Climatological Model of Over-the-Horizon Radar

Radio Science ◽  
2018 ◽  
Vol 53 (9) ◽  
pp. 988-1001
Author(s):  
M. A. Cervera ◽  
D. B. Francis ◽  
G. J. Frazer
Keyword(s):  
Climatological Model

Results from a Climatological Model of Heavy Metals in Europe’s Atmosphere

1992 ◽  
pp. 503-511
Author(s):  
Joseph Alcamo ◽  
Jerzy Bartnicki ◽  
Krzysztof Olendrzynski ◽  
Jozef Pacyna
Keyword(s):  
Heavy Metals ◽  
Climatological Model

Integration of hydro-climatological model and remote sensing for glacier mass balance estimation

2019 ◽  
Author(s):  
Iwona Podsiadlo ◽  
Claudia Paris ◽  
Francesca Bovolo ◽  
Mattia Callegari ◽  
Ludovica De Gregorio ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Mass Balance ◽  
Glacier Mass Balance ◽  
Climatological Model

scholarly journals Characterization of model errors in the calculation of tangent heights for atmospheric infrared limb measurements

2014 ◽  
Vol 7 (7) ◽  
pp. 7701-7715
Author(s):  
M. Ridolfi ◽  
L. Sgheri
Keyword(s):  
Ray Tracing ◽  
Model Errors ◽  
Index Model ◽  
Retrieval Scheme ◽  
Climatological Model ◽  
Real Atmosphere ◽  
Main Factors ◽  
Middle Infrared ◽  
Tracing Method

Abstract. We review the main factors driving the calculation of the tangent height of spaceborne limb measurements: the ray-tracing method, the refractive index model and the assumed atmosphere. We find that commonly used ray-tracing and refraction models are very accurate, at least in the middle-infrared. The factor with largest effect in the tangent height calculation is the assumed atmosphere. Using a climatological model in place of the real atmosphere may cause tangent height errors up to ±200 m. Depending on the adopted retrieval scheme, these errors may have a significant impact on the derived profiles.

scholarly journals Evidence for tropospheric wind shear excitation of high-phase-speed gravity waves reaching the mesosphere using the ray-tracing technique

2015 ◽  
Vol 15 (5) ◽  
pp. 2709-2721 ◽  
Author(s):  
M. Pramitha ◽  
M. Venkat Ratnam ◽  
A. Taori ◽  
B. V. Krishna Murthy ◽  
D. Pallamraju ◽  
...  
Keyword(s):  
Ray Tracing ◽  
Gravity Waves ◽  
High Frequency ◽  
Phase Speed ◽  
Horizontal Wind ◽  
Climatological Model ◽  
Background Temperature ◽  
The Waves ◽  
High Phase ◽  
Mf Radar

Abstract. Sources and propagation characteristics of high-frequency gravity waves observed in the mesosphere using airglow emissions from Gadanki (13.5° N, 79.2° E) and Hyderabad (17.5° N, 78.5° E) are investigated using reverse ray tracing. Wave amplitudes are also traced back, including both radiative and diffusive damping. The ray tracing is performed using background temperature and wind data obtained from the MSISE-90 and HWM-07 models, respectively. For the Gadanki region, the suitability of these models is tested. Further, a climatological model of the background atmosphere for the Gadanki region has been developed using nearly 30 years of observations available from a variety of ground-based (MST radar, radiosondes, MF radar) and rocket- and satellite-borne measurements. ERA-Interim products are utilized for constructing background parameters corresponding to the meteorological conditions of the observations. With the reverse ray-tracing method, the source locations for nine wave events could be identified to be in the upper troposphere, whereas for five other events the waves terminated in the mesosphere itself. Uncertainty in locating the terminal points of wave events in the horizontal direction is estimated to be within 50–100 km and 150–300 km for Gadanki and Hyderabad wave events, respectively. This uncertainty arises mainly due to non-consideration of the day-to-day variability in the tidal amplitudes. Prevailing conditions at the terminal points for each of the 14 events are provided. As no convection in and around the terminal points is noticed, convection is unlikely to be the source. Interestingly, large (~9 m s−1km−1) vertical shears in the horizontal wind are noticed near the ray terminal points (at 10–12 km altitude) and are thus identified to be the source for generating the observed high-phase-speed, high-frequency gravity waves.

scholarly journals The impact of large scale ionospheric structure on radio occultation retrievals

2011 ◽  
Vol 4 (12) ◽  
pp. 2837-2850 ◽  
Author(s):  
A. J. Mannucci ◽  
C. O. Ao ◽  
X. Pi ◽  
B. A. Iijima
Keyword(s):  
Electron Density ◽  
Large Scale ◽  
Radio Occultation ◽  
Quiet Time ◽  
Ionospheric Electron Density ◽  
Observation Strategy ◽  
Climatological Model ◽  
Ionospheric Data Assimilation ◽  
Using Data ◽  
The Impact

Abstract. We study the impact of large-scale ionospheric structure on the accuracy of radio occultation (RO) retrievals. We use a climatological model of the ionosphere as well as an ionospheric data assimilation model to compare quiet and geomagnetically disturbed conditions. The presence of ionospheric electron density gradients during disturbed conditions increases the physical separation of the two GPS frequencies as the GPS signal traverses the ionosphere and atmosphere. We analyze this effect in detail using ray-tracing and a full geophysical retrieval system. During quiet conditions, our results are similar to previously published studies. The impact of a major ionospheric storm is analyzed using data from the 30 October 2003 "Halloween" superstorm period. At 40 km altitude, the refractivity bias under disturbed conditions is approximately three times larger than quiet time. These results suggest the need for ionospheric monitoring as part of an RO-based climate observation strategy. We find that even during quiet conditions, the magnitude of retrieval bias depends critically on assumed ionospheric electron density structure, which may explain variations in previously published bias estimates that use a variety of assumptions regarding large scale ionospheric structure. We quantify the impact of spacecraft orbit altitude on the magnitude of bending angle and retrieval error. Satellites in higher altitude orbits (700+ km) tend to have lower residual biases due to the tendency of the residual bending to cancel between the top and bottomside ionosphere. Another factor affecting accuracy is the commonly-used assumption that refractive index is unity at the receiver. We conclude with remarks on the implications of this study for long-term climate monitoring using RO.

A Climatological Model for 1-min Precipitation Rates

1995 ◽  
Vol 34 (5) ◽  
pp. 1020-1027 ◽  
Author(s):  
Paul Tattelman ◽  
Kevin P. Larson ◽  
Andrew J. Mazzella
Keyword(s):  
Climatological Model

scholarly journals The impact of large scale ionospheric structure on radio occultation retrievals

2011 ◽  
Vol 4 (3) ◽  
pp. 2525-2565 ◽  
Author(s):  
A. J. Mannucci ◽  
C. O. Ao ◽  
X. Pi ◽  
B. A. Iijima
Keyword(s):  
Large Scale ◽  
Radio Occultation ◽  
Observation Strategy ◽  
Climatological Model ◽  
Ionospheric Data Assimilation ◽  
Using Data ◽  
Temperature Retrieval ◽  
The Impact ◽  
Retrieval Bias

Abstract. We study the impact of large-scale ionospheric structure on the accuracy of radio occultation (RO) retrievals of atmospheric parameters such as refractivity and temperature. We use a climatological model of the ionosphere as well as an ionospheric data assimilation model to compare quiet and geomagnetically disturbed conditions. The largest contributor to ionospheric bias is physical separation of the two GPS frequencies as the GPS signal traverses the ionosphere and atmosphere. We analyze this effect in detail using ray-tracing and a full geophysical retrieval system. During quiet conditions, our results are similar to previously published studies. The impact of a major ionospheric storm is analyzed using data from the 30 October 2003 "Halloween" superstorm period. The temperature retrieval bias under disturbed conditions varies from 1 K to 2 K between 20 and 32 km altitude, compared to 0.2–0.3 K during quiet conditions. These results suggest the need for ionospheric monitoring as part of an RO-based climate observation strategy. We find that even during quiet conditions, the magnitude of retrieval bias depends critically on ionospheric conditions, which may explain variations in previously published bias estimates that use a variety of assumptions regarding large scale ionospheric structure. We quantify the impact of spacecraft orbit altitude on the magnitude of bending angle error. Satellites in higher altitude orbits (≧700 km) tend to have lower biases due to the tendency of the residual bending to cancel between the top and bottomside ionosphere. We conclude with remarks on the implications of this study for long-term climate monitoring using RO.

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