Search Results

You are looking at 11 - 20 of 841 items for :

  • Cloud forcing x
  • Journal of Atmospheric and Oceanic Technology x
  • Refine by Access: All Content x
Clear All
James R. Campbell, Dennis L. Hlavka, Ellsworth J. Welton, Connor J. Flynn, David D. Turner, James D. Spinhirne, V. Stanley Scott III, and I. H. Hwang

1. Introduction The success, or failure, of global numerical climate simulations can be traced directly to the accuracy of the empirical relationships and input parameters required to replicate significant dynamic and radiative processes. Knowledge of the vertical structure of cloud and aerosol scattering properties or layers from varying climate regimes is fundamental. Analysis of surface or top-of-the-atmosphere radiative fluxes is not sufficient in itself. Models that can correctly define

Full access
Ellsworth G. Dutton

well as to short-term instrument andLOWTRAN7 input variations. LOWTRAN7 and the observations agree better, in the mean, than the commonlyaccepted uncertainties for either would suggest. Maximum cloud radiative forcing at the surface for each site isquantified as a by-product of the comparison process.1. Introduction The spectrally integrated, 2~r-sr downward longwaveirradiance at the surface, DLs, is a major componentof the earth's radiation (and subsequently the earth'senergy) budget, which

Full access
James I. Metcalf, Alexander W. Bishop, Richard C. Chanley, Timothy C. Hiett, and Pio J. Petrocchi

The Ground Based Remote Sensing Branch of theGeophysics Directorate (formerly Air Force Geophysics Laboratory) operated an 11-cm (S-band) Dopplerradar at its field site in Sudbury, Massachusetts, from1981 to 1992. This radar, first described by Bishop andArmstrong (1982), was used for investigations of thephysics and kinematics of cloud and precipitation systems, including convective storms, stratiform precipitation systems, and tropical cyclones. After 1985, itwas progressively modified to enable

Full access
G. Sanchez, A. Serrano, M. L. Cancillo, and J. A. Garcia

1. Introduction Numerous studies published over the past decades have revealed important differences in the irradiance values estimated by climate or radiative transfer models and those measured with pyranometers at the earth’s surface ( Garratt 1994 ; Kato et al. 1997 ; Halthore et al. 1998 ; Wild et al. 1998 ; Valero and bush 1999 ; Wild 2005 ). These differences could result in important variations in the subsequent calculation of the radiative forcing and climate trends. Recent studies

Full access
Grant Matthews

-predicted changes to the ERB resulting from cloud feedbacks. These are currently one of the largest uncertainties in predictions of future climate change. Anthropogenic loading of the atmosphere with greenhouse gases is expected to perturb the climate at a rate of about 0.6 W m −2 decade −1 . Models estimate that cloud–climate feedback could then further modify this forcing by ±25%, or ±0.15 W m −2 decade −1 . Cloud radiative forcing (CRF), the difference between clear and cloudy flux, is measured at around

Full access
Haobo Tan, Hanbing Xu, Qilin Wan, Fei Li, Xuejiao Deng, P. W. Chan, Dong Xia, and Yan Yin

1. Introduction Aerosol particles can impact the radiation balance of the earth’s atmosphere through scattering and absorption of solar radiation. They can also act as cloud condensation nuclei and alter the optical properties and life cycles of clouds and therefore indirectly impact the radiation balance of the earth’s atmosphere ( Chylek and Coakley 1974 ; Twomey 1977 ). Aerosol hygroscopicity describes the interaction between aerosol particles and water vapor under specific vapor conditions

Full access
J. Marshall Shepherd, Olayiwola O. Taylor, and Carlos Garza

work Such focus has led to a wealth of information on Atlanta's UHI environment. Atlanta's UHI may also impact the regional water cycle by inadvertent forcing of precipitating cloud systems. Bornstein and Lin (2000) used data from Project ATLANTA's 27 mesonet sites and eight National Weather Service sites to investigate interactions of the Atlanta UHI, its convergence zone, and convective storm initiation. In an analysis of six precipitation events during the summer of 1996, they showed that the

Full access
Daniel P. Betten, Michael I. Biggerstaff, and Louis J. Wicker

diffusion; and the time-averaged forcing of vertical momentum. We also compare the trajectory behavior obtained from the simulated supercell storm to trajectories computed from a dual-Doppler radar analysis of a well-observed supercell storm. The comparison shows that the method has utility for an organized storm that is sampled frequently relative to the evolution of the storm flow. 2. Methodology a. Numerical simulation A numerical simulation was carried out using the Cloud Model 1 (CM1), release 17

Full access
Gang Luo

the Monte Carlo model. The disagreement at smallsize ratios is caused in the simulations, where, whenthe size ratio becomes small, the normalized populationof partially cloudy pixels approaches 1 and those ofcloud-free and overcast pixels approach zero (Fig. 5),forcing the formula of Molnar and Coakley ( 1985 ) totake the value of 0.5 as the regional-scale cloud cover.In other words, sizable populations of cloud-free andovercast pixels are necessary to use the method of Molnar and Coakley (1985

Full access
Renée Elio, Johannes De Haan, and G. S. Strong

convective stormsin Alberta; METEOR interprets contoured maps of a synoptic-based instability index and of surface equivalentpotential temperature. It also gathers additional information about a variety of ongoing weather conditionsfrom three portions of surface aviation reports: the cloud cover section, the obstructions visibility, and theobservations provided in the "remarks" section. Interpreting remarks made by human observers, while usefulto a forecaster experienced with local weather conditions

Full access