An assessment of microwave absorption models and retrievals of cloud liquid water using clear‐sky data

Marchand, Roger; Ackerman, Thomas P.; Westwater, Ed R.; Clough, S. A.; Cady‐Pereira, Karen; Liljegren, J. C.

doi:10.1029/2003jd003843

Cited by 67 publications

(74 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although there are 5-years of data used per month, these distributions should be regarded as rough estimates of the month-to-month differences in LWP. This is because recent research has found that MWR uncertainties exist in the LWP retrievals that limit the attainable accuracy to between 20-30 g m À2 [Liljegren and Lesht, 1996;Westwater et al, 2001;Marchand et al, 2003;Turner et al, 2007], which represents a large uncertainty compared to many of the values shown. Still the shift shown, from smaller to larger LWP from March through June, is consistent with climatological considerations that optically thinner stratiform cloud tend to occur in spring versus summer [e.g., Leontyeva and Stamnes, 1994].…”

mentioning

confidence: 99%

Expected magnitude of the aerosol shortwave indirect effect in springtime Arctic liquid water clouds

Lubin

Vogelmann

2007

Geophysical Research Letters

View full text Add to dashboard Cite

[1] Radiative transfer simulations are used to assess the expected magnitude of the diurnally-averaged shortwave aerosol first indirect effect in Arctic liquid water clouds, in the context of recently discovered longwave surface heating of order 3 to 8 W m À2 by this same aerosol effect detected at the Barrow, Alaska, ARM Site. We find that during March and April, shortwave surface cooling by the first indirect effect is comparable in magnitude to the longwave surface heating. During May and June, the shortwave surface cooling exceeds the longwave heating. Due to multiple reflection of photons between the snow or sea ice surface and cloud base, the shortwave first indirect effect may be easier to detect in surface radiation measurements than from space. Citation: Lubin, D., and A. M. Vogelmann [2] The search for indirect aerosol effects has taken a unique turn in the Arctic, in emphasizing longwave radiation before shortwave [Garrett et al., 2002]. This is in part due to the greater importance of longwave radiation relative to shortwave at high latitudes [e.g., Intrieri et al., 2002], and also due to the availability of high quality longwave spectral radiation measurements in the Arctic from which the indirect effect can be readily identified [Garrett and Zhao, 2006;Lubin and Vogelmann, 2006]. To date, the deployment in the high Arctic of advanced longwave spectroradiometers [Turner et al., 2003;Knuteson et al., 2004] has not been matched by similar instrumentation that cover the visible through near-IR wavelengths at which clouds both absorb and scatter radiation. We therefore do not yet have a comparable spectral capability in the Arctic to rigorously identify and quantify the shortwave aerosol for all applicable liquid water paths (LWP), as has been done recently for the longwave. The purpose of this study is to demonstrate the expected relative importance of the shortwave and longwave manifestations of the aerosol first indirect effect on the springtime Arctic radiative energy balance.[3] Garrett and Zhao [2006] analyzed Fourier Transform Infrared (FTIR) spectroradiometer data from the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) program North Slope of Alaska (NSA) site at Barrow, Alaska, and found that the presence of Arctic ''haze'' -an anthropogenic aerosol primarily of Eurasian industrial origin trapped in the Arctic winter and spring troposphere [Barrie, 1986] -reduces the mean effective droplet radius r e of Arctic liquid water clouds by 3 mm. This results in an increase in mean cloud emissivity for all LWP < 80 g m À2 such that downwelling longwave radiation at the Arctic surface increases by 3.3 to 5.5 W m À2 , with all other meteorological variables held constant. Lubin and Vogelmann [2006] performed a similar analysis of NSA FTIR spectroradiometer data, and found a reduction in mean cloud droplet effective radius of 4 mm in Arctic haze relative to background aerosol, and found an increase of 8.2 W m À2 in the downwelling surface longwave flux under liquid water clouds in the ...

show abstract

mentioning

confidence: 99%

Expected magnitude of the aerosol shortwave indirect effect in springtime Arctic liquid water clouds

Lubin

Vogelmann

2007

Geophysical Research Letters

View full text Add to dashboard Cite

show abstract

“…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%

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

2014

View full text Add to dashboard Cite

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.

show abstract

“…To stabilize the temperature of the receiver components, the packaging technique described in [1] was employed, consisting of an insulated cold-plate in a box, in a temperature controlled enclosure. The resulting component plate temperature stability limited the effect of receiver-gain rate-of-change to below 100 K/Hr, requiring system gain and offset calibrations only a few times a minute to achieve a sub-K measurement precision.…”

Section: Of 29mentioning

confidence: 99%

“…Several recent advances however make the development of a 183 GHz radiometer more practical today. These include the commercial availability of subharmonically 3 OF 29 pumped Schottky mixers and conical feed horns, and an ultra stable radiometer design developed at K-band by Tanner [1].…”

Section: Introductionmentioning

confidence: 99%

“…In dry conditions, 183 GHz brightness temperature changes by approximately 20 K for each millimeter change in total water vapor, so an instrument with a 1 K radiometric measurement precision can detect 0.05 mm change in the vapor column. This same measurement resolution would require a precision of less than 0.02 K with a 22 GHz radiometer-a level of precision that only a handful of radiometers have been able to approach, requiring an expensive development effort [1]. On the other hand, the 1 K precision needed at 183 GHz is a routine radiometer design goal.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Millimeter-wave Radiometer for High Sensitivity Water Vapor Profiling in Arid Regions

Pazmany¹

2006

View full text Add to dashboard Cite

EXECUTIVE SUMMARYThe Department of Energy (DOE) awarded a Phase II SBIR contract to ProSensing on July 1, 2003 to develop an operational 183 GHz water radiometer for ultra sensitive measurement of atmospheric water vapor column and integrated liquid water content in arid climate. The instrument is intended to be deployed at the North Slope of Alaska DOE ARM (Atmospheric Radiation Measurement) program site to extend radiometric water vapor monitoring through the driest, winter months. This report summarizes the results and accomplishments of this project.As part of this Phase II SBIR contract, ProSensing Inc. developed a ground-based and an airborne version of a four-channel 183 GHz (G-band) water Vapor Radiometer (GVR). The ground-based unit (Ground GVR) was completed in early 2005 and in April that year was deployed at the Great White DOE North Slope of Alaska ARM site, where it continuously collected data for over a year. In June 2006 the instrument was returned to ProSensing for minor maintenance and improvements and was returned in August for a second year of continuous operation. At the time of this report, the instrument was collecting data at the Barrow, AK ARM site. A more compact airborne 183 GHz radiometer (Airborne GVR) was completed and ground-tested in early 2006 and was successfully test flown onboard the National Research Center (NRC) of Canada Convair aircraft in August 2006. The Airborne GVR was returned to ProSensing for calibration in September, but was returned in October to be reinstalled in the NRC Canada Covair to participate in the NASA CloudSat satellite validation flights through the spring of 2007. Details of the radiometer design and example data were documented in a paper that has been accepted to be published in the TGARS (Transactions on Geoscience and Remote Sensing) journal (original manuscript attached). The validation of the data collected in Barrow, AK was described in a separate TGARS article (also attached), written by Cadeddu et al, and also accepted for publication. The ground instrument is planned to be permanently installed at the NSA ARM site in the fall of 2007.Through November 10, 2006, $119,649 has been spent on parts, $192,579 on direct salaries with total of $683,946 out of the budgeted $683,845 spent including over-head and administrational expenses. ProSensing also invested additional company funds to support the project. A Thermotron environmental chamber was purchased and installed for $20,583.62 and since August 2006, $13,329 company R&D funds have been spent to publish a refereed journal paper on the Ground GVR, to support the Barrow measurements with the Ground GVR, and on the calibration and the airborne campaign with the Airborne GVR onboard the NRC Canada Convair aircraft. ±Index Terms-Millimeter wave radiometry, remote sensing, precipitable water vapor and liquid water path retrieval. I. IntroductionMost ground-based atmospheric water vapor radiometers are designed to measure blackbody radiation near the 22 GHz water vapor absorption line, despite the ...

show abstract

An assessment of microwave absorption models and retrievals of cloud liquid water using clear‐sky data

Cited by 67 publications

References 20 publications

Expected magnitude of the aerosol shortwave indirect effect in springtime Arctic liquid water clouds

Expected magnitude of the aerosol shortwave indirect effect in springtime Arctic liquid water clouds

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

Millimeter-wave Radiometer for High Sensitivity Water Vapor Profiling in Arid Regions

Contact Info

Product

Resources

About