Funded Projects

   Search     
Enter Search Value:
- without any prefix or suffix to find all records where a column contains the value you enter, e.g. Net
- with | prefix to find all records where a column starts with the value you enter, e.g. |Network
- with | suffix to find all records where a column ends with the value you enter, e.g. Network|
- with | prefix and suffix to find all records containing the value you enter exactly, e.g. |Network|

High-resolution tracer study of AMOC pathways and timescales

Principal Investigator (s) Igor Kamenkovich (University of Miami); Zulema Garraffo (I.M. Systems Group, Inc.); Avichal Mehra (NOAA/NCEP)

Program (s): Climate Variability and Predictability Program

Competition: AMOC-Climate Linkages in NA/SA

Year Initially Funded: 2016

Abstract:

Redistribution of heat, freshwater and carbon anomalies by the Atlantic Meridional Overturning Circulation (AMOC) plays an important role in regulating climate variability. The knowledge of pathways and timescales associated with AMOC is required for understanding linkages different parts of the global ocean and for interpretation of the observed variability. The progress in this direction is challenging because of the important modulations of these linkages by mesoscale eddy- induced mixing. The challenge comes in large part from the enormous computing costs of running extended numerical simulations and high spatial resolutions. Instead, vast majority of numerical studies of AMOC rely on coarse-resolution simulations, which parameterize all important small- scale processes. Despite significant advances in these parameterization schemes, their fidelity is challenging to establish, which results in biases and uncertainties in studies on the role of AMOC in climate and its variability. This is particularly important in light of the fact that the oceanic uptake of anomalous heat and anthropogenic carbon by AMOC in climate models represent one of the major sources of uncertainty in future climate projections.
The main goal of the proposed study is to examine pathways and timescales associated with AMOC and its interactions with the Southern Ocean, and to establish the relative importance of the mean advection and the material transport induced by mesoscale currents (“eddy mixing”). This goal will be achieved by using a highly efficient offline technique for tracer simulation, which allows multiple extended simulations at high spatial resolution and targeted sensitivity studies that can isolate and quantify the effects of mesoscale advection. The “boundary impulse response” will be used in high-resolution, high-fidelity numerical simulations of AMOC to obtain objective, non tracer-specific characterization of AMOC pathways and timescales. The importance of eddies and inhomogeneity of their transports will be analyzed using arguably the most accurate and straightforward technique of contrasting simulations with and without eddies, but with the same mean stratification. Finally, the results will be used for interpretation of the observed variability in the North and South Atlantic.
This proposal is in response to the “CVP - AMOC-Climate Linkages in the North and/or South Atlantic” Competition. This study is relevant to this competition because it aims to improve the understanding of linkages between various branches of AMOC and the rest of the climate system. Proposed techniques are perfectly suited for studies of the AMOC flow pathways in the presence of explicit effects of mesoscale eddies, and will help to identify important fingerprints of AMOC and to develop useful metrics for model evaluation. Progress in this direction is critical for reducing uncertainty in multi-decadal prediction of the Earth system and for interpretation of observations. The proposed work is relevant to NOAA’s long-term goal of “Climate Adaptation and Mitigation” and its objective of “Improved scientific understanding of the changing climate system and its impacts”, by offering a comprehensive, novel study of the pathways and timescales of AMOC that will lead to the improved understanding and modeling of the global ocean circulation and its effects on the Earth System, including sea level rise and changes in the biogeochemical cycles.

Award Number: NA16OAR4310165, NA16OAR4310166

Publications:

The Western Transition Zone as a Gatekeeper for the North Atlantic MOC Throughput

Principal Investigator (s) Martha Buckley (George Mason University); Susan Lozier (Duke University)

Program (s): Climate Variability and Predictability

Competition: AMOC-Climate Linkages in NA/SA

Year Initially Funded: 2016

Abstract:

The Atlantic Meridional Overturning Circulation (AMOC) requires significant transport between  the North Atlantic subtropical and subpolar gyres. This transport contributes appreciably to the  Atlantic’s mean ocean heat transport and its variability has been linked to climate variations on  a wide range of time scales, including paleoclimate shifts and Atlantic multidecadal sea surface  temperature variability. Despite the importance to our climate system, no clear consensus on the  dynamical mechanisms controlling this throughput and its variability has emerged to date. Fur- thermore, recent Lagrangian studies have challenged the traditional understanding of the geometry  of the throughput in both the upper and lower AMOC limbs. The goal of our work is to build on  past Eulerian and Lagrangian studies in order to work toward a consensus on AMOC variability  mechanisms.
We believe that such a consensus is possible with a focus on the dynamics at the western margin of  the subtropical-subpolar gyre boundary, a region referred to as the western transition zone (WTZ).  Our working hypothesis is that the WTZ is a gatekeeper for the throughput, whereby buoyancy  anomalies in the WTZ establish the throughput variability and influence decadal AMOC variability  in both the subtropical and subpolar gyres. Importantly, buoyancy anomalies in the WTZ are not  forced solely by local processes; rather they are the result of a wide array of ocean processes.  Thus, we may consider the WTZ an integrator of various processes, a view that may reconcile  various proposed mechanisms of AMOC variability, such as the influences of deep convection and  Rossby waves. As such, a focus on the WTZ may considerably aid the interpretation of AMOC  measurements across the RAPID and OSNAP lines.
Using Eulerian and Lagrangian studies, conducted with ocean observations and two ocean mod- els, our proposed work will address the following questions: (1) Do temporal changes in WTZ  buoyancy anomalies align with throughput changes measured in the Lagrangian frame? (2) What  mechanism creates these buoyancy anomalies? (3) On interannual to decadal time scales, what is  the relationship between WTZ buoyancy anomalies and AMOC variability in the subtropical and  subpolar gyres? To answer these questions we will: quantify AMOC pathways through the WTZ  and develop a Lagrangian metric of the throughput; use Lagrangian experiments and statistical  analyses to investigate the relationship between throughput variability and WTZ buoyancy anoma- lies; use buoyancy budgets, ocean model experiments, and adjoint experiments to understand the  origin of buoyancy anomalies in the WTZ; and determine the extent to which WTZ buoyancy and  AMOC anomalies are related to buoyancy and AMOC anomalies at other latitudes.
Our proposal is targeted at the competition “AMOC-Climate Linkages in the North/South At- lantic”, and is directly relevant to its program objectives, as well as to these research priorities  highlighted in the US AMOC 2014 annual report: (1) Provide a more detailed understanding of  AMOC flow pathways and their impact on variability; (2) Investigate connections between surface  forcing and AMOC variability; (3) Continue investigation of AMOC “fingerprints”; (4) Synthe- size results from theoretical, idealized models, and complex GCM investigations into a common  conceptual framework regarding key AMOC variability mechanisms. More broadly, our proposal  advances the field of decadal prediction by developing an improved understanding of the dynamics  of important modes of climate variability, such as the AMOC, which must be accurately captured  in models used to make decadal predictions.

Award Number: NA16OAR4310167, NA16OAR4310168

Publications:

Understanding the freshwater budget of the Atlantic Ocean: Controls, Responses, and the Role of the AMOC

Principal Investigator (s) Wei Cheng (University of Washington); John Chiang (UC Berkeley); Gokhan Danabasoglu (National Center for Atmospheric Research); Wilbert Weijer (Los Alamos National Laboratory); Dongxiao Zhang (University of Washington)

Program (s): Climate Variability and Predictability

Competition: AMOC-Climate Linkages in NA/SA

Year Initially Funded: 2016

Abstract:

The Atlantic Meridional Overturning Circulation (AMOC) is an interactive player in the Atlantic  Ocean freshwater budget. In model simulations, the AMOC responds to surface freshwater flux  (precipitation – evaporation + river runoff + ice melt; “P-E+R+M”) perturbations in the subpolar  North Atlantic; it is also influenced by P-E+R+M over the broader Atlantic through salt/freshwater  advection and inter-basin exchanges (e.g., Agulhas Leakage). In turn, the AMOC drives changes in  salt transport across 35oS and affects P-E+R+M through its influence on Atlantic sea surface  temperature, sea ice extent, and other processes. Yet, the intrinsic time scales and mechanisms driving and responding to Atlantic Ocean freshwater budget variability are not known. Moreover, changes in the global hydrological cycle, melting of the Greenland Ice Sheet, and retreat of Arctic  sea ice are among the most robust features of climate projections. We propose to investigate the  interconnections between P-E+R+M and oceanic transport of heat and freshwater/salt; and how  they affect, and are influenced by, AMOC variability on decadal to multidecadal timescales. We will perform targeted analyses of representative Coupled Model Inter-comparison Project Phase 5  (CMIP5) models; the new AMOC ensemble of NSF-DOE CESM; an eddy-permitting simulation  with the Accelerated Climate Modeling for Energy (ACME) v0 model; and output from ACME v1,  when it becomes available. In addition, we will perform perturbation experiments using the standard-resolution CESM. The objectives are: 
1. Investigate the spatio-temporal patterns of P-E+R+M associated with the AMOC  variability in the selected coupled simulations; examine how they project onto the total surface  freshwater flux variability, and how they differ among the models; 
2. Analyze the freshwater budget of the Atlantic Ocean in selected coupled climate  simulations, focusing on the interplay between P-E+R+M, storage, and interocean exchanges  due to the AMOC, the wind-driven circulation, and interocean exchange; identify drivers and  response terms, the time scales on which they operate, and their controls; 
3. Investigate the role of Agulhas Leakage in the freshwater budget of the Atlantic, by tracing  the pathway of Agulhas Leakage water through the Atlantic, and assessing its impact on the  Atlantic stratification and the AMOC; 
4. Elucidate the physical mechanisms and feedbacks that connect P-E+R+M forcing, oceanic  freshwater transport adjustment and AMOC variability through targeted experimentation using  the CESM. 
This research is responding to “CVP - AMOC-Climate Linkages in the North and/or  South Atlantic” competition. The proposed model evaluation will utilize existing and emerging  observations; the sensitivity experiments and tracer simulations are designed to understand flow  pathways of the AMOC, and how they respond to surface and inter-basin forcing changes. Both of  these aspects are listed priorities of the CVP solicitation. We anticipate that our results will improve  comparison between climate model simulations and measurements. This research also addresses an  objective of NOAA’s long-term climate goals outlined in NOAA’s Next-Generation Strategic Plan,  namely, improved scientific understanding of the changing climate system and its impacts.

Award Number: NA16OAR4310169, NA16OAR4310170, NA16OAR4310171

Publications:

An Investigation of Abyssal to Mid-depth Variations in AMOC Properties and Transports through Observations and Assimilating Models

Principal Investigator (s) Alison Macdonald (Woods Hole Oceanographic Institution); Xujing Davis (Woods Hole Oceanographic Institution); Molly Baringer (NOAA/AOML)

Program (s): Climate Variability and Predictability

Competition: AMOC-Climate Linkages in NA/SA

Year Initially Funded: 2016

Abstract:

Statement of the Problem: To understand the causes of decadal-scale variability in Atlantic overturning waters it is necessary to both recognize and connect the changes that are occurring in a moving ocean. That is, from a climate perspective, there is a need to use available information to better understand not only how ocean properties are changing, but also how dynamics may be affecting changes. While models and re-analyses look to provide a moving and even predictive three-dimensional picture, both correct and incorrect details are often lost in integration of  available outputand deep signals, in particular, may be missing from numerical integrations. On the other hand, observations capable of providing details on the characteristics of deep ocean properties and processes are, more often than not, disconnected from one another in time.

Speaking to the AMOC competition’s aim to refine present knowledge of the AMOC state,  variability and change as well as NOAA’s long term goal of an improved understanding of the  changing climate system, the goals of this project are twofold: 1) to improve understanding of  changes in the deep South Atlantic Meridional Overturning Circulation (SAMOC) properties and transports through a statistical analysis and comparison of observations and numerical model  output, and 2) to develop an understanding of where and how two particular models are  succeeding and/or failing to capture observed deep signals thought to be signatures of climate  change. Repeat hydrographic lines will be used in combination with float data and Lowered Acoustic Doppler Current Profiles together with output from two high-resolution assimilative models (HYCOM and ECCO) to develop an understanding of what changes are occurring in the observed fields, where they are occurring, how such changes are or are not reflected in the numerical fields, and whether this matters. That is, what are the overall consequences to numerical prediction of discrepancies between modeled and observed deep and bottom water changes and transport? The observation-model comparative analysis is relevant to the AMOC competition’s aim of combining existing observations with models to refine our understanding of present-day and past AMOC circulation and transport. It is also relevant to NOAA’s goal of  informing future climate-scale predictions as it lo oks to determine the importance of specific  deep/abyssal pathways and particular regions of mixing to decadal simulations.

The proposed work includes a formal collaboration with Elaine McDonagh and colleagues at the  National Oceanography Centre in Southampton and informal collaborations with Edmo Campos  and SAMOC group working towards a long-term South Atlantic observational network, as well as Tonia Capuano at the Université de Bretagne Occidentale to assist in the calculation of mixing  estimates.

Award Number: NA16OAR4310172

Publications:

Understanding drivers and impacts of CGCM biases in representing the decadal variability of Labrador Sea convection

Principal Investigator (s) Annalisa Bracco (Georgia Tech); Takamitsu Ito (Georgia Tech)

Program (s): Climate Variability and Predictability

Competition: AMOC-Climate Linkages in NA/SA

Year Initially Funded: 2016

Abstract:

The Labrador Sea (LS) is one of the few regions in the world ocean where deep convection occurs. The intense air-sea interaction drives the convective mixing and the site acts as a window through which anthropogenic carbon is sequestered into the interior ocean. Recent work highlights that buoyancy forcing over the Labrador Sea is key in controlling the Atlantic Meridional Overturning Circulation (AMOC) and that AMOC inter-annual signals are closely related to the variability of the Labrador Sea convection. Historic observations collected over the past 60 years show that the LS convective activity undergoes dramatic interannual-to-decadal variability and –within the limitation of the available measurements – no statistically significant trend. A model integration performed using a regional ocean model (ROMS, Regional Oceanic Modeling System) run at 5km horizontal resolution over the LS can reproduce the observed variability. However, coupled general circulation models (CGCMs) from the Coupled Model  Intercomparison Project Phase 5 (CMIP5) are not yet capable of representing the extent and  statistical properties of the LS convection, while often displaying a weakening trend for the past  50 years. Model biases hamper the representation of the AMOC and of the inventories of dissolved inorganic carbon, and limit our ability to project their future changes.  The overarching objectives of this project are to diagnose the sources of CGCMs biases in the LS focusing on a subset of CMIP5 runs and to quantify the impacts of those biases on the representation of carbon uptake and inventories in the basin. They will be achieved through a sensitivity study to be performed using regional ocean-only ROMS simulations covering most of the North Atlantic forced by momentum, heat and freshwater fluxes, and/or boundary conditions from the CMIP5 runs.
This project will establish cause-effect linkages between the representation of mesoscale processes, of the atmospheric forcing fields, and of the gyre circulation, and the (modeled) Labrador Sea circulation, its variability and carbon uptake characteristics.  The regional simulations will include an ocean biogeochemical and carbon cycling module. The interpretation of all model analysis will be aided by careful comparisons with shipboard and Argo measurements in the Labrador Sea, and along 53N. In this regard we will build upon our ongoing collaboration with Dr I. Yashayeav at the Bedford Institute of Oceanography. This project will contribute a better understanding of the potential predictability of Labrador Sea convection and of the natural and anthropogenically forced variability of the AMOC.
This proposal addresses the objective of the NOAA funding opportunity, CVP AMOC-Climate Linkages in the North and/or South Atlantic (NOAA-OAR-CPO-2016-2004413) to ‘refine the  current scientific understanding of the AMOC state, variability and change’ by focusing on the  interannual and decadal variability for the LS branch. The proposed work contributes to three  priorities identified in the US AMOC 2014 report and advances the NOAA’s Next-Generation  Strategic Plan to ‘improve scientific understanding of the changing climate system by diagnosing  the physical and biogeochemical biases in the CGCMs that are used in the future prediction and  projections by the Intergovernmental Panel on Climate Change’.

Award Number: NA16OAR4310173

Publications:

Transient tracer fingerprints of Atlantic Meridional Overturning Circulation in Observations and Models

Principal Investigator (s) Anand Gnanadesikan (Johns Hopkins);Thomas Haine (Johns Hopkins); Darryn Waugh (Johns Hopkins)

Program (s): Climate Variability and Predictability

Competition: AMOC-Climate Linkages in NA/SA

Year Initially Funded: 2016

Abstract:

Transient tracers offer a unique and important window into the Atlantic Meridional Overturning Circulation (AMOC). While they have been used to estimate the total rate of formation of NADW and to trace the pathways by which watermasses spread, less attention has been paid to the ways in which tracers can tell us about how the overturning is changing. Increasing amounts of observational data and model simulations with transient tracers offer new opportunities to understand the relationship between transient tracers and the large-scale ocean circulation. This proposal has three parts:
1. Analysis of coupled climate models: As demonstrated in this proposal, transient tracers in climate models can be better correlated with long-period variability in the overturning than spot measurements of the overturning itself. However, the fingerprint of overturning variability in tracers such as ideal age and oxygen has a complex three-dimensional spatial structure, with different responses at different latitudes. We propose to conduct a cross-model comparison of different models developed at NOAA GFDL as well as Earth System Models that are part of the IPCC AR5 model intercomparison. We will examine how robust the correlations with overturning are across models and evaluate how much data is required to extract them from other modes of variability. Anand Gnanadesikan will lead this part of the project.
2. Observational data analysis: We will analyze repeat hydrographic sections (Line W between Cape Cod and Bermuda, and elsewhere) to examine whether the patterns of changes in ventilation age and oxygen seen in the models also show up in the observations. We will also explore whether transient tracers in the observations are linked to changes in the stratification, as they appear to be in the models. If found, robust relationships between oxygen, stratification and age would enable a much broader mapping of changes in ventilation pathways within the North Atlantic. Darryn Waugh will take the lead in this part of the project.
3. High-resolution modeling. In order to better understanding the sources of the tracer fingerprints we see in the coupled models, we propose to conduct some high-resolution (1/10 degree) regional simulations of the North Atlantic in which different forcings are applied to change the overturning circulation and the resulting fingerprints on the tracer fields are computed. Insofar as we see the same results as the lower-resolution simulations, these results will help establish the robustness of tracer signatures of overturning change. If they show very different results, this will point to the importance of eddy processes in setting up tracer anomalies. Thomas Haine will lead this part of the project.
Key products that will emerge from this work are maps of mean age change over the North Atlantic over time and hopefully, identification of fingerprints of AMOC variability on the age and oxygen fields. This could allow extension of our estimates of AMOC variability back in time, which would also help to constrain mechanisms for AMOC variability.

Award Number: NA16OAR4310174

Publications:

The Southward Returning Pathways of the AMOC and Their Impacts on Global Sea Surface Temperature

Principal Investigator (s) Chunzai Wang (NOAA/AOML);Sang-Ki Lee (NOAA/AOML); Marlos Goes (NOAA/AOML)

Program (s): Climate Variability and Predictability

Competition: AMOC-Climate Linkages in NA/SA

Year Initially Funded: 2016

Abstract:

Our recent study showed that there exists a coherent spatial pattern of inter-hemispheric global model sea surface temperature (SST) biases in CMIP5 (Coupled Model Intercomparison Project phase 5) climate models and this global pattern of model SST biases is closely linked to the strength of simulated Atlantic Meridional Overturning Circulation (AMOC). The models with a weaker AMOC are associated with cold SST biases in the entire Northern Hemisphere, and with an anomalous atmospheric pattern that resembles the Northern Hemisphere annular mode. These models are also associated with a strengthening of Antarctic Bottom Water (AABW) formation and warm SST biases in the Southern Ocean. However, in many of these models, the amplitudes of the AMOC agree very well with or are even larger than the observed value of about 18 Sv at 26.5°N, but they still show cold SST biases in the Northern Hemisphere. This suggests that the AMOC strength may not be the only factor that causes the cold SST bias. A common symptom in these models is that the returning flow of the AMOC at depth is too shallow. A shallow returning flow would carry excessive heat southward; thus the net northward heat transport by the AMOC would be weaker than the observed. The shallow returning flow in CMIP5 models should be linked to the bias in the southward pathways of the AMOC at depth. We propose to continue our investigations to (1) diagnose the meridional heat transport and its link to model SST biases in CMIP5 models, (2) perform and analyze “robust diagnostic” simulations of the AMOC to reconstruct realistic southward returning flow pathways of the AMOC, (3) explore AMOC southward returning flow pathways and sources of the shallow returning flow of the AMOC in CMIP5 models, (4) investigate the relationship of North and South Atlantic water masses associated with the AMOC, and (5) examine the impacts of improved AMOC on global SST. We will use available hydrographic observations interpolated into isopycnal surfaces, CMIP5 outputs, and model experiments of NCAR Community Earth System Model and an intermediate complexity model.
The proposed work directly contributes to the priority for NOAA FY2016 CPO/CVP funding: “Solicits projects that will refine the current scientific understanding of the AMOC state, variability, and change. Specifically, projects are sought that use newly deployed and existing observations in combination with modeling experiments to refine our understanding of the present and historical circulation (and related transports of heat and freshwater) in the North and/or South Atlantic. An emerging priority is to provide a more detailed characterization of AMOC flow pathways and their impact on variability.” The main outcome of this study will greatly improve our understanding of the decadal predictability of the AMOC and associated climate impacts, and help improve CMIP5 models.

Award Number:

Publications:

Towards an Improved Understanding of the Initiation and Propagation of the Madden-Julian Oscillation

Principal Investigator (s) Xianan Jiang, UCLA JIFRESSE; Ming Zhao, GFDL/NOAA

Program (s): Climate Variability and Predictability

Competition: Climate Process Teams – Understanding MJO Initiation and PropagationYear

Year Initially Funded: 2015

Abstract:

The Madden-Julian Oscillation (MJO) exerts significant influences on global climate and weather, and serves as a critical basis of the “Seamless Prediction” concept by bridging the forecasting gap between medium- to long-range weather forecasts and short-term climate prediction. However, our understanding of the essential MJO physics is still elusive. The MJO remains poorly represented in current climate models, which leaves us greatly disadvantaged in undertaking climate change studies, particularly in projecting future changes in extreme events that are significantly modulated by the MJO.

Motivated by exciting recent developments in MJO observations (the DYNAMO field campaign), modeling (the MJO Task Force/GEWEX GASS MJO Inter-comparison Project), and theories (e.g., the “moisture mode”), and by taking advantage of the availability of these unprecedented datasets, we propose to form a climate process team to expedite investigations on key physical processes responsible for initiation and propagation of the MJO. This team is built upon strong expertise in MJO studies among research groups from UCLA/JPL (Jiang and Waliser, co-organizers of the MJO Task Force/GEWEX GASS global MJO evaluation project, with expertise in observational and modeling diagnosis and MJO sciences), GFDL (Zhao and Lin, members of the core GFDL model development team, with expertise in model development), UH (Wang, with expertise in MJO theories) and CSU (Johnson, one of the lead PI of the DYNAMO field campaign, with expertise in in-situ observations). The proposed work will entail observational studies, in particular by utilizing the DYNAMO in-situ and satellite observations, 27 climate model datasets from the MJO Task Force/GASS MJO Project especially with the unique model output of physical tendency terms, as well as extensive experiments based on a newly developed state-ofthe- art GCM at the NOAA GFDL (HIRAM3.5) which exhibits superior MJO skill. We will thoroughly investigate critical physical processes for the MJO instability and propagation, with a primary focus on feedbacks between environmental moisture and convection, convection and its induced circulation, and cloud-induced radiative heating and convection. This study will significantly promote our understanding of the key model physics for realistic MJO simulations, thus leads to reduction of model biases in representing the MJO, which provides a major source of global predictability on the sub-seasonal time scale.

This proposal is strongly relevant to one of the NOAA NGSP’s long-term goal, “toward an improved scientific understanding of the changing climate system”, by advancing core capabilities in “understanding and modeling” and “predictions and projections”, as well as societal challenges in “climate impacts on water resources” and “changes in extremes of weather and climate”. In particular, this research directly addresses CVP program’s FY2015 calls for “Understanding Processes Affecting Madden-Julian Oscillation Initiation and Propagation” through a climate process team with expertise on observational diagnoses, theoretical understanding, modeling of the MJO. This proposed study is also in concert with one of the main goals of the WWRP/WCRP’s recently launched Sub-seasonal to Seasonal prediction (S2S) initiative, “to improve forecast skill and understanding of the sub-seasonal to seasonal timescale”, and greatly contributes to efforts in MJO process-oriented diagnoses led by the WGNE MJO Task Force.

Award Number: NA15OAR4310177

Publications:

Improvement of MJO simulation in NCEP Coupled Forecast System: Upper ocean and air-sea coupled processes

Principal Investigator (s) Toshiaki Shinoda, Texas A&M; Alexander Soloviev, Nova Southeastern University; Wanqiu Wang, NOAA/NCEP; Ren-Chieh Lien, University of Washington; Joshua Fu, University of Hawaii; Hyodae Seo, WHOI

Program (s): Climate Variability and Predictability

Competition: Climate Process Teams – Understanding MJO Initiation and Propagation

Year Initially Funded: 2015

Abstract:

Accurate simulation and prediction of the Madden-Julian Oscillation (MJO) is one of the major challenges for climate modeling and operational weather forecasts. The MJO in the NCEP Coupled Forecast System (CFS) is too weak and propagates too slowly, particularly during its initiation and evolution over the Indian Ocean. With the objective to advance our understanding of the MJO initiation processes and improve MJO prediction, DYNAMO international field campaign provides a substantial amount of oceanic and atmospheric in-situ data. In the last few years, the DYNAMO data have been used to identify important oceanic, atmospheric, and air-sea coupled processes in the MJO initiation and propagation. A primary goal of this proposed study is to advance MJO simulation and prediction in NOAA CFS by improving the representation of the air-sea flux and upper-ocean vertical mixing. The DYNAMO data and the outcome from our previous DYNAMO projects will be maximally utilized for the improvement of MJO simulations. To accomplish this goal, we propose to:

(1) Improve the one-dimensional General Ocean Turbulence Model (GOTM) by including a new mixing scheme developed by Soloviev et al. (2001) that has realistic performance in the tropics and extra-tropics in capturing large diurnal warming and responding to strong westerly wind bursts. The improved GOTM will be tested at DYNAMO field observation sites where accurate surface fluxes as well as high quality upper ocean data are available. These schemes will be further tested in the uncoupled ocean component of CFS with an enhanced vertical resolution.
(2) Develop computationally efficient surface flux algorithm using the most updated version of TOGA COARE bulk flux algorithm, in-situ flux observations, and the method used by Kara et al. (2000, 2005). The algorithms will be carefully validated against DYNAMO observations and tested in the atmospheric component of CFS.
(3) Implement the improved ocean mixing parameterization and air-sea flux algorithm in coupled CFS, and evaluate the MJO simulation and prediction skill based on the comparison with a variety of in-situ and satellite observations, and regional coupled model experiments.

We anticipate that the proposed research with the improved CFS will result in a significant improvement in the forecast of subseasonal variability including the MJO and associated variability such as tropical storms and North America weather. The schemes developed, tested, and implemented in the project also provide guidance for improving the next generation CFS and other coupled models in the climate community, which generally have poor representation of the upper ocean processes and deficient surface fluxes critical to the simulation of the MJO.

Award Number: NA15OAR4310173 OR NA15OAR4310174 OR NA15OAR4310175 OR NA15OAR4310176

Publications:

Advancing understanding of sea ice predictability with sea ice data assimilation in a fully-coupled model with improved region-scale metrics

Principal Investigator (s) Cecilia Bitz, University of Washington; Adrian Raftery, University of Washington

Program (s): Climate Variability and Predictability

Competition: Understanding Arctic Sea Ice Mechanisms and Predictability

Year Initially Funded: 2015

Abstract:

Predictions of sea ice on subseasonal to interannual timescales has the potential to be of widespread value if they are skillful at the lead times and spatial scales needed by forecast users. Understanding sea ice predictability is needed for high-stakes decision-making, such as arises in shipping, accessing resources, and protecting Arctic communities. Current prediction efforts have focused mainly on predicting total northern hemisphere sea ice extent (SIE), termed pan-Arctic SIE. To succeed at predicting regional scales requires significant new effort in three key areas. First, data assimilation techniques must be advanced to accurately initialize sea ice and other components at proper spatial scales. Second, metrics are needed to quantify the skill at the relevant spatial scales and for patterns of interest. Identifying key metrics is motivated by the expectation that a forecast system can't be improved without first developing adequate metrics for evaluating the features of importance. And third, effective statistical post processing methods are needed to correct for systematic biases in the resulting forecasts and to compute forecast probability.

We propose to investigate methods and develop the tools needed to address these three issues in building successful forecast systems. We propose to conduct our research in a well- studied, state-of-the-art sea ice component that is part of a global climate model. To turn this global model into a premier sea ice forecast system, we will work with Jeffrey Anderson and Nancy Collins and the NCAR Data Assimilation Research Testbed to implement DART to assimilate sea ice observations.

With this data assimilating forecast system, we will develop new evaluation metrics to investigate which observations are most essential among in situ measurements (including buoy and ship-based data) and remote sensing. We plan to investigate which regions are most predictable and what mechanisms (including mechanisms that involve coupling between ice, ocean and atmosphere) are responsible. Another important part of our project is to compare predictability in our system to others. We will undertake this with our links to the Sea Ice Outlook project and by providing our research on new metrics to evaluate regional patterns to other modeling centers for detailed intercomparisons. We have plans to collaborate directly with Rym Msadek and colleagues at GFDL to undertake a detailed comparison between the two premier U.S. global climate models, which have the most advanced sea ice components and high fidelity in the Arctic Ocean and atmosphere simulations. We also have discussed collaborating with Pablo Clemente-Colon, Chief Scientists at the National Ice Center, to better address sea ice forecast users needs in the metrics of local and regional-scale sea ice that we develop.

Our project has direct relevance to NOAA CVP Competition by exploring the value of assimilating sea ice observations, developing metrics that evaluate spatial distributions relevant to sea ice, and investigating mechanisms of regional sea ice variations. Our project is aligned with NOAAs goal of improving future operational predictions on time scales of a few months to decades. Our system will be capable of informing future data acquisition.

Award Number: NA15OAR4310161

Publications:

Page  1 of 11                   First     [1]  2  3  4  5  6  7  8  9  10       Last  

CVP

    CONTACT US

    Climate Program Office
    1315 East-West Hwy, Suite 1100
    Silver Spring, MD 20910

    CPO.webmaster@noaa.gov

    ABOUT OUR ORGANIZATION

    Americans’ health, security and economic wellbeing are tied to climate and weather. Every day, we see communities grappling with environmental challenges due to unusual or extreme events related to climate and weather. In 2011, the United States experienced a record high number (14) of climate- and weather-related disasters where overall costs reached or exceeded $1 billion. Combined, these events claimed 670 lives, caused more than 6,000 injuries, and cost $55 billion in damages. Businesses, policy leaders, resource managers and citizens are increasingly asking for information to help them address such challenges.