Details:

Creators:
Robins, Robert E. ; Underwood, Kenneth ; Wang, Frank Y.
Robins, Robert E. ; Underwood, Kenneth ; Wang, Frank Y. Less -
Corporate Creators:
John A. Volpe National Transportation Systems Center (U.S.) ; Scientific Computing Associates LLC ; T & B Systems
John A. Volpe National Transportation Systems Center (U.S.) ; Scientific Computing Associates LLC ; T & B Systems Less -
Subject/TRT Terms:
[+]
Algorithms Data Collection Dry Potential Temperature Ground Effect Radar Acoustic Sounding System (RASS) Radiometers Temperature Gradients Temperature Measurement Temperature Sensors Turbulence Wakes Wake Turbulence
Resource Type:
Tech Report
Geographical Coverage:
Los Angeles (California)
Corporate Publisher:
American Meteorological Society
Abstract:
From July through September 2015, concurrent and collocated measurements of temperature profiles from two passive radiometers and a RADAR-RASS (Radio Acoustic Sounding System) were made at a site near the ocean just to the west of Los Angeles International Airport (LAX). This site is managed by the South Coast Air Quality Management District (SCAQMD). Temperature profiles for the same time period from NOAA’s Rapid Refresh (RAP) hourly-updated assimilation/modeling system were included in the collection of profile data. For all temperature profiles a standard algorithm was used to convert temperature to dry potential temperature (PT). Data acquired at times when there was precipitation or fog were discarded. Humidity effects were not considered. It is important to note that all sensors were well maintained during the data acquisition period and that the ground based remote temperature profiling instruments involved were not part of data assimilation for RAP.

The motivation for this data collection effort was the idea that intercomparisons of the data obtained from the various temperature profiling sources could be used to characterize the variability of potential temperature gradient (PTG) values. It was felt that such a study would be a useful contribution to aircraft wake turbulence R&D because PTG (along with atmospheric turbulence, wind and various aircraft parameters) is identified in the open literature as a key factor in determining the temporal and spatial evolution of wake turbulence. Note that PTG is directly related to atmospheric stability.

*Corresponding author address: Robert E. Robins, Scientific Computing Associates LLC, 1546 NE 140th Street, Seattle, WA 98125.

email: rerscicomp@gmail.com

See Reference List A for studies on temperature profile comparisons (note – At present the authors are not aware of studies on PTG comparisons), and see Reference List B for current literature on how stratification affects trailing vortex evolution.

The current effort is focused on PTG comparisons at an altitude of 250m because this level is representative for out of ground effect wake turbulence consideration. An estimate of this quantity may be obtained from the difference between PT measured at approximately 200m and 300m.

The observed scatter of PTG intercomparisons can be used as a practical way of quantifying the variability in measurements of PTG at 250m. This information is important for understanding the variability of aircraft wake vortex data as well as for providing bounds on the variability of the environmental data used for wake modeling. This effort is an integral part of the Federal Aviation Administration’s ongoing effort to examine and prototype additional weather based dynamic wake turbulence separation concepts.


Format:
PDF
Collection(s):
Volpe
Main Document Checksum:
[+]
urn:sha256:e99bdac329bf0d304c5fc77b10222899dd9870c2a1111fd5d28b6f3f4266b2db
Download URL:
https://rosap.ntl.bts.gov/view/dot/12412/dot_12412_DS1.pdf
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