|
Funded Projects
Sort by:
|
Title
|
Principal Investigator (s)
|
Topic (s)
|
Year Initially Funded
|
Year Initially Funded:
|
2010
|
Topic (s):
|
Climate Variability and Predictability |
Assessing the Sensitivity of Northward Heat Transport/Atlantic Meridional Overturning Circulation to Forcing in Existing Numerical Model Simulations
To be posted
Principal Investigator (s): Shenfu Dong, NOAA/Atlantic Oceanographic and Meteorological Lab |
Year Initially Funded:
|
2010
|
Topic (s):
|
Climate Variability and Predictability |
Ocean Climate Variability in the 20th Century
We propose conducting a series of ocean reanalyses of the 20th Century (1890-2005) using SODA to study tropical Pacific decadal variablility, its influence on El Niño, and the atmospheric teleconnections that lead to decadal climate change across North America. The study will use the SODA ocean data assimilation framework in conjunction with the recently released atmospheric reanalysis of the 20th Century to generate a state estimate of the global oceans. In addition to the baseline run, we will conduct a series of “data thinning” experiments whereby we degrade the observations to replicate data coverage for various periods of time throughout the 20th Century to calculate error in the ocean state estimate. In addition to the ocean reanalyses, we will use results from the reanalyses to drive an atmospheric general circulation model to sudy the impact of improved SST information on the modeled climate of North America. For the atmospheric modeling component we plan to utilize the Community Atmosphere Model 3 (CAM3) developed and distributed by the National Center for Atmospheric Research (NCAR). We will force the T85 resolution (1.4 degree) version of this model with the SST anomaly from SODA as well as SST reconstructions (such as HadISST) and compare the results to the results from the NCAR multi-century control runs. These control runs have been extensively analyzed and provide an accepted atmosphere background state with which we can compare our suite of runs. We will verify the model results, both from SODA and from the atmosphere model with 100-year long records from sources such as 18O from corals from the tropical Pacific, sea level records from coastal tide guages, and from observations such as global precipitation rates that are currently available.
The proposed research contributes to the goals of the Climate Variability Program by expanding our understanding of decadal climate variability, by providing initial conditions for decadal prediction models, and by exploring the causes of North American climate change. The resulting reanalysis will be available on our web site (soda.tamu.edu) to other researchers interested in topics such as AMOC and rapid climate transitions during the 20th Century.
Principal Investigator (s): Benjamin Giese, Texas A&M University |
Year Initially Funded:
|
2010
|
Topic (s):
|
Climate Variability and Predictability |
Decadal Prediction Over the Americas: Atlantic vs Pacific Processes
The relationship between sea surface temperatures (SST) and North American hydroclimate (NAH) has been the subject of much research in the past decade. Independent research and coordinated efforts such as the US CLIVAR Drought Working Group have shown in idealized experiments that low frequency internal modes of sea surface temperature variability in the Atlantic and Pacific oceans interact and influence persistent droughts and pluvials over portions of North America. Concurrently, climate modelers have recognized that accurate predictions of near term (10-30 year) climate change will require accurate simulation of these internal modes of variability in addition the committed warming and greenhouse gas forcing. Appropriately, a major component of the upcoming-coupled model inter-comparison (CMIP5) for the fifth assessment report to the IPCC will be decadal climate predictions to assess the ability of climate models to capture and simulate near term climate change. The decadal predictions will give insight into the combined effects of internal variability in the oceans and the external forcing on the potential predictability of near term climate variability, but the relative contributions of individual basins remains untested in the coupled model framework. The proposed work seeks to identify the individual contributions of internal and forced climate variability to the potential predictability of Pacific and Atlantic variability, and the relative influence of these basins on NAH. Our hypothesis is that observed NAH is driven by complimentary processes in the Pacific and North Atlantic and is predictable beyond lead times of one year. To test this we propose three main objectives:
Objective 1: Assess the potential predictability of the observed natural Atlantic and Pacific variability separately and quantify the influence of inter-basin interactions and external forcing on variability in each basin.
Objective 2: Assess the potential predictability of observed North American hydroclimate and identify the relative influence of natural variability in the Pacific and Atlantic and the GHG forcing.
Objective 3: Perform a thorough diagnostic study of the CMIP5 control, 20th Century, and near term climate projections to determine the ability of dynamical models to simulate observed decadal SST variability and predict North American hydroclimate with a focus on Pacific versus Atlantic processes.
Principal Investigator (s): Robert Burgman and Ben P. Kirtman, University of Miami Rosenstiel School of Marine and Atmospheric Science |
Year Initially Funded:
|
2010
|
Topic (s):
|
Climate Variability and Predictability |
Historical Contribution of the Saharan Air Layer to Atlantic Mixed Layer Temperatures in the Hurricane Development Region
Dust storms from Africa are a persistent feature in the skies over the northern tropical Atlantic, and strong variability in Atlantic dust cover has been observed on seasonal to decadal time scales. It is well known that over water surfaces the net radiative effect from mineral aerosols at the surface is negative, and recent work has shown that this reduction in downwelling radiation translates into localized cooling of the mixed layer. Recent studies have also demonstrated that over the last quarter century roughly 25% of the observed upward trend in sea surface temperatures can be attributed to declines in Atlantic dust cover over the same time period.
While there is compelling evidence suggesting that African dust storms contribute to Atlantic surface temperatures on decadal time-scales, to-date studies investigating dust-forcing of temperatures have generally neglected other important environmental factors that are associated with Atlantic dust outbreaks; namely the dry air, mid-level warm anomaly, and increased surface wind speed. The Saharan Air Layer (SAL) is the term given to this dry air mass that is associated with the dust, and the net effect of the reduction in water vapor, warm anomaly, and increase in surface winds is to further cool the mixed layer via negative longwave radiative forcing at the surface, and wind-driven latent and sensible heat fluxes, and vertical turbulent mixing. Therefore, it is likely that the SAL, considered in its entirety, has a stronger role in shaping Atlantic temperatures on monthly to decadal time scales than does dust alone.
At the same time, satellite, in-situ, and proxy dust records all show that Atlantic dust cover has strong decadal variability, and recent work has shown that a simple statistical model can reproduce month-to-month variability in Atlantic dust cover by considering reanalysis winds, climate indices, and observational records. Therefore, the opportunity exists to reconstruct spatial and temporal Atlantic dust storm variability from the mid-20th century to the present.
Here we propose to capitalize on studies that demonstrate techniques for modeling the radiative effects of the SAL, and that provide a basis for developing a statistical model to reconstruct historical dust cover, in order to estimate the impact of the Saharan Air Layer on Atlantic Ocean 4 surface temperatures over the last 60 years. By exploring the effect of the SAL on temperatures using an ocean general circulation model (GCM), we will quantify the effect of the SAL in shaping decadal scale surface temperature variability. We will also analyze any effect of the SAL on deep ocean temperatures and determine if there is a SAL contribution to the Atlantic meridional overturning circulation (AMOC).
In order to evaluate how aerosol cover and atmospheric winds have impacted Atlantic tropical cyclone activity on decadal time scales, we propose the following course of action:
1) Use several data sets to create a climatology of the SAL that extends back to the mid-20th century, estimating SAL vertical profiles of dust optical depth, water vapor, temperature, and winds.
2) Employ established techniques to model SAL-forced changes in surface radiative fluxes and surface turbulent heat fluxes, along with observation-based calculations of horizontal oceanic heat advection and vertical turbulent mixing, to determine the dominant processes associated with the mixed layer temperature response to the SAL.
3) Force an ocean GCM with SAL-forced surface radiative fluxes and surface wind anomalies in order to quantify the ocean temperature response to SAL variability, and determine to what degree the SAL contributes to meridional heat transport, from 1950 through the present.
The main objective of this proposal is to understand the role of the SAL in shaping Atlantic surface and subsurface temperature anomalies over the last 60 years, focusing on the SAL’s contribution to decadal scale upper ocean temperature variability, and the AMOC.
Principal Investigator (s): Amato Evan, University of Virginia |
Year Initially Funded:
|
2010
|
Topic (s):
|
Climate Variability and Predictability |
Predictability of Multi-Decadal Climate Variations in the Mediterranean "Hot Spot"
The Mediterranean region has been identified as a primary climate change “Hot Spot”, with a greenhouse gas “forced” signal projected to emerge already early in the 21st century. Natural multi-decadal fluctuations will contribute to define the climate variations which will be observed in the next few decades. The forced climate response and a linkage with the Atlantic Multi-decadal Oscillation (AMO) suggested by various studies, are both potential sources of regional predictability. A careful evaluation of the regional decadal predictive potential and of current prediction capability is urgently needed to plan for climate adaptation.
The goal of this work is to assess the degree of decadal predictability of climate anomalies in the Mediterranean region. Research will test the hypothesis that “There exists significant decadal predictability of climate anomalies in the Mediterranean region resulting from external forcings and AMO-related variability”. The proposed research has the following objectives: 1) assess the degree of predictability of past decadal climate variations in the Mediterranean region by evaluating the role of AMO-related variability and the externally forced response 2) assess the skill of CMIP5-class decadal prediction systems to hindcast past decadal Mediterranean climate anomalies and evaluate future decadal predictions. Research tasks include observational-model based analyses of the AMO-Mediterranean linkage and of CMIP5 model performance; an examination of sources of regional predictability; an evaluation of CMIP5 hindcasts prediction experiments over the Mediterranean, and of decadal predictions of future regional climate anomalies.
Work will contribute to CMIP5-related research initiatives to address decadal variability/predictability/prediction, building understanding on decadal predictability and evaluating CMIP5 decadal prediction systems taking the Mediterranean as a test-bed. This proposal addresses CVP’s FY 2010 “Decadal Climate Predictability and Prediction” priorities by performing necessary underpinning work to meet the challenge facing NOAA and the international climate community to develop Climate Services.
Principal Investigator (s): Annarita Mariotti, University of Maryland |
Year Initially Funded:
|
2010
|
Topic (s):
|
Climate Variability and Predictability |
Assessing Unstoppable Change: Ocean Heat Storage and Antarctic Glacial Ice Melt
Prediction of sea level rise from understanding and modeling of glacial and land-based ice sheet melt is difficult at best, yet of critical importance for future climate prediction. Antarctic glacial melt is particularly difficult, leading to the Antarctic's contribution to sea level rise being downplayed during IPCC assessment IV. Numerous observation and modeling studies cite the ocean as providing the source of heat for the recently observed acceleration of the Antarctic melt rate. That melt is concentrated in the West Antarctic, at the coastal margin of the Amundsen/Bellingshausen Seas (ABS). We approach this project with 17 years of gridded ocean data adjacent to the West Antarctic Peninsula (WAP) upstream of the West Antarctic Ice Sheet (WAIS) primary drainage basin. These data show that the ocean heat content on the WAP shelf (QWAP) has been rising steadily since the early 1990s, and dramatically since the 1950s, qualitatively consistent with the dramatic increase in the observed glacial melt, and with the required ocean heat. This warm water, Upper Circumpolar Deep Water (UCDW) is available for melting ice in the WAP and WAIS. We desire to determine the ultimate source of this increased ocean heat content, to estimate future warming associated with the source.
The world oceans have been absorbing heat at their surface from the warming atmosphere, and some of that heat has penetrated to depth, leading to excess ocean heat content (Qexcess); multiple studies argue that the observed Qexcess is due to absorption of anthropogenic heat. Some of this heat will reach, or is already within, southward flowing deep currents transporting it to the Antarctic Circumpolar Current (ACC), where it warms the warm deep subsurface water it already transports. The ACC transports this warmed water to the ABS shelves (the only shelves in the Antarctic where the ACC flows along the shelf-break) fueling accelerated glacier melt. The goal of this project is to assess what fraction of QWAP warming is from this Qexcess and via extrapolation, how much of this Qexcess would still be available for accelerated glacial melt in the ABS, even if there is a reduction or elimination of global warming.
The analyses will involve assessment of global historical data, beginning as a natural extension to the series of studies that have analyzed historical data to show that the ocean heat content has risen since the 1950s. We will use previously developed objectively analyzed 5° gridded composites to deal with the sparse data deeper than 300 m in earlier decades, updated to correct for XBT and Argo float biases. In our case the focus is more on change as a function of time and space, in an effort to track potential paths of heat transfer to the south (and time scales of the transfer).
We expect to reveal that amount of heat (with uncertainties) that will still be available for glacial melt regardless of changes in the rate of global warming (or even better, as a function of total global warming). In other words, climate change is already committed to accelerated glacial melt from this stored heat — knowing the magnitude and timescale of its delivery is an essential component required in our ability to model the contribution of glaciers and land-based ice sheets to future global sea level rise. Alternative methods for explaining increasing QWAP (e.g., changes in the strength of the polar westerlies) are being investigated elsewhere, but preliminary analysis of the post-1990s data suggest that both mechanisms contribute.
Principal Investigator (s): Douglas Martinson, Columbia University Lamont–Doherty Earth Observatory; Sarah Gille, Scripps Institution of Oceanography |
Year Initially Funded:
|
2010
|
Topic (s):
|
Climate Variability and Predictability |
A Study on the Predictability of Pacific Decadal Variability
The possibility of making decadal climate predictions has been recognized after the great progress made during last couple of decades in climate system modeling, seasonal to interannual climate predictions, and century-scale climate projections. Determining the sources of predictability within the climate system is still a formidable challenge for decadal climate predictions. Although studies of the subject have suggested that decadal predictability resides in both external forced variability and slow natural variability, further exploration and a better understanding of the sources of decadal predictability are needed. In this project, we propose to investigate the predictability of the Pacific decadal sea surface temperature (SST) variability, which is a major source for decadal climate anomalies over North America.
Through diagnostic studies of CIMP5 experiments and additional modeling studies, we will examine contributions to the predictability from both slow external forcing and internal dynamics, focusing on the decadal predictability in subsurface heat content and SST variability over the north and tropical Pacific. We will also explore the potential contributions to the decadal predictability from natural or forced changes in ENSO activity. The outcome of this project will add to our understanding of the predictability of Pacific decadal variability, which meets the objectives of the NOAA CVP program.
Principal Investigator (s): Fei-Fei Jin, University of Hawaii |
Year Initially Funded:
|
2010
|
Topic (s):
|
Climate Variability and Predictability |
Decadal Variability of the Atlantic Meridional Overturning Circulation and Its Impact on the Climate: Two Regimes and Rapid Transition
A control simulation in present-day conditions with the NCAR Community Climate System Model version 3 (CCSM3), a major contributor to the Intergovernmental Panel on Climate Change (IPCC) 4th Assessment Report (AR4), shows two regimes of Atlantic meridional overturning circulation (AMOC) variability, with an abrupt transition between them. We will first focus on the differences and the rapid transition between the two regimes of AMOC variability, i.e. a period with very regular and strong decadal variability, and one with irregular and weak multi-decadal variability, in terms of the mechanisms and associated global climate impact. We will then establish whether there are also multiple regimes and rapid transitions in the AMOC variability of the newly developed CCSM4 climate model, the CMIP5 participating version, and investigate and compare their mechanisms.
CCSM3 exhibits a pronounced decadal variability of the AMOC in the present-day control integrations as well as global warming integrations. Two distinct regimes of decadal AMOC variability are apparent in the 700-yr long CCSM3 control integration with T85 atmospheric resolution (CCSM3-T85): a strong 20-year periodicity is seen for 300 years before an abrupt transition to a red noise-like variability lasting for the last 250 years. In the former regime, the decadal signal is also seen in the atmosphere, while there seems to be much less climatic impact in the latter. Regime transitions have been found in many coupled climate models, but they have not been considered explicitly other than in simplified models. Such non-stationarity exists in nature (as for ENSO and NAO) and may critically influence the predictability of the system. Hence, understanding what controls them and developing a methodology to do so is important. The analysis will be based on advanced statistical methods and complemented by numerical model experiments to elucidate the findings from the statistical analysis. In addition, we propose to use linear inverse modeling to assess the predictability of the AMOC. When possible, the findings will be compared with statistical signatures derived from the observations and reanalyses, so that the reliability of the model simulations can be assessed.
Principal Investigator (s): Young-Oh Kwon and Claude Frankignoul, Woods Hole Oceanographic Institution; Gokhan Danabasoglu, National Center for Atmospheric Research |
Year Initially Funded:
|
2010
|
Topic (s):
|
Climate Variability and Predictability |
Decadal Variability of the Atlantic Meridional Overturning Circulation and Its Impact on the Climate: Two Regimes and Rapid Transition
A control simulation in present-day conditions with the NCAR Community Climate System Model version 3 (CCSM3), a major contributor to the Intergovernmental Panel on Climate Change (IPCC) 4th Assessment Report (AR4), shows two regimes of Atlantic meridional overturning circulation (AMOC) variability, with an abrupt transition between them. We will first focus on the differences and the rapid transition between the two regimes of AMOC variability, i.e. a period with very regular and strong decadal variability, and one with irregular and weak multi-decadal variability, in terms of the mechanisms and associated global climate impact. We will then establish whether there are also multiple regimes and rapid transitions in the AMOC variability of the newly developed CCSM4 climate model, the CMIP5 participating version, and investigate and compare their mechanisms.
CCSM3 exhibits a pronounced decadal variability of the AMOC in the present-day control integrations as well as global warming integrations. Two distinct regimes of decadal AMOC variability are apparent in the 700-yr long CCSM3 control integration with T85 atmospheric resolution (CCSM3-T85): a strong 20-year periodicity is seen for 300 years before an abrupt transition to a red noise-like variability lasting for the last 250 years. In the former regime, the decadal signal is also seen in the atmosphere, while there seems to be much less climatic impact in the latter. Regime transitions have been found in many coupled climate models, but they have not been considered explicitly other than in simplified models. Such non-stationarity exists in nature (as for ENSO and NAO) and may critically influence the predictability of the system. Hence, understanding what controls them and developing a methodology to do so is important. The analysis will be based on advanced statistical methods and complemented by numerical model experiments to elucidate the findings from the statistical analysis. In addition, we propose to use linear inverse modeling to assess the predictability of the AMOC. When possible, the findings will be compared with statistical signatures derived from the observations and reanalyses, so that the reliability of the model simulations can be assessed.
Principal Investigator (s): Young-Oh Kwon and Claude Frankignoul, Woods Hole Oceanographic Institution; Gokhan Danabasoglu, National Center for Atmospheric Research |
Year Initially Funded:
|
2010
|
Topic (s):
|
Climate Variability and Predictability |
Decadal and Multidecadal Variability of the AMOC in Observational Records and Numerical Models
To be posted
Principal Investigator (s): Michael McPhaden, NOAA/Pacific Marine Environmental Laboratory |
|
About Climate Variability & Predictability (CVP)
The Climate Program Office (CPO) manages competitive research programs in which NOAA funds high-priority climate science, assessments, decision support research, outreach, education, and capacity-building activities designed to advance our understanding of Earth’s climate system, and to foster the application of this knowledge in risk management and adaptation efforts. CPO-supported research is conducted in regions across the United States, at national and international scales, and globally.
Learn more...
Sandy Lucas, CVP Program Manager
Email: sandy.lucas@noaa.gov
Phone: 301-734-1253
|