GFDL - Geophysical Fluid Dynamics Laboratory

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GFDL Research Highlights

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March 23, 2015 - Understanding ENSO Diversity
The El Niño / Southern Oscillation (ENSO) is Earth's strongest interannual climate fluctuation, impacting weather, ecosystems, and economies around the world. Understanding the range of ENSO variation could help lead to longer range predictions of El Niño and La Niña events. The authors review the current state of understanding of diversity among different El Niño / Southern Oscillation (ENSO) events, which differ from event to event in their amplitude, spatial pattern, temporal evolution, dynamical mechanisms, and impacts. Read more...

March 13, 2015 - A link between the hiatus in global warming and North American drought
The authors use three GFDL climate models (CM2.1, CM2.5_FLOR, CM2.5_FLOR_FA) to study the mechanisms behind the hiatus in global warming over the last decade and their possible relationship to southwestern U.S. drought. This study suggests that a majority of the drought in the southwestern U.S. over the last decade is the result of persistent anomalous wind conditions in the tropical Pacific, and is likely due to natural variability. Read more...

March 6, 2015 - Improved Seasonal Prediction of Temperature and Precipitation over Land in a High-resolution GFDL Climate Model
Skillful seasonal predictions of surface temperature and precipitation over land are in demand, due to their importance to ecosystems and sectors such as agriculture, energy, transportation. This study demonstrates skillful seasonal prediction of near-surface air temperature and precipitation over land using a new high-resolution climate model developed at GFDL, called FLOR. The study also diagnoses the sources of the prediction skill. Read more...

February 24, 2015 - An Extreme Event of Sea-level Rise along the Northeast Coast of North America in 2009–2010
Coastal sea levels along continental margins often show significant year-to-year upward and downward fluctuations. These fluctuations are superimposed on a longer term upward trend associated with the rise in global mean sea level, with global mean sea level rising at roughly 3 mm per year during the recent 20 years of accurate satellite measures. For society, it is the regional changes along any particular coastal zone that are most important. Our analysis of multi-decadal tide gauge records along the North American east coast identified an extreme sea-level rise event during 2009–2010. Within this relatively brief two-year period, coastal sea level north of New York City jumped by up to 128 mm. This magnitude of inter-annual sea level rise is unprecedented in the tide gauge records, with statistical methods suggesting that it was a 1-in-850 year event. Read more...

February 5, 2015 - Tropical Climate Change Control of the Lower Stratospheric Circulation
Tropical air has less ozone than polar air, even though the tropical stratosphere is where most atmospheric ozone is produced. The Brewer-Dobson circulation is considered key to understanding this apparent contrast. It also brings water vapor, aerosols and other species from the troposphere up into the stratosphere. The strength of the Brewer-Dobson circulation directly affects the thermal structure of the stratosphere and upper troposphere, and impacts the transport and distribution of important climate-influencing constituents including stratospheric water vapor, ozone, and volcanic aerosols. Read more...

December 16, 2014 - Drivers of trophic amplification of ocean productivity trends in a changing climate
Earth System Models (ESMs) project that climate change will lead to approximately 1-10% declines in global ocean phytoplankton productivity by the end of the 21st century, under high carbon emissions scenarios. This decline results from projected increases in ocean stratification under global warming, which hinders the supply of deep ocean nutrients to the well-lit surface ocean. Read more...

October 12, 2014 - Karakoram snowfall less sensitive to warming than Himalayas due to a unique seasonal cycle
The high mountains of Asia, including the Karakoram, Himalayas, and Tibetan Plateau, combine to form a region of perplexing hydroclimate changes. Glaciers in the Karakoram region have exhibited mass stability or even expansion, contrasting with glacial mass loss across the nearby Himalayas and Tibetan Plateau. This suggests that different regional snowfall or temperature signals might be detected in the Karakoram region. However, the remote location, complex terrain, and multi-country fabric of high-mountain Asia have made it difficult to maintain longer-term monitoring systems of the meteorological components that can influence glacial change. Read more...

September 29, 2014 - Seasonal- and annual-mean precipitation extremes occurring during 2013: A U.S. focused analysis
Extreme seasonal/annual precipitation, defined here as ranking first, second, or third highest or lowest in the record of at least 100 years, occurred in several continental U.S. regions during 2013. The authors of this study used CMIP5 models to simulate internal climate variability and the response to historical anthropogenic and natural forcings, for the Northern Tier and the Upper Midwest regions of the U.S. This study suggests that, for these two regions, extreme annual or seasonal positive precipitation anomalies over the U.S. were at least partly attributable to a combination of anthropogenic and natural forcing. Read more...

September 17, 2014 - Retrieval of Tropical Storm Statistics by Combining Data with a High-Resolution Coupled Model
In order to produce better seasonal-to-interannual climate predictions, GFDL scientists explored improvements in the method of initializing a high-resolution coupled model. Traditionally, when observations are assimilated into a high-resolution coupled model, small-scale cyclones tend to get filtered out in the process of making corrections to the large-scale background. GFDL scientists pioneered a method of processing the large-scale background and the small-scale perturbations separately in a cyclone-permitting model. Read more...

August 22, 2014 - Predicting a decadal shift in North Atlantic climate variability using the GFDL forecast system
The goals of this research were to assess the role of AMOC in global climate and identify the predictability of the associated climate impacts. Decadal prediction experiments were conducted as part of CMIP5 using a prototype GFDL-CM2.1 forecast system. The abrupt warming of the North Atlantic subpolar gyre (SPG), observed in the mid-1990s, was used as a case study to evaluate the forecast capabilities of the model, and to better understand the reasons for the observed changes. Read more...

August 13, 2014 - Seasonal Forecasting of Regional Tropical Cyclone Activity
Tropical cyclones (TCs, which include hurricanes and typhoons) are a major climate hazard across the Northern Hemisphere, and have exhibited variability and change on year-to-year timescales. Understanding and predicting future year-to-year TC activity is central to NOAA's mission and highly relevant to society. Of particular relevance for decision support is predicting seasonal activity on regional spatial scales (scales smaller than the entire basin) – a goal that has remained elusive. Read more...

July 21, 2014 - Rapid subsurface warming and circulation changes of Antarctic coastal waters by poleward shifting winds
Projected changes in the winds circling the Antarctic may accelerate global sea level rise significantly more than previously estimated. Changes to Antarctic winds may have a profound impact on warming ocean temperatures under the ice shelves along the coastline of West and East Antarctic. Projected Antarctic wind shifts were included in a detailed global ocean model, and the authors found water up to 4°C warmer than current temperatures rose up to meet the base of the Antarctic ice shelves. Read more...

July 13, 2014 - Regional rainfall decline in Australia attributed to anthropogenic greenhouse gases and ozone levels
A suite of simulations, with a new high-resolution climate model (CM2.5) developed at GFDL, were used to study the observed long-term decline of winter rainfall over parts of southern Australia. In addition to a control simulation, ensembles of simulations were performed that included various combinations of changing radiative forcing, including those from natural sources (volcanic eruptions and solar irradiance changes) and anthropogenic sources (changes in greenhouse gases, aerosols, ozone, and land use changes). Read more...

June 26, 2014 - Trajectory sensitivity of the transient climate response to cumulative carbon emission
The insensitivity of the global climate response once emissions cease in simplified coupled climate models has been used to argue for lack of committed warming based on past carbon emissions. Additional studies have also demonstrated that the cessation of carbon emissions results in a stabilization or decrease of global mean surface air temperature. Such studies generally assume either a 1%/year increase or an instantaneous doubling/quadrupling of atmospheric CO2. Read more...

May 23, 2014 - The Role of Global Climate Change in the Extreme Low Summer Arctic Sea Ice Extent in 2012
The rapid change in summer Arctic sea ice could have significant large scale climatic, ecological, and economic impacts. Understanding the mechanisms for the recent rapid decline in summer Arctic sea ice will help to predict future changes in summer Arctic sea ice and associated climatic, ecological, and economic impacts. Read more...

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