Sea‐air and boundary layer temperatures measured by a scanning 5‐mm‐wavelength radiometer: Recent results

Westwater, Ed R.; Han, Yong; Irisov, V.; Leuskiy, V.; Trokhimovski, Y.G.; Fairall, C. W.; Jessup, Andrew T.

doi:10.1029/97rs02747

Cited by 10 publications

(9 citation statements)

References 13 publications

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“…Assuming that the instrumental random errors for the MWSR, the IRSR, and the radiosonde sensors are uncorrelated, we are able to say that the experiment achieved a RMS retrieval accuracy as low as 0.21 K for air temperature profiles up to 500 m and 0.20 for air/ sea temperature differences, with the last decreasing to 0.11 K for nighttime measurements. These values validate the accuracy estimated by previous investigators Westwater et al, 1998;Shaw et al, 2001], who considered a single scanning radiometer. These values also meet the accuracy required by marine boundary layer models to study the parameterization of atmosphere-ocean interactions [Schluessel et al, 1990;Fairall et al, 1996;Wick et al, 1996].…”

Section: Comments and Conclusionsupporting

confidence: 89%

“…However, Trokhimovski et al [1998] suggested that this technique results in an air/sea temperature difference retrieval accuracy better than 0.1 K, based on forward model simulations. Westwater et al [1998] found that microwave scanning radiometry yields rms accuracies of the order of 0.4 K for air/sea temperature difference when compared with nonscanning infrared measurements.…”

Section: Introductionmentioning

confidence: 99%

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Air temperature profile and air/sea temperature difference measurements by infrared and microwave scanning radiometers

Cimini¹,

Shaw²,

Westwater

et al. 2003

Radio Science

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[1] A system of two scanning radiometers has been developed by the National Oceanic and Atmospheric Administration/Environmental Technology Laboratory and deployed on the NOAA R/V Ronald H. Brown during the Nauru99 cruise in the tropical western Pacific in June and July 1999. The system is composed of a high-quality temperature sensor and two independent, vertically scanning radiometers, measuring atmospheric and oceanic emission in the microwave (MW), and infrared (IR) regions. Both radiometers measure emission from a uniformly mixed atmospheric gas: oxygen for MW (60 GHz) and carbon dioxide for IR (14.2 mm). The high atmospheric absorption at these frequencies allows one calibration point from the horizontal atmospheric view using the in situ temperature sensor measurements as a reference. The signal at all other scan angles is scaled relative to that at the horizontal, resulting in a differential technique that is independent of calibration offset. This technique provides continuous and accurate estimates of boundary layer air temperature profile and air/sea temperature difference. The main advantage of this technique is that the water skin temperature can be measured at different optical depths without disturbing the skin layer (magnitude order of microns). We first compare radiometric data collected during the experiment with simulations obtained by atmospheric and oceanic radiative transfer models. We then use statistical inversion techniques to estimate air temperature profiles from upward looking measurements, based on an a priori data set of about 1500 ship-based radiosonde observations. For the ''well-posed'' problem of air/sea temperature difference estimation, we apply a physical retrieval algorithm to the downward looking measurements, accounting for air attenuation and sea surface roughness. Then we show retrieval results and evaluate the achieved accuracy. Finally, we compare radiometric estimates with in situ measurements, discussing similarities and discrepancies.

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Section: Comments and Conclusionsupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Air temperature profile and air/sea temperature difference measurements by infrared and microwave scanning radiometers

Cimini¹,

Shaw²,

Westwater

et al. 2003

Radio Science

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“…D'Auria et al (1998) used 19, 35 and 85 GHz frequency observations to study cloud properties and to generate a database of cloud genera useful for radiative-transfer modelling. Westwater et al (1998) deployed a scanning MWR operating at a frequency of 5 mm (60 GHz) to study differences in boundary layer evolution over land and ocean. Their results showed the excellent agreement between atmospheric temperatures estimated by MWR and other measurements (meteorological towers and IR measurement).…”

Section: K Ramesh Et Al: Adaptive Neuro-fuzzy Inference Systemmentioning

confidence: 99%

Adaptive neuro-fuzzy inference system for temperature and humidity profile retrieval from microwave radiometer observations

et al. 2015

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Abstract. The retrieval of accurate profiles of temperature and water vapour is important for the study of atmospheric convection. Recent development in computational techniques motivated us to use adaptive techniques in the retrieval algorithms. In this work, we have used an adaptive neuro-fuzzy inference system (ANFIS) to retrieve profiles of temperature and humidity up to 10 km over the tropical station Gadanki (13.5 • N, 79.2 • E), India. ANFIS is trained by using observations of temperature and humidity measurements by co-located Meisei GPS radiosonde (henceforth referred to as radiosonde) and microwave brightness temperatures observed by radiometrics multichannel microwave radiometer MP3000 (MWR). ANFIS is trained by considering these observations during rainy and non-rainy days (ANFIS(RD + NRD)) and during non-rainy days only (AN-FIS(NRD)). The comparison of ANFIS(RD + NRD) and ANFIS(NRD) profiles with independent radiosonde observations and profiles retrieved using multivariate linear regression (MVLR: RD + NRD and NRD) and artificial neural network (ANN) indicated that the errors in the AN-FIS(RD + NRD) are less compared to other retrieval methods.The Pearson product movement correlation coefficient (r) between retrieved and observed profiles is more than 92 % for temperature profiles for all techniques and more than 99 % for the ANFIS(RD + NRD) technique Therefore this new techniques is relatively better for the retrieval of temperature profiles. The comparison of bias, mean absolute error (MAE), RMSE and symmetric mean absolute percentage error (SMAPE) of retrieved temperature and relative humidity (RH) profiles using ANN and ANFIS also indicated that profiles retrieved using ANFIS(RD + NRD) are significantly better compared to the ANN technique. The analysis of profiles concludes that retrieved profiles using ANFIS techniques have improved the temperature retrievals substantially; however, the retrieval of RH by all techniques considered in this paper (ANN, MVLR and ANFIS) has limited success.

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“…In this paper we analyze only data which are supported by the meteorological and turbulent flux measurements. Figure 4 shows the difference between water skin and air temperature determined by a scanning 5 mm radiometer Westwater et al, 1998] and wind speed U and direction rpt• measured from FLIP. The time intervals of blimp measurements are indicated in Figure 4 by horizontal lines.…”

Section: Paper Number 1999jc900315mentioning

confidence: 99%

Microwave polarimetric measurements of the sea surface brightness temperature from a blimp during the Coastal Ocean Probing Experiment (COPE)

Trokhimovski¹,

Irisov²,

Westwater³

et al. 2000

J. Geophys. Res.

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Abstract. Experimental data obtained with a microwave dual-frequency radiometer at 23.87 and 31.65 GHz and a polarimeter at 37.0 GHz installed on a blimp during the Coastal Ocean Probing Experiment in 1995 are analyzed. Observations of the downwelling atmospheric radiation as a function of angle were used to achieve a highly accurate absolute calibration. The dependence of the sea surface brightness temperature on nadir and azimuthal angles is considered. The experimental data are compared with theoretical calculations based on several models of sea wave spectra. (Figures 1 and 2). The radiometers could be scanned in elevation and azimuth to measure the angular and azimuthal dependence of the sea 6501

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Sea‐air and boundary layer temperatures measured by a scanning 5‐mm‐wavelength radiometer: Recent results

Abstract: In atmospheric studies, low-level temperature gradients are also important to meteorology and air pollution studies. The gradients can be determined 291

Cited by 10 publications

References 13 publications

Air temperature profile and air/sea temperature difference measurements by infrared and microwave scanning radiometers

Air temperature profile and air/sea temperature difference measurements by infrared and microwave scanning radiometers

Adaptive neuro-fuzzy inference system for temperature and humidity profile retrieval from microwave radiometer observations

Microwave polarimetric measurements of the sea surface brightness temperature from a blimp during the Coastal Ocean Probing Experiment (COPE)

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