Geophysical Fluid Dynamics Laboratory

About: Geophysical Fluid Dynamics Laboratory is a facility organization based out in Princeton, New Jersey, United States. It is known for research contribution in the topics: Climate model & Climate change. The organization has 525 authors who have published 2432 publications receiving 264545 citations. The organization is also known as: GFDL.

Top-down isoprene emissions over tropical South America inferred from SCIAMACHY and OMI formaldehyde columns

Abstract: JOURNAL OF GEOPHYSICAL RESEARCH: ATMOSPHERES, VOL. 118, 6849–6868, doi:10.1002/jgrd.50552, 2013 Top-down isoprene emissions over tropical South America inferred from SCIAMACHY and OMI formaldehyde columns Michael P. Barkley, 1 Isabelle De Smedt, 2 Michel Van Roozendael, 2 Thomas P. Kurosu, 3,4 Kelly Chance, 3 Almut Arneth, 5,6 Daniel Hagberg, 5 Alex Guenther, 7 Fabien Paulot, 8 Eloise Marais, 8 and Jingqiu Mao 9 Received 22 October 2012; revised 4 April 2013; accepted 2 June 2013; published 27 June 2013. [ 1 ] We use formaldehyde (HCHO) vertical column measurements from the Scanning Imaging Absorption spectrometer for Atmospheric Chartography (SCIAMACHY) and Ozone Monitoring Instrument (OMI), and a nested-grid version of the GEOS-Chem chemistry transport model, to infer an ensemble of top-down isoprene emission estimates from tropical South America during 2006, using different model configurations and assumptions in the HCHO air-mass factor (AMF) calculation. Scenes affected by biomass burning are removed on a daily basis using fire count observations, and we use the local model sensitivity to identify locations where the impact of spatial smearing is small, though this comprises spatial coverage over the region. We find that the use of the HCHO column data more tightly constrains the ensemble isoprene emission range from 27–61 Tg C to 31–38 Tg C for SCIAMACHY, and 45–104 Tg C to 28–38 Tg C for OMI. Median uncertainties of the top-down emissions are about 60–260% for SCIAMACHY, and 10–90% for OMI. We find that the inferred emissions are most sensitive to uncertainties in cloud fraction and cloud top pressure (differences of ˙10%), the a priori isoprene emissions (˙20%), and the HCHO vertical column retrieval (˙30%). Construction of continuous top-down emission maps generally improves GEOS-Chem’s simulation of HCHO columns over the region, with respect to both the SCIAMACHY and OMI data. However, if local time top-down emissions are scaled to monthly mean values, the annual emission inferred from SCIAMACHY are nearly twice those from OMI. This difference cannot be explained by the different sampling of the sensors or uncertainties in the AMF calculation. Citation: Barkley, M. P., et al. (2013), Top-down isoprene emissions over tropical South America inferred from SCIAMACHY and OMI formaldehyde columns, J. Geophys. Res. Atmos., 118, 6849–6868, doi:10.1002/jgrd.50552. 1. Introduction Additional supporting information may be found in the online version of this article. EOS Group, Department of Physics and Astronomy, University of Leicester, Leicester, UK. Belgian Institute for Space Aeronomy (BIRA-IASB), Brussels, Belgium. Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts, USA. Now at Jet Propulsion Laboratory, Pasadena California, USA. Department of Physical Geography and Ecosystems Analysis, Geobio- sphere Science Center, Lund University, Lund, Sweden. Atmospheric Environmental Research/Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, Karlsruhe, Germany. National Center of Atmospheric Research, Boulder, Colorado, USA. Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts, USA. Geophysical Fluid Dynamics Laboratory, Princeton University, Princeton, New Jersey, USA. Corresponding author: M. P. Barkley, EOS Group, Department of Physics and Astronomy, University of Leicester, Leicester, LE1 7RH, UK. (mpb14@le.ac.uk) ©2013. American Geophysical Union. All Rights Reserved. 2169-897X/13/10.1002/jgrd.50552 [ 2 ] It is well established that terrestrial vegetation emit a diverse range of reactive biogenic volatile organic com- pounds (BVOCs) into the atmosphere, which serve impor- tant roles in the biosphere and which influence atmospheric chemistry and climate [Kesselmeier and Staudt, 1999; Laothawornkitkul et al., 2009]. The most important of these compounds is isoprene, whose global emissions of 400– 600 Tg C a –1 comprise approximately half of the total BVOC budget [Guenther et al., 1995, 2006; Arneth et al., 2008]. Isoprene has a significant impact on tropospheric photochemistry, by influencing the formation of tropo- spheric ozone [Paulot et al., 2012] and secondary organic aerosol [Kanakidou et al., 2005] and by affecting the oxi- dation capacity of the atmosphere [Lelieveld et al., 2008; Taraborrelli et al., 2012]. Isoprene emissions are highly uncertain [Arneth et al., 2008], especially from tropical regions where there is a notable lack of observational data to constrain current bottom-up models [e.g., Guenther et al., 2006; Arneth et al., 2007; Lathiere et al., 2010]. Given that tropical ecosystems may contribute up to 75% of global

The Stability and Genesis of Rossby Vortices

Abstract: The stability and genesis of the vortices associated with long solitary divergent Rossby waves-the Rossby vortices–are studied numerically using the single-layer (SL) model with Jovian parameters. Vortex behavior depends on location and on balances among the translation, twisting, steepening, dispersion and advection processes. Advection is the main preserver of vortices. The solutions provide an explanation for the origin, uniqueness and longevity of the Great Red Spot (GRS). In midlatitudes, stable anticyclones exist in a variety of sizes and balances: from the large planetary-geostrophic (PG) and medium intermediate-geostrophic (IG) vortices that propagate westward, to the small quasi-geostrophic (QG) vortices that migrate equatorward. These vortices all merge during encounters. Geostrophic vortices in the f0-plane system adjust toward symmetry by rotating; those on the sphere adjust by rotating and propagating. Stable cyclones exist mainly at the QG scale or on the f0-plane. In low latitudes ...

Multimodel projections of climate change from short‐lived emissions due to human activities

Abstract: [1] We use the GISS (Goddard Institute for Space Studies), GFDL (Geophysical Fluid Dynamics Laboratory) and NCAR (National Center for Atmospheric Research) climate models to study the climate impact of the future evolution of short-lived radiatively active species (ozone and aerosols). The models used mid-range A1B emission scenarios, independently calculated the resulting composition change, and then performed transient simulations to 2050 examining the response to projected changes in short-lived species and to changes in both long-lived and short-lived species together. By 2050, two models show that the global mean annual average warming due to long-lived GHGs (greenhouse gases) is enhanced by 20–25% due to the radiatively active short-lived species. One model shows virtually no effect from short-lived species. Intermodel differences are largely related to differences in emissions projections for short-lived species, which are substantial even for a particular storyline. For aerosols, these uncertainties are usually dominant, though for sulfate uncertainties in aerosol physics are also substantial. For tropospheric ozone, uncertainties in physical processes are more important than uncertainties in precursor emissions. Differences in future atmospheric burdens and radiative forcing for aerosols are dominated by divergent assumptions about emissions from South and East Asia. In all three models, the spatial distribution of radiative forcing is less important than that of climate sensitivity in predicting climate impact. Both short-lived and long-lived species appear to cause enhanced climate responses in the same regions of high sensitivity rather than short-lived species having an enhanced effect primarily near polluted areas. Since short-lived species can significantly influence climate, regional air quality emission control strategies for short-lived pollutants may substantially impact climate over large (e.g., hemispheric) scales.

Representation of the carbon cycle in box models and GCMs: 1. Solubility pump

Abstract: [1] Bacastow [1996], Broecker et al. [1999], and Archer et al. [2000] have called attention recently to the fact that box models and general circulation models (GCMs) represent the thermal partitioning of CO2 between the warm surface ocean and cold deep ocean in different ways. They attribute these differences to mixing and circulation effects in GCMs that are not resolved in box models. The message that emerges from these studies is that box models have overstated the importance of the ocean's polar regions in the carbon cycle. A reduced role for the polar regions has major implications for the mechanisms put forth to explain glacial - interglacial changes in atmospheric CO2. In parts 1 and 2 of this paper, a new analysis of the ocean's carbon pumps is carried out to examine these findings. This paper, part 1, shows that unresolved mixing and circulation effects in box models are not the main reason for box model-GCM differences. The main factor is very different kinds of restrictions on gas exchange in polar areas. Polar outcrops in GCMs are much smaller than in box models, and they are assumed to be ice covered in an unrealistic way. This finding does not support a reduced role for the ocean's polar regions in the cycling of organic carbon, the subject taken up in part 2.

The Southern Oscillation and El Niño

Abstract: Publisher Summary This chapter examines the various aspects of the southern oscillation (SO) and El Nino. Over the tropical Pacific Ocean, the SO is associated with large year-to-year variations in the intensity of the trade winds and in rainfall patterns. The SO also has a signature that extends into the middle latitudes of each hemisphere during its winter season. Interannual sea-surface temperature variations in the tropical Pacific Ocean are primarily associated with a phenomenon known as El Nino. A typical El Nino-Southern Oscillation (ENSO) episode evolves in two stages. One stage involves principally the eastern tropical Pacific, and the other involves the central and western Pacific. The differences between individual ENSO events reflect the relative strengths, and on rare occasions the order of occurrence of the two stages. The eastward displacement in the tropical Pacific of the warm surface waters and the atmospheric convection affected the atmospheric circulation globally. The oceanic changes during ENSO are caused primarily by the weakening of the trade winds. The close relation between El Nino events and the seasonal cycle suggests that the phase of the initial perturbations that trigger instabilities cannot be random.