scholarly journals The nonlinear variation of drought and its relation to atmospheric circulation in Shandong Province, East China

PeerJ ◽  
2015 ◽  
Vol 3 ◽  
pp. e1289 ◽  
Author(s):  
Baofu Li ◽  
Zhongsheng Chen ◽  
Xingzhong Yuan
Keyword(s):  
Atmospheric Circulation ◽  
Decadal Variability ◽  
Southern Oscillation ◽  
Linear Trend ◽  
Pearson Correlation ◽  
Phase Changes ◽  
Drought Severity ◽  
Nonlinear Variation ◽  
Decadal Scale ◽  
Annual Scale

Considerable attention has recently been devoted to the linear trend of drought at the decadal to inter-decadal time scale; however, the nonlinear variation of drought at multi-decadal scales and its relation to atmospheric circulation need to be further studied. The linear and nonlinear variations of the Palmer drought severity index (PDSI) in Shandong from 1900 to 2012 and its relations to the Pacific decadal oscillation (PDO), El Niño-Southern Oscillation (ENSO), Siberian high (SH) and Southern Oscillation (SO) phase changes from multi-scale are detected using linear regression, the Mann–Kendall test, ensemble empirical mode decomposition (EEMD) and the Pearson correlation analysis method. The results indicate that the PDSI shows no statistically significant linear change trend from 1900 to 2012; however, before (after) the late 1950s, PDSI shows a significant upward (downward) trend (P< 0.01) with a linear rate of 0.28/decade (−0.48/decade). From 1900 to 2012, the PDSI also exhibits a nonlinear variation trend at the inter-annual scale (quasi-3 and quasi-7-year), inter-decadal scale (quasi-14-year) and multi-decadal scale (quasi-46 and quasi-65-year). The variance contribution rate of components from the inter-annual scale is the largest, reaching 38.7%, and that from the inter-decadal scale and multi-decadal scale are 18.9% and 19.0%, respectively, indicating that the inter-annual change exerts a huge influence on the overall PDSI change. The results also imply that the effect of the four atmospheric circulations (PDO, ENSO, SH, SO) on PDSI at the multi-decadal variability scale are more important than that at the other scales. Consequently, we state that PDSI variation at the inter-annual scale has more instability, while that at the inter-decadal and multi-decadal scale is more strongly influenced by natural factors.

Spatial Patterns and Frequency of Unforced Decadal-Scale Changes in Global Mean Surface Temperature in Climate Models

2016 ◽  
Vol 29 (17) ◽  
pp. 6245-6257 ◽  
Author(s):  
Eleanor A. Middlemas ◽  
Amy C. Clement
Keyword(s):  
Surface Temperature ◽  
Time Scale ◽  
Decadal Variability ◽  
Southern Oscillation ◽  
Climate System ◽  
Ocean Dynamics ◽  
Cmip5 Models ◽  
Global Mean Temperature ◽  
Decadal Scale ◽  
Global Mean

Abstract The causes of decadal time-scale variations in global mean temperature are currently under debate. Proposed mechanisms include both processes internal to the climate system as well as external forcing. Here, the robustness of spatial and time scale characteristics of unforced (internal) decadal variability among phase 5 of the Coupled Model Intercomparison Project (CMIP5) preindustrial control runs is examined. It is found that almost all CMIP5 models produce an interdecadal Pacific oscillation–like pattern associated with decadal variability, but the frequency of decadal-scale change is model dependent. To assess the roles of atmosphere and ocean dynamics in producing decadal variability, two preindustrial control Community Climate System model (version 4) configurations are compared: one with an atmosphere coupled to a slab ocean and the other fully coupled to a dynamical ocean. Interactive ocean dynamics are not necessary to produce an IPO-like pattern but affect the magnitude and frequency of the decadal changes primarily by impacting the strength of El Niño–Southern Oscillation. However, low-frequency El Niño–Southern Oscillation variability and skewness explains up to only 54% of the spread in frequency of decadal swings in global mean temperature among CMIP5 models; there may be other internal mechanisms that can produce such diversity. The spatial pattern of decadal changes in surface temperature are robust and can be explained by atmospheric processes interacting with the upper ocean, while the frequency of these changes is not well constrained by models.

scholarly journals On the relationship between large-scale climate modes and regional synoptic patterns that drive Victorian rainfall

2008 ◽  
Vol 5 (5) ◽  
pp. 2791-2815 ◽  
Author(s):  
D. Verdon-Kidd ◽  
A. S. Kiem
Keyword(s):  
Large Scale ◽  
Climate Models ◽  
Southern Oscillation ◽  
Southern Annular Mode ◽  
Global Climate Models ◽  
Phase Changes ◽  
Rainfall Forecasting ◽  
Climate Modes ◽  
Synoptic Patterns ◽  
Decadal Scale

Abstract. In this paper regional (synoptic) and large-scale climate drivers of rainfall are investigated for Victoria, Australia. A non-linear classification methodology known as self-organizing maps (SOM) is used to identify 20 key regional synoptic patterns, which are shown to capture a range of significant synoptic features known to influence the climate of the region. Rainfall distributions are assigned to each of the 20 patterns for nine rainfall stations located across Victoria, resulting in a clear distinction between wet and dry synoptic types at each station. The influence of large-scale climate modes on the frequency and timing of the regional synoptic patterns is also investigated. This analysis revealed that phase changes in the El Niño Southern Oscillation (ENSO), the Southern Annular Mode (SAM) and/or Indian Ocean Dipole (IOD) are associated with a shift in the relative frequency of wet and dry synoptic types. Importantly, these results highlight the potential to utilise the link between the regional synoptic patterns derived in this study and large-scale climate modes to improve rainfall forecasting for Victoria, both in the short- (i.e. seasonal) and long-term (i.e. decadal/multi-decadal scale). In addition, the regional and large-scale climate drivers identified in this study provide a benchmark by which the performance of Global Climate Models (GCMs) may be assessed.

scholarly journals On the relationship between large-scale climate modes and regional synoptic patterns that drive Victorian rainfall

2009 ◽  
Vol 13 (4) ◽  
pp. 467-479 ◽  
Author(s):  
D. C. Verdon-Kidd ◽  
A. S. Kiem
Keyword(s):  
Relative Frequency ◽  
Large Scale ◽  
Climate Models ◽  
Southern Oscillation ◽  
Global Climate Models ◽  
Phase Changes ◽  
Rainfall Forecasting ◽  
Climate Modes ◽  
Synoptic Patterns ◽  
Decadal Scale

Abstract. In this paper regional (synoptic) and large-scale climate drivers of rainfall are investigated for Victoria, Australia. A non-linear classification methodology known as self-organizing maps (SOM) is used to identify 20 key regional synoptic patterns, which are shown to capture a range of significant synoptic features known to influence the climate of the region. Rainfall distributions are assigned to each of the 20 patterns for nine rainfall stations located across Victoria, resulting in a clear distinction between wet and dry synoptic types at each station. The influence of large-scale climate modes on the frequency and timing of the regional synoptic patterns is also investigated. This analysis revealed that phase changes in the El Niño Southern Oscillation (ENSO), the Indian Ocean Dipole (IOD) and/or the Southern Annular Mode (SAM) are associated with a shift in the relative frequency of wet and dry synoptic types on an annual to inter-annual timescale. In addition, the relative frequency of synoptic types is shown to vary on a multi-decadal timescale, associated with changes in the Inter-decadal Pacific Oscillation (IPO). Importantly, these results highlight the potential to utilise the link between the regional synoptic patterns derived in this study and large-scale climate modes to improve rainfall forecasting for Victoria, both in the short- (i.e. seasonal) and long-term (i.e. decadal/multi-decadal scale). In addition, the regional and large-scale climate drivers identified in this study provide a benchmark by which the performance of Global Climate Models (GCMs) may be assessed.

scholarly journals Interannual Variability of Rhine River Streamflow and Its Relationship with Large-Scale Anomaly Patterns in Spring and Autumn

2012 ◽  
Vol 13 (1) ◽  
pp. 172-188 ◽  
Author(s):  
Monica Ionita ◽  
Gerrit Lohmann ◽  
Norel Rimbu ◽  
Silvia Chelcea
Keyword(s):  
Atmospheric Circulation ◽  
Large Scale ◽  
Decadal Variability ◽  
Southern Oscillation ◽  
Circulation Pattern ◽  
Northwestern Part ◽  
Rhine River ◽  
Climate Anomaly ◽  
Atmospheric Circulation Pattern ◽  
Streamflow Variability

Abstract Interannual-to-decadal variability of Rhine River streamflow and their relationship with large-scale climate anomaly patterns for spring [March–May (MAM)] and autumn [September–November (SON)] are investigated through a statistical analysis of observed streamflow data and global climate anomaly fields. A wavelet analysis reveals that spring streamflow variability is nonstationary with enhanced variability in the 8–16-yr band from 1860 to 1900 and in the 2–8 and 16–30 yr after 1960. A composite analysis reveals that streamflow anomalies during spring are related to a sea surface temperature (SST) pattern that resembles the corresponding El Niño–Southern Oscillation (ENSO) SST pattern. The corresponding atmospheric circulation pattern favors enhanced moisture advection over the Rhine catchment area during positive streamflow anomalies. During autumn, the streamflow variability follows a distribution similar to spring streamflow, but with a strong peak in the 30–60-yr band. Autumn streamflow anomalies are significantly related only with the North Atlantic SST anomalies. The atmospheric circulation pattern associated with high streamflow during autumn, which is more regional than the corresponding spring pattern, shows a deep low pressure system over the British Isles and the northwestern part of Europe and a shift southward of the Atlantic jet axis. The orientation of the axis of the Atlantic and African jets, as well as the advection of the moist air from the ocean, plays a crucial role in the variability of Rhine streamflow both in spring and autumn.

Global modulation of ENSO teleconnections by Pacific Decadal Variability

2021 ◽  
Author(s):  
Nicola Maher ◽  
Antonietta Capotondi ◽  
Jennifer Kay
Keyword(s):  
Decadal Variability ◽  
Southern Oscillation ◽  
Research Question ◽  
Flood Frequency ◽  
Phase Changes ◽  
Historical Period ◽  
Single Model ◽  
Enso Teleconnections ◽  
Pacific Decadal Variability ◽  
Observational Record

&lt;p&gt;The El Ni&amp;#241;o Southern Oscillation (ENSO) is the leading mode of global climate variability on interannual timescales. On longer time-scales, decadal variability in the Pacific is responsible for modulating the rate of global warming (Meehl et al 2013, Maher et al 2014 Henley &amp; King 2017). Whether Pacific Decadal Variability (PDV) modulates ENSO teleconnections is an important research question that has largely been investigated using the observational record. PDV is shown to modulate Australian rainfall (Power et al 1999, Arblaster et al 2002, Verdon et al, 2004, King et al 2013), which has impacts for flood frequency (Franks and Kuczera, 2002, Kiem et al, 2003, Pui et al 2011). PDV has also been shown to modulate ENSO precipitation teleconnections over Africa (Dong &amp; Dai 2015), Texas (Khedun et al 2014), and Europe (Zanchettin et al 2008) as well as ENSO temperature teleconnections over New Zealand (Salinger et al 2001). While these observationally based studies suggest connections between ENSO teleconnections and PDV, the short observational record contains only two PDV phase changes. In addition, calculating PDV using a lowpass filter on the region that contains ENSO could also cause statistical artefacts in the results (Power at al, 2006, Westra et al 2015). These limitations can be addressed using climate models. Arblaster et al (2002) use atmosphere only simulations and find similar results to observational studies over Australia. Dong and Dai (2015) further investigate global modulation using 4 ensemble members of a single model. These modelling studies are limited in their use of single models and while they include a larger dataset than the observational record, previous work has only used small ensemble sizes. In this study, we address both the issue of small datasets and the dependence on results on the model used by utilising four single model initial-condition large ensembles.&amp;#160; Each model ensemble has a minimum of 20 members enabling investigation of multiple realizations of PDV and ENSO covariability. Over the historical period, using one ensemble member results in a record that is indeed too short to accurately quantify the influence of PDV on ENSO teleconnections. We then composite events for different phases of the PDV and ENSO using all ensemble members. Initial results show that PDV strongly influences ENSO temperature teleconnections over North America.&amp;#160; We find that stronger teleconnections occur when an El Ni&amp;#241;o occurs during a positive phase of PDV or a La Ni&amp;#241;a occurs in a negative phase of the PDV. Similarly, PDV phase affects precipitation over Australia, where co-occurring El Ni&amp;#241;o and positive PDV phases and La Ni&amp;#241;a and negative PDV phases have larger precipitation anomalies. Finally we investigate whether this modulation of ENSO teleconnections by the PDV is projected to change under strong anthropogenic forcing. We find greater inter-model agreement for precipitation teleconnections than for temperature teleconnections.&amp;#160; Ongoing work will assess the underlying physical mechanisms behind these results.&amp;#160;&lt;/p&gt;

Interdecadal Amplitude Modulation of El Niño–Southern Oscillation and Its Impact on Tropical Pacific Decadal Variability*

2013 ◽  
Vol 26 (18) ◽  
pp. 7280-7297 ◽  
Author(s):  
Tomomichi Ogata ◽  
Shang-Ping Xie ◽  
Andrew Wittenberg ◽  
De-Zheng Sun
Keyword(s):  
Amplitude Modulation ◽  
El Niño ◽  
Decadal Variability ◽  
El Nino ◽  
Southern Oscillation ◽  
Tropical Pacific ◽  
Sea Surface ◽  
El Nino Southern Oscillation ◽  
Pacific Decadal Variability ◽  
Decadal Scale

Abstract The amplitude of El Niño–Southern Oscillation (ENSO) displays pronounced interdecadal modulations in observations. The mechanisms for the amplitude modulation are investigated using a 2000-yr preindustrial control integration from the Geophysical Fluid Dynamics Laboratory Climate Model, version 2.1 (GFDL CM2.1). ENSO amplitude modulation is highly correlated with the second empirical orthogonal function (EOF) mode of tropical Pacific decadal variability (TPDV), which features equatorial zonal dipoles in sea surface temperature (SST) and subsurface temperature along the thermocline. Experiments with an ocean general circulation model indicate that both interannual and decadal-scale wind variability are required to generate decadal-scale tropical Pacific temperature anomalies at the sea surface and along the thermocline. Even a purely interannual and sinusoidal wind forcing can produce substantial decadal-scale effects in the equatorial Pacific, with SST cooling in the west, subsurface warming along the thermocline, and enhanced upper-ocean stratification in the east. A mechanism is proposed by which residual effects of ENSO could serve to alter subsequent ENSO stability, possibly contributing to long-lasting epochs of extreme ENSO behavior via a coupled feedback with TPDV.

scholarly journals A Global Dataset of Palmer Drought Severity Index for 1870–2002: Relationship with Soil Moisture and Effects of Surface Warming

2004 ◽  
Vol 5 (6) ◽  
pp. 1117-1130 ◽  
Author(s):  
Aiguo Dai ◽  
Kevin E. Trenberth ◽  
Taotao Qian
Keyword(s):  
Soil Moisture ◽  
Palmer Drought Severity Index ◽  
Southern Oscillation ◽  
Linear Trend ◽  
Severity Index ◽  
Drought Severity ◽  
Surface Warming ◽  
Precipitation Decrease ◽  
Global Land ◽  
Drought Severity Index

Abstract A monthly dataset of Palmer Drought Severity Index (PDSI) from 1870 to 2002 is derived using historical precipitation and temperature data for global land areas on a 2.5° grid. Over Illinois, Mongolia, and parts of China and the former Soviet Union, where soil moisture data are available, the PDSI is significantly correlated (r = 0.5 to 0.7) with observed soil moisture content within the top 1-m depth during warm-season months. The strongest correlation is in late summer and autumn, and the weakest correlation is in spring, when snowmelt plays an important role. Basin-averaged annual PDSI covary closely (r = 0.6 to 0.8) with streamflow for seven of world's largest rivers and several smaller rivers examined. The results suggest that the PDSI is a good proxy of both surface moisture conditions and streamflow. An empirical orthogonal function (EOF) analysis of the PDSI reveals a fairly linear trend resulting from trends in precipitation and surface temperature and an El Niño– Southern Oscillation (ENSO)-induced mode of mostly interannual variations as the two leading patterns. The global very dry areas, defined as PDSI &lt; −3.0, have more than doubled since the 1970s, with a large jump in the early 1980s due to an ENSO-induced precipitation decrease and a subsequent expansion primarily due to surface warming, while global very wet areas (PDSI &gt; +3.0) declined slightly during the 1980s. Together, the global land areas in either very dry or very wet conditions have increased from ∼20% to 38% since 1972, with surface warming as the primary cause after the mid-1980s. These results provide observational evidence for the increasing risk of droughts as anthropogenic global warming progresses and produces both increased temperatures and increased drying.

scholarly journals A Basic Effect of Cloud Radiative Effects on Tropical Sea Surface Temperature Variability

2020 ◽  
Vol 33 (10) ◽  
pp. 4333-4346 ◽  
Author(s):  
Ying Li ◽  
David W. J. Thompson ◽  
Dirk Olonscheck
Keyword(s):  
Atmospheric Circulation ◽  
Time Scales ◽  
Southern Oscillation ◽  
Critical Role ◽  
Surface Energy Budget ◽  
Sea Surface ◽  
Turbulent Heat ◽  
Radiative Effects ◽  
Decadal Scale ◽  
Cloud Radiative Effects

AbstractCloud radiative effects (CREs) are known to play a central role in governing the long-term mean distribution of sea surface temperatures (SSTs). Very recent work suggests that CREs may also play a role in governing the variability of SSTs in the context of El Niño–Southern Oscillation. Here, the authors exploit numerical simulations in the Max Planck Institute Earth System Model with two different representations of CREs to demonstrate that coupling between CREs and the atmospheric circulation has a much more general and widespread effect on tropical climate than that indicated in previous work. The results reveal that coupling between CREs and the atmospheric circulation leads to robust increases in SST variability on time scales longer than a month throughout the tropical oceans. Remarkably, cloud–circulation coupling leads to more than a doubling of the amplitude of decadal-scale variability in tropical-mean SSTs. It is argued that the increases in tropical SST variance derive primarily from the coupling between SSTs and shortwave CREs: Coupling increases the memory in shortwave CREs on hourly and daily time scales and thus reddens the spectrum of shortwave CREs and increases their variance on time scales spanning weeks to decades. Coupling between SSTs and CREs does not noticeably affect the variance of SSTs in the extratropics, where the effects from variability in CREs on the surface energy budget are much smaller than the effects from the turbulent heat fluxes. The results indicate a basic but critical role of CREs in climate variability throughout the tropics.

scholarly journals Long-Term Trend and Decadal Variability of Persistence of Daily 500-mb Geopotential Height Anomalies during Boreal Winter

2009 ◽  
Vol 137 (10) ◽  
pp. 3519-3534 ◽  
Author(s):  
Ruiqiang Ding ◽  
Jianping Li
Keyword(s):  
Atmospheric Circulation ◽  
Geopotential Height ◽  
Decadal Variability ◽  
Linear Trend ◽  
Winter Season ◽  
Tropical Pacific ◽  
High Latitudes ◽  
Low Pass ◽  
Northern And Southern Hemispheres ◽  
The Tropical Pacific

Abstract An analysis has been made of the trend and decadal variability of persistence of daily 500-mb (hPa) geopotential height anomalies for the winter season. The persistence is measured based on autocorrelations at 1- and 5-day lags (denoted r1 and r5, respectively) and the effective time between independent samples T0. The results from linear trend analysis show that there exist significant trends of persistence of daily 500-mb geopotential height anomalies in some regions of the world. The regions with a significant decreasing trend are found to be mainly located at mid–high latitudes of the Northern and Southern Hemispheres, while the regions with a significant increasing trend are mainly located in the tropical Pacific Ocean. For other variables including sea level pressure (SLP), 1000-mb height, and 200-mb height, the persistence of daily anomalies also exhibits similar trends in these regions. It is speculated that the enhanced baroclinicity and advection are possibly responsible for the significant downward trend of persistence mainly occurring in the southern and northern mid–high latitudes, while the increased coupling between the atmospheric circulation and sea surface temperature (SST) could contribute to the increase of persistence in the tropical Pacific. An empirical orthogonal function (EOF) analysis based on the 7-yr Gaussian low-pass-filtered series of winter season r1 and r5 of 500-mb height (linear trend removed before the low-pass filtering) is presented. The results suggest that there is prominent decadal variability of persistence in some regions of the Northern and Southern Hemispheres and tropics. When compared with r1, r5 has decadal variations with larger magnitude and larger spatial scale. It is found that the decadal variability of persistence is closely related to decadal fluctuations of large-scale atmospheric circulation patterns.

CORRELATION BETWEEN RAINFALL PATTERN AND OIL PALM PERFORMANCE IN SUMATRA AND BORNEO ISLAND DURING EL NIÑO 2015

2018 ◽  
Vol 24 (2) ◽  
pp. 87-96
Author(s):  
Iput Pradiko ◽  
Eko Novandy Ginting ◽  
Nuzul Hijri Darlan ◽  
Winarna Winarna ◽  
Hasril Hasan Siregar
Keyword(s):  
Oil Palm ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Pearson Correlation ◽  
Rainfall Data ◽  
Rainfall Pattern ◽  
Dry Spell ◽  
Male Flowers ◽  
Central South

El Niño 2015 is one of the strongest El Niño. Drought stress due to El Niño could affect oil palm performances. This study was conducted to determine rainfall pattern and oil palm performance in Sumatra and Borneo Island during El Niño 2015. Data employed in this study is monthly rainfall data, Southern Oscillation Index (SOI) January-December 2015, andoil palm performances. Pearson correlation between SOI and rainfall data was used to analyze rainfall pattern, while oil palm performances were observed based on morphological conditions. Result shows that southern part of Sumatra and mostly part of Borneo suffer from more dry spell, dry month, and water deficit such as 37-133 days, 3-5 months, and 349-524 mm respectively. Analysis of rainfall pattern shows that Jambi, South Sumatra, Lampung, Central, South, and East Borneo are significantly (r ≥ +0,60) affected by El Niño 2015. Oil palms in southern part of Sumatra and mostly part of Borneo are suffer from drought stressmarked by the emergence of more than two spear fronds, appearing of many male flowers, malformations on bunches, fronds tend to hanging down, and lower fronds tend to dry.

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