Path- and Area-Integrated Rainfall Measurement by Microwave Attenuation in the 1–3 cm Band

Atlas, David; Ulbrich, Carlton W.

doi:10.1175/1520-0450(1977)016<1322:paairm>2.0.co;2

Cited by 470 publications

(342 citation statements)

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“…In addition to these processes, the BL UFP can be impacted by in-cloud processes due to UFP mixing into cloud, followed by coagulation with cloud droplets. [Atlas and Ulbrich, 1977]. The collection efficiency is a function of airflow around the falling raindrop and depends on aerosol size.…”

Section: Methodsmentioning

confidence: 99%

Precipitation removal of ultrafine aerosol particles from the atmospheric boundary layer

Andronache

2004

J. Geophys. Res.

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[1] Ultrafine particles (UFP) formed in the boundary layer (BL) by nucleation processes need to grow up to a diameter d p $ 100 nm to become activated as cloud droplets (CD). The time required to reach d p = 100 nm is about 2-3 days for a typical growth rate of 5 nm h À1 . If precipitation occurs, most UFP are too small to become CD, and some particles are removed by scavenging processes. A model to estimate the UFP wet removal from the BL by rainfall and coagulation is presented. The scavenging coefficient that describes the decay of aerosol mass in various size bins is a function of aerosol size (d p ), rainfall rate (R), and BL background aerosol. The model is applied to determine the UFP 0.5-folding time (t 05 ) during rain events and results show that t 05 $ 1 hour for R $ 1 mm h À1 for newly created particles (d p < 10 nm) and t 05 $ 1 day for larger UFP (d p $ 10-100 nm). To infer the likelihood of UFP removal at a given location, the average time interval (Dt) between rain events with rainfall rate R = 1 mm h À1 at stations with different precipitation regimes was determined. Results show that on average, UFP are very effectively removed from the BL by below-cloud scavenging in tropical regions (Dt $ 1 day), removed to a significant extent in eastern U.S. regions (Dt $ 3 days), and are less likely to be removed in southwest U.S. regions (Dt $ 6-8 days), where the frequency of dry periods is high and UFP have sufficient time to grow.

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Section: Methodsmentioning

confidence: 99%

Precipitation removal of ultrafine aerosol particles from the atmospheric boundary layer

Andronache

2004

J. Geophys. Res.

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“…Atlas and Ulbrich (1977) and Q t (D) = CD for the microwave attenuation cross section as in Atlas and Ulbrich (1974). In the latter expression C and n would be dependent on radar wavelength and temperature.…”

Section: Generalization Of Rain Parameter Diagrammentioning

confidence: 72%

“…Each of these investigations uses raindrop size spectra collected with a momentum disdrometer which were analyzed to determine empirical t relations between R and each of the remote measurables Z, E, and A. For the latter measurable several radar wavelengths were considered and the results are discussed in Atlas and Ulbrich (1977) and reviewed in the next section; in this section only those results for the wavelength X= 3.22 cm A are illustrated. The Z-R, E-R and A-R relations found from these empirical analyses were then tested for accuracy of prediction in the manner described above.…”

Section: Simulations Of Remote Rainfall Measurementmentioning

confidence: 96%

“…It is sufficient to show as illustrations of the kinds of results obtained from such analyses those given by Ulbrich and Atlas (1977), Atlas and Ulbrich (1977), and by Ulbrich (1981). Each of these investigations uses raindrop size spectra collected with a momentum disdrometer which were analyzed to determine empirical t relations between R and each of the remote measurables Z, E, and A.…”

Section: Simulations Of Remote Rainfall Measurementmentioning

confidence: 99%

“…Only in the special case of ti 1 cm does the empirical A-R relation produce significantly better agreement between calculated and actual rainfall rates. The fortuitous circumstances which produce this good agreement are described by Atlas and Ulbrich (1977) and reviewed in the next section.…”

Section: Simulations Of Remote Rainfall Measurementmentioning

confidence: 99%

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The multiparameter remote measurement of rainfall

1984

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This paper is a critical survey of the measurement of rainfall by remote sensors. It is shown that single‐parameter radar rainfall measurements are limited because both reflectivity and rain rate are dependent on at least two parameters of the drop size distribution, viz., representative raindrop size and number concentration. Simulations are presented which use experimental raindrop size spectra and show the improvement in accuracy attainable through the use of combinations of two and three remote measurables. The spectrum of remote measurables is then reviewed. These include path integrated techniques of radiometry and of microwave and optical attenuation. A carefully designed short‐path microwave attenuation experiment which employs these techniques is sufficiently persuasive to show that the disappointing results achieved in many others was due largely to a combination of rain sampling problems and vertical air motions between the path and the gages. Other experiments reviewed show that when paths are colinear, attenuation deduced from radar and radiometry is in good agreement with that measured directly. Several dual‐wavelength radar methods are described which were aimed at improved measurements in small range increments but have produced generally disappointing results. However, when the total path attenuation estimated in this way, or by radiometry, is used as a constraint on the retrieval of rain profiles from the radar, the results are more promising. Selected experiments involving combinations of two or more of the three measurables, radar reflectivity Z, attenuation, and/or radiometry, show considerable promise when adequate account is taken of the sampling and air motion problems. The best results in gate‐by‐gate measurements have been achieved with dual polarization or differential reflectivity (ZDR). However, even these are subject to potentially large errors when the rainfall does not behave according to a priori assumptions embodied in the technique. An accompanying paper in this issue shows that the use of a third remote parameter in addition to Z and ZDR offers great promise. With a growing appreciation of the needs and the capabilities of the various techniques, the future of highly improved remote rainfall measurements seems bright.

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Two and a half years of country-wide rainfall maps using radio links from commercial cellular telecommunication networks

2016

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Although rainfall estimation employing microwave links from cellular telecommunication networks is recognized as a new promising measurement technique, its potential for long‐term large‐scale operational rainfall monitoring remains to be demonstrated. This study contributes to this endeavor by deriving a continuous series of rainfall maps from a large 2.5 year microwave link data set of, on average, 3383 links (2044 link paths) covering Netherlands (∼3.5 × 104 km2), a midlatitude country (∼5°E, ∼52°N) with a temperate climate. Maps are extensively verified against an independent gauge‐adjusted radar rainfall data set for different temporal (15 min, 1 h, 1 day, 1 month) and spatial (0.9, 74 km2) scales. The usefulness of different steps in the rainfall retrieval algorithm, i.e., a wet‐dry classification method and a filter to remove outliers, is systematically assessed. A novel dew filter is developed to correct for dew‐induced wet antenna attenuation, which, although a relative underestimation of 6% to 9% is found, generally yields good results. The microwave link rainfall estimation technique performs well for the summer months (June, July, August), even outperforming interpolation of automatic rain gauge data (with a density of ∼1 gauge per 1000 km2), but large deviations are found for the winter months (December, January, February). These deviations are generally expected to be related to frozen or melting precipitation. Hence, our results show the potential of commercial microwave links for long‐term large‐scale operational rainfall monitoring.

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Path- and Area-Integrated Rainfall Measurement by Microwave Attenuation in the 1–3 cm Band

Cited by 470 publications

References 0 publications

Precipitation removal of ultrafine aerosol particles from the atmospheric boundary layer

Precipitation removal of ultrafine aerosol particles from the atmospheric boundary layer

The multiparameter remote measurement of rainfall

Two and a half years of country-wide rainfall maps using radio links from commercial cellular telecommunication networks

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