Negative Phase Of Interdecadal Pacific Oscillation Research Articles

Temporal and Spatial Surface Heat Source Variation in the Gurbantunggut Desert from 1950 to 2021

Based on data from the Gurbantunggut Desert, the largest fixed/semi-fixed desert in China, and ERA5-Land reanalysis data, the long-term variations and spatial surface heat source (SHS) differences in the Gurbantunggut Desert are discussed herein. The results show the following: (1) The hourly SHS at the Kelameili station during the 2013–2021 period was a weak heat source at night; contrastingly, it was a strong heat source during the day. The duration of the hourly SHS increased gradually from January to July, but it decreased gradually from July to December. The daily SHS showed obvious seasonal variation, reaching the maximum in summer and the minimum in winter. The ERA5-Land reanalysis can reproduce all the variation characteristics of the SHS well. (2) The climatology (i.e., multi-year mean) of the monthly SHS intensity was lower than 50 W/m2 during the January–March and September–December periods in the Gurbantunggut Desert, indicating a weak heat source. On the other hand, the climatology recorded in April–August was higher than 50 W/m2, with a strong heat source. From the perspective of spatial distribution, the eastern and western regions of the Gurbantunggut Desert show strong heat sources, while the central region shows weak heat sources. The spatial distribution of the first and second modes of the empirical orthogonal function (EOF) decomposition reflected the consistent spatial variability and a north–south (or east–west) polarity variation of the monthly SHS in the Gurbantunggut Desert, respectively. (3) The yearly SHS showed negative anomalies during the 1950–1954, 1964–1982 and 2004–2015 periods, and positive anomalies during the 1955–1963, 1983–2003 and 2016–2021 periods in the Gurbantunggut Desert. Additionally, the time series of the SHS anomalies was positively correlated with the Interdecadal Pacific Oscillation (IPO) index. During the negative IPO phase, the yearly SHS showed a negative anomaly in the Gurbantunggut Desert, while the yearly SHS showed a positive anomaly during the positive IPO phase in most regions of the Gurbantunggut Desert.

Interdecadal Pacific Oscillation modulation of ENSO teleconnections in its decaying stages: Relations with Indian Ocean basin‐wide mode and South American precipitation

AbstractThis study examines the Interdecadal Pacific Oscillation (IPO) modulation of the El Niño–Southern Oscillation (ENSO) teleconnections in its decaying stages with the tropical ocean by focusing on the Indian Ocean Basin‐Wide (IOBW) mode and the precipitation over South America (SA) in the 1901–2012 period. Composite analyses revealed that the ENSO teleconnections are IPO‐modulated due to the differential ENSO decaying speed, which is slower during the positive than negative IPO phase, for both El Niño (EN) and La Niña (LN) cases. Negative precipitation anomalies related to EN persist over northeastern SA until austral winter for the positive IPO phase (POS IPO), while significant opposite sign anomalies occur in this region for the negative IPO phase (NEG IPO). These results are associated with the Walker circulation's reversal during NEG IPO which is, in turn, accompanied by negative IOBW. During the POS IPO, the positive IOBW causes upward movements over there and, by continuity, downward movements over SA. In the NEG IPO, for LN events the wave train originating in the north of Australia propagates toward subtropical SA, which, coupled with the surface circulation, causes dryness in this region. In addition, the rapid decay of LN in the NEG IPO, followed by the emergence of EN, caused changes in the Walker circulation, such that enhanced upward movements occurred over the Pacific and SA region, and downward movements over the Indian Ocean until austral winter. In turn, the slower decay of the LN in the POS IPO maintains strong subsidence over the central Pacific and weak upward motions over western SA. So, the EN (LN) and positive (negative) IOBW during the POS (NEG) IPO prolong the scarcity of precipitation over equatorial (subtropical) SA. Persistent dry periods over these regions during the ENSO decaying stage might have important implications for the seasonal forecasts.

The Controlling Mechanisms of the Recent Global Warming Hiatus: A Focus on the Internal Variabilities

A flattening trend of global surface temperature from 1998 to 2013 is generally referred to global warming hiatus. In this review, its basics and controlling mechanisms are the focuses with the latter receiving more attention. The mechanisms for the hiatus are largely derived from internal climate variabilities which could be divided into sea surface temperature (SST) and energy variabilities. The major SST variabilities are Interdecadal Pacific Oscillation (IPO) and Atlantic Multi-decadal Oscillation (AMO). The negative phase of IPO during the hiatus is associated with strengthened Pacific trade winds that enhance subsurface heat uptake, which is generally thought to be the predominant mechanism for the hiatus. Furthermore, AMO influences the global surface temperature at decadal time scales, or even the IPO, which are considered to be the main drivers of hiatus. As for the energy variabilities, vertical uptake and interbasin redistribution of heat are also suggested to be capable of leading to a hiatus period. There was significant warming of global ocean below 700 m during the hiatus as an evidence for the storage of excessive heat in deep ocean. And various heat redistribution patterns like those through ITF or AMOC could also play a significant role in regulating the hiatus.

The Influence of Interannual and Decadal Indo-Pacific Sea Surface Temperature Variability on Australian Monsoon Rainfall

Abstract Monsoonal rainfall in northern Australia (AUMR) varies substantially on interannual, decadal, and longer time scales, profoundly impacting natural systems and agricultural communities. Some of this variability arises in response to sea surface temperature (SST) variability in the Indo-Pacific linked to both El Niño–Southern Oscillation (ENSO) and the interdecadal Pacific oscillation (IPO). Here we use observations to investigate unresolved issues regarding the influence of the IPO and ENSO on AUMR. Specifically, we show that during negative IPO phases, central Pacific (CP) El Niño events are associated with below-average rainfall over northeast Australia, an anomalous anticyclonic pattern to the northwest of Australia, and eastward moisture advection toward the date line. In contrast, CP La Niña events (distinct from eastern Pacific La Niña events) during negative IPO phases drive significantly wet conditions over much of northern Australia, a strengthened Walker circulation, and large-scale moisture flux convergence. During positive IPO phases, the impact of CP El Niño and CP La Niña events on AUMR is weaker. The influence of central Pacific SSTs on AUMR has been stronger during the recent (post-1999) negative IPO phase. The extent to which this strengthening is associated with climate change or merely natural internal variability is not known.

Reconstructing an Interdecadal Pacific Oscillation Index from a Pacific Basin–Wide Collection of Ice Core Records

AbstractUsing an assemblage of four ice cores collected around the Pacific basin, one of the first basinwide histories of Pacific climate variability has been created. This ice core–derived index of the interdecadal Pacific oscillation (IPO) incorporates ice core records from South America, the Himalayas, the Antarctic Peninsula, and northwestern North America. The reconstructed IPO is annually resolved and dates to 1450 CE. The IPO index compares well with observations during the instrumental period and with paleo-proxy assimilated datasets throughout the entire record, which indicates a robust and temporally stationary IPO signal for the last ~550 years. Paleoclimate reconstructions from the tropical Pacific region vary greatly during the Little Ice Age (LIA), although the reconstructed IPO index in this study suggests that the LIA was primarily defined by a weak, negative IPO phase and hence more La Niña–like conditions. Although the mean state of the tropical Pacific Ocean during the LIA remains uncertain, the reconstructed IPO reveals some interesting dynamical relationships with the intertropical convergence zone (ITCZ). In the current warm period, a positive (negative) IPO coincides with an expansion (contraction) of the seasonal latitudinal range of the ITCZ. This relationship is not stationary, however, and is virtually absent throughout the LIA, suggesting that external forcing, such as that from volcanoes and/or reduced solar irradiance, could be driving either the ITCZ shifts or the climate dominating the ice core sites used in the IPO reconstruction.

Decadal Modulation of the ENSO–Indian Ocean Basin Warming Relationship during the Decaying Summer by the Interdecadal Pacific Oscillation

AbstractMany previous studies have shown that an Indian Ocean basin warming (IOBW) occurs usually during El Niño–Southern Oscillation (ENSO) decaying spring to summer seasons through modifying the equatorial zonal circulation. Decadal modulation associated with the interdecadal Pacific oscillation (IPO) is further investigated here to understand the nonstationary ENSO–IOBW relationship during ENSO decaying summer (July–September). During the positive IPO phase, significant warm sea surface temperature (SST) anomalies are observed over the tropical Indian Ocean in El Niño decaying summers and vice versa for La Niña events, while these patterns are not well detected in the negative IPO phase. Different decaying speeds of ENSO associated with the IPO phase, largely controlled by both zonal advective and thermocline feedbacks, are suggested to be mainly responsible for these different ENSO–IOBW relationships. In contrast to ENSO events in the negative IPO phase, the ones in the positive IPO phase display a slower decaying speed and delay their transitions both from a warm to a cold state and a cold to a warm state. The slower decay of El Niño and La Niña thereby helps to sustain the teleconnection forcing over the equatorial Indian Ocean and corresponding SST anomalies there can persist into summer. This IPO modulation of the ENSO–IOBW relationship carries important implications for the seasonal prediction of the Indian Ocean SST anomalies and associated summer climate anomalies.

Pacific Mean-State Control of Atlantic Multidecadal Oscillation–El Niño Relationship

AbstractWe investigate the potential impacts of the interdecadal Pacific oscillation (IPO) and Atlantic multidecadal oscillation (AMO) on El Niño and the associated atmosphere and ocean dynamics by using the Community Earth System Model–Large Ensemble Simulation (CESM-LENS). The individual effects of IPO and AMO on El Niño frequency and the underlying atmosphere–ocean processes are well reproduced in CESM-LENS and agree with previous studies. However, the sensitivity of El Niño frequency to the AMO is robust mainly during the negative IPO phase and very weak during the positive IPO phase. Further analysis suggests that the atmospheric mean state in the Pacific is much amplified during the negative IPO phase, facilitating the AMO-induced interocean atmospheric teleconnections. More specifically, during the negative IPO phase of the amplified mean state, the positive AMO enhances ascending motion from the northeastern Pacific, which in turn increases subsidence into the southeast Pacific through local anomalous Hadley circulation. The associated low-level easterly wind anomalies in the central equatorial Pacific are also reinforced by amplified upper-level divergence over the Maritime Continent to enhance the negative IPO, which is unfavorable for El Niño occurrence. Conversely, the negative AMO nearly cancels out the suppressing effect of the negative IPO on El Niño occurrence. During the positive IPO phase of the weakened atmospheric mean state, however, the AMO-induced interocean atmospheric teleconnections are much weaker; thus, neither the positive nor the negative AMO has any significant impact on El Niño occurrence.

Understanding the inter‐decadal variability of autumn precipitation over North Central China using model simulations

AbstractA recent study has shown a robust relationship between the Pacific Decadal Oscillation (PDO) and inter‐decadal variations in autumn precipitation over North Central China (NCC). However, the physical processes underlying these inter‐decadal precipitation variations are not fully understood. Here we analyse multi‐member ensembles of atmospheric reanalysis and model simulations to examine the atmospheric and precipitation responses to sea surface temperature (SST) forcing. Despite the large inter‐member spread resulting from atmospheric internal variability, the model simulations forced by the observed SSTs show an important role of mid‐latitude atmospheric circulation in influencing the inter‐decadal precipitation variations over NCC. We also analyse the sensitivity experiments using three atmospheric models forced by the Inter‐decadal Pacific Oscillation (IPO)/PDO‐like SST fields. The results suggest that the SST anomalies associated with a negative IPO phase can induce anomalous positive pressure anomalies over the East Asia‐Japan‐North Pacific region, which weakens the East Asian trough (EAT) and produces southerly advection of warm and moist air into NCC, leading to increased precipitation there. This study provides a depiction of how the IPO/PDO‐associated SSTs induce inter‐decadal oscillations in mid‐latitude atmospheric circulations, which in turn cause inter‐decadal precipitation variations over NCC.

Pacific Ocean Variability Influences the Time of Emergence of a Seasonally Ice‐Free Arctic Ocean

AbstractThe Arctic Ocean is projected to become seasonally ice‐free before midcentury unless greenhouse gas emissions are rapidly reduced, but exactly when this could occur depends considerably on internal climate variability. Here we show that trajectories to an ice‐free Arctic are modulated by concomitant shifts in the Interdecadal Pacific Oscillation (IPO). Trajectories starting in the negative IPO phase become ice‐free 7 years sooner than those starting in the positive IPO phase. Trajectories starting in the negative IPO phase subsequently transition toward the positive IPO phase, on average, with an associated strengthening of the Aleutian Low, increased poleward energy transport, and faster sea‐ice loss. The observed IPO began to transition away from its negative phase in the past few years. If this shift continues, our results suggest increased likelihood of accelerated sea‐ice loss over the coming decades, and an increased risk of an ice‐free Arctic within the next 20–30 years.

Tropical Decadal Variability and the Rate of Arctic Sea Ice Decrease

AbstractThe trend for cold‐season (November‐December‐January‐February, NDJF) decreases in Arctic sea ice extent from 2000 to 2014 was about a factor of two larger than the 1979–2000 trend, and the warm‐season (June‐July‐August‐September, JJAS) trend was about a factor of three larger. Sensitivity experiments with an atmospheric model show that a negative convective heating anomaly in the tropical Pacific, associated with the negative Interdecadal Pacific Oscillation phase after 2000, produces an atmospheric teleconnection pattern over the Arctic comparable to the observations in NDJF but not JJAS. A positive convective heating anomaly over the tropical Atlantic, associated with warming sea surface temperatures there in the 2000–2014 period, produces a teleconnection pattern over the Arctic comparable to the observations in JJAS but not NDJF. Thus, the observed anomalously strong Arctic surface winds and sea ice drifts after 2000, which produced accelerated decreases in sea ice extent, likely had contributions from decadal‐time scale variability in the tropical Pacific and Atlantic.

Global ocean heat content redistribution during the 1998–2012 Interdecadal Pacific Oscillation negative phase

Previous studies have linked the slowdown in global surface temperature warming during the 1998–2012 period to a negative Interdecadal Pacific Oscillation (IPO) phase. Here, we investigate the changes in ocean heat content (OHC) during this period. We compare two ensembles of coupled model experiments with either zero or observed prescribed tropical Pacific wind stress interannual anomalies. This successfully constrains the global surface temperature, sea level pressure and OHC patterns associated with the IPO phase transition around 1998. The negative IPO phase (1998–2012) is associated with a global ocean heat redistribution. The anomalously cold tropical Pacific Ocean leads to an increased oceanic uptake in this region, and a global OHC increase of 4 × 1022 J. The cold equatorial Pacific also forces mid-latitude wind changes through atmospheric teleconnections, leading to an enhanced wind-driven heat transport convergence at 40°N and 40°S. Enhanced Pacific easterlies also yield an enhanced heat transport to the Indian Ocean via the Indonesian throughflow. As a result, the anomalous Pacific heat uptake is entirely exported towards the North Pacific (~ 50%), Indian (~ 30%) and Southern (~ 20%) Oceans. A significant fraction of this heat is released back to the atmosphere in the North Pacific and Indian basins, and transported across 31°S in the Indian Ocean. Overall, OHC increases most in the Southern Ocean (~ 60% of global changes) and northern Pacific (~ 40%), with negligible changes in the Indian and Atlantic basins. These results point to the major importance of oceanic circulation in re-distributing the Pacific heat uptake globally during negative IPO phases.

Trajectories toward the 1.5°C Paris target: Modulation by the Interdecadal Pacific Oscillation

AbstractGlobal temperature is rapidly approaching the 1.5°C Paris target. In the absence of external cooling influences, such as volcanic eruptions, temperature projections are centered on a breaching of the 1.5°C target, relative to 1850–1900, before 2029. The phase of the Interdecadal Pacific Oscillation (IPO) will regulate the rate at which mean temperature approaches the 1.5°C level. A transition to the positive phase of the IPO would lead to a projected exceedance of the target centered around 2026. If the Pacific Ocean remains in its negative decadal phase, the target will be reached around 5 years later, in 2031. Given the temporary slowdown in global warming between 2000 and 2014, and recent initialized decadal predictions suggestive of a turnaround in the IPO, a sustained period of rapid temperature rise might be underway. In that case, the world will reach the 1.5°C level of warming several years sooner than if the negative IPO phase persists.

Rainfall Variability in the Shoalhaven River Catchment and its Relation to Climatic Indices

The management of the Shoalhaven River, in southern Australia, is important for water supply and floodplain issues including flooding and acid sulphate soil management. Analysis of the spatial variation in rainfall was performed in order to assess temporal and geographical variability within this east Australian catchment and its relationship to large-scale climate drivers, such as the Southern Oscillation Index (SOI), the Interdecadal Pacific Oscillation (IPO), particularly in its negative phase, and the Atmospheric Blocking Index. A total of 141 rain gauges located within a 10-km buffer around the perimeter of the Shoalhaven catchment provided rainfall information spanning from 1885 to 2011. The highest annual mean was in 1950 (1670 mm), with other wet years in 1959 (1564 mm) and 1974 (1571 mm), and the lowest mean was in 1982 (440 mm) and 1944 (446 mm). In the calendar year of 2011 (922 mm), March accounted for 14.5 % of the annual rainfall while April, May and September accounted for less than 5 %. Interpolation between rainfall gauges indicated that the highest rainfall areas occurred in the lower catchment, adjacent to the coast, where there is a pronounced orographic effect. Although it has been implied that drought in this region is related to El Nino years, there was only a weak positive correlation between catchment rainfall and SOI which was moderately enhanced during negative phases of IPO. Seasonal influence of Atmospheric Blocking could be detected on the rain-gauge records during April–October. These findings provide insights not only for this catchment but also for other parts of southeast Australia, implying that coastal catchments may not have strong linkages to key climatic drivers as previously inferred, and management actions and planning on the basis of these climatic indices are not recommended.

Climate change, Pacific climate drivers and observed precipitation variability in Tahiti, French Polynesia

CR Climate Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials CR 63:157-170 (2015) - DOI: https://doi.org/10.3354/cr01288 Climate change, Pacific climate drivers and observed precipitation variability in Tahiti, French Polynesia M. Hopuare1,2,*, M. Pontaud2, J.-P. Céron3, P. Ortéga1, V. Laurent4 1GePaSud Laboratory, 98702 Tahiti, French Polynesia 2CNRM GAME UMR 3589, Météo France/CNRS, 31057 Toulouse, France 3Direction de la Climatologie, Météo France, 31057 Toulouse, France 4Direction Inter Régionale de Polynésie Française, Météo France, 98702 Tahiti, French Polynesia *Corresponding author: marania.hopuare@meteo.fr ABSTRACT: This study addresses the low-frequency variability of precipitation and the detection of climate change over Tahiti, a small orographic island in French Polynesia in the tropical South Pacific. The analysis of new homogenized rainfall amounts over the period 1961-2011 shows no significant trend related to climate change, but highlights the interactions between ENSO, the South Pacific Convergence Zone (SPCZ) and rainfall during the latest positive phase of the Interdecadal Pacific Oscillation (IPO) (1977-1999). During this particular phase, the SPCZ is closer to Tahiti and induces positive large-scale precipitation. On interannual time scales, more frequent and strong El Niño events favour a northward SPCZ migration. This northern position causes a surface flux over Tahiti Island, which forces orographic precipitation on the windward side. During the negative phase of IPO, no clear link is established between SPCZ, ENSO and rainfall variability. KEY WORDS: Rainfall variability · Climate change · ENSO · South Pacific Convergence Zone · SPCZ · Interdecadal Pacific Oscillation · IPO · Tahiti Full text in pdf format PreviousCite this article as: Hopuare M, Pontaud M, Céron JP, Ortéga P, Laurent V (2015) Climate change, Pacific climate drivers and observed precipitation variability in Tahiti, French Polynesia. Clim Res 63:157-170. https://doi.org/10.3354/cr01288 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in CR Vol. 63, No. 2. Online publication date: April 29, 2015 Print ISSN: 0936-577X; Online ISSN: 1616-1572 Copyright © 2015 Inter-Research.

Drivers of decadal hiatus periods in the 20th and 21st centuries

AbstractThe latest generation of climate model simulations are used to investigate the occurrence of hiatus periods in global surface air temperature in the past and under two future warming scenarios. Hiatus periods are identified in three categories: (i) those due to volcanic eruptions, (ii) those associated with negative phases of the Interdecadal Pacific Oscillation (IPO), and (iii) those affected by anthropogenically released aerosols in the mid‐twentieth century. The likelihood of future hiatus periods is found to be sensitive to the rate of change of anthropogenic forcing. Under high rates of greenhouse gas emissions there is little chance of a hiatus decade occurring beyond 2030, even in the event of a large volcanic eruption. We further demonstrate that most nonvolcanic hiatuses across Coupled Model Intercomparison Project 5 (CMIP5) models are associated with enhanced cooling in the equatorial Pacific linked to the transition to a negative IPO phase.

Climate controls on longshore sediment transport

Subtle changes in the directional wave climate driven by changes in large scale climate variability have the potential to result in spatial changes (erosion and accretion) of sandy coastlines due to deviations in longshore sediment transport supply. 50+ years of hindcast offshore directional wave conditions for southeast Queensland, Australia were used to derive yearly wave climates that were input into a spectral wave model to estimate nearshore breaking wave conditions and resulting longshore sediment transport along a 35km stretch of sandy coastline. Resulting temporal deviations in net annual longshore transport were smoothed using a 5-year Hamming filter and compared against two climate indices known to influence the Australian climate: the Southern Oscillation Index (SOI) and the Inter-decadal Pacific Oscillation (IPO). During the negative IPO phase (more El Niño like) deviations in estimated transport were significantly correlated to the SOI index at −1 year lag and correlated to the IPO index at +1 year lag. During positive phases of the IPO (more La Niña like) highest correlations were found at 6 year lag (SOI) and −10 year lag (IPO). A linear regression model combining the influence of both indices explained 65% of the predicted variability in longshore transport during negative phases of the IPO and 48% of the variance during positive phases of the IPO. During positive phases of the IPO, the SOI index was shown to dominate model response and may indicate an increase in the influence of the South Pacific Convergence Zone with respect to the wave climate off the east coast of Australia. A model spanning both phases and only considering positive lags (knowledge of past climate indices) explained approximately half of the predicted variability in longshore transport over the entire record length. The results presented here indicate strong links between these large scale climate indices and estimated longshore transport (0.69≤R≤0.83), such that a simple model derived from knowledge of these indices could be used as a first pass estimate of spatial and temporal variability in longshore sediment transport and resulting large scale coastal evolution.

Influence of large‐scale climate modes on daily synoptic weather types over New Zealand

AbstractThis article examines the influence of El Niño Southern Oscillation (ENSO), Southern Annular Mode (SAM) and Interdecadal Pacific Oscillation (IPO) on the synoptic weather types over New Zealand. The effects of ENSO (indicated by the Southern Oscillation Index, SOI), SAM and IPO on the occurrence of synoptic types are estimated in a holistic framework using the maximum likelihood method via applications of generalized linear models, both annually and by seasons. The average within‐class variations in the intensity and air‐mass characteristics (as expressed in the Auckland Airport meteorological variables) of synoptic systems were examined for individual types at the annual level. The results show that ENSO, SAM and IPO have significant effects on the probability of occurrence and to lesser degree the intensity and air‐mass characteristics of some synoptic types. The effects vary considerably with seasons, synoptic types and phases of SOI, SAM and IPO and it is the confounding effects of different large‐scale modes that lead to the observed changes in the type frequencies. The findings, with respect to ENSO and SAM in all cases and for IPO at the seasonal level, are in good agreement with the literature. However, the annual changes in type frequencies associated with the 1976/1977 IPO phase shift do not support the observed changes in the strength of anomalous southwesterly windflows over New Zealand, and the influence of the recent negative IPO phase also appears different from what we expect based on the existing research. It appears that the interaction between IPO and ENSO is important for understanding the observed climatic effects of IPO on New Zealand's weather and climate. This aspect deserves further attention in future studies. The findings from this work have important methodological and practical implications for New Zealand climate research. Copyright © 2012 Royal Meteorological Society