The ARM Southern Great Plains Central Facility Best Estimate Radiative Flux CD

Long, CN

doi:10.2172/1020734

Cited by 3 publications

(2 citation statements)

References 5 publications

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“…Most previous studies made direct comparisons between point measurements and model grid box output under the assumptions that temporal sampling at a point yields the equivalent of a two‐dimensional slice through a three‐dimensional model grid box, and the fraction of the grid filled by clouds in the two‐dimensional grid slice represents the amount of cloud in the three‐dimensional volume [ Mace et al , ; Hogan et al , ; Comstock and Jakob , ; Boyle et al , ; Bouniol et al , ]. Attempts have been made to quantitatively relate point measurements to areal averages represented by model grid boxes as a function of time averaging [ Barnett et al , ; Long , ; Yang et al , ]. As the model horizontal resolution becomes coarser, longer time averaging is needed from observations in order to match the scales.…”

Section: Methodsmentioning

confidence: 99%

Low‐cloud characteristics over the tropical western Pacific from ARM observations and CAM5 simulations

et al. 2015

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This study evaluates the ability of the Community Atmospheric Model version 5 (CAM5) to reproduce low clouds observed by the Atmospheric Radiation Measurement (ARM) cloud radar at Manus Island of the tropical western Pacific during the Years of Tropical Convection. Here low clouds are defined as clouds with their tops below the freezing level and bases within the boundary layer. Low‐cloud statistics in CAM5 simulations and ARM observations are compared in terms of their general occurrence, mean vertical profiles, fraction of precipitating versus nonprecipitating events, diurnal cycle, and monthly time series. Other types of clouds are included to put the comparison in a broader context. The comparison shows that the model overproduces total clouds and their precipitation fraction but underestimates low clouds in general. The model, however, produces excessive low clouds in a thin layer between 954 and 930 hPa, which coincides with excessive humidity near the top of the mixed layer. This suggests that the erroneously excessive low clouds stem from parameterization of both cloud and turbulence mixing. The model also fails to produce the observed diurnal cycle in low clouds, not exclusively due to the model coarse grid spacing that does not resolve Manus Island. This study demonstrates the utility of ARM long‐term cloud observations in the tropical western Pacific in verifying low clouds simulated by global climate models, illustrates issues of using ARM observations in model validation, and provides an example of severe model biases in producing observed low clouds in the tropical western Pacific.

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Section: Methodsmentioning

confidence: 99%

Low‐cloud characteristics over the tropical western Pacific from ARM observations and CAM5 simulations

et al. 2015

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“…The final mixed layer height estimate was from the MERRA-2 reanalysis product which provided mixed layer depths every 3 hr at 36.0°N 97.5°W, slightly departed from the SGP ground site. Broadband shortwave irradiance was provided from a value-added product derived from three radiometer systems located at the SGP central facility (Long, 2002). Temperature and RH data were measured onboard the G-1 aircraft and on the radiosondes, giving some vertical information.…”

Section: Meteorological Datamentioning

confidence: 99%

Look Up: Probing the Vertical Profile of New Particle Formation and Growth in the Planetary Boundary Layer With Models and Observations

O’Donnell

Akherati

et al. 2023

JGR Atmospheres

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The processes of new particle formation (NPF) and growth are important contributors to cloud condensation nuclei (CCN) concentrations, and CCN are important for climate from their impact on planetary radiative forcing. While the general ubiquity and importance of NPF is v • I would also like to extend the greatest appreciation to my advisor, Jeffrey Pierce, for his well-rounded support, affirmation, motivation, and patience throughout this project. I am consistently reminded of Jeff's enthusiasm and depth of knowledge about aerosol microphysics, and I have always appreciated our conversations about science and life in general.

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Evaluation of the NCEP Global Forecast System at the ARM SGP Site

Yang

Pan

Krueger

et al. 2006

Monthly Weather Review

124

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This study evaluates the performance of the National Centers for Environmental Prediction Global Forecast System (GFS) against observations made by the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) Program at the southern Great Plains site for the years 2001–04. The spatial and temporal scales of the observations are examined to search for an optimum approach for comparing grid-mean model forecasts with single-point observations. A single-column model (SCM) based upon the GFS was also used to aid in understanding certain forecast errors. The investigation is focused on the surface energy fluxes and clouds. Results show that the overall performance of the GFS model has been improving, although certain forecast errors remain. The model overestimated the daily maximum latent heat flux by 76 W m−2 and the daily maximum surface downward solar flux by 44 W m−2, and underestimated the daily maximum sensible heat flux by 44 W m−2. The model’s surface energy balance was reached by a cancellation of errors. For clouds, the GFS was able to capture the observed evolutions of cloud systems during major synoptic events. However, on average, the model largely underestimated cloud fraction in the lower and midtroposphere, especially for daytime nonprecipitating low clouds because shallow convection in the GFS does not produce clouds. Analyses of surface radiative fluxes revealed that the diurnal cycle of the model’s surface downward longwave flux (SDLW) was not in phase with that of the ARM-observed SDLW. SCM experiments showed that this error was caused by an inaccurate scaling factor, which was a function of ground skin temperature and was used to adjust the SDLW at each model time step to that computed by the model’s longwave radiative transfer routine once every 3 h. A method has been proposed to correct this error in the operational forecast model. It was also noticed that the SDLW biases changed from mostly negative in 2003 to slightly positive in 2004. This change was traced back to errors in the near-surface air temperature. In addition, the SDLW simulated with the newly implemented Rapid Radiative Transfer Model longwave routine in the GFS is usually 5–10 W m−2 larger than that simulated with the previous routine. The forecasts of surface downward shortwave flux (SDSW) were relatively accurate under clear-sky conditions. The errors in SDSW were primarily caused by inaccurate forecasts of cloud properties. Results from this study can be used as guidance for the further development of the GFS.

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The ARM Southern Great Plains Central Facility Best Estimate Radiative Flux CD

Cited by 3 publications

References 5 publications

Low‐cloud characteristics over the tropical western Pacific from ARM observations and CAM5 simulations

Low‐cloud characteristics over the tropical western Pacific from ARM observations and CAM5 simulations

Look Up: Probing the Vertical Profile of New Particle Formation and Growth in the Planetary Boundary Layer With Models and Observations

Evaluation of the NCEP Global Forecast System at the ARM SGP Site

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