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Robert A. Baum

Abstract

This report, in two parts, consists of: 1) A summary of the statistics of the 1974 tropical cyclone activity in the eastern North Pacific Ocean. Storm tracks and activity tables comparing recent years are included. 2) A satellite picture analysis of individual storms and a sequence of daily pictures of eastern North Pacific hurricanes of the 1974 season.

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Robert A. Baum

Abstract

A summary of the 1975 Reason is presented. Included are seasonal statistics and forecast verification, storm tracks, and comparisons with activity in recent years.

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Robert A. Baum

Abstract

The 1973 tropical cyclone season in the eastern North Pacific Ocean is discussed and compared with recent past seasons. A comparison between reconnaissance aircraft wind speed estimates and satellite derived storm intensity is presented. The storm track and a brief discussion of each storm are included.

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ROBERT A. BAUM

Abstract

The 1972 tropical cyclone season in the eastern North Pacific Ocean is discussed and compared with past hurricane seasons. Pictures from the Advanced Technology Satellite series (ATS 1 and 3) show five storms or developing storms at, one time. Storm tracks and a brief discussion of each storm are included.

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ROBERT A. BAUM

Abstract

A résumé of the 1969 tropical cyclone season of the eastern North Pacific Ocean is presented. A comparison between aircraft reconnaissance and satellite wind-speed estimates is made with limited data. The presentation is a chronicle of individual tropical storms and hurricanes during 1969, including satellite pictures and near-synoptic post-reconnaissance debriefings.

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Robert W. Lenhard
and
Werner A. Baum

Abstract

The concept of a satisfactory normal monthly temperature is considered. January and July mean temperature records at seven stations in the United States are examined. It is found that, except in the western United States in summer, such temperature records may be accepted as constituting a random sample. It is also found that, in general, mean monthly temperatures are not normally distributed.

The method of confidence limits is applied to determination of a satisfactory normal temperature. Seasonal and geographical variations in reliability of normal temperatures are observed. Consideration is given to the adequacy with which the normal characterizes the temperature record, and to the influence of trends and cyclic fluctuations on this adequacy. It is suggested that a normal of desired reliability be computed from the most recent portion of the record to be most representative.

In general, normals computed for different periods of record will differ; but these differences may have little practical significance when the magnitude of the effect is considered relative to the requirements of the application.

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Bryan A. Baum
,
W. Paul Menzel
,
Richard A. Frey
,
David C. Tobin
,
Robert E. Holz
,
Steve A. Ackerman
,
Andrew K. Heidinger
, and
Ping Yang

Abstract

This paper summarizes the Collection-6 refinements in the Moderate Resolution Imaging Spectroradiometer (MODIS) operational cloud-top properties algorithm. The focus is on calibration improvements and on cloud macrophysical properties including cloud-top pressure–temperature–height and cloud thermodynamic phase. The cloud phase is based solely on infrared band measurements. In addition, new parameters will be provided in Collection 6, including cloud-top height and a flag for clouds near the tropopause. The cloud parameters are improved primarily through 1) improved knowledge of the spectral response functions for the MODIS 15-μm carbon dioxide bands gleaned from comparison of coincident MODIS and Atmospheric Infrared Sounder (AIRS) radiance measurements and 2) continual comparison of global MODIS and Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) instantaneous cloud products throughout the course of algorithm refinement. Whereas the cloud-top macrophysical parameters were provided through Collection 5 solely at 5-km spatial resolution, these parameters will be available additionally at 1-km spatial resolution in Collection 6.

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Chenxi Wang
,
Ping Yang
,
Steven Platnick
,
Andrew K. Heidinger
,
Bryan A. Baum
,
Thomas Greenwald
,
Zhibo Zhang
, and
Robert E. Holz

Abstract

A computationally efficient high-spectral-resolution cloudy-sky radiative transfer model (HRTM) in the thermal infrared region (700–1300 cm−1, 0.1 cm−1 spectral resolution) is advanced for simulating the upwelling radiance at the top of atmosphere and for retrieving cloud properties. A precomputed transmittance database is generated for simulating the absorption contributed by up to seven major atmospheric absorptive gases (H2O, CO2, O3, O2, CH4, CO, and N2O) by using a rigorous line-by-line radiative transfer model (LBLRTM). Both the line absorption of individual gases and continuum absorption are included in the database. A high-spectral-resolution ice particle bulk scattering properties database is employed to simulate the radiation transfer within a vertically nonisothermal ice cloud layer. Inherent to HRTM are sensor spectral response functions that couple with high-spectral-resolution measurements in the thermal infrared regions from instruments such as the Atmospheric Infrared Sounder (AIRS) and Infrared Atmospheric Sounding Interferometer. When compared with the LBLRTM and the discrete ordinates radiative transfer model (DISORT), the root-mean-square error of HRTM-simulated single-layer cloud brightness temperatures in the thermal infrared window region is generally smaller than 0.2 K. An ice cloud optical property retrieval scheme is developed using collocated AIRS and Moderate Resolution Imaging Spectroradiometer (MODIS) data. A retrieval method is proposed to take advantage of the high-spectral-resolution instrument. On the basis of the forward model and retrieval method, a case study is presented for the simultaneous retrieval of ice cloud optical thickness τ and effective particle size D eff that includes a cloud-top-altitude self-adjustment approach to improve consistency with simulations.

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Chenxi Wang
,
Ping Yang
,
Bryan A. Baum
,
Steven Platnick
,
Andrew K. Heidinger
,
Yongxiang Hu
, and
Robert E. Holz

Abstract

A computationally efficient radiative transfer model (RTM) is developed for the inference of ice cloud optical thickness and effective particle size from satellite-based infrared (IR) measurements and is aimed at potential use in operational cloud-property retrievals from multispectral satellite imagery. The RTM employs precomputed lookup tables to simulate the top-of-the-atmosphere (TOA) radiances (or brightness temperatures) at 8.5-, 11-, and 12-μm bands. For the clear-sky atmosphere, the optical thickness of each atmospheric layer resulting from gaseous absorption is derived from the correlated-k-distribution method. The cloud reflectance, transmittance, emissivity, and effective temperature are precomputed using the Discrete Ordinate Radiative Transfer model (DISORT). For an atmosphere containing a semitransparent ice cloud layer with a visible optical thickness τ smaller than 5, the TOA brightness temperature differences (BTDs) between the fast model and the more rigorous DISORT results are less than 0.1 K, whereas the BTDs are less than 0.01 K if τ is larger than 10. With the proposed RTM, the cloud optical and microphysical properties are retrieved from collocated observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) in conjunction with the Modern Era Retrospective-Analysis for Research and Applications (MERRA) data. Comparisons between the retrieved ice cloud properties (optical thickness and effective particle size) based on the present IR fast model and those from the Aqua/MODIS operational collection-5 cloud products indicate that the IR retrievals are smaller. A comparison between the IR-retrieved ice water path (IWP) and CALIOP-retrieved IWP shows robust agreement over most of the IWP range.

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Hearing on Senate Resolution 281

before the Subcommittee on Ocean and International Environment, Committee on Foreign Relations, United States Senate, July 27,1972

Dr. Richard J. Reed
,
Robert M. White
,
Gordon J. F. MacDonald
,
Thomas F. Malone
, and
Werner A. Baum
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