Stephen Zebiak

Stephen Zebiak
Columbia University | CU · International Research Institute for Climate and Society

About

142
Publications
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Publications

Publications (142)
Technical Report
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In 2005, the International Research Institute for Climate and Society published its assessment of key gaps in the use of climate information for health, agriculture, water and other sectors in countries across Africa. The results from the report were less than stellar. After an extensive review of use of climate information in the development secto...
Article
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While seasonal outlooks have been operational for many years, until recently the extended-range timescale referred to as subseasonal-to-seasonal (S2S) has received little attention. S2S prediction fills the gap between short-range weather prediction and long-range seasonal outlooks. Decisions in a range of sectors are made in this extended-range le...
Research
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A White Paper of the Climate Services Partnership Working Group on Climate Service Ethics
Article
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Throughout at least the past several centuries, El Niño-Southern Oscillation (ENSO) has played a significant role in human response to climate. Over time, increased attention on ENSO has led to a better understanding of both the physical mechanisms, and the environmental and societal consequences of the phenomenon. The prospects for seasonal climat...
Article
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Throughout at least the past several centuries, El Niño-Southern Oscillation (ENSO) has played a significant role in human response to climate. Over time, increased attention on ENSO has led to a better understanding of both the physical mechanisms, and the environmental and societal consequences of the phenomenon. The prospects for seasonal climat...
Article
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This paper provides a historical overview of the development and mainstreaming of global agendas on climate risk management and climate services from the vantage point of the International Research Institute for Climate and Society (IRI), and present two examples that illustrate how efforts to mainstream these agendas shaped both the institute and...
Article
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An empirical model for the temperature of subsurface water entrained into the ocean mixed layer (Te) is presented and evaluated to improve sea surface temperature anomaly (SSTA) simulations in an intermediate ocean model (IOM) of the tropical Pacific. An inverse modeling approach is adopted to estimate Te from an SSTA equation using observed SST an...
Presentation
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The SMAP Mission is currently planned for launch in late 2014 to provide global measurements of soil moisture and freeze/thaw state. For mission planning, a Testbed Facility is in place to test software that will be used to automatically generate the science data products once SMAP is in orbit. Early distribution of a subset of these testbed data p...
Article
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Madeleine C. Thomson and colleagues call on climate and health researchers, policy-makers and practitioners to work together to tackle infectious diseases.
Article
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Recurrence times for extreme drought events in the African Sahel are estimated using a classical peaks-over-threshold model. Results, which are computed for both mean seasonal rainfall and fractional area in drought, suggest that the distribution of dry extremes after about 1970 is statistically distinct from that of preceding years. This finding t...
Article
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The performance of different models and procedures for forecasting aggregated May-July streamflow for the Churchill Falls basin on the Quebec-Labrador peninsula is compared. The models compared have different lead times and include an autoregressive model using only past streamflow data, an autoregressive with exogenous input model utilizing both p...
Article
Results from diagnostic analyses to understand the seasonal evolution of the large-scale climatic state responsible for the development and melt of the winter snowpack, and spring-early summer precipitation in the Churchill Falls region on the Quebec-Labrador Peninsula, Canada, are presented in the context of the development of an empirical model f...
Article
The El Niño–Southern Oscillation (ENSO) cycle of alternating warm El Niño and cold La Niña events is the dominant year-to-year climate signal on Earth. ENSO originates in the tropical Pacific through interactions between the ocean and the atmosphere, but its environmental and socioeconomic impacts are felt worldwide. Spurred on by the powerful 1997...
Article
This study uses a hybrid coupled model (referred to as the general-circulation model (GCM)/Zebiak/Cane (ZC) model), which consists of the Goddard Institute for Space Studies' (GISS) Atmospheric general-circulation model (AGCM) coupled to the oceanic component of the ZC intermediate model to assess the impact of global warming on El Niño behavior, w...
Article
The Big Brother Experiment methodology of Denis etal. (Clim Dyn 18:627-646, 2002) is applied to test the downscaling ability of a one-way nested regional climate model. This methodology consists of first obtaining a reference climate by performing a large domain, high resolution regional climate model simulation—the Big Brother. The small scales ar...
Article
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The International Research Institute for Climate Prediction (IRI) and Ceara Foundation for Meteorology and Water Resources (FUNCEME) in Brazil have developed a dynamical downscaling prediction system for Northeast Brazil (the Nordeste) and have been issuing seasonal rainfall forecasts since December 2001. To the authors' knowledge, this is the firs...
Article
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We present a method for the ensemble seasonal prediction of human St. Louis encephalitis (SLE) incidence and SLE virus transmission in Florida. We combine empirical relationships between modeled land surface wetness and the incidence of human clinical cases of SLE and modeled land surface wetness and the occurrence of SLE virus transmission through...
Article
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A new intermediate coupled model (ICM) is presented and employed to make retrospective predictions of tropical Pacific sea surface temperature (SST) anomalies. The ocean dynamics is an extension of the McCreary baroclinic modal model to include varying stratification and certain nonlinear effects. A standard configuration is chosen with 10 baroclin...
Article
The properties of tropical cyclones in three low-resolution atmospheric general circulation models (AGCMs) in seven ocean basins are discussed. The models are forced by prescribed, observed sea surface temperatures over a period of 40 yr, and their simulations of tropical cyclone activity are compared with observations. The model cyclone characteri...
Article
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The potential predictability associated with the remote influence of midlatitude tropospheric anomalies over the North Pacific or the North Atlantic, via a seesawlike interannual oscillation between the surface Aleutian and Icelandic lows (AL and IL, respectively) is investigated. Data from a 24-member ensemble of 50-yr atmospheric general circulat...
Article
The ODASI consortium is focused activity of the NOAA/OGP/Climate Diagnostics and Experimental Prediction Program with the goal of improving ocean data assimilation methods and their implementations in support of seasonal forecasts with coupled general circulation models. The consortium is undertaking coordinated assimilation experiments, with commo...
Article
The response of El Niño to natural radiative forcing changes over the past 1000 yr is investigated based on numerical experiments employing the Zebiak-Cane model of the tropical Pacific coupled ocean-atmosphere system. Previously published empirical results demonstrating a statistically significant tendency toward El Niño conditions in response to...
Article
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An improved Bayesian optimal weighting scheme is developed and used to combine six atmospheric general circulation model (GCM) seasonal hindcast ensembles. The approach is based on the prior belief that the forecast probabilities of tercile-category precipitation and near-surface temperature are equal to the climatological ones. The six GCMs are in...
Article
An embedding approach is developed and tested to improve El Niño Southern Oscillation (ENSO) simulations in a hybrid coupled model (HCM), focusing on the ocean thermocline effects on sea surface temperature (SST) in the eastern equatorial Pacific. The NOAA/GFDL Modular Ocean Model (MOM 3) is coupled to a statistical atmospheric model that estimates...
Article
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Disease transmission forecasts can help minimize human and domestic animal health risks by indicating where disease control and prevention efforts should be focused. For disease systems in which weather-related variables affect pathogen proliferation, dispersal, or transmission, the potential for disease forecasting exists. We present a seasonal fo...
Data
The Topographically-Based Hydrology (TBH) Model
Data
Dependence in the Transmission Number Category Data
Article
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Forecasts of El Niño climate events are routinely provided and distributed, but the limits of El Niño predictability are still the subject of debate. Some recent studies suggest that the predictability is largely limited by the effects of high-frequency atmospheric 'noise', whereas others emphasize limitations arising from the growth of initial err...
Article
The performance of different models and procedures for forecasting aggregated May–July streamflow for Churchill Falls basin in northeastern Canada is compared. The forecasts are based on available hydroclimatic information. The predictors include past streamflow, precipitation and temperature over the basin, along with selected sea surface temperat...
Article
Full-text available
The International Research Institute (IRI) for Climate Prediction seasonal forecast system is based largely on the predictions of ensembles of several atmospheric general circulation models (AGCMs) forced by two versions of an SST prediction—one consisting of persisted SST anomalies from the current observations and one of evolving SST anomalies as...
Article
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The methodology for dynamical climate downscaling is studied using the second-generation regional climate model (RegCM2). The question addressed is, in order to simulate high-resolution details as accurately as possible, what strategy should be taken: continuous long-term integration in climate prediction mode or consecutive short-term integrations...
Article
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1] A new intermediate coupled model (ICM) is developed and used to simulate and predict sea surface temperature (SST) variability in the tropical Pacific. The ocean component is based on an intermediate complexity model developed by Keenlyside and Kleeman [2002] that is an extension of the McCreary [1981] baroclinic modal model to include varying s...
Article
Full-text available
A regional modeling intercomparison project for South America among the (1) Scripps Experimental Climate Prediction Center regional spectral model (RSM), (2) Florida State University nested regional spectral model (FSUNRSM), (3) Goddard Institute for Space Studies regional climate model (RCM), and (4) IRI regional climate model (RegCM2) is describe...
Article
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A Bayesian methodology is used to assess the information content of categorical, probabilistic forecasts of seasonal-mean precipitation derived from General Circulation Model (GCM) forecast ensembles. A "prior" forecast given by climatological probabilities of each category is combined with categorical probabilistic forecasts derived from several G...
Conference Paper
Results from diagnostic analyses to understand the seasonal evolution of the large scale climatic state responsible for the development and melt of the winter snowpack, and spring-early summer precipitation in the Churchill Falls region of Québec are presented in the context of the development of an empirical model for seasonal to annual streamflow...
Article
An ensemble local hydrologic forecast derived from the seasonal forecasts of the International Research Institute for Climate Prediction (IRI) is presented. Three-month seasonal forecasts were used to resample historical meteorological conditions and generate ensemble forcing datasets for a TOPMODEL-based hydrology model. Eleven retrospective forec...
Article
A hybrid ocean-atmosphere coupled model is used to study the interannual variability of sea surface temperature and wind stress over the tropical Atlantic. The coupled model is composed of a statistical atmospheric component model that uses sea surface temperature anomalies (SSTA) over the tropical oceans to forecast wind stress anomalies over the...
Article
The sensitivity of simulated interannual variability to thermocline impacts on sea surface temperature (SST) is examined in a hybrid coupled model (HCM) of the tropical Pacific climate system, consisting of the latest version of the GFDL/NOAA Modular Ocean Model (MOM 3) and the atmospheric component of the Cane-Zebiak (CZ) coupled model. Standard c...
Article
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A simple scheme is proposed for penetrating atmospheric momentum flux over the ocean surface boundary layer or mixed layer (BL/ML) and is tested in the z-coordinate NOAA/Geophysical Fluid Dynamics Laboratory Modular Ocean Model (MOM 3) for improving its performance. Analogous to the treatment in layered ocean models, wind stress is applied, as a bo...
Article
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Dynamical seasonal forecasts of tropical storm frequency require robust and efficient algorithms for detection and tracking of tropical storms in atmospheric general circulation models (AGCMs). Tropical storms are generally detected when dynamic and thermodynamic variables meet specified criteria. Here, it is shown that objectively defined model- a...
Article
We present an ensemble local hydrologic forecast derived from the seasonal forecasts of the International Research Institute (IRI) for Climate Prediction. Three- month seasonal forecasts were used to resample historical meteorological conditions and generate ensemble forcing datasets for a TOPMODEL-based hydrology model. Eleven retrospective foreca...
Article
Full-text available
A Bayesian methodology is used to assess the information content of categorical, probabilistic forecasts of specific variables derived from a general circulation model (GCM) forecast ensemble, and to combine a "prior" forecast (climatological probabilities of each category) with a categorical probabilistic forecast derived from a GCM ensemble to de...
Article
Although the link between insolation and climate is commonly thought to be in the high northern latitudes in summer, our results show that the start of the last glaciation in marine isotope stage (MIS) 5d was associated with a change of insolation during the transitional seasons in the low latitudes. A simplified coupled ocean-atmosphere model show...
Article
A common modeling infrastructure ad hoc working group evolved from an NSF/NCEP workshop in 1998, in recognition of the need for the climate and weather modeling communities to develop a more organized approach to building the software that underlies modeling and data analyses. With its significant investment of pro bono time, the working group made...
Article
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We describe the behaviour of 23 dynamical ocean-atmosphere models, in the context of comparison with observations in a common framework. Fields of tropical sea surface temperature (SST), surface wind stress and upper ocean vertically averaged temperature (VAT) are assessed with regard to annual mean, seasonal cycle, and interannual variability char...
Article
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INTRODUCTION Presently, and historically, El Nino has been characterized by one index, namely its strength. The measure of strength is most commonly taken as the average sea surface temperature (SST) anomaly over a fixed region. The NINO3.4 region (5S-5N; 170W-120W) has been shown in many studies to be one of the most relevant regions to average ov...
Article
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The utility of a Kalman filter (KF) for initialization of an intermediate nonlinear coupled model for El Niño-Southern Oscillation prediction is studied via an approximation of the nonlinear coupled model by a system of seasonally dependent linear models. The low-dimensional nature of such an approximation allows one to determine a sequence of ``pe...
Article
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An ensemble of twenty four coupled ocean-atmosphere models has been compared with respect to their performance in the tropical Pacific. The coupled models span a large portion of the parameter space and differ in many respects. The intercomparison includes TOGA (Tropical Ocean Global Atmosphere)-type models consisting of high-resolution tropical oc...
Article
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A historical wind stress data is obtained based on the 925hPa winds of NCEP reanalysis data and is compared to the FSU wind stress. A particular difference between the two wind stress data appears in the eastern Pacific. The prediction experiments with an intermediate ocean and statistical atmosphere model indicate that the prediction skill of the...
Article
This review paper presents an assessment of the current state of knowledge and capability in seasonal climate prediction at the end of the 20th century. The discussion covers the full range of issues involved in climate forecasting, including (1) the theory and empirical evidence for predictability; (2) predictions of surface boundary conditions, s...
Article
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A new version of the GFDL Modular Ocean Model (MOM 3) is used to simulate interannual and interdecadal variability over the entire Pacific basin from January 1948 to April 2000, forced by NCEP reanalysis atmosphere-ocean fluxes. The MOM 3 with high resolution and sophisticated physics realistically reproduces the subduction of temperature and salin...
Article
Elevated heating by cumulus convection and sea surface temperature gradients are both thought to contribute to surface winds over tropical oceans. The relative strength and role of each mechanism is examined by imposing forcing derived from data on a linear primitive equation model with idealized parameterizations for the two forcings, and comparin...
Article
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The eastern Pacific and Atlantic Intertropical Convergence Zones (ITCZ) exhibit the largest year-to-year variations in boreal spring. We show evidence suggesting that Atlantic ITCZ April-May variability is linked to that for the eastern Pacific through the Walker circulation as it responds to changes in equatorial Pacific convection. Analysis of IT...
Article
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A serious problem in the initialization of a climate forecast model is the model-data incompatibility caused by systematic model biases. Here we use the La-mont model to demonstrate that these biases can be effec-tively reduced with a simple statistical correction, and the bias-corrected model can have a more realistic internal vari-ability as well...
Article
Previous diagnostic studies of surface wind momentum balances over tropical oceans showed that, under a linear friction assumption, the meridional friction coefficient is two to three times larger than the zonal friction coefficient, and that both friction coefficients exhibit a pronounced meridional dependence. The authors' diagnosis of a global m...