http://www.gfdl.noaa.gov/index/news-app Research highlights from www.gfdl.noaa.gov en 2012-02-13T11:57:07-05:00 hourly 1 1970-01-01T00:00+00:00 http://www.gfdl.noaa.gov/index/news-app/story.49/title.the-future-of-hurricane-activity-why-models-differ-among-themselves One aspect of uncertainty in future projections of basin-wide hurricane activities stems from the variety of projections of the spatial pattern of tropical warming. A tropical cyclone permitting high-resolution, global atmospheric model is used to explore hurricane frequency response to sea surface temperature (SST) anomalies generated by coupled models for the late 21st century using the SRES A1B scenario. Weather and Atmospheric Dynamics 2012-02-03 http://www.gfdl.noaa.gov/index/news-app/story.48/title.pathways-between-primary-production-and-fisheries-yields-of-large-marine-ecosystems There is considerable uncertainty in projections of the impact of climate on fisheries yields due to uncertainties in climate change impacts on primary production and the processes controlling how much primary production is transferred to fish. Primary production and proxies such as chlorophyll have proven to be useful predictors of fisheries yields at regional scales but show much less skill when applied globally. The marine food web dynamics that control the transfer of energy from phytoplankton to fish are complex and it has been postulated that the relationship between primary production and fisheries production may differ dramatically between ecosystems due to changes in planktonic foodweb structure. Climate and Ecosystems 2012-01-24 http://www.gfdl.noaa.gov/index/news-app/story.30/title.anthropogenic-aerosols-and-the-weakening-of-the-south-asian-summer-monsoon An important part of the global water cycle, the South Asian summer monsoon provides about 80% of the region’s annual precipitation, and touches the lives of more than 20% of the world’s population. Using the NOAA/GFDL state-of-the-art global climate model that accounts for all the known natural and anthropogenic forcings, we have investigated what caused the observed decrease in the South Asian summer monsoon rainfall over the second half of the 20th century. Was the widespread drying due to natural factors or human activities? Atmospheric Physics Chemistry and Climate 2011-09-29 http://www.gfdl.noaa.gov/index/news-app/story.26/title.climatological-characteristics-of-arctic-and-antarctic-surface-based-inversions Surface-based inversions (SBI) are frequent features of the Arctic and Antarctic atmospheric boundary layer and influence important climate processes. However, prior to this study, climatological polar SBI properties had not been fully characterized, nor had climate model simulations of SBIs been compared comprehensively to observations. Atmospheric Physics Chemistry and Climate 2011-09-12 http://www.gfdl.noaa.gov/index/news-app/story.27/title.different-magnitudes-of-projected-subsurface-ocean-warming-around-greenland-and-antarctica Recent acceleration of Greenland and Antarctic outlet glaciers and ice flows is closely linked to ocean warming, especially in the subsurface layer. This land ice melt will cause sea level rise. Climate and Ecosystems 2011-07-03 http://www.gfdl.noaa.gov/index/news-app/story.33/title.sensitivity-of-the-aerosol-indirect-effect-to-subgrid-variability-in-the-cloud-parame The recently developed GFDL AM3 model (Donner et. al 2011) incorporates a prognostic treatment of cloud drop number to simulate the aerosol indirect effect. The present work explores formulation sensitivities by constructing three alternate model configurations (S1, S2, S3). These alternate configurations exhibit only small differences in their present day climatology. Atmospheric Physics Chemistry and Climate 2011-07-01 http://www.gfdl.noaa.gov/index/news-app/story.32/title.the-gfdl-cm3-model Earlier generations of climate models at GFDL have specified cloud properties to be independent of atmospheric aerosol composition, despite fairly well-understood (at least for liquid clouds) dependence of cloud droplet number on aerosol composition and size distribution. Cloud drop number in turn exerts a major control on cloud radiation, notably albedo, and microphysics and macrophysics, notably cloud structure and lifetimes. Aerosol-cloud interactions are likely to be important in anthropogenic climate change. They have been difficult to incorporate in climate models because they occur at scales much smaller than resolved by climate models. CM3 parameterizes these smaller scales using probability distribution functions for motions smaller than those it explicitly resolves. Atmospheric Physics Chemistry and Climate 2011-07-01 http://www.gfdl.noaa.gov/index/news-app/story.28/title.raining-from-the-ground-up Though it is obvious that rainfall moistens the land surface, our scientific understanding of how land surface moisture may interact with the atmosphere to encourage or suppress subsequent rainfall is limited. Using data from the North American Regional Reanalysis (NARR, Mesinger et al., 2006), this study shows that the likelihood of afternoon rainfall in the eastern United States and Mexico is strongly linked to evaporation from the land surface earlier in the day. Climate Change Variability and Prediction 2011-06-05 http://www.gfdl.noaa.gov/index/news-app/story.31/title.downward-shortwave-surface-flux-in-the-gfdl-cm2-1-general-circulation-model The downward solar flux at the surface is an important component of the earth's climate system, being a major factor governing the surface temperature and hydrologic cycle. The availability of derived flux climatologies from both ground-based measurements and satellite-based estimates provide a reference for properly assessing general circulation model biases, not only in the surface irradiance, but in the atmospheric factors (aerosols, clouds, and water vapor) affecting it. Atmospheric Physics Chemistry and Climate 2011-04-22 http://www.gfdl.noaa.gov/index/news-app/story.34/title.north-american-isoprene-influence-on-intercontinental-ozone-pollution Changing land-use and climate may increase biogenic isoprene emissions, which could offset the benefits from North American air pollution controls for both domestic and European air quality (surface ozone). Both anthropogenic and biogenic emission changes are reflected in peroxy acetyl nitrate (PAN), which may serve as a more effective indicator of intercontinental emission changes than ozone itself. Atmospheric Physics Chemistry and Climate 2011-02-22 http://www.gfdl.noaa.gov/index/news-app/story.35/title.the-meteorological-nature-of-variable-soluble-iron-transport-and-deposition-within-the-north-atlantic-ocean-basin- Biological productivity in vast regions of the oceans is known to be limited by the supply of iron, an essential nutrient to marine organisms, impacting carbon export to the ocean floor. The atmospheric source of iron originates from desert mineral dust aerosols and is converted to a bio-available form of soluble iron during transport. Little is known of the magnitude and variability of soluble iron deposition (SFeD) and the character of its transport. We have used the GFDL Global Chemical Transport Model to examine the emission of mineral dust (~3.5% Fe) during Saharan desert dust storms; the chemical processing of iron to a soluble form during transport; and the subsequent dry surface deposition and precipitation scavenging deposition to the North Atlantic Ocean. Atmospheric Physics Chemistry and Climate 2011-02-01 http://www.gfdl.noaa.gov/index/news-app/story.39/title.sensitivity-of-the-noy-budget-over-the-united-states-to-anthropogenic-and-lightning-nox-in-summer- The study by Fang et al. [2010] examines the implications of new estimates of the anthropogenic and lightning nitrogen oxide (NOx) sources for the budget of oxidized nitrogen (NOy) over the United States in summer using a 3-D global chemical transport model (MOZART-4). NOy export and burden response less than linearly to either NOx emission changes due to the NOy partitioning change and the corresponding lifetime change. Lightning NOx contributes 24%−43% of the free tropospheric (FT) NOy export from the U.S. to the North Atlantic and 28%−34% to the NOy wet deposition over the United States. Atmospheric Physics Chemistry and Climate 2010-10-01 http://www.gfdl.noaa.gov/index/news-app/story.38/title.sensitivity-of-polar-ozone-to-sea-surface-temperatures-and-halogen-amounts- The results of the simulations of Austin and Wilson (2010) suggest the importance of including a coupled ocean on stratospheric processes as well as realistic bromine amounts, including the very short lived species. The figure shows the calculated area of the ozone hole (colored lines and triangles), together with observations (black triangles). With SSTs from the CM2 coupled ocean-atmosphere experiment, the simulated ozone hole (blue) tends to be slightly larger (by about 6%) than simulated with observed SSTs used as forcing (red curve and points). For the low Bromine simulation (green), which corresponds approximately to just the long lived bromine species, the ozone hole was smaller by about 10%. Atmospheric Physics Chemistry and Climate 2010-10-01 http://www.gfdl.noaa.gov/index/news-app/story.37/title.multi-variate-probability-density-functions-with-dynamics-for-cloud-droplet-activation-in-large-scale-models Multi-variate probability density functions with dynamics (MVD PDFs) have been incorporated into the single-column version of GFDL AM3 and extended to treat aerosol activation. MVD PDFs are unique in that they predict the joint distribution of temperature, water mass, and vertical velocity. The distribution of vertical velocity is then a natural link to aerosol activation. This paper presents the first results on the effects of aerosols and precipitation on cloud fraction and cloud liquid using the MVD PDFs and the first results on cloud droplet number concentrations obtained from the distributions of vertical velocity predicted by the MVD PDFs. Atmospheric Physics Chemistry and Climate 2010-10-01 http://www.gfdl.noaa.gov/index/news-app/story.29/title.simulations-of-underwater-plumes-of-dissolved-oil-in-the-gulf-of-mexico A simple model of the temperature-dependent biological decay of dissolved oil is embedded in an ocean climate model and used to simulate underwater plumes of dissolved and suspended oil originating from a point source in the northern Gulf of Mexico, with an upper-bound supply rate estimated from the contemporary analysis of the Deepwater Horizon blowout. The behavior of plumes at different depths is found to be determined by the combination of sheared current strength and the vertical profile of decay rate. Oceans and Climate 2010-08-18 http://www.gfdl.noaa.gov/index/news-app/story.40/title.two-opposing-effects-of-absorbing-aerosols-on-global-mean-precipitation As they heat up both the atmosphere and the surface, absorbing aerosols affect precipitation in opposite ways. When simulating with a coupled general circulation-ocean model the overall hydrological response to increased black carbon levels, the researchers found that the net effect on global-mean precipitation is slightly negative.The effect is too small to outweigh the 2-3 % increase in global precipitation per each degree of greenhouse warming. But absorbing aerosols could have a more pronounced impact on moist convection and general circulation than carbon dioxide and non-absorbing aerosols, such as sulfate, which merely scatter solar radiation, the authors suggest. Atmospheric Physics Chemistry and Climate 2010-07-02 http://www.gfdl.noaa.gov/index/news-app/story.41/title.observational-constraints-on-the-global-atmospheric-budget-of-ethanol Vaishali Naik, Arlene Fiore, Larry Horowitz from GFDL along with co-authors from NASA-AMES, NCAR, NOAA ESRL, University of Minnesota and University of California at Berkeley applied the global chemical-transport model MOZART-4 in conjunction with available observations from several regions around the globe to place constraints on the global budget of atmospheric ethanol. Their analysis indicates that over continental regions, ethanol concentrations predominantly reflect direct anthropogenic and biogenic emission sources. Furthermore, the authors find that current levels of ethanol measured in remote regions are an order of magnitude larger than those in the model, suggesting a major gap in the understanding of the sources and sinks of ethanol. Stronger constraints on the present-day budget and distribution of ethanol and other volatile organic compounds are needed to assess the impacts of increasing the use of ethanol as a fuel Atmospheric Physics Chemistry and Climate 2010-06-17 http://www.gfdl.noaa.gov/index/news-app/story.42/title.export-of-asian-pollution-to-the-western-pacific Quantifying pollution inflow and outflow over East Asia in spring with regional and global models by Meiyun Lin (now at Princeton U), Tracey Holloway (U Wisconsin), Greg Carmichael (U Iowa), and Arlene Fiore (NOAA GFDL) explores two high-resolution atmospheric chemistry models to examine the role of mesoscale versus synoptic scale processes in controlling pollution export from East Asia. Their results indicate the importance of rapid pollution venting through deep convection that develops along the leading edge of frontal system convergence bands. This transport mechanism is well captured in a high-resolution climate-chemistry model (WRF-Chem), but not adequately resolved in either of two coarse-resolution global models compared with aircraft observations of pollution lofting, suggesting a real need for high-resolution model studies of global pollution transport. Atmospheric Physics Chemistry and Climate 2010-05-06 http://www.gfdl.noaa.gov/index/news-app/story.44/title.identification-of-anthropogenic-and-natural-dust-sources-using-modis-deep-blue-level-2-data Explores a new method to detect anthropogenic and natural dust sources from satellite data in the eastern part of West Africa. The anthropogenic contribution appears to be significant around the lake Chad, but the magnitude of these sources seem weaker than the natural sources, in particular relative to the Bodele depression. Atmospheric Physics Chemistry and Climate 2010-03-09