scholarly journals Climatology of High Cloud Dynamics Using Profiling ARM Doppler Radar Observations

2013 ◽  
Vol 26 (17) ◽  
pp. 6340-6359 ◽  
Author(s):  
Heike Kalesse ◽  
Pavlos Kollias
Keyword(s):  
Great Plains ◽  
Doppler Radar ◽  
Doppler Velocity ◽  
High Cloud ◽  
Cloud Properties ◽  
Atmospheric Radiation Measurement ◽  
Air Motion ◽  
Standard Deviations ◽  
Macrophysical Properties ◽  
High Clouds

Abstract Ice cloud properties are influenced by cloud-scale vertical air motion. Dynamical properties of ice clouds can be determined via Doppler measurements from ground-based, profiling cloud radars. Here, the decomposition of the Doppler velocities into reflectivity-weighted particle velocity Vt and vertical air motion w is described. The methodology is applied to high clouds observations from 35-GHz profiling millimeter wavelength radars at the Atmospheric Radiation Measurement Program (ARM) Southern Great Plains (SGP) climate research facility in Oklahoma (January 1997–December 2010) and the ARM Tropical Western Pacific (TWP) site in Manus (July 1999–December 2010). The Doppler velocity measurements are used to detect gravity waves (GW), whose correlation with high cloud macrophysical properties is investigated. Cloud turbulence is studied in the absence and presence of GW. High clouds are less turbulent when GW are observed. Probability density functions of Vt, w, and high cloud macrophysical properties for the two cloud subsets (with and without GW) are presented. Air-density-corrected Vt for high clouds for which GW (no GW) were detected amounted to hourly means and standard deviations of 0.89 ± 0.52 m s−1 (0.8 ± 0.48 m s−1) and 1.03 ± 0.41 m s−1 (0.86 ± 0.49 m s−1) at SGP and Manus, respectively. The error of w at one standard deviation was estimated as 0.15 m s−1. Hourly means of w averaged around 0 m s−1 with standard deviations of ±0.27 (SGP) and ±0.29 m s−1 (Manus) for high clouds without GW and ±0.22 m s−1 (both sites) for high clouds with GW. The midlatitude site showed stronger seasonality in detected high cloud properties.

scholarly journals Radar Refractivity Retrieval: Validation and Application to Short-Term Forecasting

2005 ◽  
Vol 44 (3) ◽  
pp. 285-300 ◽  
Author(s):  
Tammy M. Weckwerth ◽  
Crystalyne R. Pettet ◽  
Frédéric Fabry ◽  
Shin Ju Park ◽  
Margaret A. LeMone ◽  
...  
Keyword(s):  
Great Plains ◽  
Doppler Radar ◽  
Doppler Velocity ◽  
Good Representation ◽  
Short Term ◽  
Near Surface ◽  
National Network ◽  
Low Level ◽  
Short Term Forecasting ◽  
Convection Initiation

Abstract This study will validate the S-band dual-polarization Doppler radar (S-Pol) radar refractivity retrieval using measurements from the International H2O Project conducted in the southern Great Plains in May–June 2002. The range of refractivity measurements during this project extended out to 40–60 km from the radar. Comparisons between the radar refractivity field and fixed and mobile mesonet refractivity values within the S-Pol refractivity domain show a strong correlation. Comparisons between the radar refractivity field and low-flying aircraft also show high correlations. Thus, the radar refractivity retrieval provides a good representation of low-level atmospheric refractivity. Numerous instruments that profile the temperature and moisture are also compared with the refractivity field. Radiosonde measurements, Atmospheric Emitted Radiance Interferometers, and a vertical-pointing Raman lidar show good agreement, especially at low levels. Under most daytime summertime conditions, radar refractivity measurements are representative of an ∼250-m-deep layer. Analyses are also performed on the utility of refractivity for short-term forecasting applications. It is found that the refractivity field may detect low-level boundaries prior to the more traditional radar reflectivity and Doppler velocity fields showing their existence. Data from two days on which convection initiated within S-Pol refractivity range suggest that the refractivity field may exhibit some potential utility in forecasting convection initiation. This study suggests that unprecedented advances in mapping near-surface water vapor and subsequent improvements in predicting convective storms could result from implementing the radar refractivity retrieval on the national network of operational radars.

Cirrus Microphysical Properties and Air Motion Statistics Using Cloud Radar Doppler Moments. Part II: Climatology

2008 ◽  
Vol 47 (12) ◽  
pp. 3221-3235 ◽  
Author(s):  
Min Deng ◽  
Gerald G. Mace
Keyword(s):  
Great Plains ◽  
Seasonal Variations ◽  
Radiative Heating ◽  
Ice Clouds ◽  
Cloud Radar ◽  
Microphysical Properties ◽  
Cloud Properties ◽  
Early Afternoon ◽  
Seasonal And Diurnal Variations ◽  
Air Motion

Abstract The algorithm described in Part I has been applied to the millimeter cloud radar observations from January 1999 to December 2005 at the Atmospheric Radiation Measurement Program (ARM) Southern Great Plains (SGP) and Tropical Western Pacific (including Manus and Nauru) sites. Approximately 10 000 cirrus hours from each of these sites were analyzed. Retrieved cloud properties including condensed mass, particle size, optical depth, and in-cloud vertical air motions were analyzed in terms of their geographical, seasonal, and diurnal variations. The analysis shows that tropical ice clouds observed by millimeter radar are very different from ice clouds at SGP, with the tropical clouds having slightly larger particle sizes and greater ice masses and being more likely to be associated with ascending air motions, in addition to being colder and higher in altitude. A positive residual of derived in-cloud air motion found in the tropical data likely provides evidence for lofting of air into the tropopause transition layer as a result of radiative heating. The midlatitude cirrus demonstrate strong seasonal variations with more frequent, thicker clouds occurring during the summer than during the winter. Very subtle seasonal variations are found for tropical ice clouds, and evidence is presented that cirrus properties vary interannually and are correlated with El Niño oscillations. In addition, it is found that tropical cirrus demonstrate a stronger diurnal cycle than cirrus of the midlatitudes, with the in-cloud updrafts peaking in the early afternoon.

scholarly journals First Observations of Tracking Clouds Using Scanning ARM Cloud Radars

2014 ◽  
Vol 53 (12) ◽  
pp. 2732-2746 ◽  
Author(s):  
Paloma Borque ◽  
Pavlos Kollias ◽  
Scott Giangrande
Keyword(s):  
Great Plains ◽  
Temporal Evolution ◽  
Department Of Energy ◽  
High Temporal Resolution ◽  
Advantages And Disadvantages ◽  
Weather Radars ◽  
Maximum Reflectivity ◽  
Cloud Properties ◽  
Atmospheric Radiation Measurement ◽  
Size Threshold

AbstractTracking clouds using scanning cloud radars can help to document the temporal evolution of cloud properties well before large-drop formation (weather radar “first echo”). These measurements also complement cloud and precipitation tracking using geostationary satellites and weather radars. Here, two-dimensional (2D) along-wind range–height indicator observations of a population of shallow cumuli (with and without precipitation) from the 35-GHz scanning Atmospheric Radiation Measurement Program (ARM) cloud radar (SACR) at the U.S. Department of Energy (DOE)–ARM Southern Great Plains (SGP) site are presented. Observations from the ARM SGP network of scanning precipitation radars are used to provide the larger-scale context of the cloud field and to highlight the advantages of the SACR to detect the numerous small nonprecipitating cloud elements. A new cloud identification and tracking algorithm (CITA) is developed to track cloud elements. In CITA, a cloud element is identified as a region having a contiguous set of pixels exceeding a preset reflectivity and size threshold. The high temporal resolution of the SACR 2D observations (30 s) allows for an area superposition criteria algorithm to match cloud elements at consecutive times. Following CITA, the temporal evolution of cloud-element properties (number, size, and maximum reflectivity) is presented. The vast majority of the designated elements during this cumulus event were short-lived nonprecipitating clouds having an apparent life cycle shorter than 15 min. The advantages and disadvantages of cloud tracking using an SACR are discussed.

scholarly journals High Cloud Properties from Three Years of MODIS Terra and Aqua Collection-4 Data over the Tropics

2007 ◽  
Vol 46 (11) ◽  
pp. 1840-1856 ◽  
Author(s):  
Gang Hong ◽  
Ping Yang ◽  
Bo-Cai Gao ◽  
Bryan A. Baum ◽  
Yong X. Hu ◽  
...  
Keyword(s):  
Cloud Fraction ◽  
South Pacific Convergence Zone ◽  
Convergence Zone ◽  
Ice Clouds ◽  
High Cloud ◽  
Convective Clouds ◽  
Cloud Properties ◽  
Deep Convective Clouds ◽  
The Tropics ◽  
High Clouds

Abstract This study surveys the optical and microphysical properties of high (ice) clouds over the Tropics (30°S–30°N) over a 3-yr period from September 2002 through August 2005. The analyses are based on the gridded level-3 cloud products derived from the measurements acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments aboard both the NASA Earth Observing System Terra and Aqua platforms. The present analysis is based on the MODIS collection-4 data products. The cloud products provide daily, weekly, and monthly mean cloud fraction, cloud optical thickness, cloud effective radius, cloud-top temperature, cloud-top pressure, and cloud effective emissivity, which is defined as the product of cloud emittance and cloud fraction. This study is focused on high-level ice clouds. The MODIS-derived high clouds are classified as cirriform and deep convective clouds using the International Satellite Cloud Climatology Project (ISCCP) classification scheme. Cirriform clouds make up more than 80% of the total high clouds, whereas deep convective clouds account for less than 20% of the total high clouds. High clouds are prevalent over the intertropical convergence zone (ITCZ), the South Pacific convergence zone (SPCZ), tropical Africa, the Indian Ocean, tropical America, and South America. Moreover, land–ocean, morning–afternoon, and summer–winter variations of high cloud properties are also observed.

scholarly journals Evaluation of gridded scanning ARM cloud radar reflectivity observations and vertical doppler velocity retrievals

2014 ◽  
Vol 7 (4) ◽  
pp. 1089-1103 ◽  
Author(s):  
K. Lamer ◽  
A. Tatarevic ◽  
I. Jo ◽  
P. Kollias
Keyword(s):  
Great Plains ◽  
Spatial Scales ◽  
Domain Size ◽  
Horizontal Wind ◽  
Cape Cod ◽  
Doppler Velocity ◽  
Cloud Radar ◽  
Stratiform Clouds ◽  
Atmospheric Observations ◽  
Atmospheric Radiation Measurement

Abstract. The scanning Atmospheric Radiation Measurement (ARM) cloud radars (SACRs) provide continuous atmospheric observations aspiring to capture the 3-D cloud-scale structure. Sampling clouds in 3-D is challenging due to their temporal–spatial scales, the need to sample the sky at high elevations and cloud radar limitations. Thus, a suggested scan strategy is to repetitively slice the atmosphere from horizon to horizon as clouds advect over the radar (Cross-Wind Range-Height Indicator – CW-RHI). Here, the processing and gridding of the SACR CW-RHI scans are presented. First, the SACR sample observations from the ARM Southern Great Plains and Cape Cod sites are post-processed (detection mask, gaseous attenuation correction, insect filtering and velocity de-aliasing). The resulting radial Doppler moment fields are then mapped to Cartesian coordinates with time as one of the dimensions. Next the Cartesian-gridded Doppler velocity fields are decomposed into the horizontal wind velocity contribution and the vertical Doppler velocity component. For validation purposes, all gridded and retrieved fields are compared to collocated zenith-pointing ARM cloud radar measurements. We consider that the SACR sensitivity loss with range, the cloud type observed and the research purpose should be considered in determining the gridded domain size. Our results also demonstrate that the gridded SACR observations resolve the main features of low and high stratiform clouds. It is established that the CW-RHI observations complemented with processing techniques could lead to robust 3-D cloud dynamical representations up to 25–30 degrees off zenith. The proposed gridded products are expected to advance our understanding of 3-D cloud morphology, dynamics and anisotropy and lead to more realistic 3-D radiative transfer calculations.

Characterization of Vertical Velocity and Drop Size Distribution Parameters in Widespread Precipitation at ARM Facilities

2012 ◽  
Vol 51 (2) ◽  
pp. 380-391 ◽  
Author(s):  
Scott E. Giangrande ◽  
Edward P. Luke ◽  
Pavlos Kollias
Keyword(s):  
Standard Deviation ◽  
Size Distribution ◽  
Great Plains ◽  
Rainfall Rate ◽  
Doppler Velocity ◽  
Small Scale ◽  
Drop Diameter ◽  
Dual Frequency ◽  
Raindrop Size Distribution ◽  
Air Motion

AbstractExtended, high-resolution measurements of vertical air motion and median volume drop diameter D0 in widespread precipitation from three diverse Atmospheric Radiation Measurement Program (ARM) locations [Lamont, Oklahoma, Southern Great Plains site (SGP); Niamey, Niger; and Black Forest, Germany] are presented. The analysis indicates a weak (0–10 cm−1) downward air motion beneath the melting layer for all three regions, a magnitude that is to within the typical uncertainty of the retrieval methods. On average, the hourly estimated standard deviation of the vertical air motion is 0.25 m s−1 with no pronounced vertical structure. Profiles of D0 vary according to region and rainfall rate. The standard deviation of 1-min-averaged D0 profiles for isolated rainfall rate intervals is 0.3–0.4 mm. Additional insights into the form of the raindrop size distribution are provided using available dual-frequency Doppler velocity observations at SGP. The analysis suggests that gamma functions better explain paired velocity observations and radar retrievals for the Oklahoma dataset. This study will be useful in assessing uncertainties introduced in the measurement of precipitation parameters from ground-based and spaceborne remote sensors that are due to small-scale variability.

scholarly journals Ground-based all-sky mid-infrared and visible imagery for purposes of characterizing cloud properties

2014 ◽  
Vol 7 (2) ◽  
pp. 637-645 ◽  
Author(s):  
D. I. Klebe ◽  
R. D. Blatherwick ◽  
V. R. Morris
Keyword(s):  
Great Plains ◽  
Precipitable Water ◽  
Mid Infrared ◽  
Cloud Properties ◽  
Cloud Height ◽  
Calibration Methods ◽  
Cloud Temperature ◽  
Atmospheric Radiation Measurement ◽  
Community Data ◽  
And Performance

Abstract. This paper describes the All Sky Infrared Visible Analyzer (ASIVA), a multi-purpose visible and infrared sky imaging and analysis instrument whose primary function is to provide radiometrically calibrated imagery in the mid-infrared (mid-IR) atmospheric window. This functionality enables the determination of diurnal fractional sky cover and estimates of sky/cloud temperature from which one can derive estimates of sky/cloud emissivity and cloud height. This paper describes the calibration methods and performance of the ASIVA instrument with particular emphasis on data products being developed for the meteorological community. Data presented here were collected during the Solmirus' ASIVA campaign conducted at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) Climate Research Facility from 21 May to 27 July 2009. The purpose of this campaign was to determine the efficacy of IR technology in providing reliable nighttime sky cover data. Significant progress has been made in the analysis of the campaign data over the past several years and the ASIVA has proven to be an excellent instrument for determining sky cover as well as the potential for determining sky/cloud temperature, sky/cloud emissivity, precipitable water vapor (PWV), and ultimately cloud height.

scholarly journals Ground-based all-sky mid-infrared and visible imagery for purposes of characterizing cloud properties

2013 ◽  
Vol 6 (4) ◽  
pp. 7985-8019
Author(s):  
D. I. Klebe ◽  
R. D. Blatherwick ◽  
V. R. Morris
Keyword(s):  
Great Plains ◽  
Mid Infrared ◽  
Southern Great Plains ◽  
Cloud Properties ◽  
Analysis Instrument ◽  
Calibration Methods ◽  
Cloud Temperature ◽  
Atmospheric Radiation Measurement ◽  
Community Data ◽  
And Performance

Abstract. This paper describes the All Sky Infrared Visible Analyzer (ASIVA), a multi-purpose visible and infrared sky imaging and analysis instrument whose primary function is to provide radiometrically calibrated imagery in the mid-infrared (mid-IR) atmospheric window. This functionality enables the determination of diurnal hemispherical cloud fraction (HCF) and estimates of sky/cloud temperature from which one can derive estimates of cloud emissivity and cloud height. This paper describes the calibration methods and performance of the ASIVA instrument with particular emphasis on data products being developed for the meteorological community. Data presented here were collected during a field campaign conducted at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) Climate Research Facility from 21 May to 27 July 2009. The purpose of this campaign was to determine the efficacy of IR technology in providing reliable nighttime HCF data. Significant progress has been made in the analysis of the campaign data over the past several years and the ASIVA has proven to be an excellent instrument for determining HCF as well as several other important cloud properties.

scholarly journals Comparison of ISS–CATS and CALIPSO–CALIOP Characterization of High Clouds in the Tropics

2020 ◽  
Vol 12 (23) ◽  
pp. 3946
Author(s):  
Pasquale Sellitto ◽  
Silvia Bucci ◽  
Bernard Legras
Keyword(s):  
Optical Properties ◽  
Space Station ◽  
Satellite Observation ◽  
Observation Data ◽  
Upper Troposphere ◽  
Cloud Properties ◽  
Synchronous Orbit ◽  
The Tropics ◽  
High Clouds

Clouds in the tropics have an important role in the energy budget, atmospheric circulation, humidity, and composition of the tropical-to-global upper-troposphere–lower-stratosphere. Due to its non-sun-synchronous orbit, the Cloud–Aerosol Transport System (CATS) onboard the International Space Station (ISS) provided novel information on clouds from space in terms of overpass time in the period of 2015–2017. In this paper, we provide a seasonally resolved comparison of CATS characterization of high clouds (between 13 and 18 km altitude) in the tropics with well-established CALIPSO (Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observation) data, both in terms of clouds’ occurrence and cloud optical properties (optical depth). Despite the fact that cloud statistics for CATS and CALIOP are generated using intrinsically different local overpass times, the characterization of high clouds occurrence and optical properties in the tropics with the two instruments is very similar. Observations from CATS underestimate clouds occurrence (up to 80%, at 18 km) and overestimate the occurrence of very thick clouds (up to 100% for optically very thick clouds, at 18 km) at higher altitudes. Thus, the description of stratospheric overshoots with CATS and CALIOP might be different. While this study hints at the consistency of CATS and CALIOP clouds characterizaton, the small differences highlighted in this work should be taken into account when using CATS for estimating cloud properties and their variability in the tropics.

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