An aperture synthesis system produces ringing at sharp edges and other transitions in the observed field. In this article, we have developed an efficient multispectral deconvolution method, based on ...the Split Bregman total variation minimization technique, and it was successful in reducing image ringing, blurring, and distortion, while sharpening the image and preserving the information content. We also present a multispectral multi-frame super-resolution method that is robust to image noise and noise in the point spread function (PSF) and leads to additional improvements in spatial resolution. The methodologies are based on current research in sparse optimization and compressed sensing, which lead to unprecedented efficiencies in solving image reconstruction problems.
Aqua carries three microwave radiometers that form an integral part of the Atmospheric Infrared Sounder (AIRS) sounding suite. Two Advanced Microwave Sounding Unit-A modules, one operating with two ...channels in the 23-31-GHz range and one operating with 12 channels in the 50-60-GHz range and one channel at 89 GHz, provide all-weather temperature soundings and cloud information. The Humidity Sounder for Brazil operates with four channels in the 150-190-GHz range and provides all-weather humidity and cloud soundings. All are cross-track scanners, as is AIRS. While there are significant differences between these three instruments, they are sufficiently alike that a common approach can be used to calibrate them. We describe the instruments and their heritage, the onboard calibration system, and the ground-based calibration processing.
We report W-band GaN MMIC's that produce 96% more power at a frequency of 88 GHz in continuous wave (CW) operation than the highest power reported in this frequency band for the best competing solid ...state technology, the InP HEMT. W-band power module containing a single three stage GaN MMIC chip with 600 μm wide output stage produced over 842 mW of output power in CW-mode, with associated PAE of 14.7% and associated power gain of 9.3 dB. This performance was measured at MMIC drain bias of 14 V.
The atmospheric moisture and temperature profiles from the Atmospheric Infrared Sounder (AIRS)/Advanced Microwave Sounding Unit on the NASA Aqua mission, in combination with the precipitation from ...the Tropical Rainfall Measuring Mission (TRMM), are employed to study the vertical moist thermodynamic structure and spatial-temporal evolution of the Madden-Julian oscillation (MJO). The AIRS data indicate that, in the Indian Ocean and western Pacific, the temperature anomaly exhibits a trimodal vertical structure: a warm (cold) anomaly in the free troposphere (800-250 hPa) and a cold (warm) anomaly near the tropopause (above 250 hPa) and in the lower troposphere (below 800 hPa) associated with enhanced (suppressed) convection. The AIRS moisture anomaly also shows markedly different vertical structures as a function of longitude and the strength of convection anomaly. Most significantly, the AIRS data demonstrate that, over the Indian Ocean and western Pacific, the enhanced (suppressed) convection is generally preceded in both time and space by a low-level warm and moist (cold and dry) anomaly and followed by a low-level cold and dry (warm and moist) anomaly. The MJO vertical moist thermodynamic structure from the AIRS data is in general agreement, particularly in the free troposphere, with previous studies based on global reanalysis and limited radiosonde data. However, major differences in the lower-troposphere moisture and temperature structure between the AIRS observations and the NCEP reanalysis are found over the Indian and Pacific Oceans, where there are very few conventional data to constrain the reanalysis. Specifically, the anomalous lower-troposphere temperature structure is much less well defined in NCEP than in AIRS for the western Pacific, and even has the opposite sign anomalies compared to AIRS relative to the wet/dry phase of the MJO in the Indian Ocean. Moreover, there are well-defined eastward-tilting variations of moisture with height in AIRS over the central and eastern Pacific that are less well defined, and in some cases absent, in NCEP. In addition, the correlation between MJO-related midtropospheric water vapor anomalies and TRMM precipitation anomalies is considerably more robust in AIRS than in NCEP, especially over the Indian Ocean. Overall, the AIRS results are quite consistent with those predicted by the frictional Kelvin-Rossby wave/conditional instability of the second kind (CISK) theory for the MJO. PUBLICATION ABSTRACT
Previous multispectral sounders have consisted of infrared and microwave instruments operated asynchronously, with the data interpolated during ground processing to common fields of view (FOVs) for ...geophysical retrieval processing. To help achieve the high retrieval accuracy required for the Atmospheric Infrared Sounder (AIRS) system, the four instruments making up the AIRS suite are aligned and synchronized in such a way as to achieve common FOVs without interpolation. We describe the system, how the alignment is accomplished, and the plans to verify performance after launch and compensate for misalignments that might be revealed then.
This study explores relationships between lightning, cloud microphysics, and tropical cyclone (TC) storm structure in Hurricane Karl (16 September 2010) using data collected by the NASA DC-8 and ...Global Hawk (GH) aircraft during NASAs Genesis and Rapid Intensification Processes (GRIP) experiment. The research capitalizes on the unique opportunity provided by GRIP to synthesize multiple datasets from two aircraft and analyze the microphysical and kinematic properties of an electrified TC. Five coordinated flight legs through Karl by the DC-8 and GH are investigated, focusing on the inner-core region (within 50 km of the storm center) where the lightning was concentrated and the aircraft were well coordinated. GRIP datasets are used to compare properties of electrified and nonelectrified inner-core regions that are related to the noninductive charging mechanism, which is widely accepted to explain the observed electric fields within thunderstorms. Three common characteristics of Karls electrified regions are identified: 1) strong updrafts of 10-20 m s super(-1), 2) deep mixed-phase layers indicated by reflectivities >30 dBZ extending several kilometers above the freezing level, and 3) microphysical environments consisting of graupel, very small ice particles, and the inferred presence of supercooled water. These characteristics describe an environment favorable for in situ noninductive charging and, hence, TC electrification. The electrified regions in Karls inner core are attributable to a microphysical environment that was conducive to electrification because of occasional, strong convective updrafts in the eyewall.
The Aqua, SNPP (Suomi National Polar-orbiting Partnership), and JPSS (Joint Polar Satellite System) satellites carry a combination of hyperspectral infrared
sounders (AIRS, Atmospheric Infrared ...Sounder, and CrIS, Cross-track Infrared Sounder) and high-spatial-resolution narrowband imagers (MODIS, Moderate Resolution Imaging Spectroradiometer, and VIIRS, Visible Infrared Imaging Radiometer Suite). They provide an opportunity to acquire high-quality, long-term cloud
data records and are a key component of the existing Program of Record of
cloud observations. By matching observations from sounders and imagers
across different platforms at the pixel scale, this study evaluates the
self-consistency and continuity of cloud retrievals from Aqua and SNPP by multiple
algorithms, including the AIRS version 7 retrieval algorithm and the
Community Long-term Infrared Microwave Combined Atmospheric Product System (CLIMCAPS) version 2 for sounders and the
standard Aqua MODIS collection 6.1 and the NASA MODIS–VIIRS continuity cloud
products for imagers. Metrics describing detailed statistical distributions
at the sounder field of view (FOV) and the joint histograms of cloud properties
are evaluated. These products are found to be highly consistent despite their
retrieval from different sensors using different algorithms. Differences
between the two sounder cloud products are mainly due to cloud clearing and
the treatment of clouds in scenes with unsuccessful atmospheric profile
retrievals. The sounder subpixel cloud heterogeneity evaluated using the
standard deviation of imager retrievals at the sounder FOV shows good agreement
between the standard and continuity products from different satellites.
However, the impact of algorithm and instrument differences between MODIS and
VIIRS is revealed in cloud top pressure retrievals and in the imager cloud
distribution skewness. Our study presents a unique aspect to examine NASA's
progress toward building a continuous cloud data record with sufficient
quality to investigate clouds' role in global environmental change.
The Humidity Sounder for Brazil (HSB) is a crucial component of the Atmospheric Infrared Sounder (AIRS) sounding suite and a valuable contribution from Brazil to the National Aeronautics and Space ...Administration's Aqua mission. Its design and functionality are practically identical to that of the Advanced Microwave Sounding Unit-B - proven on the latest National Oceanic and Atmospheric Administration's weather satellites. We briefly discuss its heritage, the measurement concept and principle of operation, and the design. The complex multinational acquisition process employed for HSB is described, along with the approach to be used for operations, derivation of radiometric and geophysical data products, and validation of those products - with emphasis on activities in Brazil. We also describe postlaunch research plans and discuss the importance of humidity observations in tropical regions like Brazil.
The Jet Propulsion Laboratory's High-Altitude Monolithic Microwave Integrated Circuit (MMIC) Sounding Radiometer (HAMSR) is a 25-channel cross-track scanning microwave sounder with channels near the ...60- and 118-GHz oxygen lines and the 183-GHz water-vapor line. It has previously participated in three hurricane field campaigns, namely, CAMEX-4 (2001), Tropical Cloud Systems and Processes (2005), and NASA African Monsoon Multidisciplinary Analyses (2006). The HAMSR instrument was recently extensively upgraded for the deployment on the Global Hawk (GH) unmanned aerial vehicle platform. One of the major upgrades is the addition of a front-end low-noise amplifier, developed by JPL, to the 183-GHz channel which reduces the noise in this channel to less than 0.1 K at the sensor resolution (~2 km). This will enable HAMSR to observe much smaller scale water-vapor features. Another major upgrade is an enhanced data system that provides onboard science processing capability and real-time data access. HAMSR has been well characterized, including passband characterization, along-scan bias characterization, and calibrated noise-performance characterization. The absolute calibration is determined in-flight and has been estimated to be better than 1.5 K from previous campaigns. In 2010, HAMSR participated in the NASA Genesis and Rapid Intensification Processes campaign on the GH to study tropical cyclone genesis and rapid intensification. HAMSR-derived products include observations of the atmospheric state through retrievals of temperature, water-vapor, and cloud-liquid-water profiles. Other products include convective intensity, precipitation content, and 3-D storm structure.
Ground based tests of the GeoSTAR (geostationary synthetic thinned array radiometer) demonstrator instrument are reported which simulate the view of the Earth from geosynchronous Earth orbit (GEO). ...The test used a 4-meter target disk mounted on a tower above the instrument to simulate the brightness of the earth with a contrasting cold background. Continuous observations at 50.3 GHz for over 100 hours, along with simultaneous atmospheric measurements from independent radiometers, yielded an excellent data set with which to test all aspects of the GeoSTAR calibration. This paper presents a preliminary look at these data, and presents an algorithm to remove the aliased background from the synthesized image.
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