Review of Radiosonde Humidity and Temperature Errors

Pratt, Robert W.

doi:10.1175/1520-0426(1985)002<0404:rorhat>2.0.co;2

Cited by 51 publications

(37 citation statements)

References 0 publications

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“…The large amplitudes are 1 m s Ϫ1 for winds, 1°C for temperature, and 5% for relative humidity, and the small amplitudes are 0.5 m s Ϫ1 for winds, 0.5°C for temperature, and 2.5% for relative humidity. These amplitudes are comparable to estimates of observational error for these fields (e.g., Pratt 1985;Nuss and Brown 1987). For the final two members, lateral boundary conditions receive large (LBCL) or small (LBCS) perturbations instead of the initial conditions.…”

Section: Simulationssupporting

confidence: 76%

Influence of Arctic Wetlands on Arctic Atmospheric Circulation

et al. 2007

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The Arctic's land surface has large areas of wetlands that exchange moisture, energy, and momentum with the atmosphere. The authors use a mesoscale, pan-Arctic model simulating the summer of 1986 to examine links between the wetlands and arctic atmospheric dynamics and water cycling. Simulations with and without wetlands are compared to simulations using perturbed initial and lateral boundary conditions to delineate when and where the wetlands influence rises above nonlinear internal variability. The perturbation runs expose the temporal variability of the circulation's sensitivity to changes in lower boundary conditions. For the wetlands cases examined here, the period of the most significant influence is approximately two weeks, and the wetlands do not introduce new circulation changes but rather appear to reinforce and modify existing circulation responses to perturbations. The largest circulation sensitivity, and thus the largest wetlands influence, occurs in central Siberia. The circulation changes induced by adding the wetlands appear as a propagating, equivalent barotropic wave. The wetlands anomaly circulation spreads alterations of surface fluxes to other locations, which undermines the potential for the wetlands to present a distinctive, spatially fixed forcing to atmospheric circulation. Using the climatology of artic synoptic-storm occurrence to indicate when the arctic circulation is most sensitive to altered forcing, the results suggest that the circulation is susceptible to the direct influence of wetlands for a limited time period extending from spring thaw of wetlands until synoptic-storm occurrence diminishes in midsummer. Sensitivities in arctic circulation uncovered through this work occur during a period of substantial transition from a fundamentally frozen to thawed state, a period of major concern for impacts of greenhouse warming on pan-Arctic climate. Changing arctic climate could alter the behavior revealed here. ABSTRACT The Arctic's land surface has large areas of wetlands that exchange moisture, energy, and momentum with the atmosphere. The authors use a mesoscale, pan-Arctic model simulating the summer of 1986 to examine links between the wetlands and arctic atmospheric dynamics and water cycling. Simulations with and without wetlands are compared to simulations using perturbed initial and lateral boundary conditions to delineate when and where the wetlands influence rises above nonlinear internal variability. The perturbation runs expose the temporal variability of the circulation's sensitivity to changes in lower boundary conditions. For the wetlands cases examined here, the period of the most significant influence is approximately two weeks, and the wetlands do not introduce new circulation changes but rather appear to reinforce and modify existing circulation responses to perturbations. The largest circulation sensitivity, and thus the largest wetlands influence, occurs in central Siberia. The circulation changes induced by adding the wetlands appear as a propagating, eq...

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Section: Simulationssupporting

confidence: 76%

Influence of Arctic Wetlands on Arctic Atmospheric Circulation

et al. 2007

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“…time lag of the hygristor in adjusting to temperature changes of the ambient air and heating of the hygristor and adjacent layer of air by solar radiation [Pratt, 1985]. Although the source of errors is partly corrected (or at least improved) [Elliot and Gaffen, 1991], this experiment is still valuable to obtain implications for case studies using the old data sets.…”

Section: Radiosonde Error Experimentsmentioning

confidence: 99%

“…Most contemporary radiosonde instruments show extremely low performance in measuring relative humidity (RH), especially at cold and dry regions [Pratt, 1985 vapor is a major ingredient in nonlinear interactions among complex microphysical processes in cloud. The strong nonlinearity imposed by the vapor perturbations can effectively contribute to the growth and decay of perturbations in other variables and change dynamical evolution of the storm, and thus affect its predictability significantly.…”

mentioning

confidence: 99%

Nonlinearity and predictability of convective rainfall associated with water vapor perturbations in a numerically simulated storm

Park¹

1999

J. Geophys. Res.

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Abstract. Predictability of convective rainfall in a numerically simulated storm is assessed in conjunction with nonlinearity imposed by systematic perturbations in water vapor using a three-dimensional cloud model (ARPS). Nonlinearity is explicitly quantified using the tangent linear approximation, and predictability is measured by the noise-to-signal ratio. It is found that the behavior of nonlinearity at an early period of error insertion exerts strong influence on error dynamics and prcdictability in the future. The rate of increase in nonlinearity is larger for perturbations with larger magnitude and positive direction. Although dynamics of individual storms are sensitive to specified perturbations, the predictability limits generally go beyond 140 min after perturbations are introduced. The major contribution to the total error in the domain-integrated accumulated rainfall fields comes from the phase error rather than the amplitude error, especially under the region of secondary storms. The location and general behavior of the main storm (supercell) is predictable in a longer timescale than suggested by Lorenz's theoretical analysis. On the basis of the results from this study, some implications for practical storm-scale predictability are discussed. IntroductionThe growth and decay of perturbations in initial conditions essentially determine the predictability of atmospheric flow. Predictability refers to the degree of divergence among predictions started from nearby initial conditions through the time domain and thus depends on the sensitivity of system behavior to initial conditions. A predictability limit (or horizon) is a time after which prediction becomes useless no matter how accurately the initial condition may be obtained [Lighthill, 1986].Since Thompson [1957] 31,575

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“…The comparison of GOES retrievals to radiosonde measurements is not ideal due to differing measurement characteristics (point volumetric), collocation errors (matches are restricted to 0.25°), time differences (within 1 h), and radiosonde errors (Pratt 1985;Schmidlin 1988). However, it has become the standard approach for GOES sounding validation.…”

Section: A Soundingsmentioning

confidence: 99%

Application ofGOES-8/9Soundings to Weather Forecasting and Nowcasting

Menzel

Holt²,

Schmit³

et al. 1998

Bull. Amer. Meteor. Soc.

109

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Since April 1994 a new generation of geostationary sounders has been measuring atmospheric radiances in 18 infrared spectral bands and thus providing the capability for investigating oceanographic and meteorological phenomena that far exceed those available from the previous generation of Geostationary Operational Environmental Satellites (GOES). Menzel and Purdom foreshadowed many of the anticipated improvements from the GOES-8/9 sounders. This article presents some of the realizations; it details the in-flight performance of the sounder, presents both validated operational as well as routinely available experimental products, and shows the impact on nowcasting and forecasting activities.For the first time operational hourly sounding products over North America and adjacent oceans are now possible with the GOES-8/9 sounders. The GOES-8/9 sounders are making significant contributions by depicting moisture changes for numerical weather prediction models over the continental United States, monitoring winds over oceans, and supplementing the National Weather Service's Automated Surface Observing System with upper-level cloud information. Validation of many sounding products has been accomplished by comparison with radiosondes and aircraft measurements. Considerable progress has been made toward assimilation of soundings from clear skies and cloud properties in cloudy regions in operational as well as research forecast models; GOES-8/9 moisture soundings are now being used in the operational Eta regional forecast model.

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Review of Radiosonde Humidity and Temperature Errors

Cited by 51 publications

References 0 publications

Influence of Arctic Wetlands on Arctic Atmospheric Circulation

Influence of Arctic Wetlands on Arctic Atmospheric Circulation

Nonlinearity and predictability of convective rainfall associated with water vapor perturbations in a numerically simulated storm

Application ofGOES-8/9Soundings to Weather Forecasting and Nowcasting

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