Further improvements and validation for the Navy Atmospheric Vertical Surface Layer Model (NAVSLaM)

Frederickson, Paul A.

doi:10.1109/usnc-ursi.2015.7303526

Cited by 24 publications

(19 citation statements)

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“…The MAGIC data can be used for this purpose although the spatial coverage is limited. The EDH climatology data we used here were computed using the Navy Atmospheric Vertical Surface Layer Model (NAVSLaM) [ Frederickson , ]. The input to NAVSLaM is the atmospheric temperature and specific humidity at 2 m, wind speed at 10 m in the Climate Forecast System Reanalysis data set.…”

Section: Comparison Of Observations With Climatologysupporting

confidence: 91%

Anomalous propagation conditions over eastern Pacific Ocean derived from MAGIC data

2016

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This study characterizes the evaporation and elevated ducts, the most common types of ducts observed over the ocean, along a track of around 4000 km between the California coast and Hawaii. We analyzed 1 year (2012–2013) of ship‐based measurements made during the Marine Atmospheric Radiation Measurement GPCI (GEWEX cloud system study Pacific Cross‐Section Intercomparison) Investigation of Clouds (MAGIC) campaign. During this period, the ship made multiple transects between Southern California and Hawaii. While the ship‐based in situ measurements and the radiosonde data served as the primary data source, a marine atmospheric surface layer model adapted from the Coupled Ocean‐Atmosphere Response Experiment 3.0 surface flux scheme is used to diagnose evaporative duct properties. Calculated mean evaporation duct heights based on shipboard measurements were found to increase steadily from 7 m offshore California to about 15 m near Hawaii. Overall 78% of duct heights are below 20 m. On average the evaporation duct strength is between ≈ 25 and 35 M units near Hawaii and about 15 M units near the California coast. A gradual transition from stratocumulus (Sc) dominated offshore California to trade wind regime with cumulus (Cu) clouds takes place along MAGIC track. The measured marine atmospheric boundary layer (MABL) height and the capping inversion characteristics are significantly different in the two regimes with MABL decoupling occurring in the longitude range between 125°W and 140°W along the track. The characteristics of the elevated ducts, obtained from the rawinsonde sounding profiles, are also different in the two regions west and east of the MABL decoupling region. Approximately 70–80% of the elevated ducts occur below 1.5 km east of the decoupling region, whereas almost equal percentage of ducts forms at heights above 1.5 km on the west side.

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Section: Comparison Of Observations With Climatologysupporting

confidence: 91%

Anomalous propagation conditions over eastern Pacific Ocean derived from MAGIC data

2016

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“…Depending on whether an "instantaneous" or "time-averaged" (i.e., turbulence is averaged out) predictive capability is needed, there have been two primary approaches to solving this environmental issue. The first, which addresses more of the time-averaged atmospheric condition scenario, is the development of robust numerical weather prediction (NWP) approaches [Fairall et al, 1996[Fairall et al, , 2003Haack et al, 2010;Frederickson et al, 2008;Frederickson, 2010]. For the "instantaneous" conditions, inversion approaches have become the most commonly implemented method, such as refractivity from clutter (RFC) techniques [Rogers et al, 2000;Gerstoft et al, 2003;Karimian et al, 2011Karimian et al, , 2013.…”

Section: Introductionmentioning

confidence: 99%

Global sensitivity of parabolic equation radar wave propagation simulation to sea state and atmospheric refractivity structure

Lentini

Hackett

2015

Radio Science

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Inadequate representation of the environment is a limitation for prediction of radar system performance as well as for validation of propagation codes. To improve understanding of how different environmental effects/parameters compete and compare, this study examines the sensitivity of radar wave propagation to a suite of environmental parameters for low grazing angle near‐surface radar systems at 3–15 GHz at horizontal and vertical polarizations. A global sensitivity analysis method is used, which accounts for parameter interactions, and propagation is modeled using the parabolic equation method. Environmental parameters examined include eight sea state parameters and eight parameters characterizing the vertical structure and character of range‐independent refractivity profiles. The relative importance of parameters varies more with frequency than polarization, and parameter interactions are found to be significant. Atmospheric mixed layer parameters are found to be the most sensitive, particularly the thickness of the mixed layer. The most significant ocean surface parameter is swell period, although sea directionality is important at 3 GHz and sea surface roughness and salinity are important at 9 and 15 GHz. Because of the spatial variability of sensitivity throughout the domain, regional analysis is performed to determine the most important parameters in different regions of the domain (1000 m in altitude and 60 km in range). These regional sensitivity results, along with those for the whole domain, provide guidance on prioritization of environmental characterization in numerical weather prediction and inversion studies (e.g., refractivity from clutter studies), which are two common methods currently used to address environmental effects on propagation.

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“…NAVSLaM is the U.S. Navy model for characterizing nearsurface radio-frequency refractivity over the ocean. NAVSLaM employs the Monin-Obukhov similarity theory (MOST) to find the air-sea fluxes, and, in conjunction with near-surface profiles of temperature and humidity, determines modified refractivity profiles [2]. In what follows, these profiles are taken as "ground truth" in comparison with XBBR determined estimates.…”

Section: Socal 2013 Resultsmentioning

confidence: 99%

“…The propagation loss between transmitters at multiple heights and receivers at multiple heights was measured, and the received power recorded at each of the receivers from each of the transmitters, standardized by the total received power, was compared to Variable Terrain Radio Parabolic Equation (VTRPE) [1] model predictions in order to estimate the EDH. Point meteorological data was also recorded and used with the Navy Atmospheric Vertical Surface Layer Model (NAVSLaM) [2] to obtain in-situ measurements of the EDH. Comparisons show a high degree of correlation between EDH values inferred from XBBR and from meteorological information.…”

mentioning

confidence: 99%

<inline-formula> <tex-math notation="LaTeX">$X$ </tex-math> </inline-formula>-Band Beacon-Receiver Array Evaporation Duct Height Estimation

Pozderac

Johnson

Yardim

et al. 2018

IEEE Trans. Antennas Propagat.

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Abstract-Two recent experimental campaigns have provided the opportunity to measure radiowave propagation and atmospheric conditions with the X-Band Beacon-Receiver (XBBR) array system. The XBBR consists of vertical arrays of transmitters and receivers for measuring X-band radio frequency propagation. When used to measure propagation near the sea surface, the resulting data can be used to obtain information on the evaporation duct height (EDH) and the refractivity profile of the lower atmosphere. Since ducted propagation acts as a leaky waveguide, the vertical array elements in various transmit and receive height combinations effectively observe differing combinations of the modal components propagating in the duct. The use of all transmitter/receiver combinations therefore improves estimation of duct properties.The first campaign deployed the XBBR off the coast of San Diego, CA during the SoCal 2013 experiment. The second campaign took place in La Jolla, CA at the Scripps Institution of Oceanography Pier for long-term measurement of propagation in the marine atmospheric boundary layer. The propagation loss between transmitters at multiple heights and receivers at multiple heights was measured, and the received power recorded at each of the receivers from each of the transmitters, standardized by the total received power, was compared to Variable Terrain Radio Parabolic Equation (VTRPE) [1] model predictions in order to estimate the EDH. Point meteorological data was also recorded and used with the Navy Atmospheric Vertical Surface Layer Model (NAVSLaM) [2] to obtain in-situ measurements of the EDH. Comparisons show a high degree of correlation between EDH values inferred from XBBR and from meteorological information.

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Further improvements and validation for the Navy Atmospheric Vertical Surface Layer Model (NAVSLaM)

Cited by 24 publications

References 0 publications

Anomalous propagation conditions over eastern Pacific Ocean derived from MAGIC data

Anomalous propagation conditions over eastern Pacific Ocean derived from MAGIC data

Global sensitivity of parabolic equation radar wave propagation simulation to sea state and atmospheric refractivity structure

<inline-formula> <tex-math notation="LaTeX">$X$ </tex-math> </inline-formula>-Band Beacon-Receiver Array Evaporation Duct Height Estimation

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