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R. J. Anderson

Abstract

A bow-mounted propeller anemometer and fast-response temperature sensors were operated during several cruises of CSS Dawson. Spectra of wind speed and temperature fluctuations were measured over the open ocean for a wind speed range of 6 to 21 m s−1 and a sea-air temperature difference range of ±6°C. Wind stress on the sea surface and sensible heat fluxes were determined by the inertial-dissipation method over a wide range of wind speeds for both stable and unstable atmospheric conditions. Neutral drag and sensible beat flux coefficients as functions of the wind speed at a 10-m reference height are in excellent agreement with the only existing eddy fluxes measured over the ocean from a stable platform and also with open sea inertial-dissipation measurements from a ship.

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R. C. Anderson
and
J. G. Pipes

Abstract

A simplified model of Jovian clouds was used to fit the shape of the geometric albedo curve between 1800 and 1950 Å. Absorption by uniform layers of gaseous and solid cubic ammonia over a gray surface resulted in a curve that was in good agreement with reported experimental measurements.

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F. R. Bellaire
and
L. J. Anderson

A new thermocouple psychrometer, designed to indicate true air temperature and humidity in remote locations, is described. In order to minimize maintenance, it utilizes natural ventilation, but provides adequate shielding of sensing elements against radiation. Wet and dry bulb temperature errors of less than + 0.1C° are obtained in winds above 1 mph.

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M. Segal
,
R. W. Arritt
,
J. Shen
,
C. Anderson
, and
M. Leuthold

Abstract

In this note the forcing of cumulus cloud clearing over and downwind from lakes during the warm season is evaluated conceptually by modeling and observational approaches. It is suggested that drying by dynamically induced subsidence and suppression of the CBL over the lake mutually contribute to the cloud clearing. The effect of background flow speed and the extent of potential clearing area is illustrated. Various implications of the cloud clearing are discussed.

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L. R. Wyatt
,
L. J. Ledgard
, and
C. W. Anderson

Abstract

The maximum-likelihood method is used to extract parameters of two-parameter models of the directional spreading of short wind waves from the power spectrum of high-frequency (HF) radar backscatter. The wind waves have a wavelength of half the radio wavelength that, for the data presented here, is at a frequency of 0.53 Hz. The parameters are short-wave direction, which at this frequency can be identified with wind direction, and the directional spread angle, the parameterization of which is model dependent. For the data presented here, the results suggest that the Donelan directional spreading model provides a better description of directional spreading than the cos s model. The HF radar and wave buoy measurements are compared and show good agreement. Measurements are presented that show the temporal and spatial structure of the short-wave field responding to the passage of a frontal system.

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M. Segal
,
M. Leuthold
,
R. W. Arritt
,
C. Anderson
, and
J. Shen

The diversity of small lakes' (size < 50 km) configurations, sizes, surrounding terrain, and land use combined with relative sparsity of observations complicates the observational evaluation of the lake breezes (LB) that are induced by these lakes. In the present article observational data obtained from available documents, data archives, and special projects were surveyed to suggest characterization of the LB features. The observational survey was complemented by conceptual evaluations. A preliminary generalization of the LB intensity and inland penetration in relation to the surrounding land use was inferred. The conceptual evaluation suggested that for a given lake width the prime factor affecting the LB intensity is the magnitude of the surface sensible heat flux over the surrounding land. Cooling related to the lake water temperature was indicated to have usually a secondary effect on the LB intensity for small lakes. Surface observations implied that the onshore penetration of the LB by the early afternoon hours is typically less than the characteristic width of the lake. Lower atmosphere observations indicated that the vertical extent of the LB may reach several hundred meters. Implications of the observed LB features in support of characterization of the real-world vegetation breeze are discussed.

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V. J. OLIVER
,
R. K. ANDERSON
, and
E. W. FERGUSON

Abstract

TIROS photographs of cloud patterns in the vicinity of the jet stream are examined and compared with surface, upper air, and pilot-report data. It is found that with certain conditions of lighting and satellite attitude the northern edge of the cirrus cloud shield, which lies immediately south of the jet, can be easily identified by a shadow cast by the higher cloud deck on the lower underlying surface. This shadow identifies the cloud structure associated with the jet stream. Differences in texture and pattern also help to identify the northern limits of the high-level cirrus and thus aid in positioning the jet stream.

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R. C. Anderson
,
J. G. Pipes
,
A. L. Broadfoot
, and
L. Wallace

Abstract

The results of two Aerobee rocket flights are reported. One obtained spectra of Venus from 3200 to 1900 Å at 16.5 Å resolution and the other spectra of Jupiter from 32M to 1800 Å at 28 Å resolution. The spectra of both planets are of much higher statistical accuracy than those that have been obtained previously. The peculiarities indicated by the previous observations are not confirmed. In particular, there does not appear to be an absorption feature in the Jupiter spectrum at 2600 Å or an ozone absorption in the Venus spectrum.

Two extreme models are used to interpret the data: the reflecting layer model and the cloud model. We find that the CO2 abundances for Venus and the H2 abundances for Jupiter, deduced with the reflecting layer model from observations in the red and IR parts of the spectrum, are much ton large to be compatible with the UV albedos. In terms of the cloud model, the albedos of both planets down to 2200 Å are the result of the decreasing single scattering albedo of the cloud particles and the increasing Rayleigh scattering. These two effects produce an almost constant geometric albedo from 2800 to 2200 Å. Below 2200 Å, the Venus albedo drops sharply due to CO2, absorption; the Jupiter albedo drops off by a factor of 4 due to NH3 absorption, an unidentified absorber, a decrease in the cloud particle albedo, or Borne combination of these effects.

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Baird Langenbrunner
,
J. David Neelin
,
Benjamin R. Lintner
, and
Bruce T. Anderson

Abstract

Projections of modeled precipitation (P) change in global warming scenarios demonstrate marked intermodel disagreement at regional scales. Empirical orthogonal functions (EOFs) and maximum covariance analysis (MCA) are used to diagnose spatial patterns of disagreement in the simulated climatology and end-of-century P changes in phase 5 of the Coupled Model Intercomparison Project (CMIP5) archive. The term principal uncertainty pattern (PUP) is used for any robust mode calculated when applying these techniques to a multimodel ensemble. For selected domains in the tropics, leading PUPs highlight features at the margins of convection zones and in the Pacific cold tongue. The midlatitude Pacific storm track is emphasized given its relevance to wintertime P projections over western North America. The first storm-track PUP identifies a sensitive region of disagreement in P increases over the eastern midlatitude Pacific where the storm track terminates, related to uncertainty in an eastward extension of the climatological jet. The second PUP portrays uncertainty in a zonally asymmetric meridional shift of storm-track P, related to uncertainty in the extent of a poleward jet shift in the western Pacific. Both modes appear to arise primarily from intermodel differences in the response to radiative forcing, distinct from sampling of internal variability. The leading storm-track PUPs for P and zonal wind change exhibit similarities to the leading uncertainty patterns for the historical climatology, indicating important and parallel sensitivities in the eastern Pacific storm-track terminus region. However, expansion coefficients for climatological uncertainties tend to be weakly correlated with those for end-of-century change.

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R. J. Breeding
,
P. L. Haagenson
,
J. A. Anderson
,
J. P. Lodge Jr.
, and
J. F. Stampfer Jr.

Abstract

The records from pollutant sensors abroad two aircraft are compared. The aircraft flew along arcs of either 80 or 120 km radius from the Gateway Arch in St. Louis. One aircraft contained a light-scattering instrument which determined the concentrations of particles with radii between 0.15 and 0.30 μm and between 0.30 and 1.3 μm. The other airplane contained an integrating nephelometer, a condensation nucleus counter, and an ozone monitor. It appears that neither the concentration of the condensation nuclei nor the ozone concentration are as reliable indicators of the location of the St. Louis plume at these distances as are data from the light-scattering particle counter or the nephelometer.

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