Experimental Evaluation of Ground-Based Microwave Radiometric Sensing of Atmospheric Temperature and Water Vapor Profiles

Decker, M. T.; Westwater, Ed R.; Guiraud, F. O.

doi:10.1175/1520-0450(1978)017<1788:eeogbm>2.0.co;2

Cited by 117 publications

(70 citation statements)

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“…The LWC profiling method in this study combines LWP statistical inversion retrievals (e.g., Westwater and Guiraud 1980) with a vertical cloud model (e.g., Karstens et al 1994;Löhnert and Crewell 2003) as LWC = LWC ad [1.239 − 0.145ln(h)], where LWC ad is the adiabatic LWC (Lewis 1951;Mizuno 2000) and h is the height (m) from the cloud base, which is obtained from the infrared TB and temperature profile of the first guess. Another method to obtain the LWC profile, the neural network method, combines liquid profile climatology from historical radiosondes (Decker et al 1978) with microwave and infrared observations ). The neural network method has demonstrated a LWC profile retrieval accuracy of 50% or better when compared to balloon-borne supercooled liquid sensors (Ware et al 2003;Serke et al 2013) and radar (Campos et al 2014).…”

Section: Methodsmentioning

confidence: 99%

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Ground-Based Microwave Radiometer Variational Analysis during No-Rain and Rain Conditions

Araki¹,

Murakami²,

Ishimoto³

et al. 2015

SOLA

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Ground-based microwave radiometer (MWR) has been used for high-frequency retrievals of thermodynamic environments. However, raindrops on the radome of MWR and in the air cause errors in retrievals during precipitation events. Although a recent study has noted that off-zenith observations with neural networks (NN) reduce the retrieval errors, the effect of off-zenith observations with one-dimensional variational (1DVAR) technique, which is known to be more accurate than other methods, has not been studied. We developed a new 1DVAR technique that considers the effect of cloud liquid water. We statistically investigated the accuracy of vertical profiles of atmospheric temperature and water vapor retrieved by NN and 1DVAR techniques by using zenith and off-zenith observation at 15° elevation angle under no-rain and rainy conditions and compared them with results of radiosonde observations. The results showed that the 1DVAR technique outperforms NN and numerical model simulation in the estimation of thermodynamic profiles under no-rain conditions. The results also indicated that the error in retrieved profiles in the low-level troposphere can be reduced by the 1DVAR technique by using off-zenith observations even under rainy conditions with rainfall rate less than 1.0 mm h −1 , especially when the environment cannot be accurately reproduced by a numerical model.(Citation: Araki, K., M. Murakami, H. Ishimoto, and T. Tajiri, 2015: Ground-based microwave radiometer variational analysis during no-rain and rain conditions. SOLA, 11, 108−112,

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Section: Methodsmentioning

confidence: 99%

“…The NN is trained by using a series of historical radiosonde data at Tateno, including modeled liquid profile (Decker et al 1978;Ware et al 2013). The vertical resolutions of NN-derived profiles are 50 m from the surface to 500 m, 100 m to 2 km, and 250 m to 10 km.…”

Section: Methodsmentioning

confidence: 99%

Ground-Based Microwave Radiometer Variational Analysis during No-Rain and Rain Conditions

Araki¹,

Murakami²,

Ishimoto³

et al. 2015

SOLA

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“…Stähli et al, 2013;Löhnert and Maier, 2012;Sánchez et al, 2013;Navas-Guzmán et al, 2016). Nevertheless, the specific effect of cloud liquid water on microwave temperature measurements has only been assessed in few studies (Decker et al, 1978;Cimini et al, 2011;Chan and Lee, 2015). Decker et al (1978) attempted a correction of temperature retrievals from a basic three-channel microwave radiometer by considering the absorption of cloud liquid water based on radiosonde measurements.…”

Section: Bernet Et Al: Cloud Effect On Temperature Retrievals Fromentioning

confidence: 99%

“…Nevertheless, the specific effect of cloud liquid water on microwave temperature measurements has only been assessed in few studies (Decker et al, 1978;Cimini et al, 2011;Chan and Lee, 2015). Decker et al (1978) attempted a correction of temperature retrievals from a basic three-channel microwave radiometer by considering the absorption of cloud liquid water based on radiosonde measurements. They stated that the correction for clouds can effectively reduce the error of temperature measurements.…”

Section: Bernet Et Al: Cloud Effect On Temperature Retrievals Fromentioning

confidence: 99%

The effect of cloud liquid water on tropospheric temperature retrievals from microwave measurements

2017

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Abstract. Microwave radiometry is a suitable technique to measure atmospheric temperature profiles with high temporal resolution during clear sky and cloudy conditions. In this study, we included cloud models in the inversion algorithm of the microwave radiometer TEMPERA (TEMPErature RAdiometer) to determine the effect of cloud liquid water on the temperature retrievals. The cloud models were built based on measurements of cloud base altitude and integrated liquid water (ILW), all performed at the aerological station (MeteoSwiss) in Payerne (Switzerland). Cloud base altitudes were detected using ceilometer measurements while the ILW was measured by a HATPRO (Humidity And Temperature PROfiler) radiometer. To assess the quality of the TEMPERA retrieval when clouds were considered, the resulting temperature profiles were compared to 2 years of radiosonde measurements. The TEMPERA instrument measures radiation at 12 channels in the frequency range from 51 to 57 GHz, corresponding to the left wing of the oxygen emission line complex. When the full spectral information with all the 12 frequency channels was used, we found a marked improvement in the temperature retrievals after including a cloud model. The chosen cloud model influenced the resulting temperature profile, especially for high clouds and clouds with a large amount of liquid water. Using all 12 channels, however, presented large deviations between different cases, suggesting that additional uncertainties exist in the lower, more transparent channels. Using less spectral information with the higher, more opaque channels only also improved the temperature profiles when clouds where included, but the influence of the chosen cloud model was less important. We conclude that tropospheric temperature profiles can be optimized by considering clouds in the microwave retrieval, and that the choice of the cloud model has a direct impact on the resulting temperature profile.

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“…Therefore, absorption caused by water droplets in clouds can be considered independent of their droplet size distribution and can be linearly related to cloud liquid water density. The estimation of this parameter, as well as the detection of cloud layers, can be performed through a variety of cloud detection algorithms detailed in the literature [19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Atmospheric Propagation at 100 and 300 Ghz: Assessment of a Method to Identify Rainy Conditions During Radiosoundings

Soria¹,

Riera²,

Garcia‐del‐Pino³

et al. 2012

PIER

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Abstract-The influence of atmospheric gases and tropospheric phenomena becomes more relevant at frequencies within the THz band (100 GHz to 10 THz), severely affecting the propagation conditions. The use of radiosoundings in propagation studies is a well established measurement technique in order to collect information about the vertical structure of the atmosphere, from which gaseous and cloud attenuation can be estimated with the use of propagation models. However, some of these prediction models are not suitable to be used under rainy conditions. In the present study, a method to identify the presence of rainy conditions during radiosoundings is introduced, with the aim of filtering out these events from yearly statistics of predicted atmospheric attenuation. The detection procedure is based on the analysis of a set of parameters, some of them extracted from synoptical observations of weather (SYNOP reports) and other derived from radiosonde observations (RAOBs). The performance of the method has been evaluated under different climatic conditions, corresponding to three locations in Spain, where colocated rain gauge data were available. Rain events detected by the method have been compared with those precipitations identified by the rain gauge. The pertinence of the method is discussed on the basis of an analysis of cumulative distributions of total attenuation at 100 and 300 GHz. This study demonstrates that the proposed method can be useful to identify events probably associated to rainy conditions. Hence, it can be considered as a suitable algorithm in order to filter out this kind of events from annual attenuation statistics.

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Experimental Evaluation of Ground-Based Microwave Radiometric Sensing of Atmospheric Temperature and Water Vapor Profiles

Cited by 117 publications

References 0 publications

Ground-Based Microwave Radiometer Variational Analysis during No-Rain and Rain Conditions

Ground-Based Microwave Radiometer Variational Analysis during No-Rain and Rain Conditions

The effect of cloud liquid water on tropospheric temperature retrievals from microwave measurements

Atmospheric Propagation at 100 and 300 Ghz: Assessment of a Method to Identify Rainy Conditions During Radiosoundings

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