Noise Performance of the CrIS Instrument

The Cross-track Infrared Sounder (CrIS) is a spaceborne Fourier transform spectrometer (FTS) that was launched into orbit on 28 October 2011 onboard the Suomi National Polar-orbiting Partnership satellite. CrIS is a sophisticated sounding sensor that accurately measures upwelling infrared radiance at high spectral resolution. Data obtained from this sensor are used for atmospheric profiles retrieval and assimilation by numerical weather prediction models. Optimum vertical sounding resolution is achieved with high spectral resolution and multiple spectral channels; however, this can lead to increased noise. The CrIS instrument is designed to overcome this problem. Noise Equivalent Differential Radiance (NEdN) is one of the key parameters of the Sensor Data Record product. The CrIS on-orbit NEdN surpassesmission requirements with margin and has comparable or better performance when compared to heritage hyperspectral sensors currently on orbit. This paper describes CrIS noise performance through the characterization of the sensor’s NEdN and compares it to calibration data obtained during ground test. In addition, since FTS sensors can be affected by vibration that leads to spectrally correlated noise on top of the random noise inherent to infrared detectors, this paper also characterizes the CrIS NEdN with respect to the correlated noise contribution to the total NEdN. Lastly, the noise estimated from the imaginary part of the complex FTS spectra is extremely useful to assess andmonitor in-flight FTS sensor health. Preliminary results on the imaginary spectra noise analysis are also presented

Surface cloud forcing in the East Pacific stratus deck/cold tongue/ITCZ complex

Author Posting. © American Meteorological Society 2006. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Climate 19 (2006): 392–409, doi:10.1175/JCLI3620.1.Data from the Eastern Pacific Investigation of Climate Studies (EPIC) mooring array are used to evaluate the annual cycle of surface cloud forcing in the far eastern Pacific stratus cloud deck/cold tongue/intertropical convergence zone complex. Data include downwelling surface solar and longwave radiation from 10 EPIC-enhanced Tropical Atmosphere Ocean (TAO) moorings from 8°S, 95°W to 12°N, 95°W, and the Woods Hole Improved Meteorology (IMET) mooring in the stratus cloud deck region at 20°S, 85°W. Surface cloud forcing is defined as the observed downwelling radiation at the surface minus the clear-sky value. Solar cloud forcing and longwave cloud forcing are anticorrelated at all latitudes from 12°N to 20°S: clouds tended to reduce the downward solar radiation and to a lesser extent increase the downward longwave radiation at the surface. The relative amount of solar radiation reduction and longwave increase depends upon cloud type and varies with latitude. A statistical relationship between solar and longwave surface cloud forcing is developed for rainy and dry periods and for the full record length in six latitudinal regions: northeast tropical warm pool, ITCZ, frontal zone, cold tongue, southern, and stratus deck regions. The buoy cloud forcing observations and empirical relations are compared with the International Satellite Cloud Climatology Project (ISCCP) radiative flux data (FD) dataset and are used as benchmarks to evaluate surface cloud forcing in the NCEP Reanalysis 2 (NCEP2) and 40-yr ECMWF Re-Analysis (ERA-40). ERA-40 and NCEP2 cloud forcing (both solar and longwave) showed large discrepancies with observations, being too large in the ITCZ and equatorial regions and too weak under the stratus deck at 20°S and north to the equator during the cool season from July to December. In particular the NCEP2 cloud forcing at the equator was nearly identical to the ITCZ region and thus had significantly larger solar cloud forcing and smaller longwave cloud forcing than observed. The net result of the solar and longwave cloud forcing deviations is that there is too little radiative warming in the ITCZ and southward to 8°S during the warm season and too much radiative warming under the stratus deck at 20°S and northward to the equator during the cold season.This research was supported by grants from the NOAA Office of Global Programs, Pan American Climate Studies

Satellite moisture profiling of the tropical eastern Pacific convergence zone

Spring 1998.Bibliography: leaves 123-126

The Radiation Budget Instrument (RBI): Instrument Overview and Calibration Features

For the past three decades, the ERBE and CERES instruments have established a long-term data record for the total radiance being emitted and reflected from the Earth. This data record is critical to understanding the Earth’s radiation balance, which in turn is a key driver to climate change. NASA has recently selected Exelis to build the follow-on instrument which will continue the ERBE/CERES data records into the future. This new instrument is called the Radiation Budget Instrument, or RBI. Its first flight will be on the JPSS-2 satellite, which is planned for launched in 2021. RBI measures upwelling Earth radiance over an extremely broad spectral range, from the ultraviolet (0.3 microns) to the far-infrared (100 microns), separated into three spectral bands. RBI includes advanced onboard calibration sub-systems which ensure the highly precise radiometric accuracy and precision that are required to fulfill the radiation balance mission. RBI leverages existing flight-proven designs for many of its components; most of these components are taken from the successful Cross-track Infrared Sounder (CrIS) instrument, which has flown on the S-NPP satellite since 2011. This paper will describe the RBI mission, the key requirements for the RBI instrument, and the overall instrument design approach to be used. In particular, we will focus on details of the onboard calibration targets, and how these targets are used to ensure that calibration performance is maintained over the life of the instrument. Projections of RBI performance against the key requirements will also be discussed. RBI development plans and schedules will also be discussed

Radiation Budget Instrument (RBI) Performance Update

For the past three decades, the ERBE and CERES instruments have established a long-term data record for the total radiance being emitted and reflected from the Earth. This data record is critical to understanding the Earth’s radiation balance, which in turn is a key driver to climate change. The Radiation Budget Instrument (RBI) will continue the ERBE/CERES data records into the future. RBI’s first flight will be on the JPSS-2 satellite, which is planned for launch in 2021. RBI measures upwelling Earth radiance over an extremely broad spectral range, from the ultraviolet (0.3 microns) to the far-infrared (100 microns), separated into three spectral bands. RBI includes advanced onboard calibration sub-systems which provide the exceptionally precise radiometric accuracy and precision needed to fulfill the radiation balance mission. This paper will describe the RBI mission and the overall RBI instrument design approach, including recent design updates and details of the onboard calibration targets. The latest radiometric and spectral performance projections for the instrument will also be provided. In addition, test results from an RBI instrument prototype called the Radiometric Test Model will be discussed

Radiation Budget Instrument (RBI): Final Design and Initial EDU Test Results

For the past three decades, the Earth Radiation Budget Experiment (ERBE) and Clouds and the Earth’s Radiant Energy System (CERES) instruments have established a long-term data record for the total radiance being emitted and reflected from the Earth. This data record is critical to understanding the Earth’s radiation balance, which in turn is a key driver of seasonal weather and long-term climate measurements. The Radiation Budget Instrument (RBI) will continue the ERBE/CERES data records into the future. RBI measures upwelling Earth radiance over an extremely broad spectral range, from the ultraviolet (0.3 microns) to the far-infrared (100 microns), separated into three spectral bands. RBI includes advanced onboard calibration subsystems which provide the exceptionally precise radiometric uncertainty (with requirements of approximately 0.5%-1.0%) and repeatability (with requirements less than 0.25%) needed to fulfill the radiation balance mission. RBI’s first flight will be on the JPSS-2 satellite, which is planned for launch in 2021. RBI has recently completed its Critical Design Review (CDR), and testing of an Engineering Development Unit (EDU) is underway. This paper will describe final design of the RBI flight instrument and provide the latest projections for the radiometric and spectral performance of the instrument. In addition, test results from the EDU prototype will be discussed in detail

A Constellation of Fourier Transform Spectrometer (FTS) CubeSats for Global Measurements of Three-Dimensional Winds

Global measurements of vertically-resolved atmospheric wind profiles offer the potential for improved weather forecasts, including superior predictions of atmospheric wind patterns. A small-satellite constellation utilizing Fourier Transform Spectrometer (FTS) instruments onboard 6U CubeSats can provide measurements of global tropospheric wind profiles from space at very low cost. These small satellites are called FTS CubeSats. The constellation consists of groups of three FTS CubeSats flying in formation and separated by a specified time delay. This geometry enables moisture-field measurements which can be combined to provide vertically-resolved profiles of the wind field on a global basis. This paper will focus on recent advances in the maturity of the FTS CubeSat concept which includes an update of the flight concept, test results from a prototype of the FTS CubeSat, and development of more effective wind extraction algorithms