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.

Low-Frequency Variability of Surface Air Temperature in a 1000-Year Integration of a Coupled Atmosphere-Ocean-Land Surface Model

Abstract: The study analyzes the variability of surface air temperature (SAT) and sea surface temperature (SST) obtained from a 1000-yr integration of a coupled atmosphere-ocean-land surface model, which consists of general circulation models of the atmosphere and oceans and a heat and water budget model of land surface. It also explores the role of oceans in maintaining the variability of SAT by comparing the long-term integration of the coupled model with those of two simpler models. They are 1 ) a “mixed layer model,” that is, the general circulation model of the atmosphere combined with a simple slab model of the mixed layer ocean, and 2) a “fixed SST model,” that is, the same atmosphere model overlying seasonally varying, prescribed SST. With the exception of the tropical Pacific, both the coupled and mixed layer models are capable of approximately simulating the standard deviations of observed annual and 5-yr-mean anomalies of local SAT. The standard deviation tends to be larger over continents than ...

An intercomparison of cloud-resolving models with the atmospheric radiation measurement summer 1997 intensive observation period data

Abstract: SUMMARY This paper reports an intercomparison study of midlatitude continental cumulus convection simulated by eight two-dimensional and twothree-dimensional cloud-resolving models (CRMs), driven by observed large-scale advective temperature and moisture tendencies, surface turbulent euxes, and radiative-heating proe les during three sub-periods of the summer 1997 Intensive Observation Period of the US Department of Energy’s Atmospheric Radiation Measurement (ARM) program. Each sub-period includes two or three precipitation events of various intensities over a span of 4 or 5 days. The results can be summarized as follows. CRMs can reasonably simulate midlatitude continental summer convection observed at the ARM Cloud and Radiation Testbed site in terms of the intensity of convective activity, and the temperature and specie c-humidity evolution. Delayed occurrences of the initial precipitation events are a common feature for all three sub-cases among the models. Cloud mass e uxes, condensate mixing ratios and hydrometeor fractions produced by all CRMs are similar. Some of the simulated cloud properties such as cloud liquid-water path and hydrometeor fraction are rather similar to available observations. All CRMs produce large downdraught mass euxes with magnitudes similar to those of updraughts, in contrast to CRM results for tropical convection. Some inter-model differences in cloud properties are likely to be related to those in the parametrizations of microphysical processes. There is generally a good agreement between the CRMs and observations with CRMs being signie cantly better than single-column models (SCMs), suggesting that current results are suitable for use in improving parametrizations in SCMs. However, improvements can still be made in the CRM simulations; these include the proper initialization of the CRMs and a more proper method of diagnosing cloud boundaries in model outputs for comparison with satellite and radar cloud observations.

Climate variability modulates western US ozone air quality in spring via deep stratospheric intrusions

Abstract: Deep stratospheric ozone intrusions can elevate western US ground-level ozone to unhealthy concentrations, but the factors driving interannual variability are poorly understood. Here, the authors combine observations and numerical simulations showing a link between intrusion events and strong La Nina winters.

Observational constraints on the chemistry of isoprene nitrates over the eastern United States

Abstract: incompatible with the observations. We find that � 50% of the isoprene nitrate production in the model occurs via reactions of isoprene (or its oxidation products) with the NO3 radical, but note that the isoprene nitrate yield from this pathway is highly uncertain. Using recent estimates of rapid reaction rates with ozone, 20–24% of isoprene nitrates are lost via this pathway, implying that ozonolysis is an important loss process for isoprene nitrates. Isoprene nitrates are shown to have a major impact on the nitrogen oxide (NOx =N O +N O2) budget in the summertime U.S. continental boundary layer, consuming 15–19% of the emitted NOx, of which 4–6% is recycled back to NOx and the remainder is exported as isoprene nitrates (2–3%) or deposited (8–10%). Our constraints on reaction rates, branching ratios, and deposition rates need to be confirmed through further laboratory and field measurements. The model systematically underestimates free tropospheric concentrations of organic nitrates, indicating a need for future investigation of the processes controlling the observed distribution.

Mineral dust aerosols in the NASA Goddard Institute for Space Sciences ModelE atmospheric general circulation model

Abstract: [1] We describe an updated model of the dust aerosol cycle embedded within the NASA Goddard Institute for Space Studies ‘ModelE’ atmospheric general circulation model (AGCM). The model dust distribution is compared to observations ranging from aerosol optical thickness and surface concentration to deposition and size distribution. The agreement with observations is improved compared to previous distributions computed by either an older version of the GISS AGCM or an offline tracer transport model. The largest improvement is in dust transport over the Atlantic due to increased emission over the Sahara. This increase comes from subgrid wind fluctuations associated with dry convective eddies driven by intense summertime heating. Representation of ‘preferred sources’ of soil dust particles is also fundamental to the improvement. The observations suggest that deposition is too efficient in the model, partly due to AGCM rainfall errors.