Advanced microwave sounding unit cloud and precipitation algorithms

Weng, Fuzhong; Zhao, Limin; Ferraro, Ralph; Poe, G.A.; Li, Xiaofan; Grody, Norman C.

doi:10.1029/2002rs002679

Cited by 277 publications

(187 citation statements)

References 16 publications

(30 reference statements)

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“…For example, for the AMSU-A sensor, which is dedicated to temperature measurements, such asymmetries have been reported by Weng et al [1999Weng et al [ , 2003. They proposed that the asymmetry could have resulted from several causes such as errors in polarization angle alignment and antenna pointing angle.…”

Section: Introductionmentioning

confidence: 95%

Monitoring scan asymmetry of microwave humidity sounding channels using simultaneous all angle collocations (SAACs)

et al. 2013

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[1] Simultaneous all angle collocations (SAACs) of microwave humidity sounders (AMSU-B and MHS) on-board polar orbiting satellites are used to estimate scan-dependent biases. This method has distinct advantages over previous methods, such as that the estimated scan-dependent biases are not influenced by diurnal differences between the edges of the scan and the biases can be estimated for both sides of the scan. We find the results are robust in the sense that biases estimated for one satellite pair can be reproduced by double differencing biases of these satellites with a third satellite. Channel 1 of these instruments shows the least bias for all satellites. Channel 2 has biases greater than 5 K, thus needs to be corrected. Channel 3 has biases of about 2 K and more and they are time varying for some of the satellites. Channel 4 has the largest bias which is about 15 K when the data are averaged for 5 years, but biases of individual months can be as large as 30 K. Channel 5 also has large and time varying biases for two of the AMSU-Bs. NOAA-15 (N15) channels are found to be affected the most, mainly due to radio frequency interference (RFI) from onboard data transmitters. Channel 4 of N15 shows the largest and time varying biases, so data of this channel should only be used with caution for climate applications. The two MHS instruments show the best agreement for all channels. Our estimates may be used to correct for scan-dependent biases of these instruments, or at least used as a guideline for excluding channels with large scan asymmetries from scientific analyses.

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Section: Introductionmentioning

confidence: 95%

Monitoring scan asymmetry of microwave humidity sounding channels using simultaneous all angle collocations (SAACs)

et al. 2013

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“…Emission from partially snow-covered land surface is obscured by water vapor absorption in that band. Moreover the chan-nels operating at frequencies greater than 85 GHz are more sensitive to scattering by snow so that it is possible to monitor snowfall within the atmosphere (Weng et al 2003;Skofronick-Jackson et al 2004;. The forthcoming Global Precipitation Mission (GPM) will include millimeter-wave radiometers to measure snowfall.…”

Section: Introductionmentioning

confidence: 99%

A Simple Model of the Millimeter-Wave Scattering Parameters of Randomly Oriented Aggregates of Finite Cylindrical Ice Hydrometeors

Weinman

Kim

2007

Journal of the Atmospheric Sciences

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Spaceborne millimeter-wave radiometric measurements offer the potential to observe snowfall at high latitudes. A spaceborne W-band cloud radar on CloudSat has been able to observe snow. There is thus a need for a relatively simple representation of millimeter-wave scattering parameters of snow that can be incorporated into algorithms to retrieve snowfall from remotely sensed millimeter-wave brightness temperature measurements and for computing the millimeter-wave backscatter phase function of randomly oriented aggregates of ice prisms or columns.The extinction coefficients, asymmetry factors, and backscatter phase functions describing scattering by randomly oriented aggregates of elongated cylinders were computed from the discrete dipole approximation. These parameters were also computed by means of a T-matrix model applied to single blunt cylinders by employing a phase delay that only depended on the frequency and the ratio of the volume to the projected area of the cylindrical aggregates. These scattering parameters were fitted by empirical analytical functions that only depended on that phase delay. This permitted consideration of numerous aggregate shapes with far less computational effort than that required by the discrete dipole approximation.The results of this analysis were applied to measurements of millimeter-wave extinction, radar reflectivity, and snow size distributions obtained during the SNOW-TWO field experiment conducted by the U.S. Army in 1984. Although the simultaneity of the various measurements was not well documented, the theoretical results fell within the range of measurement uncertainty. Model results of the extinction coefficient and asymmetry factor needed to compute 183-GHz brightness temperatures measured by the NOAA Advanced Microwave Sounding Unit-B (AMSU-B) radiometers are presented in the appendix.

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“…In the NOAA-18 MHS L1C data we have not found any systematic instrumental error. Weng et al (2003) developed an algorithm to retrieve the IWP using ice scattering at 89 and 150 GHz, which is known as the NOAA operational IWP product. Their retrieval algorithm yields effective ice particle size and IWP with cloud top and base temperatures derived from simultaneous AMSU-A channels.…”

Section: Description Of Data Sets and Modelsmentioning

confidence: 99%

CloudSat-constrained cloud ice water path and cloud top height retrievals from MHS 157 and 183.3 GHz radiances

Gong

2014

Atmos. Meas. Tech.

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Abstract. Ice water path (IWP) and cloud top height (h t ) are two of the key variables in determining cloud radiative and thermodynamical properties in climate models. Large uncertainty remains among IWP measurements from satellite sensors, in large part due to the assumptions made for cloud microphysics in these retrievals. In this study, we develop a fast algorithm to retrieve IWP from the 157, 183.3 ± 3 and 190.3 GHz radiances of the Microwave Humidity Sounder (MHS) such that the MHS cloud ice retrieval is consistent with CloudSat IWP measurements. This retrieval is obtained by constraining the empirical forward models between collocated and coincident measurements of CloudSat IWP and MHS cloud-induced radiance depression (T cir ) at these channels. The empirical forward model is represented by a lookup table (LUT) of T cir -IWP relationships as a function of h t and the frequency channel. With h t simultaneously retrieved, the IWP is found to be more accurate. The useful range of the MHS IWP retrieval is between 0.5 and 10 kg m −2 , and agrees well with CloudSat in terms of the normalized probability density function (PDF). Compared to the empirical model, current operational radiative transfer models (RTMs) still have significant uncertainties in characterizing the observed T cir -IWP relationships. Therefore, the empirical LUT method developed here remains an effective approach to retrieving ice cloud properties from the MHS-like microwave channels.

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Advanced microwave sounding unit cloud and precipitation algorithms

Cited by 277 publications

References 16 publications

Monitoring scan asymmetry of microwave humidity sounding channels using simultaneous all angle collocations (SAACs)

Monitoring scan asymmetry of microwave humidity sounding channels using simultaneous all angle collocations (SAACs)

A Simple Model of the Millimeter-Wave Scattering Parameters of Randomly Oriented Aggregates of Finite Cylindrical Ice Hydrometeors

CloudSat-constrained cloud ice water path and cloud top height retrievals from MHS 157 and 183.3 GHz radiances

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