A Multiwire Hot-Wire Device for Measurment of Icing Severity, Total Water Content, Liquid Water Content, and Droplet Diameter

2005 ◽  
Author(s):  
Lyle Lilie ◽  
Edward Emery ◽  
J. Strapp ◽  
Julia Emery
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Droplet Diameter ◽  
Liquid Water Content ◽  
Total Water Content ◽  
Hot Wire ◽  
Total Water

Airborne Measurement of Liquid and Total Water Content

2011 ◽  
Vol 28 (9) ◽  
pp. 1088-1103 ◽  
Author(s):  
German Vidaurre ◽  
John Hallett ◽  
David C. Rogers
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Single Point ◽  
Liquid Water Content ◽  
Point Of View ◽  
Total Water Content ◽  
Total Water ◽  
Single Probe ◽  
Stratiform Clouds ◽  
Spatial Differences

Abstract Two identical liquid water content (LWC) King probes—one total water content/liquid water content (TWC/LWC) Nevzorov probe and two constant-temperature T probes that are different in size to distinguish particles of different densities and diameters (section 2c)—were flown during the Alliance Icing Research Study (AIRS) II field campaign in the fall of 2003. This paper assesses measurements performed during several flights in mostly stratiform clouds. The two LWC King probes tracked well; however, discrepancies of up to 0.1 g m−3 for 1-s LWC measurements of 0.3 g m−3 were observed. Agreement between probes of different geometry and size was generally favorable, while levels of disagreement between the probes changed during numerous cloud penetrations from less than 20% up to a factor of 2, varying with flight conditions and microphysical structure of the cloud. Disagreement between probes was even larger when detecting ice water content (IWC). Measurement differences were attributed to different collection efficiencies resulting from preferred particle size, shape, and density and local aerodynamic effects around the aircraft. Measurements from a single probe are subject to uncertainty at a single point in time beyond the noise and drift level of the instrument. This uncertainty is evaluated considering particle habit, diameter, and density, and probe geometry and size, in addition to particle impact, breakup/splash, and bounce. From a working point of view, the intercomparison of several probes is subject to real but unknown spatial differences because of different locations between air samples. Comparison of identical probes is not appropriate because each measurement in itself is unique by definition. Thus, instead of duplication of instruments, subject to these levels of agreement, the use of a single probe is a practical approach while remaining aware of its limitations and capabilities.

scholarly journals On the Use of Hot-Wire Anemometers for Turbulence Measurements in Clouds

2007 ◽  
Vol 24 (6) ◽  
pp. 980-993 ◽  
Author(s):  
Holger Siebert ◽  
Katrin Lehmann ◽  
Raymond A. Shaw
Keyword(s):  
Wind Tunnel ◽  
Flow Velocity ◽  
Water Content ◽  
Liquid Water ◽  
Liquid Water Content ◽  
Hot Wire ◽  
Mean Flow ◽  
Velocity Signal ◽  
Turbulence Measurements ◽  
Mean Flow Velocity

The use of a hot-wire anemometer for high-resolution turbulence measurements in a two-phase flow (e.g., atmospheric clouds) is discussed. Experiments in a small wind tunnel (diameter of 0.2 and 2 m in length) with a mean flow velocity in the range between 5 and 16 m s−1 are performed. In the wind tunnel a spray with a liquid water content of 0.5 and 2.5 g m−3 is generated. After applying a simple despiking algorithm, power spectral analysis shows the same results as spectra observed without spray under similar flow conditions. The flattening of the spectrum at higher frequencies due to impacting droplets could be reduced significantly. The time of the signal response of the hot wire to impacting droplets is theoretically estimated and compared with observations. Estimating the fraction of time during which the velocity signal is influenced by droplet spikes, it turns out that the product of liquid water content and mean flow velocity should be minimized. This implies that for turbulence measurements in atmospheric clouds, a slowly flying platform such as a balloon or helicopter is the appropriate instrumental carrier. Examples of hot-wire anemometer measurements with the helicopter-borne Airborne Cloud Turbulence Observation System (ACTOS) are presented.

scholarly journals Response of the Nevzorov hot wire probe in Arctic clouds dominated by very large droplet sizes

2009 ◽  
Vol 2 (3) ◽  
pp. 1293-1320
Author(s):  
A. Schwarzenboeck ◽  
G. Mioche ◽  
A. Armetta ◽  
A. Herber ◽  
J.-F. Gayet
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Collection Efficiency ◽  
Supercooled Liquid ◽  
Liquid Water Content ◽  
The Arctic ◽  
Asymmetry Factor ◽  
Pure Liquid ◽  
Hot Wire ◽  
Data Set

Abstract. During the airborne research mission ASTAR 2004 (Arctic Study of Tropospheric Aerosols, Clouds and Radiation) performed over the island of Svalbard in the Arctic a constant-temperature hot-wire Nevzorov Probe designed for aircraft measurements, has been used onboard the aircraft POLAR 2. The Nevzorov probe measured liquid water (LWC) and total condensed water content (TWC) in supercooled liquid and partly mixed phase clouds, respectively. As for other hotwire probes the calculation of LWC and/or TWC (and thus the ice water content IWC) has to take into account the collection efficiencies of the two separate sensors for LWC and TWC which both react differently with respect to cloud phase and what is even more difficult to quantify with respect to the size of ice and liquid cloud particles. The study demonstrates that during pure liquid cloud sequences the ASTAR data set of the Nevzorov probe allowed to improve the quantification of the collection efficiency, particularly of the LWC probe part with respect to water. The improved quantification of liquid water content should lead to improved retrievals of IWC content. Simultaneous retrievals of LWC and IWC are correlated with the asymmetry factor derived from the Polar Nephelometer instrument.

scholarly journals A Technique for Estimating Liquid Droplet Diameter and Liquid Water Content in Stratocumulus Clouds Using Radar and Lidar Measurements

2020 ◽  
Vol 37 (11) ◽  
pp. 2145-2161
Author(s):  
Jothiram Vivekanandan ◽  
Virendra P. Ghate ◽  
Jorgen B. Jensen ◽  
Scott M. Ellis ◽  
M. Christian Schwartz
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Droplet Diameter ◽  
Particle Diameter ◽  
Liquid Water Content ◽  
Lidar Measurements ◽  
Stratocumulus Clouds ◽  
Characteristic Particle ◽  
Lidar Observations

AbstractThis paper describes a technique for estimating the liquid water content (LWC) and a characteristic particle diameter in stratocumulus clouds using radar and lidar observations. The uncertainty in LWC estimate from radar and lidar measurements is significantly reduced once the characteristic particle diameter is known. The technique is independent of the drop size distribution. It is applicable for a broad range of W-band reflectivity Z between −30 and 0 dBZ and all values of lidar backscatter β observations. No partitioning of cloud or drizzle is required on the basis of an arbitrary threshold of Z as in prior studies. A method for estimating droplet diameter and LWC was derived from the electromagnetic simulations of radar and lidar observations. In situ stratocumulus cloud and drizzle probe spectra were input to the electromagnetic simulation. The retrieved droplet diameter and LWC were validated using in situ measurements from the southeastern Pacific Ocean. The retrieval method was applied to radar and lidar measurements from the northeastern Pacific. Uncertainty in the retrieved droplet diameter and LWC that are due to the measurement errors in radar and lidar backscatter measurements are 7% and 14%, respectively. The retrieved LWC was validated using the concurrent G-band radiometer estimates of the liquid water path.

scholarly journals Response of the Nevzorov hot wire probe in clouds dominated by droplet conditions in the drizzle size range

2009 ◽  
Vol 2 (2) ◽  
pp. 779-788 ◽  
Author(s):  
A. Schwarzenboeck ◽  
G. Mioche ◽  
A. Armetta ◽  
A. Herber ◽  
J.-F. Gayet
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Collection Efficiency ◽  
Supercooled Liquid ◽  
Liquid Water Content ◽  
The Arctic ◽  
Asymmetry Factor ◽  
Pure Liquid ◽  
Hot Wire ◽  
Data Set

Abstract. During the airborne research mission ASTAR 2004 (Arctic Study of Tropospheric Aerosols, Clouds and Radiation) performed over the island of Svalbard in the Arctic a constant-temperature hot-wire Nevzorov Probe designed for aircraft measurements, has been used onboard the aircraft POLAR 2. The Nevzorov probe measured liquid water (LWC) and total condensed water content (TWC) in supercooled liquid and partly mixed phase clouds, respectively. As for other hotwire probes the calculation of LWC and/or TWC (and thus the ice water content IWC) has to take into account the collection efficiencies of the two separate sensors for LWC and TWC which both react differently with respect to cloud phase and what is even more difficult to quantify with respect to the size of ice and liquid cloud particles. The study demonstrates that during pure liquid cloud sequences the ASTAR data set of the Nevzorov probe allowed to improve the quantification of the collection efficiency, particularly of the LWC probe part with respect to water. The improved quantification of liquid water content should lead to improved retrievals of IWC content. Simultaneous retrievals of LWC and IWC are correlated with the asymmetry factor derived from the Polar Nephelometer instrument.

Icing Conditions Encountered by a Research Aircraft

1984 ◽  
Vol 23 (10) ◽  
pp. 1427-1440 ◽  
Author(s):  
Wayne R. Sand ◽  
William A. Cooper ◽  
Marcia K. Politovich ◽  
Donald L. Veal
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Droplet Diameter ◽  
Supercooled Liquid ◽  
Liquid Water Content ◽  
Ice Accumulation ◽  
Research Aircraft ◽  
Median Diameter ◽  
Different Seasons ◽  
Diameter Droplet

Abstract The characteristics of clouds which have led to airframe icing on an instrumented Beechcraft Super King Air are summarized. The icing encounters occurred at altitudes from 0–8000 m MSL, in summer and winter, in stratiform and cumuliform clouds, and at temperatures from 0 to −30°C. The characteristics of icing encounters in different areas and in different seasons are compared. The fraction of measurements exceeding various threshold values of liquid water content, average liquid water content over a given distance, volume-median droplet diameter, droplet concentration, ice crystal concentration, and potential ice accumulation are given. The effects of these cloud characteristics on aircraft performance were measured by comparing the rate of climb of the aircraft with ice to the rate of climb for the clean aircraft under the same conditions. Most icing encounters led to a reduction in the rate of climb that increased linearly with the path integral of the supercooled liquid water content. The volume-median diameter had little correlation with changes in performance. Some potentially hazardous conditions, which decreased the rate of climb capability of this aircraft by 7–9 m s−1, are also discussed.

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