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I. T. Wang

Abstract

Analytical relations are developed that relate the Monin-Obukhov parameter to a modified bulk Richardson number expressed in terms of measured wind speed and vertical temperature difference. Measured Monin-Obukhov parameters and Richardson numbers are compared with those calculated using these relations as well as those using the conversion schemes developed earlier by Golder. Measured surface heat and momentum fluxes under unstable conditions are also compared with those predicted using the present simple estimating scheme. Effects of different choices of parameters in the flux-profile relationship with respect to the predicted stability parameters and to the plume dispersion parameters are discussed.

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I. T. Wang
,
R. L. Myers
, and
C. M. McKinley

Abstract

By using an integrated form of the Businger-Dyer flux-gradient equations, routine measurements of wind speed and vertical temperature difference in the surface layer are related to low-level atmospheric turbulence and stability. It is suggested that surface wind speed and vertical temperature difference can be used directly to determine the vertical plume diffusion parameter for unstable conditions without using the conventional Pasquill stability index. Their application in the conventional stability scheme, for both stable and unstable conditions, is also discussed in detail.

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C. Prabhakara
,
I. Wang
,
A. T. C. Chang
, and
P. Gloersen

Abstract

The Nimbus 7 Scanning Multichannel Microwave Radiometer (SMMR) brightness temperature measurements over the global oceans have been examined with the help of statistical and empirical techniques. Such analyses show that zonal averages of brightness temperature measured by SMMR, over the oceans, on a large scale are primarily influenced by the water vapor in the atmosphere. Liquid water in the clouds and rain, which has a much smaller spatial and temporal scale, contributes substantially to the variability of the SMMR measurements within the latitudinal zones. The surface wind not only increase the surface emissivity but through its interactions with the atmosphere produces correlations, in the SMMR brightness temperature data, that have significant meteorological implications. It is found that a simple meteorological model can explain the general characteristics of these data. With the help of this model, methods are developed for investigation of surface temperature, liquid water content in the atmosphere, and surface wind speed over the global oceans. Monthly mean estimates of the sea surface temperature and surface winds are compared with ship measurements. Estimates of liquid water content in the atmosphere are consistent with earlier satellite measurements.

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William D. Collins
,
Junyi Wang
,
Jeffrey T. Kiehl
,
Guang J. Zhang
,
Daniel I. Cooper
, and
William E. Eichinger

Abstract

The properties of the marine boundary layer produced by the National Center for Atmospheric Research (NCAR) Community Climate Model version 3 (CCM3) are compared with observations from two experiments in the central and western equatorial Pacific. The main objective of the comparison is determining the accuracy of the ocean–atmosphere fluxes calculated by the model. The vertical thermodynamic structure and the surface fluxes calculated by the CCM3 have been validated against data from the Central Equatorial Pacific Experiment (CEPEX) and the Tropical Ocean Global Atmosphere–Tropical Atmosphere Ocean (TOGA–TAO) buoy array. The mean latent heat flux for the TOGA–TAO array is 92 W m−2, and the model estimate of latent flux is 109 W m−2. The bias of 17 W m−2 is considerably smaller than the overestimation of the flux by the previous version of the CCM. The improvement in the latent heat flux is due to a reduction in the surface winds caused by nonlocal effects of a new convective parameterization. The agreement between the mean sensible heat flux for the TOGA–TAO array and the model estimate has also been improved in the new version of the model. The current version of the CCM overestimates the sensible heat flux by 3.4 W m−2. The atmospheric temperature and water vapor mixing ratio from the lowest model layer are within 0.3 K and 0.4 g kg−1 of measurements obtained from radiosondes. The mean model value of the boundary layer height is within 13 m of the average height derived from a Raman lidar on board a ship in the CEPEX domain. There is some evidence that the biases in the model can be reduced further by modifying the bulk formulation of the surface fluxes.

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A. Bodas-Salcedo
,
K. D. Williams
,
M. A. Ringer
,
I. Beau
,
J. N. S. Cole
,
J.-L. Dufresne
,
T. Koshiro
,
B. Stevens
,
Z. Wang
, and
T. Yokohata

Abstract

Current climate models generally reflect too little solar radiation over the Southern Ocean, which may be the leading cause of the prevalent sea surface temperature biases in climate models. The authors study the role of clouds on the radiation biases in atmosphere-only simulations of the Cloud Feedback Model Intercomparison Project phase 2 (CFMIP2), as clouds have a leading role in controlling the solar radiation absorbed at those latitudes. The authors composite daily data around cyclone centers in the latitude band between 40° and 70°S during the summer. They use cloud property estimates from satellite to classify clouds into different regimes, which allow them to relate the cloud regimes and their associated radiative biases to the meteorological conditions in which they occur. The cloud regimes are defined using cloud properties retrieved using passive sensors and may suffer from the errors associated with this type of retrievals. The authors use information from the Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) lidar to investigate in more detail the properties of the “midlevel” cloud regime. Most of the model biases occur in the cold-air side of the cyclone composite, and the cyclone composite accounts for most of the climatological error in that latitudinal band. The midlevel regime is the main contributor to reflected shortwave radiation biases. CALIPSO data show that the midlevel cloud regime is dominated by two main cloud types: cloud with tops actually at midlevel and low-level cloud. Improving the simulation of these cloud types should help reduce the biases in the simulation of the solar radiation budget in the Southern Ocean in climate models.

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D. N. Whiteman
,
B. Demoz
,
K. Rush
,
G. Schwemmer
,
B. Gentry
,
P. Di Girolamo
,
J. Comer
,
I. Veselovskii
,
K. Evans
,
S. H. Melfi
,
Z. Wang
,
M. Cadirola
,
B. Mielke
,
D. Venable
, and
T. Van Hove

Abstract

The NASA Goddard Space Flight Center (GSFC) Scanning Raman Lidar (SRL) participated in the International H2O Project (IHOP), which occurred in May and June 2002 in the midwestern part of the United States. The SRL received extensive optical modifications prior to and during the IHOP campaign that added new measurement capabilities and enabled unprecedented daytime water vapor measurements by a Raman lidar system. Improvements were also realized in nighttime upper-tropospheric water vapor measurements. The other new measurements that were added to the SRL for the IHOP deployment included rotational Raman temperature, depolarization, cloud liquid water, and cirrus cloud ice water content. In this first of two parts, the details of the operational configuration of the SRL during IHOP are provided along with a description of the analysis and calibration procedures for water vapor mixing ratio, aerosol depolarization, and cirrus cloud extinction-to-backscatter ratio. For the first time, a Raman water vapor lidar calibration is performed, taking full account of the temperature sensitivity of water vapor and nitrogen Raman scattering. Part II presents case studies that permit the daytime and nighttime error statistics to be quantified.

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H. J. S. Fernando
,
I. Gultepe
,
C. Dorman
,
E. Pardyjak
,
Q. Wang
,
S. W Hoch
,
D. Richter
,
E. Creegan
,
S. Gaberšek
,
T. Bullock
,
C. Hocut
,
R. Chang
,
D. Alappattu
,
R. Dimitrova
,
D. Flagg
,
A. Grachev
,
R. Krishnamurthy
,
D. K. Singh
,
I. Lozovatsky
,
B. Nagare
,
A. Sharma
,
S. Wagh
,
C. Wainwright
,
M. Wroblewski
,
R. Yamaguchi
,
S. Bardoel
,
R. S. Coppersmith
,
N. Chisholm
,
E. Gonzalez
,
N. Gunawardena
,
O. Hyde
,
T. Morrison
,
A. Olson
,
A. Perelet
,
W. Perrie
,
S. Wang
, and
B. Wauer

Abstract

C-FOG is a comprehensive bi-national project dealing with the formation, persistence, and dissipation (life cycle) of fog in coastal areas (coastal fog) controlled by land, marine, and atmospheric processes. Given its inherent complexity, coastal-fog literature has mainly focused on case studies, and there is a continuing need for research that integrates across processes (e.g., air–sea–land interactions, environmental flow, aerosol transport, and chemistry), dynamics (two-phase flow and turbulence), microphysics (nucleation, droplet characterization), and thermodynamics (heat transfer and phase changes) through field observations and modeling. Central to C-FOG was a field campaign in eastern Canada from 1 September to 8 October 2018, covering four land sites in Newfoundland and Nova Scotia and an adjacent coastal strip transected by the Research Vessel Hugh R. Sharp. An array of in situ, path-integrating, and remote sensing instruments gathered data across a swath of space–time scales relevant to fog life cycle. Satellite and reanalysis products, routine meteorological observations, numerical weather prediction model (WRF and COAMPS) outputs, large-eddy simulations, and phenomenological modeling underpin the interpretation of field observations in a multiscale and multiplatform framework that helps identify and remedy numerical model deficiencies. An overview of the C-FOG field campaign and some preliminary analysis/findings are presented in this paper.

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H. J. S. Fernando
,
I. Gultepe
,
C. Dorman
,
E. Pardyjak
,
Q. Wang
,
S. W Hoch
,
D. Richter
,
E. Creegan
,
S. Gaberšek
,
T. Bullock
,
C. Hocut
,
R. Chang
,
D. Alappattu
,
R. Dimitrova
,
D. Flagg
,
A. Grachev
,
R. Krishnamurthy
,
D. K. Singh
,
I. Lozovatsky
,
B. Nagare
,
A. Sharma
,
S. Wagh
,
C. Wainwright
,
M. Wroblewski
,
R. Yamaguchi
,
S. Bardoel
,
R. S. Coppersmith
,
N. Chisholm
,
E. Gonzalez
,
N. Gunawardena
,
O. Hyde
,
T. Morrison
,
A. Olson
,
A. Perelet
,
W. Perrie
,
S. Wang
, and
B. Wauer
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T. Eidhammer
,
P. J. DeMott
,
A. J. Prenni
,
M. D. Petters
,
C. H. Twohy
,
D. C. Rogers
,
J. Stith
,
A. Heymsfield
,
Z. Wang
,
K. A. Pratt
,
K. A. Prather
,
S. M. Murphy
,
J. H. Seinfeld
,
R. Subramanian
, and
S. M. Kreidenweis

Abstract

The initiation of ice in an isolated orographic wave cloud was compared with expectations based on ice nucleating aerosol concentrations and with predictions from new ice nucleation parameterizations applied in a cloud parcel model. Measurements of ice crystal number concentrations were found to be in good agreement both with measured number concentrations of ice nuclei feeding the clouds and with ice nuclei number concentrations determined from the residual nuclei of cloud particles collected by a counterflow virtual impactor. Using lognormal distributions fitted to measured aerosol size distributions and measured aerosol chemical compositions, ice nuclei and ice crystal concentrations in the wave cloud were reasonably well predicted in a 1D parcel model framework. Two different empirical parameterizations were used in the parcel model: a parameterization based on aerosol chemical type and surface area and a parameterization that links ice nuclei number concentrations to the number concentrations of particles with diameters larger than 0.5 μm. This study shows that aerosol size distribution and composition measurements can be used to constrain ice initiation by primary nucleation in models. The data and model results also suggest the likelihood that the dust particle mode of the aerosol size distribution controls the number concentrations of the heterogeneous ice nuclei, at least for the lower temperatures examined in this case.

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P. Joe
,
S. Belair
,
N.B. Bernier
,
V. Bouchet
,
J. R. Brook
,
D. Brunet
,
W. Burrows
,
J.-P. Charland
,
A. Dehghan
,
N. Driedger
,
C. Duhaime
,
G. Evans
,
A.-B. Filion
,
R. Frenette
,
J. de Grandpré
,
I. Gultepe
,
D. Henderson
,
A. Herdt
,
N. Hilker
,
L. Huang
,
E. Hung
,
G. Isaac
,
C.-H. Jeong
,
D. Johnston
,
J. Klaassen
,
S. Leroyer
,
H. Lin
,
M. MacDonald
,
J. MacPhee
,
Z. Mariani
,
T. Munoz
,
J. Reid
,
A. Robichaud
,
Y. Rochon
,
K. Shairsingh
,
D. Sills
,
L. Spacek
,
C. Stroud
,
Y. Su
,
N. Taylor
,
J. Vanos
,
J. Voogt
,
J. M. Wang
,
T. Wiechers
,
S. Wren
,
H. Yang
, and
T. Yip

Abstract

The Pan and Parapan American Games (PA15) are the third largest sporting event in the world and were held in Toronto in the summer of 2015 (10–26 July and 7–15 August). This was used as an opportunity to coordinate and showcase existing innovative research and development activities related to weather, air quality (AQ), and health at Environment and Climate Change Canada. New observational technologies included weather stations based on compact sensors that were augmented with black globe thermometers, two Doppler lidars, two wave buoys, a 3D lightning mapping array, two new AQ stations, and low-cost AQ and ultraviolet sensors. These were supplemented by observations from other agencies, four mobile vehicles, two mobile AQ laboratories, and two supersites with enhanced vertical profiling. High-resolution modeling for weather (250 m and 1 km), AQ (2.5 km), lake circulation (2 km), and wave models (250-m, 1-km, and 2.5-km ensembles) were run. The focus of the science, which guided the design of the observation network, was to characterize and investigate the lake breeze, which affects thunderstorm initiation, air pollutant transport, and heat stress. Experimental forecasts and nowcasts were provided by research support desks. Web portals provided access to the experimental products for other government departments, public health authorities, and PA15 decision-makers. The data have been released through the government of Canada’s Open Data Portal and as a World Meteorological Organization’s Global Atmospheric Watch Urban Research Meteorology and Environment dataset.

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