A Simple Mechanism for ENSO Residuals and Asymmetry

2006 ◽  
Vol 19 (13) ◽  
pp. 3167-3179 ◽  
Author(s):  
Paul S. Schopf ◽  
Robert J. Burgman
Keyword(s):  
Southern Oscillation ◽  
Finite Amplitude ◽  
Lagrangian Description ◽  
Temperature Structure ◽  
Kinematic Effect ◽  
Simple Mechanism ◽  
Surface Temperatures ◽  
Mean Temperature ◽  
Decadal Scale ◽  
Mean Sea Surface

Abstract A simple mechanism is offered that accounts for a change in the long-term (decadal scale) mean of ocean temperatures as the El Niño–Southern Oscillation (ENSO) amplitude changes. It is intended as an illustration of a kinematic effect of oscillating a nonlinear temperature profile with finite-amplitude excursions that will cause the Eulerian time mean temperature to rise (fall) where the curvature of the temperature is positive (negative) as the amplitude of the oscillations increases. This mechanism is found to be able to mimic observed changes in the mean sea surface temperatures in the Pacific between the 1920s, 1960s, and 1990s due to the changing ENSO amplitude. The effects alter both the calculated mean surface temperatures and the time mean temperatures at depth. It also results in a skewness of the temperature distribution that shares many properties with the observed SST. In this model, the time-local gradients of temperature never change if referenced to a single isotherm (i.e., the Lagrangian description is one of DT/Dt = 0). This implies that changes in the amplitude of ENSO will have no influence on the stability of the underlying system, and that the simple Eulerian decadal mean temperature structure has no predictive value. This is in direct contrast to recent work that ascribes a change in ENSO statistics as due to a change in the background state.

scholarly journals The Influence of Sea Surface Temperatures on the Northern Winter Stratosphere: Ensemble Simulations with the MAECHAM5 Model

2006 ◽  
Vol 19 (16) ◽  
pp. 3863-3881 ◽  
Author(s):  
E. Manzini ◽  
M. A. Giorgetta ◽  
M. Esch ◽  
L. Kornblueh ◽  
E. Roeckner
Keyword(s):  
Lower Stratosphere ◽  
Southern Oscillation ◽  
Internal Variability ◽  
Sea Surface ◽  
Sea Surface Temperatures ◽  
Mean Flow ◽  
Enso Events ◽  
Surface Temperatures ◽  
Northern Winter ◽  
Mean State

Abstract The role of interannual variations in sea surface temperatures (SSTs) on the Northern Hemisphere winter polar stratospheric circulation is addressed by means of an ensemble of nine simulations performed with the middle atmosphere configuration of the ECHAM5 model forced with observed SSTs during the 20-yr period from 1980 to 1999. Results are compared to the 40-yr ECMWF Re-Analysis (ERA-40). Three aspects have been considered: the influence of the interannual SST variations on the climatological mean state, the response to El Niño–Southern Oscillation (ENSO) events, and the influence on systematic temperature changes. The strongest influence of SST variations has been found for the warm ENSO events considered. Namely, it has been found that the large-scale pattern associated with the extratropical tropospheric response to the ENSO phenomenon during northern winter enhances the forcing and the vertical propagation into the stratosphere of the quasi-stationary planetary waves emerging from the troposphere. This enhanced planetary wave disturbance thereafter results in a polar warming of a few degrees in the lower stratosphere in late winter and early spring. Consequently, the polar vortex is weakened, and the warm ENSO influence clearly emerges also in the zonal-mean flow. In contrast, the cold ENSO events considered do not appear to have an influence distinguishable from that of internal variability. It is also not straightforward to deduce the influence of the SSTs on the climatological mean state from the simulations performed, because the simulated internal variability of the stratosphere is large, a realistic feature. Moreover, the results of the ensemble of simulations provide weak to negligible evidence for the possibility that SST variations during the two decades considered are substantially contributing to changes in the polar temperature in the winter lower stratosphere.

Quantifying Teleconnection pathways leading to Low Rainfall anomalies during Boreal Summer in Indonesian Borneo

2021 ◽  
Author(s):  
Timothy Lam ◽  
Marlene Kretschmer ◽  
Samantha Adams ◽  
Alberto Arribas ◽  
Rachel Prudden ◽  
...  
Keyword(s):  
Causal Inference ◽  
Climate Model ◽  
Southern Oscillation ◽  
Sea Surface ◽  
Boreal Summer ◽  
Climate Indices ◽  
Sea Surface Temperatures ◽  
Study Region ◽  
Surface Temperatures ◽  
Rainfall Anomalies

<p>Teleconnections are sources of predictability for regional weather and climate, which can be represented by causal relationships between climate features in physically separated regions. In this study, teleconnections of low rainfall anomalies in Indonesian Borneo are analysed and quantified using causal inference theory and causal networks. Causal hypotheses are first developed based on climate model experiments in literature and then justified by means of partial regression analysis between NCEP reanalysis sea surface temperatures and climate indices (drivers) and rainfall data in Indonesian Borneo from various sources (target variable). We find that, as previous studies have highlighted, El Niño Southern Oscillation (ENSO) has a profound effect on rainfall in Indonesia Borneo, with positive Niño 3.4 index serving as a direct driver of low rainfall, also partially through reduced sea surface temperatures (SSTs) over Indonesian waters. On the other hand, while Indian Ocean Dipole (IOD) influences Indonesian Borneo rainfall through SSTs over the same area as a thermodynamic effect, its remaining effect has shifted at multidecadal timescale, opening the rooms for further research. This work informs the potential of a systematic causal approach to statistical inference as a powerful tool to verify and explore atmospheric teleconnections and enables seasonal forecasting to strengthen prevention and control of drought and fire multihazards over peatlands in the study region.</p><p>Keywords: Tropical teleconnections, Causal inference, Climate variability, Drought, Indonesia</p>

The Interdecadal Timescale—Synthesis

2003 ◽  
Author(s):  
Douglas G. Goodin ◽  
Maurice J. McHugh
Keyword(s):  
Southern Oscillation ◽  
Ecological Effect ◽  
Circulation System ◽  
Causal Mechanism ◽  
Global Circulation ◽  
Ecosystem Effects ◽  
Atmospheric Circulation Indices ◽  
Decadal Scale ◽  
Climate Analysis

The five chapters of part III provide a broad overview of decadal-scale climate processes and their ecological effect in a variety of ecosystems. Written by authors with disciplinary backgrounds that encompass climatology, biometeorology, and ecology, the chapters range from cross-site climate analysis with little direct attention to ecosystem effects (e.g., McHugh and Goodin, chapter 11; Hayden and Hayden, chapter 14) to more intensive studies of direct climate/ecological interaction at single sites or over more defined geographical areas (e.g., Greenland, chapter 13; Juday et al., chapter 12; Milne et al., chapter 15). Separately, each of these chapters contributes to understanding some aspect of the interaction of climate and ecology. As an integrated whole, they encapsulate many of the cross-disciplinary problems confronted by LTER scientists as they explore the interaction of climate and ecology. Despite the widely varying topics addressed and the disparate backgrounds of the contributors, similar themes emerge in each of the chapters. Here, we elucidate these themes and place them within the framework questions that have guided this volume. Climatologists have long recognized the existence of cyclical or quasi-cyclical modes or patterns in the global circulation system. Typically, these patterns are characterized by variation in the strength or position of semipermanent pressure centers within the global circulation system. These variations occur at timescales ranging from seasonal to decadal, and such variability is frequently invoked as a causal mechanism for climatic trends or fluctuation at these various timescales. A variety of indexes have been constructed to characterize these pressure patterns and the teleconnections that result from them (see van Loon and Rogers 1978, Rogers 1984, and Trenberth and Hurrell 1994 for in-depth discussion of the derivation and interrelationships of atmospheric circulation indices). Evidence of some of these patterns recurs throughout each of the chapters, suggesting their importance in decadal-scale climate/ecology interactions at LTER sites. Although the chapters in this section concentrate on interdecadal variability, climate variability is a multiscale phenomenon in both space and time. Several authors acknowledge this, notably Milne et al. (chapter 15), McHugh and Goodin (chapter 11), and Greenland (chapter 13). Each of these chapters notes the importance of nondecadal variations, particularly the El Niño–Southern Oscillation (ENSO) phenomenon.

scholarly journals Long-term Lidar Observations of the Gravity Wave Activity near the Mesopause at Arecibo

2018 ◽  
Author(s):  
Xianchang Yue ◽  
Jonathan S. Friedman ◽  
Qihou Zhou ◽  
Xiongbin Wu ◽  
Jens Lautenbach
Keyword(s):  
Potential Energy ◽  
Gravity Wave ◽  
Inversion Layer ◽  
Lower Thermosphere ◽  
Temperature Inversion ◽  
Temperature Structure ◽  
Mean Temperature ◽  
The Mean ◽  
Highly Correlated ◽  
Lidar Observations

Abstract. 11-years long K Doppler lidar observations of temperature profiles in the mesosphere and lower thermosphere (MLT) between 85 and 100 km, conducted at the Arecibo Observatory, Puerto Rico (18.35° N, 66.75° W), are used to estimate seasonal variations of the mean temperature, the squared Brunt-Väisälä frequency, and the gravity wave potential energy in a composite year. The following unique features are obtained: (1) The mean temperature structure shows similar characteristics as a prior report based on a smaller dataset: (2) The profiles of the squared Brunt-Väisälä frequency usually reach the maxima at or just below the temperature inversion layer when that layer is present. The first complete range-resolved climatology of potential energy of temperature fluctuations in the tropical MLT exhibits an altitude dependent combination of annual oscillation (AO) and semiannual oscillation (SAO). Between 88 to 96 km altitude, the amplitudes of AO and SAO are comparable, and their phases are almost the same and quite close to day of year (DOY) 100. Below 88 km, the SAO amplitude is significantly larger than AO and the AO phase shifts to DOY 200 and after. At 97 to 98 km altitude, the amplitudes of AO and SAO reach their minima, and both phases shift significantly. Above that, the AO amplitude becomes greater. The annual mean potential energy profile reaches the minimum at 91 to 92 km altitude. The altitude-dependent SAO of the potential energy is found to be highly correlated with the satellite observed mean zonal winds reported in the literature.

scholarly journals GCM Systematic Error Correction and Specification of the Seasonal Mean Pacific–North America Region Atmosphere from Global SSTs

1999 ◽  
Vol 12 (1) ◽  
pp. 273-288 ◽  
Author(s):  
Thomas M. Smith ◽  
Robert E. Livezey
Keyword(s):  
North America ◽  
General Circulation ◽  
Southern Oscillation ◽  
Circulation Model ◽  
Systematic Errors ◽  
Sea Surface ◽  
Average Output ◽  
Surface Temperatures ◽  
Model Variability ◽  
The U.S

Abstract Specifications of 1- and 3-month mean Pacific–North America region 700-hPa heights and U.S. surface temperatures and precipitation, from global sea surface temperatures (SSTs) and the ensemble average output of multiple runs of a general circulation model with the same SSTs prescribed, were explored with canonical correlation analysis. In addition to considerable specification skill, the authors found that 1) systematic errors in SST-forced model variability had substantial linear parts, 2) use of both predictor fields usually enhanced specification performance for the U.S. fields over that for just one of the predictor fields, and 3) skillful specification and model correction of the heights and temperatures were also possible for nonactive or transitional El Niño–Southern Oscillation situations.

scholarly journals Long-term lidar observations of the gravity wave activity near the mesopause at Arecibo

2019 ◽  
Vol 19 (5) ◽  
pp. 3207-3221
Author(s):  
Xianchang Yue ◽  
Jonathan S. Friedman ◽  
Qihou Zhou ◽  
Xiongbin Wu ◽  
Jens Lautenbach
Keyword(s):  
Gravity Wave ◽  
Lower Thermosphere ◽  
Strong Support ◽  
Temporal Correlation ◽  
Temperature Inversion ◽  
Dynamical Instability ◽  
Temperature Structure ◽  
Mesopause Region ◽  
Mean Temperature ◽  
Lidar Observations

Abstract. Using 11-year-long K Doppler lidar observations of temperature profiles in the mesosphere and lower thermosphere (MLT) between 85 and 100 km, conducted at the Arecibo Observatory, Puerto Rico (18.35∘ N, 66.75∘ W), seasonal variations of mean temperature, the squared Brunt–Väisälä frequency, N2, and the gravity wave potential energy (GWPE) are estimated in a composite year. The following unique features are obtained. (1) The mean temperature structure shows similar characteristics to an earlier report based on a smaller dataset. (2) Temperature inversion layers (TILs) occur at 94–96 km in spring, at ∼92 km in summer, and at ∼91 km in early autumn. (3) The first complete range-resolved climatology of GWPE derived from temperature data in the tropical MLT exhibits an altitude-dependent combination of annual oscillation (AO) and semiannual oscillation (SAO). The maximum occurs in spring and the minimum in summer, and a second maximum is in autumn and a second minimum in winter. (4) The GWPE per unit volume reduces below ∼97 km altitude in all seasons. The reduction of GWPE is significant at and below the TILs but becomes faint above; this provides strong support for the mechanism that the formation of upper mesospheric TILs is mainly due to the reduction of GWPE. The climatology of GWPE shows an indeed pronounced altitudinal and temporal correlation with the wind field in the tropical mesopause region published in the literature. This suggests the GW activity in the tropical mesopause region should be manifested mainly by the filtering effect of the critical level of the local background wind and the energy conversion due to local dynamical instability.

scholarly journals Sub-decadal- to decadal-scale climate cyclicity during the Holsteinian interglacial (MIS 11) evidenced in annually laminated sediments

2011 ◽  
Vol 7 (3) ◽  
pp. 987-999 ◽  
Author(s):  
A. Koutsodendris ◽  
A. Brauer ◽  
H. Pälike ◽  
U. C. Müller ◽  
P. Dulski ◽  
...  
Keyword(s):  
Time Series ◽  
Southern Oscillation ◽  
Laminated Sediments ◽  
Solar Cycles ◽  
The North ◽  
Decadal Scale ◽  
Time Series Analyses ◽  
Diatom Blooms ◽  
Winter Time ◽  
The North Atlantic Oscillation

Abstract. To unravel the short-term climate variability during Marine Isotope Stage (MIS) 11, which represents a close analogue to the Holocene with regard to orbital boundary conditions, we performed microfacies and time series analyses on a ~3200-yr-long record of annually laminated Holsteinian lake sediments from Dethlingen, northern Germany. These biogenic varves comprise two sub-layers: a light sub-layer, which is controlled by spring/summer diatom blooms, and a dark sub-layer consisting mainly of amorphous organic matter and fragmented diatom frustules deposited during autumn/winter. Time series analyses were performed on the thickness of the light and dark sub-layers. Signals exceeding the 95% and 99% confidence levels occur at periods that are near-identical to those known from modern instrumental data and Holocene palaeoclimatic records. Spectral peaks at periods of 90, 25, and 10.5 yr are likely associated with the 88-, 22- and 11-yr solar cycles, respectively. This variability is mainly expressed in the light sub-layer spectra, suggesting solar influence on the palaeoproductivity of the lake. Significant signals at periods between 3 and 5 yr and at ∼6 yr are strongest expressed in the dark sub-layer spectra and may reflect an influence of the El Niño-Southern Oscillation (ENSO) and the North Atlantic Oscillation (NAO) during autumn/winter. Our results suggest that solar forcing and ENSO/NAO-like variability influenced central European climate during MIS 11 similarly to the present interglacial, thus demonstrating the comparability of the two interglacial periods at sub-decadal to decadal timescales.

scholarly journals PDO–ENSO Effects in the Climate of Mexico

2006 ◽  
Vol 19 (24) ◽  
pp. 6433-6438 ◽  
Author(s):  
Edgar G. Pavia ◽  
Federico Graef ◽  
Jorge Reyes
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
La Niña ◽  
Climate Anomalies ◽  
Enso Events ◽  
La Nina ◽  
Mean Temperature ◽  
The Pacific

Abstract The role of the Pacific decadal oscillation (PDO) in El Niño–Southern Oscillation (ENSO)-related Mexican climate anomalies during winter and summer is investigated. The precipitation and mean temperature data of approximately 1000 stations throughout Mexico are considered. After sorting ENSO events by warm phase (El Niño) and cold phase (La Niña) and prevailing PDO phase: warm or high (HiPDO) and cold or low (LoPDO), the authors found the following: 1) For precipitation, El Niño favors wet conditions during summers of LoPDO and during winters of HiPDO. 2) For mean temperature, cooler conditions are favored during La Niña summers and during El Niño winters, regardless of the PDO phase; however, warmer conditions are favored by the HiPDO during El Niño summers.

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