Precipitation, Temperature, and Teleconnection Signals across the Combined North American, Monsoon Asia, and Old World Drought Atlases

Abstract The tree-ring-based North American Drought Atlas (NADA), Monsoon Asia Drought Atlas (MADA), and Old World Drought Atlas (OWDA) collectively yield a near-hemispheric gridded reconstruction of hydroclimate variability over the last millennium. To test the robustness of the large-scale representation of hydroclimate variability across the drought atlases, the joint expression of seasonal climate variability and teleconnections in the NADA, MADA, and OWDA are compared against two global, observation-based PDSI products. Predominantly positive (negative) correlations are determined between seasonal precipitation (surface air temperature) and collocated tree-ring-based PDSI, with average Pearson’s correlation coefficients increasing in magnitude from boreal winter to summer. For precipitation, these correlations tend to be stronger in the boreal winter and summer when calculated for the observed PDSI record, while remaining similar for temperature. Notwithstanding these differences, the drought atlases robustly express teleconnection patterns associated with El Niño–Southern Oscillation (ENSO), the North Atlantic Oscillation (NAO), the Pacific decadal oscillation (PDO), and the Atlantic multidecadal oscillation (AMO). These expressions exist in the drought atlas estimates of boreal summer PDSI despite the fact that these modes of climate variability are dominant in boreal winter, with the exception of the AMO. ENSO and NAO teleconnection patterns in the drought atlases are particularly consistent with their well-known dominant expressions in boreal winter and over the OWDA domain, respectively. Collectively, the findings herein confirm that the joint Northern Hemisphere drought atlases robustly reflect large-scale patterns of hydroclimate variability on seasonal to multidecadal time scales over the twentieth century and are likely to provide similarly robust estimates of hydroclimate variability prior to the existence of widespread instrumental data.

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Interhemispheric asymmetry of climate change projections of boreal winter surface winds in CanESM5 large ensemble simulations

10.21203/rs.3.rs-476108/v1 ◽

2021 ◽

Author(s):

Bin Yu ◽

Xuebin Zhang ◽

Guilong Li ◽

Wei Yu

Keyword(s):

Climate Variability ◽

Wind Power ◽

Atmospheric Circulation ◽

Large Scale ◽

Boreal Winter ◽

Interhemispheric Asymmetry ◽

Large Ensemble ◽

Internal Climate Variability ◽

Climate Simulations ◽

Extreme Wind

Abstract A recent study of future changes in global wind power using an ensemble of ten CMIP5 climate simulations indicated an interhemispheric asymmetry of wind power changes over the 21st century, featured by power decreases across the Northern Hemisphere mid-latitudes and increases across the tropics and subtropics of the Southern Hemisphere. Here we analyze future global projections of surface mean and extreme winds by means of a single-model initial-condition 50-member ensemble of climate simulations generated with CanESM5, the Canadian model participated in CMIP6. We analyze the ensemble mean and spread of boreal winter mean and extreme wind trends over the next half-century (2021-2070) and explore the contribution of internal climate variability to these trends. Surface wind speed is projected to mostly decrease in northern mid-low latitudes and southern mid-latitudes and increase in northern high latitudes and southern tropical and subtropical regions, with considerable regional variations. Large ensemble spreads are apparent, especially with remarkable differences over northern parts of South America and northern Russia. The interhemispheric asymmetry of wind projections is found in most ensemble members, and can be related to large-scale changes in surface temperature and atmospheric circulation. The extreme wind has similar structure of future projections, whereas its reductions tend to be more consistent over northern mid-latitudes. The projected mean and extreme wind changes are attributed to changes in both externally anthropogenic forced and internal climate variability generated components. The spread in wind projections is partially due to large-scale atmospheric circulation variability.

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Dendroclimatology in the Eastern Mediterranean

Radiocarbon ◽

10.1017/s0033822200050360 ◽

2014 ◽

Vol 56 (04) ◽

pp. S61-S68

Author(s):

Ramzi Touchan ◽

David M. Meko ◽

Kevin J. Anchukaitis

Keyword(s):

Resource Management ◽

Climate Variability ◽

20Th Century ◽

Tree Ring ◽

Large Scale ◽

Eastern Mediterranean ◽

Spatial Scales ◽

Climatic Variation ◽

Ring Network ◽

The Past

Dendroclimatology in the Eastern Mediterranean (EM) region has made important contributions to the understanding of climate variability on timescales of decades to centuries. These contributions, beginning in the mid-20th century, have value for resource management, archaeology, and climatology. A gradually expanding tree-ring network developed by the first author over the past 15 years has been the framework for some of the most important recent advances in EM dendroclimatology. The network, now consisting of 79 sites, has been widely applied in large-scale climatic reconstruction and in helping to identify drivers of climatic variation on regional to global spatial scales. This article reviews EM dendroclimatology and highlights contributions on the national and international scale.

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Large-scale transport into the Arctic: the roles of the midlatitude jet and the Hadley Cell

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-5511-2019 ◽

2019 ◽

Vol 19 (8) ◽

pp. 5511-5528 ◽

Cited By ~ 3

Author(s):

Huang Yang ◽

Darryn W. Waugh ◽

Clara Orbe ◽

Guang Zeng ◽

Olaf Morgenstern ◽

...

Keyword(s):

Large Scale ◽

Climate Model ◽

Source Region ◽

Meridional Flow ◽

Hadley Cell ◽

The Arctic ◽

Boreal Summer ◽

Boreal Winter ◽

Meridional Transport ◽

Fixed Lifetime

Abstract. Transport from the Northern Hemisphere (NH) midlatitudes to the Arctic plays a crucial role in determining the abundance of trace gases and aerosols that are important to Arctic climate via impacts on radiation and chemistry. Here we examine this transport using an idealized tracer with a fixed lifetime and predominantly midlatitude land-based sources in models participating in the Chemistry Climate Model Initiative (CCMI). We show that there is a 25 %–45 % difference in the Arctic concentrations of this tracer among the models. This spread is correlated with the spread in the location of the Pacific jet, as well as the spread in the location of the Hadley Cell (HC) edge, which varies consistently with jet latitude. Our results suggest that it is likely that the HC-related zonal-mean meridional transport rather than the jet-related eddy mixing is the major contributor to the inter-model spread in the transport of land-based tracers into the Arctic. Specifically, in models with a more northern jet, the HC generally extends further north and the tracer source region is mostly covered by surface southward flow associated with the lower branch of the HC, resulting in less efficient transport poleward to the Arctic. During boreal summer, there are poleward biases in jet location in free-running models, and these models likely underestimate the rate of transport into the Arctic. Models using specified dynamics do not have biases in the jet location, but do have biases in the surface meridional flow, which may result in differences in transport into the Arctic. In addition to the land-based tracer, the midlatitude-to-Arctic transport is further examined by another idealized tracer with zonally uniform sources. With equal sources from both land and ocean, the inter-model spread of this zonally uniform tracer is more related to variations in parameterized convection over oceans rather than variations in HC extent, particularly during boreal winter. This suggests that transport of land-based and oceanic tracers or aerosols towards the Arctic differs in pathways and therefore their corresponding inter-model variabilities result from different physical processes.

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Association of Convection with the 5-Day Rossby–Haurwitz Wave

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-14-0316.1 ◽

2015 ◽

Vol 72 (9) ◽

pp. 3309-3321 ◽

Cited By ~ 4

Author(s):

Malcolm J. King ◽

Matthew C. Wheeler ◽

Todd P. Lane

Keyword(s):

Large Scale ◽

Southern Oscillation ◽

Tropical Convection ◽

Marshall Islands ◽

Eastern Pacific ◽

Boreal Summer ◽

Boreal Winter ◽

Tropical Andes ◽

Quasi Biennial Oscillation ◽

Frequency Spectra

Abstract The seasonality, regionality, and nature of the association between tropical convection and the 5-day wavenumber-1 Rossby–Haurwitz wave are examined. Spectral coherences between daily outgoing longwave radiation (OLR), a proxy for convection, and 850-hPa zonal wind over the period January 1979–February 2013 are compared for different seasons and for phases of El Niño–Southern Oscillation (ENSO) and the quasi-biennial oscillation (QBO). Increased coherence, indicating a stronger association, occurs in boreal spring and autumn, with slightly reduced coherence in boreal summer and significantly reduced coherence in boreal winter. The regionality of the association is examined using lagged-regression techniques. Significant local signals in tropical convection are found over West Africa, the tropical Andes, the eastern Pacific Ocean, and the Marshall Islands. The relative phasing between the 5-day wave wind and OLR signals is in quadrature in Africa and the Marshall Islands, in phase with easterlies over the Andes, and out of phase with easterlies over the eastern Pacific. Frequency spectra of precipitation averaged over the identified local regions reveal spectral peaks in the 4–6-day range. The phasing between the large-scale wind and local convection signals suggests that the 5-day wave is actively modulating the convection around the Americas.

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Variations in Climate Since 1602 as Reconstructed from Tree Rings

Quaternary Research ◽

10.1016/0033-5894(79)90090-5 ◽

1979 ◽

Vol 12 (1) ◽

pp. 18-46 ◽

Cited By ~ 93

Author(s):

Harold C. Fritts ◽

G. Robert Lofgren ◽

Geoffrey A. Gordon

Keyword(s):

20Th Century ◽

Tree Ring ◽

North American ◽

High Frequency ◽

Large Scale ◽

Transfer Functions ◽

The United States ◽

Seasonal Temperature ◽

Synoptic Scale ◽

The Past

Spatial anomalies of tree-ring chronologies can provide information on high-frequency spatial anomalies in paleoclimate representing droughts, colder-than-normal intervals, and other synoptic-scale features. Examples are presented in which 65 tree-ring chronologies are calibrated with spatial anomalies in North American meteorological records of seasonal temperature and precipitation, and with sea-level pressure over the North American and North Pacific sectors. Multivariate transfer functions are obtained that scale and convert the past spatial variations in the tree-ring record into estimates of past variations in the meteorological record. Objective verifications of the reconstructions are obtained using independent meteorological observations for time periods other than those used in the calibration. Historical information or other proxy data from the 19th century are also used for verifying the decadal (or longer) and regional reconstructions and for identifying strengths and weaknesses of the various sources of information. The reconstructed winter and summer temperatures for the United States and southwestern Canada and winter precipitation for the Columbia Basin and California during the 17th through 19th centuries were found to differ from the 20th century means with large-scale variations evident. Extreme winters similar to 1976–77 are also identified and found to be more frequent in the past, especially in the 17th century. The climatic reconstructions in this time domain are dominated by high-frequency, synoptic-scale fluctuations that can be interpreted as cyclonic-scale changes in atmospheric circulation. Such reconstructions may be useful for testing various climatic models and estimates developed primarily from 20th-century meteorological data against the longer estimated record for the 17th through 19th centuries.

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Systematic Comparison of ENSO Teleconnection Patterns between Models and Observations

Journal of Climate ◽

10.1175/jcli-d-11-00175.1 ◽

2012 ◽

Vol 25 (2) ◽

pp. 425-446 ◽

Cited By ~ 42

Author(s):

Xiaosong Yang ◽

Timothy DelSole

Keyword(s):

Surface Air Temperature ◽

Significance Test ◽

Winter Precipitation ◽

Teleconnection Pattern ◽

Boreal Summer ◽

Boreal Winter ◽

Multimodel Ensemble ◽

Coupled Models ◽

Teleconnection Patterns ◽

The Tropical Pacific

Abstract This paper applies a new field significance test to establish the existence and consistency of ENSO teleconnection patterns across models and observations. An ENSO teleconnection pattern is defined as a field of regression coefficients between an index of the tropical Pacific sea surface temperature and a field of variables such as surface air temperature or precipitation. The test is applied to boreal winter and summer in six continents using observations and hindcasts from the Development of a European Multimodel Ensemble System for Seasonal-to-Interannual Prediction (DEMETER) and the ENSEMBLE-based predictions of climate changes and their impacts (ENSEMBLES) projects. This comparison represents one of the most comprehensive and up-to-date assessments of the extent to which ENSO teleconnection patterns exist and can be reproduced by coupled models. Statistically significant ENSO teleconnection patterns are detected in both observations and models and in all continents and in both winter and summer seasons, except in two cases: 1) Europe (both seasons and variables), and 2) North America (both variables in boreal summer). Despite many ENSO teleconnection patterns being significant, however, the patterns do not necessarily agree between observations and models. The degree of agreement between models and observations is characterized as “robust,” “moderate,” or “low.” Only Australia and South America are found to have robust agreement between ENSO teleconnection patterns, and then only for limited seasons and variables. Although many of our conclusions regarding teleconnection patterns conform to previous studies, there are exceptions, including the fact that the teleconnection for boreal winter precipitation is generally accepted to exist in Africa but in fact has only low agreement with model simulations, while that in Asia is not widely recognized to exist but is found to be significant and in moderate agreement with model teleconnections.

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Relative Importance of Internal Climate Variability versus Anthropogenic Climate Change in Global Climate Change

Journal of Climate ◽

10.1175/jcli-d-20-0424.1 ◽

2021 ◽

Vol 34 (2) ◽

pp. 465-478

Author(s):

Jie Chen ◽

Xiangquan Li ◽

Jean-Luc Martel ◽

François P. Brissette ◽

Xunchang J. Zhang ◽

...

Keyword(s):

Climate Change ◽

Climate Variability ◽

Global Climate ◽

Regional Climate ◽

Baseline Period ◽

Anthropogenic Climate Change ◽

Boreal Summer ◽

Boreal Winter ◽

Internal Climate Variability ◽

Equatorial Band

AbstractTo better understand the role of internal climate variability (ICV) in climate change impact studies, this study quantifies the importance of ICV [defined as the intermember variability of a single model initial-condition large ensemble (SMILE)] in relation to the anthropogenic climate change (ACC; defined as multimodel ensemble mean) in global and regional climate change using a criterion of time of emergence (ToE). The uncertainty of the estimated ToE is specifically investigated by using three SMILEs to estimate the ICV. The results show that using 1921–40 as a baseline period, the annual mean precipitation ACC is expected to emerge within this century over extratropical regions as well as along the equatorial band. However, ToEs are unlikely to occur, even by the end of this century, over intratropical regions outside of the equatorial band. In contrast, annual mean temperature ACC has already emerged from the temperature ICV for most of the globe. Similar spatial patterns are observed at the seasonal scale, while a weaker ACC for boreal summer (June–August) precipitation and additional ICV for boreal winter (December–February) temperature translate to later ToEs for some regions. In addition, the uncertainty of ToE related to the choice of a SMILE is mostly less than 20 years for annual mean precipitation and temperature. However, it can be as large as 90 years for annual mean precipitation over some regions. Overall, results indicate that the choice of a SMILE is a significant source of uncertainty in the estimation of ToE and results based on only one SMILE should be interpreted with caution.

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The Relationship between the Wintertime Cold Extremes over East Asia with Large-Scale Atmospheric and Oceanic Teleconnections

Atmosphere ◽

10.3390/atmos10120813 ◽

2019 ◽

Vol 10 (12) ◽

pp. 813 ◽

Cited By ~ 1

Author(s):

Ye Yang ◽

Naru Xie ◽

Meng Gao

Keyword(s):

East Asia ◽

Large Scale ◽

Southern Oscillation ◽

Low Frequency ◽

Surface Air Temperature ◽

Boreal Winter ◽

Key Factors ◽

Teleconnection Patterns ◽

The Relationship ◽

Cold Extremes

The influence of large-scale teleconnection patterns, Western Pacific (WP), Arctic Oscillation (AO) and El Niño-Southern Oscillation (ENSO), on the minimum surface air temperature (Tmin) anomalies and extremes over East Asia during the boreal winter from 1979 to 2017 were investigated by the composite analysis in terms of atmospheric and oceanic processes. The relationship between the Tmin and the geopotential height at 500 hPa (Z500) as well as sea surface temperature (SST) were first examined. Then we explored and estimated the contribution of the teleconnection patterns to the occurrence of extremely cold days and months quantitatively, and discussed other key factors in relation to the cold extremes. The WP and AO patterns play an important part in the prevalence of significant Tmin variability, whereas the effect of ENSO is relatively weak. Most of the cold extremes tend to appear in the negative phase of teleconnections, while there some extremes that occur in the opposite phase. In addition, the extreme months are more related to the preferred phase of the dominant pattern when compared to days. We conclude that the daily extremes are primarily triggered by the local-synoptic atmospheric circulations embedded in the large-scale teleconnection patterns, while the monthly extremes have a closer relationship with these low-frequency patterns.

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Introductory Overview

Climate Variability and Ecosystem Response in Long-Term Ecological Research Sites ◽

10.1093/oso/9780195150599.003.0022 ◽

2003 ◽

Author(s):

Douglas G. Goodin

Keyword(s):

Time Series ◽

Power Spectrum ◽

Climate Variability ◽

Spectrum Analysis ◽

North American ◽

Southern Oscillation ◽

Power Spectrum Analysis ◽

Teleconnection Patterns ◽

Modes Of Variability ◽

Scale Fluctuation

Timescale is the organizing framework of this volume. In various sections, we consider the effects of climate variability on ecosystems at timescales ranging from weeks or months to centuries. In part III, we turn our attention to interdecadal-scale events. The timescales we consider are not absolutely defined, but for our purposes we define the interdecadal scale to encompass effects occurring with recurring cycles generally ranging from 10 to 50 years. A recurring theme in many of the chapters in this section is the effect on ecosystem response of teleconnection patterns associated with recognized quasi-periodic atmospheric circulation modes. These circulation modes include the well-known El Niño– Southern Oscillation (ENSO) phenomenon, which is generally thought to recur at shorter, interdecadal timescales but also includes some longer-term periodicities. Several other climate variability modes, including the Pacific North American index (PNA), North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO), and North Pacific index (NP) also show strong interdecadal scale signatures and figure prominently in the chapters of part III. McHugh and Goodin begin the section by examining the climate record at several North American LTER sites for evidence of interdecadal-scale fluctuation. They note that interdecadal-scale contributions to climate variability can best be described in terms of two types of variation: (1) discontinuities in mean value, and (2) the presence of trends in the data. Evaluation of interdecadal periodicities in LTER data is complicated by the relatively short time series of observations available. McHugh and Goodin approach the problem mainly through the use of power spectrum analysis, a widely used tool for evaluating the periodicity in a time series of data. Principal components analysis is used to decompose the time series of growing-season climate data for each of the LTER sites into their principal modes of variability. These modes are then subjected to power spectrum analysis to evaluate the proportions of the variance in the data occurring at various timescales. McHugh and Goodin’s results suggest that significant effects on precipitation and temperature at interdecadal timescales are uncommon in these data, although significant periodicities at both shorter and longer frequencies do emerge from the data (a finding of relevance to other sections of this volume).

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Consistency and the Lack Thereof in Pacific Decadal Oscillation Impacts on North American Winter Climate

Journal of Climate ◽

10.1175/jcli-d-14-00143.1 ◽

2014 ◽

Vol 27 (19) ◽

pp. 7410-7431 ◽

Cited By ~ 25

Author(s):

Stephanie A. McAfee

Keyword(s):

Climate Variability ◽

Pacific Decadal Oscillation ◽

North American ◽

Climate Models ◽

Full Range ◽

Circulation Pattern ◽

Climatic Impact ◽

Winter Climate ◽

Teleconnection Patterns ◽

The Impact

Abstract Impacts of the Pacific decadal oscillation (PDO) on North American climate were initially assessed over one negative (~1943 to 1976) and one positive (1977 to ~1990) PDO regime. Release of the Twentieth Century Reanalysis and the recent occurrence of negative PDO years make it possible to study the stability of PDO teleconnections. This analysis identified consistency in broad-scale teleconnection patterns but also critical differences in the amplitude of circulation pattern, temperature, and precipitation anomalies between comparable phases of the PDO. Many of these discrepancies were apparent after controlling for long-term trends and the impact of ENSO and were associated with variability in Atlantic Ocean temperatures and in the northern annular mode. Results from this study suggest that not all of the climate variability attributed to the PDO derives solely from fluctuations in Pacific sea surface temperatures (SSTs), that the climatic impact of these SST anomalies varies over time, or that the PDO might have a “mixed” state with muted teleconnections. Any of these conclusions has substantial implications for reconstruction of the PDO and its use to understand past hydrologic or ecological changes. They suggest that evaluation of climate models on the basis of their ability to simulate teleconnection patterns of low-frequency modes of climate variability should be undertaken with the recognition that observational records may not be long enough to capture the full range of variability in teleconnection patterns.

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