Modifications to the Water Vapor Continuum in the Microwave Suggested by Ground-Based 150-GHz Observations

Turner, David D.; Cadeddu, Maria; Löhnert, Ulrich; Crewell, Susanne; Vogelmann, Andrew M.

doi:10.1109/tgrs.2009.2022262

Cited by 95 publications

(116 citation statements)

References 43 publications

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“…At this stage, the quality of radiosonde measurements and radiometric calibration is estimated. One of the strongest conclusions of [57], confirmed also in [63], is that the original model of [54] does not match the observations at 150 or 31.4 GHz. Unfortunately, many groups are still using the water vapor continuum model from this model (e.g., the models in the intercomparison study of [62]).…”

Section: Atmospheric Absorption Modelmentioning

confidence: 99%

“…A lot of studies were devoted to the investigations of the oxygen and water vapor coefficient  O2 and  H2O dependency on frequency (ν), atmospheric temperature (T), pressure (P), and water vapor density ρ [52][53][54][55][56][57][58]. In order to properly account for the radiative contribution of these gases, the radiative transfer models use the results of the accurate laboratory measurements of the parameters of their resonance lines (e.g., frequencies, strengths, half widths, shapes, temperature and pressure dependencies, etc.…”

Section: Atmospheric Absorption Modelmentioning

confidence: 99%

“…There are contributions in the far wings of the absorption lines, considered in most models as a -continuum‖ non-resonant absorption model. Improving the accuracy of the continuum absorption models has been an ongoing challenge for the radiative transfer community [57], especially for water vapor absorption. Some of the investigators adopt the parameters of a chosen spectral model and slightly modify either the strength of one or more lines or some other parameters.…”

Section: Atmospheric Absorption Modelmentioning

confidence: 99%

“…Since the accuracy of the absorption model dramatically influences the radiative transfer modeling results, many studies inter compared different absorption models [57,[60][61][62][63]. Such intercomparison is usually fulfilled for the downwelling radiation to minimize the errors associated with inaccurate estimation of the ocean constituent of the radiation.…”

Section: Atmospheric Absorption Modelmentioning

confidence: 99%

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An Updated Geophysical Model for AMSR-E and SSMIS Brightness Temperature Simulations over Oceans

2014

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Abstract:In this study, we considered the geophysical model for microwave brightness temperature (BT) simulation for the Atmosphere-Ocean System under non-precipitating conditions. The model is presented as a combination of atmospheric absorption and ocean emission models. We validated this model for two satellite instruments-for Advanced Microwave Sounding Radiometer-Earth Observing System (AMSR-E) onboard Aqua satellite and for Special Sensor Microwave Imager/Sounder (SSMIS) onboard F16 satellite of Defense Meteorological Satellite Program (DMSP) series. We compared simulated BT values with satellite BT measurements for different combinations of various water vapor and oxygen absorption models and wind induced ocean emission models. A dataset of clear sky atmospheric and oceanic parameters, collocated in time and space with satellite measurements, was used for the comparison. We found the best model combination, providing the least root mean square error between calculations and measurements. A single combination of models ensured the best results for all considered radiometric channels. We also obtained the adjustments to simulated BT values, as averaged differences between the model simulations and satellite measurements. These adjustments can be used in any research based on modeling data for removing model/calibration inconsistencies. We demonstrated the application of the model by means of the development of the new algorithm for sea surface wind speed retrieval from AMSR-E data.

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Section: Atmospheric Absorption Modelmentioning

confidence: 99%

Section: Atmospheric Absorption Modelmentioning

confidence: 99%

Section: Atmospheric Absorption Modelmentioning

confidence: 99%

Section: Atmospheric Absorption Modelmentioning

confidence: 99%

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An Updated Geophysical Model for AMSR-E and SSMIS Brightness Temperature Simulations over Oceans

2014

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“…The main factor contributing to the atmospheric opacity is water vapor, which very efficiently absorbs light in the THz range , Kuhn et al 2002 due to a continuum absorption spectrum formed by collisionally broadened absorption lines of water vapor in this frequency range (Clough et al 1989, Pickett et al 1998, Turner et al 2009). In order to characterize a site according to its atmospheric transparency to THz radiation, it is necessary to retrieve the precipitable water vapor (pwv) profile using remote sensing techniques such as microwave radiometry (Peter & Wentz & Meissner 2016), radiosonde humidity measurements (Liljegren et al 2001, Luini & Riva 2016, or indirectly via models of in situ climatological measurements (Lew & Uscka-Kowalkowska 2016) or GPS-delay studies (Bevis et al 1992, Niell et al 2001, Wang et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Low Dimensional Embedding of Climate Data for Radio Astronomical Site Testing in the Colombian Andes

Molano¹,

Suárez²,

Restrepo

et al. 2017

PASP

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Abstract. We set out to evaluate the potential of the Colombian Andes for millimeter-wave astronomical observations. Previous studies for astronomical site testing in this region have suggested that nighttime humidity and cloud cover conditions make most sites unsuitable for professional visible-light observations. Millimeter observations can be done during the day, but require that the precipitable water vapor column above a site stays below ∼10 mm. Due to a lack of direct radiometric or radiosonde measurements, we present a method for correlating climate data from weather stations to sites with a low precipitable water vapor column. We use unsupervised learning techniques to low-dimensionally embed climate data (precipitation, rain days, relative humidity, and sunshine duration) in order to group together stations with similar long-term climate behavior. The data were taken over a period of 30 years by 2046 weather stations across the Colombian territory. We find 6 regions with unusually dry, clear-sky conditions, ranging in elevations from 2200 to arXiv:1705.06121v4 [astro-ph.IM] 15 Sep 2017Low Dimensional Embedding of Climate Data for Radio Astronomical Site Testing 2 3800 masl. We evaluate the suitability of each region using a quality index derived from a Bayesian probabilistic analysis of the station type and elevation distributions. Two of these regions show a high probability of having an exceptionally low precipitable water vapor column. We compared our results with global precipitable water vapor maps and find a plausible geographical correlation with regions with low water vapor columns (∼ 10 mm) at an accuracy of ∼ 20 km. Our methods can be applied to similar datasets taken in other countries as a first step toward astronomical site evaluation.

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Observed relations between snowfall microphysics and triple‐frequency radar measurements

et al. 2015

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Recently published studies of triple-frequency radar observations of snowfall have demonstrated that naturally occurring snowflakes exhibit scattering signatures that are in some cases consistent with spheroidal particle models and in others can only be explained by complex aggregates. Until recently, no in situ observations have been available to investigate links between microphysical snowfall properties and their scattering properties. In this study, we investigate for the first time relations between collocated ground-based triple-frequency observations with in situ measurements of snowfall at the ground. The three analyzed snowfall cases obtained during a recent field campaign in Finland cover light to moderate snowfall rates with transitions from heavily rimed snow to open-structured, low-density snowflakes. The observed triple-frequency signatures agree well with the previously published findings from airborne radar observations. A rich spatiotemporal structure of triple-frequency observations throughout the cloud is observed during the three cases, which often seems to be related to riming and aggregation zones within the cloud. The comparison of triple-frequency signatures from the lowest altitudes with the ground-based in situ measurements reveals that in the presence of large (>5 mm) snow aggregates, a bending away in the triple-frequency space from the curve of classical spheroid scattering models is always observed. Rimed particles appear along an almost horizontal line in the triple-frequency space, which was not observed before. Overall, the three case studies indicate a close connection of triple-frequency signatures and snow particle structure, bulk snowfall density, and characteristic size of the particle size distribution.

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Modifications to the Water Vapor Continuum in the Microwave Suggested by Ground-Based 150-GHz Observations

Cited by 95 publications

References 43 publications

An Updated Geophysical Model for AMSR-E and SSMIS Brightness Temperature Simulations over Oceans

An Updated Geophysical Model for AMSR-E and SSMIS Brightness Temperature Simulations over Oceans

Low Dimensional Embedding of Climate Data for Radio Astronomical Site Testing in the Colombian Andes

Observed relations between snowfall microphysics and triple‐frequency radar measurements

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