin ◽  
The Impact ◽  
Standard Tree

Abstract. Climate reconstructions provide important insight into past climate variability and help us to understand the large-scale climate drivers and impact of climate change. However, our knowledge about long-term year-to-year climate variability is still limited due to the lack of high-resolution reconstructions. Here, we present the first precipitation reconstructions based on tree rings from Pinus koraiensis (Korean pine) from three sites placed along a latitudinal (330 km) gradient in the Sikhote-Alin' mountains in the Russian Far East. The tree-ring width chronologies were built using standard tree-ring procedures. We reconstructed the April–June precipitation for the southern Sikhote-Alin' (SSA), March–June precipitation for the central Sikhote-Alin' (CSA) and March–July precipitation for the northwestern Sikhote-Alin' (NSA) over the years 1602 to 2013, 1804 to 2009 and 1858 to 2013, respectively. We found that an important limiting factor for Korean pine growth was precipitation within the period when the air current coming from the continent during the cold period is replaced with the impact of the wet ocean air current. We identified that common wet years for SSA, CSA and NSA occurred in 1805, 1853, 1877, 1903, 1906, 1927, 1983 and 2009 and common dry years occurred in 1821, 1869, 1919, 1949 and 2003. Our reconstructions have 3-, 15- and 60-year periods, which suggests the influence of the El Niño–Southern Oscillation and Pacific Decadal Oscillation on the region's climate and relevant processes. Despite the impact of various global processes, the main contribution to precipitation formation in the study area is still made by the Pacific Ocean, which determines their amount and periodicity.

UNIVERSAL MULTIFRACTAL CHARACTERIZATION AND SIMULATION OF SPEECH

1992 ◽  
Vol 02 (03) ◽  
pp. 715-719
Author(s):  
CHRIS LARNDER ◽  
NICOLAS DESAULNIERS-SOUCY ◽  
SHAUN LOVEJOY ◽  
DANIEL SCHERTZER ◽  
CLAUDE BRAUN ◽  
...  
Keyword(s):  
Time Scale ◽  
Scale Invariance ◽  
Characteristic Time ◽  
Low Frequency ◽  
Characteristic Time Scale ◽  
Low Frequencies ◽  
Universal Behavior ◽  
Nonlinear Mixing

In the 1970's it was found that; for low frequencies (<10 Hz), speech is scaling: it has no characteristic time scale. Now such scale invariance is associated with multiscaling statistics, and multifractal structures. Just as Gaussian noises frequently arise because they are generically produced by sums of many independent noise processes, scaling noises have an analogous universal behavior arising from nonlinear mixing of processes. We show that low frequency speech is consistent with these ideas, and use the measured parameters to produce stochastic speech simulations which are strikingly similar to real speech.

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