Bruce I. Hauss

Improved VIIRS Day/Night Band Imagery With Near-Constant Contrast

The Suomi-NPP Visible Infrared Imager Radiometer Suite (VIIRS) instrument provides the next generation of visible/infrared imaging including the day/night band (DNB) with nominal bandwidth from 500 to 900 nm. Previous to VIIRS, the Defense Meteorological Satellite Program Operational Linescan System (OLS) measured radiances that spanned over seven orders of magnitude, using an onboard gain adjustment to provide the capability to image atmospheric features across the solar terminator, to observe nighttime light emissions over the globe, and to monitor the global distribution of clouds. The VIIRS DNB detects radiances that span over eight orders of magnitude, and because it has 13-14-b quantization (compared with 6 b for OLS) with three gain stages, the DNB has its full dynamic range at every part of the scan. One process that is applied to the VIIRS DNB radiances is a solar/lunar zenith angle dependent gain adjustment to create near-constant contrast (NCC) imagery. The at-launch NCC algorithm was designed to reproduce the OLS capability and, thus, was constrained to solar and lunar angles from 0° to 105°. This limitation has, in part, lead to suboptimal imagery due to the assumption that DNB radiances fall off exponentially beyond twilight. The VIIRS DNB ultrasensitivity in low-light conditions enables it to detect faint emissions from a phenomenon called airglow, thus invalidating the exponential fall-off assumption. Another complication to the NCC imagery algorithm is the stray light contamination that contaminates the DNB radiances in the astronomical twilight region. We address these issues and develop a solution that leads to high-quality imagery for all solar and lunar conditions.

Passive millimeter wave sensors for detection of buried mines

The detection of land mines and other ordnance on the battlefield has grown in importance with their increased use, not only for military personnel, but for civilians after hostilities have ceased. The need for new approaches and sensors to increase the speed and efficiency of methods to clear mines is an issue that must be addressed. A method to detect metal mines, on top of or buried under dry sand, is demonstrated using the passive detection of naturally occurring millimeter wave radiation (at 44 GHz) emanating from the scene. Measurements will be shown that indicate the feasibility of detection of metal under at least 3 inches of dry sand.

A passive millimeter wave camera for aircraft landing in low visibility conditions

Fog and low visibility conditions have hampered aviation since its inception. Fog-related accidents are numerous, and canceled take-offs and landings due to fog and low visibility conditions (Cat III) have significant economic impact on airlines, parcel carriers and general aviation. Millimeter waves have good propagation properties in weather and give adequate spatial resolution when used to image the forward scene. Passive millimeter wave focal plane array cameras are new sensors which, integrated into future guidance and landing systems, promise to be an effective aid, or alternative, to existing technology for aircraft landings and take-offs under Cat III conditions. They can produce visual-like radiometric images at real time frame rates (up to 30 Hz), and are directly amenable to image fusion with infrared and visible images. TRW has been actively involved in developing and productizing this technology both at the hardware and the system levels. >

Passive millimeter-wave video camera

A passive millimeter-wave (PMMW) camera capable of generating a real time display of the imaged scene, similar to video cameras, has been developed at TRW and is undergoing field testing. The camera operates at 89 GHz, acquiring images at a frame rate of 17 Hz. This work reports on the video imaging generated by the camera. This research is carried out under the Passive Millimeter-Wave Camera Consortium, a cost-shared program between the Defense Advanced Research Programs Agency and an industrial consortium that includes Honeywell, McDonnell Douglas and TRW. It is managed for the Department of Defense by NASA-LaRC.

End-to-end performance assessment of the National Polar-orbiting Operational Environmental Satellite System environmental data records

The tri-agency Integrated Program Office (IPO) is managing the development of the National Polar-orbiting Operational Environmental Satellite System (NPOESS). Later this decade, the IPO, through its prime contractor, Northrop Grumman Space Technology (NGST), will launch NPOESS spacecraft into three orbital planes (1330, 1730, and 2130 equatorial ascending nodal crossing times) to provide global coverage with a data refresh rate of approximately four hours. A globally distributed ground system will deliver 95 percent of the data within 26 minutes from the time of on-orbit collection. With the development of NPOESS, we are evolving the existing “weather” satellites into integrated environmental observing systems. To meet user-validated requirements, NPOESS will deliver global data for 55 Environmental Data Records (EDRs). Performance characteristics and attributes have been defined for each of the 55 parameters, including: horizontal/vertical resolution; mapping accuracy; measurement range; measurement precision and uncertainty; refresh rate; data latency; and geographic coverage. Long-term stability requirements have been defined for key parameters to ensure temporal consistency and continuity of data over the operational life of NPOESS. The actual EDR performances will be a result of the sensor and algorithm performances. In order for NPOESS program to determine estimates of EDR performance based on current design data and to assess potential sensor design changes or algorithm modifications, NGST developed an Integrated Weather Products Test Bed (IWPTB). This system can generate simulated radiances from mission/orbit variable, sensor variables, atmospheric and background conditions, and radiative transfer models. These simulated radiances at aperture are used with sensor models and spacecraft factors to generate simulated radiometric temperatures which are processed by science retrieval code to generate EDRs. This paper presents an assessment of the impact of the VIIRS sensor design modification to correct Modulated Instrument Background in the sensor’s optical train. This assessment, which focuses on the Sea Surface Temperature EDR in particular, was generated by the IWPTB end-to-end performance assessment capability.

Detection of land mines via a passive microwave radiometer

The concept of using passive microwave radiometers for the detection of buried objects is well rooted in the theory of radiation propagation through lossy media. As the dielectric discontinuity at the boundary layer between the foreign object and the soil cause a reflection of the incoming radiation,the object present different radiometric properties than the surrounding background, and becomes detectable as a change in the antenna temperature. Under a contract from the US Armys Night Vision and Electronics Sensors, TRW has designed and built two hand-held man- portable units, which employ the cold radiometric sky as the illuminating source. The units work at 1.7 and 5 GHz using direct RF-gain, total-power radiometers. The units were field-tested at the Army facility at Fort AP Hill during October of 1998. The test yielded a very exciting detection rate of 100 percent and a false alarm rate of 0.28/m2.

Detection of metal and plastic mines using passive millimeter waves

In a continuing effort to develop new sensor technologies for the detection of land mines and other UXO, a variety of plastic and metal mines were acquired for detection tests utilizing a passive millimeter wave sensor at 44 GHz and at 12 GHz. These inert mines were surface- laid, covered with dry leaves, or buried in sand or soil, and the resulting target scene was scanned from an overhead position using the single channel sensor, generating a 2D image of the minefield.

Differentiating between Clouds and Heavy Aerosols in Sun-Glint Regions

Abstract An approach is presented to distinguish between clouds and heavy aerosols in sun-glint regions with automated cloud classification algorithms developed for the National Polar-orbiting Operational Environmental Satellite System (NPOESS) program. The approach extends the applicability of an algorithm that has already been applied successfully in areas outside the geometric and wind-induced sun-glint areas of the earth over both land and water surfaces. The successful application of this approach to include sun-glint regions requires an accurate cloud phase analysis, which can be degraded, especially in regions of sun glint, because of poorly calibrated radiances of the National Aeronautics and Space Administration (NASA) Moderate Resolution Imaging Spectroradiometer (MODIS) sensor. Consequently, procedures have been developed to replace bad MODIS level 1B (L1B) data, which may result from saturation, dead/noisy detectors, or data dropouts, with radiometrically reliable values to create the Visible ...

Passive millimeter wave camera for enhanced vision systems

Passive millimeter wave (PMMW) sensors have been proposed as forward vision sensors for enhanced vision systems used in low visibility aircraft landing. This work reports on progress achieved to date in the development and manufacturing of a demonstration PMMW camera. The unit is designed to be ground and flight tested starting 1996. The camera displays on a head-up or head-down display unit a real time true image of the forward scene. With appropriate head-up symbology and accurate navigation guidance provided by global positioning satellite receivers on-board the aircraft, pilots can autonomously (without ground assist) execute category 3 low visibility take-offs and landings on non-equipped runways. We shall discuss utility of fielding these systems to airlines and other users.

A high‐performance approach for brightness temperature inversion

Brightness temperature inversion is one of the most essential tasks in satellite remote sensing data processing. Accurate calculation of brightness temperature is crucial for many remote sensing applications, such as land surface temperature retrieval, sea surface temperature retrieval, and active fire detection. Due to the huge amount of remote sensing data, performance is also very important for operational use. Major current approaches for brightness temperature inversion are iteration methods, Look‐Up‐Table (LUT) methods, and empirical formula methods. Some of these algorithms can invert brightness temperature efficiently with limited accuracy, while others can invert brightness temperature at high accuracy but have lower performance. It is desirable to develop an algorithm that can make the balance of accuracy and performance more flexible and can invert brightness temperature efficiently even at high accuracy. In this paper, we analyse the advantages and limitations of the current algorithms for brightness temperature inversion, and propose a new approach based on the high‐order approximation of the relationship between band‐averaged radiance and brightness temperature. Our approach has the advantages of high accuracy and flexibility. It can be vectorized easily to exploit the advanced features of current computing platforms and improve performance in operational data processing. For validation and analysis, we have applied this method to brightness temperature inversion of MODIS thermal infrared (TIR) measurements and compared with other algorithms for accuracy and performance. The results demonstrate that our approach can be used for operational data processing more flexibly and efficiently.