Using Lunar Observations to Assess Terra MODIS Thermal Emissive Bands Calibration

MODIS collects data in both the reflected solar and thermal emissive regions using 36 spectral bands. The center wavelengths of these bands cover the3.7 to 14.24 micron region. In addition to using its on-board calibrators (OBC), which include a full aperture solar diffuser (SD) and a blackbody (BB), lunar observations have been scheduled on a regular basis to support both Terra and Aqua MODIS on-orbit calibration and characterization. This paper provides an overview of MODIS lunar observations and their applications for the reflective solar bands (RSB) and thermal emissive bands (TEB) with an emphasis on potential calibration improvements of MODIS band 21 at 3.96 microns. This spectral band has detectors set with low gains to enable fire detection. Methodologies are proposed and examined on the use of lunar observations for the band 21 calibration. Also presented in this paper are preliminary results derived from Terra MODIS lunar observations and remaining challenging issues

Multi-stage collaborative efficiency measurement of scitech finance: network-DEA analysis and spatial impact research

Sci-tech and finance plays an increasingly important role and have become an important driving force in economic development. In China, the problem of insufficient financial support for sci-tech innovation is important to enterprises. According to the internal relationship between different stages of Sci-tech and the finance system, this paper is aimed at exploring the efficiency measurement method between sci-tech and finance systems. Firstly the multi-stage collaborative structure of sci-tech finance is built, where the system of sci-tech is divided into three stages including the R&D stage, transformation stage of sci-tech achievements and industrialization stage, and the financing channel is the input of the finance system into the sci-tech system at different stages. The measurement method of the multi-stage collaborative efficiency between sci-tech and finance systems is put forward by the framework of network DEA. Then, taking China as an example, we collect the information of 30 provinces and cities from 2009 to 2016 and measure the efficiency of each system and the collaborative efficiency of the both. The efficiency’s spatial correlation is tested by means of Moran index. Finally, the influencing factors of the collaborative efficiency are analyzed based on the spatial econometric regression model, which considers the financing channels and human capital. To sum up, there are significant differences in the sci-tech finance collaborative efficiency among regions in China. Among them, the collaborative efficiency of Beijing, Shanghai and Jiangsu ranks in the top three. Comparing the different stages of the sci-tech system, the commercialization stage is a weak link in many regions of China. Human capital and financing channels of sci-tech finance have different degrees of positive impact on the sci-tech finance collaborative efficiency. Among them, human capital plays a greater role in promoting the sci-tech finance collaborative development

Measurement method and model simulation of the benchmark line in the deformed frame of a heavy vehicle

Wheel alignment is an important item of vehicle detection to ensure the vehicle safety. The precision of wheel alignment is determined by the benchmark line which is the center line of the vehicle frame. A measurement method of the benchmark line for the deformed frame of heavy vehicle is deduced by constructing a model which consists of a laser bar with two laser range finders and a measurement bar with scale. The simulations are performed on a model of typical heavy vehicle CA1190 whose frame size is 11230 mm×860 mm. The simulation results of the center points are solved by the least squares method while the fitting line of the points for the benchmark line is also achieved in the simulation

Comparison of MODIS Solar Diffuser Stability Monitor Calibration Results for Different Operational Configurations

The MODIS instruments on the Terra and Aqua spacecraft use a sunlit solar diffuser (SD), with an optional SD attenuation screen (SDS), to calibrate the reflective solar bands. A solar diffuser stability monitor (SDSM) is used to track the SD reflectance degradation on orbit, by taking a ratio of the detector response when viewing the SD compared to the response when viewing the sun. The MODIS SDSMs have been operated both with and without the SDS in place. The SDSMs have also been operated in both a fixed and an alternating mode. In the alternating mode, the SDSM detectors view the SD, sun, and a dark background in an alternating pattern with the view changing on every MODIS scan within a single orbit. In the fixed mode, the SDSM detectors are fixed on the sun view for one orbit, and then are fixed on the SD view for the following orbit. This paper reviews the history of the SDSM operational configurations used throughout the MODIS missions and discusses the differences in the SD degradation results, which may be due to differences in sun-satellite geometry, SD signal level, and stray light effects. We highlight Aqua SDSM results from two recent dates in October 2017 and July 2019, where both the fixed and alternating mode calibrations were run on the same day, providing clear examples of the calibration differences. Additionally, we show how mixing the results from calibrations done with and without the SDS for Aqua MODIS can provide more stable results

On-Orbit Characterization of the MODIS SDSM Screen for Solar Diffuser Degradation Estimation

MODIS reflective solar bands (RSB) are calibrated on-orbit using a solar diffuser (SD) with its degradation tracked by an on-board solar diffuser stability monitor (SDSM). The SDSM has nine detectors with wavelengths from 0.41 to 0.94 micrometers. It is operated during each scheduled SD calibration event, making alternate observations of the Sun and the SD. Due to erroneous design parameters, which led to misalignment of the key elements in the SDSM, there are significant ripples in the Sun view responses as the solar viewing angle changes. At the mission beginning, the effect of the ripples was eliminated by normalizing each SDSM detector response to the response of detector 9 (D9) at 0.94 micrometers, assuming that D9 had no degradation. However, D9 degradation increases over MODIS operation times. Degradation of up to 2% has been recently observed in D9 for Terra MODIS. A newly implemented approach reduces the Sun view ripples using a look-up table (LUT) constructed using SDSM data carefully selected from a short period early in the mission lifetime. In this paper, we provide an overview of different approaches that have been applied over the years by the MODIS Characterization Support Team (MCST) to track the on-orbit SD degradation. We evaluate the overall SD and SDSM on-orbit performance for both Terra and Aqua MODIS, as well as the impact on the MODIS RSB calibration uncertainty

Measurement method and model simulation of the benchmark line in the deformed frame of a heavy vehicle

Wheel alignment is an important item of vehicle detection to ensure the vehicle safety. The precision of wheel alignment is determined by the benchmark line which is the center line of the vehicle frame. A measurement method of the benchmark line for the deformed frame of heavy vehicle is deduced by constructing a model which consists of a laser bar with two laser range finders and a measurement bar with scale. The simulations are performed on a model of typical heavy vehicle CA1190 whose frame size is 11230 mm×860 mm. The simulation results of the center points are solved by the least squares method while the fitting line of the points for the benchmark line is also achieved in the simulation

Status of Aqua MODIS Instrument On-Orbit Operation and Calibration

The Aqua MOderate resolution Imaging Spectroradiometer (MODIS) has successfully operated for nearly a decade, since its launch in May 2002. MODIS was developed and designed with improvements over its heritage sensors in terms of its overall spectral, spatial, and temporal characteristics, and with more stringent calibration requirements. MODIS carries a set of on-board calibrators that can be used to track and monitor its on-orbit radiometric, spectral, and spatial performance. Since launch, extensive instrument calibration and characterization activities have been scheduled and executed by the MODIS Characterization Support Team (MCST). These efforts are made to assure the quality of instrument calibration and L 1B data products, as well as support all science disciplines (land, ocean, and atmospheric) for continuous improvements of science data product quality. MODIS observations from both Terra and Aqua have significantly contributed to the science and user community over a wide range of research activities and applications. This paper provides an overview of Aqua MODIS on-orbit operation and calibration activities, instrument health status, and on-board calibrators (OBC) performance. On-orbit changes of key sensor parameters, such as spectral band radiometric responses, center wavelengths, and bandwidth, are illustrated and compared with those derived from its predecessor, Terra MODIS. Lessons and challenges identified from Aqua MODIS performance are also discussed in this paper. These lessons are not only critical to future improvements of Aqua MODIS on-orbit operation and calibration but also beneficial to its follow-on instrument, the Visible Infrared Imager Radiometer Suite (VIIRS) to be launched on NPOESS Preparatory Project (NPP) spacecraft