Mapping Large-scale Climate Variability to Hydrological Extremes: An Application of the Linear Inverse Model to Subseasonal Prediction

2020 ◽  
pp. 1-58
Author(s):  
Kai-Chih Tseng ◽  
Nathaniel C. Johnson ◽  
Eric D. Maloney ◽  
Elizabeth A. Barnes ◽  
Sarah B. Kapnick
Keyword(s):  
Climate Variability ◽  
Large Scale ◽  
Teleconnection Pattern ◽  
Inverse Model ◽  
Tropical Convection ◽  
Madden Julian Oscillation ◽  
Atmospheric Rivers ◽  
Hydrological Extremes ◽  
The Pacific ◽  
Linear Inverse Model

AbstractThe excitation of the Pacific-North American (PNA) teleconnection pattern by the Madden-Julian Oscillation (MJO) has been considered as one of the most important predictability sources on subseasonal timescales over the extratropical Pacific and North America. However, until recently, the interactions between tropical heating and other extratropical modes and their relationships to subseasonal prediction have received comparatively little attention. In this study, a linear inverse model (LIM) is applied to examine the tropical-extratropical interactions. The LIM provides a means of calculating the response of a dynamical system to a small forcing by constructing a linear operator from the observed covariability statistics of the system. Given the linear assumptions, it is shown that the PNA is one of a few leading modes over the extratropical Pacific that can be strongly driven by tropical convection while other extratropical modes present at most a weak interaction with tropical convection. In the second part of this study, a two-step linear regression is introduced which leverages a LIM and large-scale climate variability to the prediction of hydrological extremes (e.g. atmospheric rivers) on subseasonal timescales. Consistent with the findings of the first part, most of the predictable signals on subseasonal timescales are determined by the dynamics of MJO-PNA teleconnection while other extratropical modes are important only at the shortest forecast leads.

scholarly journals Forecasting Pacific SSTs: Linear Inverse Model Predictions of the PDO

2008 ◽  
Vol 21 (2) ◽  
pp. 385-402 ◽  
Author(s):  
Michael A. Alexander ◽  
Ludmila Matrosova ◽  
Cécile Penland ◽  
James D. Scott ◽  
Ping Chang
Keyword(s):  
Inverse Model ◽  
Enso Events ◽  
Enso Teleconnections ◽  
Four Seasons ◽  
Global Trend ◽  
The Pacific ◽  
Model Predictions ◽  
Sea Surface Temperature Anomalies ◽  
Linear Inverse Model ◽  
The Individual

Abstract A linear inverse model (LIM) is used to predict Pacific (30°S–60°N) sea surface temperature anomalies (SSTAs), including the Pacific decadal oscillation (PDO). The LIM is derived from the observed simultaneous and lagged covariance statistics of 3-month running mean Pacific SSTA for the years 1951–2000. The model forecasts exhibit significant skill over much of the Pacific for two to three seasons in advance and up to a year in some locations, particulary for forecasts initialized in winter. The predicted and observed PDO are significantly correlated at leads of up to four seasons, for example, the correlation exceeds 0.6 for 12-month forecasts initialized in January–March (JFM). The LIM-based PDO forecasts are more skillful than persistence or a first-order autoregressive model, and have comparable skill to LIM forecasts of El Niño SSTAs. Filtering the data indicates that much of the PDO forecast skill is due to ENSO teleconnections and the global trend. Within LIM, SST anomalies can grow due to constructive interference of the empirically determined modes, even though the individual modes are damped over time. For the Pacific domain, the basinwide SST variance can grow for ∼14 months, consistent with the skill of the actual predictions. The optimal structure (OS), the initial SSTA pattern that LIM indicates should increase the most rapidly with time, is clearly relevant to the predictions, as the OS develops into a mature ENSO and PDO event 6–10 months later. The OS is also consistent with the seasonal footprinting mechanism (SFM) and the meridional mode (MM); the SFM and MM involve a set of atmosphere–ocean interactions that have been hypothesized to initiate ENSO events.

scholarly journals Influence of Modes of Climate Variability on Global Temperature Extremes

2008 ◽  
Vol 21 (15) ◽  
pp. 3872-3889 ◽  
Author(s):  
Jesse Kenyon ◽  
Gabriele C. Hegerl
Keyword(s):  
North America ◽  
Climate Variability ◽  
Large Scale ◽  
Southern Oscillation ◽  
Temperature Extremes ◽  
Modes Of Variability ◽  
The North ◽  
The Pacific ◽  
The North Atlantic Oscillation ◽  
Modes Of Climate Variability

Abstract The influence of large-scale modes of climate variability on worldwide summer and winter temperature extremes has been analyzed, namely, that of the El Niño–Southern Oscillation, the North Atlantic Oscillation, and Pacific interdecadal climate variability. Monthly indexes for temperature extremes from worldwide land areas are used describe moderate extremes, such as the number of exceedences of the 90th and 10th climatological percentiles, and more extreme events such as the annual, most extreme temperature. This study examines which extremes show a statistically significant (5%) difference between the positive and negative phases of a circulation regime. Results show that temperature extremes are substantially affected by large-scale circulation patterns, and they show distinct regional patterns of response to modes of climate variability. The effects of the El Niño–Southern Oscillation are seen throughout the world but most clearly around the Pacific Rim and throughout all of North America. Likewise, the influence of Pacific interdecadal variability is strongest in the Northern Hemisphere, especially around the Pacific region and North America, but it extends to the Southern Hemisphere. The North Atlantic Oscillation has a strong continent-wide effect for Eurasia, with a clear but weaker effect over North America. Modes of variability influence the shape of the daily temperature distribution beyond a simple shift, often affecting cold and warm extremes and sometimes daytime and nighttime temperatures differently. Therefore, for reliable attribution of changes in extremes as well as prediction of future changes, changes in modes of variability need to be accounted for.

scholarly journals Using avalanche problems to examine the effect of large-scale atmosphere-ocean oscillations on avalanche hazard in western Canada

2020 ◽  
Author(s):  
Pascal Haegeli ◽  
Bret Shandro ◽  
Patrick Mair
Keyword(s):  
Large Scale ◽  
Southern Oscillation ◽  
Teleconnection Pattern ◽  
Western Canada ◽  
Winter Weather ◽  
Negative Effects ◽  
Weather Patterns ◽  
Avalanche Hazard ◽  
The Pacific ◽  
Hazard Response

Abstract. Numerous large-scale atmosphere-ocean oscillations including the El Niño-Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO), the Pacific North American Teleconnection Pattern (PNA) and the Artic Oscillation (AO) are known to substantially affect winter weather patterns in western Canada. Several studies have examined the effect of these oscillations on avalanche hazard using long-term avalanche activity records from highway avalanche safety programs. While these studies offer valuable insights, they do not offer a comprehensive perspective on the influence of these oscillations because the underlying data only represent the conditions at a few point locations in western Canada where avalanches are tightly managed. We present a new approach for gaining insight into the relationship between atmosphere-ocean oscillations and avalanche hazard in western Canada that uses avalanche problem information published in public avalanche bulletins during the winters of 2010 to 2019. For each avalanche problem type, we calculate seasonal prevalence values for each forecast area, elevation band and season, which are then included in a series of beta mixed-effects regression models to explore both the overall and regional effects of the Pacific-centered oscillations (PO; including ENSO, PDO, PNA) and AO on the nature of avalanche hazard in the study area. Even though our study period is short, we find significant negative effects of PO on the prevalence of Storm slab avalanche problems, Wind slab avalanche problems, and Dry loose avalanche problems, which agree reasonably well with the known impacts of PO on winter weather in western Canada. The analysis also reveals a positive relationship between AO and the prevalence of Deep persistent slab avalanche problems particularly in the Rocky Mountains. In addition, we also find several smaller-scale patterns that highlight that the avalanche hazard response to these oscillations varies regionally. Our study shows that the forecaster judgment included in the avalanche problem assessments adds considerable value for these types of climate analyses. Since the predictability of the most important atmosphere-ocean oscillations is continuously improving, a better understanding of their effect on avalanche hazard can contribute to the development of informative seasonal avalanche forecasts and a better understanding of the effect of climate change on avalanche hazard.

Simulations of Atmospheric Rivers, Their Variability, and Response to Global Warming Using GFDL’s New High-Resolution General Circulation Model

2020 ◽  
Vol 33 (23) ◽  
pp. 10287-10303
Author(s):  
Ming Zhao
Keyword(s):  
Global Warming ◽  
General Circulation ◽  
Large Scale ◽  
Southern Oscillation ◽  
Geographical Location ◽  
Circulation Model ◽  
Teleconnection Pattern ◽  
Width Ratio ◽  
Atmospheric Rivers ◽  
Length Width

AbstractA 50-km-resolution GFDL AM4 well captures many aspects of observed atmospheric river (AR) characteristics including the probability density functions of AR length, width, length–width ratio, geographical location, and the magnitude and direction of AR mean vertically integrated vapor transport (IVT), with the model typically producing stronger and narrower ARs than the ERA-Interim results. Despite significant regional biases, the model well reproduces the observed spatial distribution of AR frequency and AR variability in response to large-scale circulation patterns such as El Niño–Southern Oscillation (ENSO), the Northern and Southern Hemisphere annular modes (NAM and SAM), and the Pacific–North American (PNA) teleconnection pattern. For global warming scenarios, in contrast to most previous studies that show a large increase in AR length and width and therefore the occurrence frequency of AR conditions at a given location, this study shows only a modest increase in these quantities. However, the model produces a large increase in strong ARs with the frequency of category 3–5 ARs rising by roughly 100%–300% K−1. The global mean AR intensity as well as AR intensity percentiles at most percent ranks increases by 5%–8% K−1, roughly consistent with the Clausius–Clapeyron scaling of water vapor. Finally, the results point out the importance of AR IVT thresholds in quantifying modeled AR response to global warming.

scholarly journals Formation Mechanisms of the Pacific–North American Teleconnection with and without Its Canonical Tropical Convection Pattern

2017 ◽  
Vol 30 (9) ◽  
pp. 3139-3155 ◽  
Author(s):  
Ying Dai ◽  
Steven B. Feldstein ◽  
Benkui Tan ◽  
Sukyoung Lee
Keyword(s):  
North American ◽  
Wave Train ◽  
Dominant Role ◽  
Teleconnection Pattern ◽  
Wave Activity ◽  
Tropical Convection ◽  
Formation Mechanisms ◽  
Convection Pattern ◽  
Pacific North American ◽  
The Pacific

The mechanisms that drive the Pacific–North American (PNA) teleconnection pattern with and without its canonical tropical convection pattern are investigated with daily ERA-Interim and NOAA OLR data (the former pattern is referred to as the convective PNA, and the latter pattern is referred to as the nonconvective PNA). Both the convective and nonconvective positive PNA are found to be preceded by wave activity fluxes associated with a Eurasian wave train. These wave activity fluxes enter the central subtropical Pacific, a location that is favorable for barotropic wave amplification, just prior to the rapid growth of the PNA. The wave activity fluxes are stronger for the positive nonconvective PNA, suggesting that barotropic amplification plays a greater role in its development. The negative convective PNA is also preceded by a Eurasian wave train, whereas the negative nonconvective PNA grows from the North Pacific contribution to a circumglobal teleconnection pattern. Driving by high-frequency eddy vorticity fluxes is largest for the negative convective PNA, indicating that a positive feedback may be playing a more dominant role in its development. The lifetimes of convective PNA events are found to be longer than those of nonconvective PNA events, with the former (latter) persisting for about three (two) weeks. Furthermore, the frequency of the positive (negative) convective PNA is about 40% (60%) greater than that of the positive (negative) nonconvective PNA.

scholarly journals The Interaction of the Madden–Julian Oscillation and the Arctic Oscillation

2005 ◽  
Vol 18 (1) ◽  
pp. 143-159 ◽  
Author(s):  
Shuntai Zhou ◽  
Alvin J. Miller
Keyword(s):  
Large Scale ◽  
Arctic Oscillation ◽  
Winter Season ◽  
The Arctic ◽  
Height Anomaly ◽  
Madden Julian Oscillation ◽  
Regional Effect ◽  
The Pacific ◽  
Action Center ◽  
The Arctic Oscillation

Abstract Tropical and extratropical interactions on the intraseasonal time scale are studied in the context of the Arctic Oscillation (AO) and the Madden–Julian oscillation (MJO). To simplify the discussion, a high (low) MJO phase is defined as strong (suppressed) convective activity over the Indian Ocean. In the Northern Hemisphere (NH) winter season, a high (low) AO phase is found more likely coupled with a high (low) MJO phase. Based on the regressed patterns and composites of various dynamical fields and quantities, possible mechanisms linking the AO and the MJO are examined. The analysis indicates that the MJO influence on extratropical circulations seems more evident than the AO influence on tropical circulations. The MJO interacts with the AO through meridional dispersion of Rossby waves in the Pacific sector. The geopotential height anomaly center over the North Pacific associated with the MJO can either reinforce or offset the AO Pacific action center. As a result, the AO pattern can be greatly affected by the MJO. When the AO and the MJO are in the same (opposite) phase, the Pacific action center becomes much stronger (weaker) than the Atlantic action center. The eddy momentum transports associated with the MJO in the Pacific sector are closely related to the retraction and extension of tropical Pacific easterlies and the subtropical Asian–Pacific jet. Because of its large scale, this regional effect is also reflected in the zonal mean state of wave transport and wave forcing on zonal wind, which in turn affects the phase of the AO.

A Comparison of OLR and Circulation-Based Indices for Tracking the MJO

2014 ◽  
Vol 142 (5) ◽  
pp. 1697-1715 ◽  
Author(s):  
George N. Kiladis ◽  
Juliana Dias ◽  
Katherine H. Straub ◽  
Matthew C. Wheeler ◽  
Stefan N. Tulich ◽  
...  
Keyword(s):  
Real Time ◽  
Outgoing Longwave Radiation ◽  
Seasonal Cycle ◽  
Large Scale ◽  
Longwave Radiation ◽  
Tropical Convection ◽  
Madden Julian Oscillation ◽  
Primary Interest ◽  
Large Scale Circulation ◽  
Reasonable Approximation

Abstract Two univariate indices of the Madden–Julian oscillation (MJO) based on outgoing longwave radiation (OLR) are developed to track the convective component of the MJO while taking into account the seasonal cycle. These are compared with the all-season Real-time Multivariate MJO (RMM) index of Wheeler and Hendon derived from a multivariate EOF of circulation and OLR. The gross features of the OLR and circulation of composite MJOs are similar regardless of the index, although RMM is characterized by stronger circulation. Diversity in the amplitude and phase of individual MJO events between the indices is much more evident; this is demonstrated using examples from the Dynamics of the Madden–Julian Oscillation (DYNAMO) field campaign and the Year of Tropical Convection (YOTC) virtual campaign. The use of different indices can lead to quite disparate conclusions concerning MJO timing and strength, and even as to whether or not an MJO has occurred. A disadvantage of using daily OLR as an EOF basis is that it is a much noisier field than the large-scale circulation, and filtering is necessary to obtain stable results through the annual cycle. While a drawback of filtering is that it cannot be done in real time, a reasonable approximation to the original fully filtered index can be obtained by following an endpoint smoothing method. When the convective signal is of primary interest, the authors advocate the use of satellite-based metrics for retrospective analysis of the MJO for individual cases, as well as for the analysis of model skill in initiating and evolving the MJO.

scholarly journals Madden-Julian oscillation winds excite an intraseasonal see-saw of ocean mass that affects Earth’s polar motion

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
M. Afroosa ◽  
B. Rohith ◽  
Arya Paul ◽  
Fabien Durand ◽  
Romain Bourdallé-Badie ◽  
...  
Keyword(s):  
Large Scale ◽  
Tropical Indian Ocean ◽  
Polar Axis ◽  
Global Scale ◽  
Pacific Basin ◽  
Ocean Bottom ◽  
Madden Julian Oscillation ◽  
Ocean Mass ◽  
The Pacific ◽  
The Pacific Ocean

AbstractStrong large-scale winds can relay their energy to the ocean bottom and elicit an almost immediate intraseasonal barotropic (depth independent) response in the ocean. The intense winds associated with the Madden-Julian Oscillation over the Maritime Continent generate significant intraseasonal basin-wide barotropic sea level variability in the tropical Indian Ocean. Here we show, using a numerical model and a network of in-situ bottom pressure recorders, that the concerted barotropic response of the Indian and the Pacific Ocean to these winds leads to an intraseasonal see-saw of oceanic mass in the Indo-Pacific basin. This global-scale mass shift is unexpectedly fast, as we show that the mass field of the entire Indo-Pacific basin is dynamically adjusted to Madden-Julian Oscillation in a few days. We find this large-scale ocean see-saw, induced by the Madden-Julian Oscillation, has a detectable influence on the Earth’s polar axis motion, in particular during the strong see-saw of early 2013.

Footprints of Tropical Cyclones in WNP Summer Monsoon Variability

2020 ◽  
Author(s):  
Huang-Hsiung Hsu
Keyword(s):  
Climate Variability ◽  
Tropical Cyclones ◽  
Large Scale ◽  
Climate Models ◽  
Southern Oscillation ◽  
Intraseasonal Oscillation ◽  
Low Frequency ◽  
Monsoon Trough ◽  
Teleconnection Pattern ◽  
Large Scale Circulation

<p>Tropical cyclones (TCs) in the western North Pacific (WNP) are modulated by large-scale circulation systems such monsoon trough, intraseasonal oscillation, teleconnection pattern, El Niño and Southern Oscillation, and some interdecadal oscillations. While the low-frequency, large-scale circulation produces a clustering effect on TCs, the latter in return leave marked footprints in climate mean state and variability because of large amplitudes in circulation and strong heating. In this study, we applied PV inversion technique to remove TCs from reanalysis and evaluate their contribution to mean circulation and climate variability. It is found that the mean climatological circulation (e.g., low-level monsoon trough and upper-tropospheric anticyclone) would be much weaker with TCs removed. Intraseasonal and interannual variance of certain variables could decrease by as much as 40–50 percent. An accompanied study indicated that TCs had slowed down the sea surface warming in the WNP for the past few decades because of TC-induced cooling. Our results suggest that TC effect has to be considered to understand the climate variability in the tropical atmosphere and ocean. The ensemble effect of TCs, at least in the statistical sense, has to be resolved in climate models to better simulate climate variability and produce more reliable climate projection in the TC-prone regions.</p>

scholarly journals Using avalanche problems to examine the effect of large-scale atmosphere–ocean oscillations on avalanche hazard in western Canada

2021 ◽  
Vol 15 (3) ◽  
pp. 1567-1586
Author(s):  
Pascal Haegeli ◽  
Bret Shandro ◽  
Patrick Mair
Keyword(s):  
Large Scale ◽  
Southern Oscillation ◽  
Teleconnection Pattern ◽  
The Arctic ◽  
Western Canada ◽  
Winter Weather ◽  
Negative Effects ◽  
Avalanche Hazard ◽  
The Pacific ◽  
The Arctic Oscillation

Abstract. Numerous large-scale atmosphere–ocean oscillations including the El Niño–Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO), the Pacific North American Teleconnection Pattern (PNA), and the Arctic Oscillation (AO) are known to substantially affect winter weather patterns in western Canada. Several studies have examined the effect of these oscillations on avalanche hazard using long-term avalanche activity records from highway avalanche safety programmes. We present a new approach for gaining additional insight into these relationships that uses avalanche problem information published in public avalanche bulletins during the winters of 2010 to 2019. For each avalanche problem type, we calculate seasonal prevalence values for each forecast area, elevation band, and season, which are then included in a series of beta mixed-effects regression models to explore both the overall and regional effects of the Pacific-centered oscillations (POs; including ENSO, PDO, and PNA) and AO on the nature of avalanche hazard in the study area. We find significant negative effects of PO on the prevalence of storm slab avalanche problems, wind slab avalanche problems, and dry loose avalanche problems, which agree reasonably well with the known impacts of PO on winter weather in western Canada. The analysis also reveals a positive relationship between AO and the prevalence of deep persistent slab avalanche problems, particularly in the Rocky Mountains. In addition, we find several smaller-scale patterns that highlight that the avalanche hazard response to these oscillations varies regionally. Even though our study period is short, our study shows that the forecaster judgement included in avalanche problem assessments can add considerable value for these types of analyses. Since the predictability of the most important atmosphere–ocean oscillations is continuously improving, a better understanding of their effect on avalanche hazard can contribute to the development of informative seasonal avalanche forecasts in a relatively simple way.

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