Trutinor: A Conceptual Study for a Next-Generation Earth Radiant Energy Instrument

Uninterrupted and overlapping satellite instrument measurements of Earth’s radiation budget from space are required to sufficiently monitor the planet’s changing climate, detect trends in key climate variables, constrain climate models, and quantify climate feedbacks. The Clouds and Earth’s Radiant Energy System (CERES) instruments are currently making these vital measurements for the scientific community and society, but with modern technologies, there are more efficient and cost-effective alternatives to the CERES implementation. We present a compact radiometer concept, Trutinor (meaning “balance” in Latin), with two broadband channels, shortwave (0.2–3 μm) and longwave (5–50 μm), capable of continuing the CERES record by flying in formation with an existing imager on another satellite platform. The instrument uses a three-mirror off-axis anastigmat telescope as the front optics to image these broadband radiances onto a microbolometer array coated with gold black, providing the required performance across the full spectral range. Each pixel of the sensor has a field of view of 0.6°, which was chosen so the shortwave band can be efficiently calibrated using the Moon as an on-orbit light source with the same angular extent, thereby reducing mass and improving measurement accuracy, towards the goal of a gap-tolerant observing system. The longwave band will utilize compact blackbodies with phase-change cells for an absolute calibration reference, establishing a clear path for SI-traceability. Trutinor’s instrument breadboard has been designed and is currently being built and tested.

Poly-3-thienylboronic acid: a chemosensitive derivative of polythiophene

Poly-3-thiopheneboronic acid was synthesized by electrochemical polymerization from 3-thienylboronic acid dissolved in the mixture of boron trifluoride diethyl etherate and acetonitrile. Cyclic voltammetry during electropolymerization shows oxidative and reductive peaks growing in each next cycle. An investigation by scanning electron microscopy displayed the polymer layer like a highly flexible film of 110 nm thick with grains of 60–120 nm in size. Strong negative solvatochromic effect was observed. Optical spectra of poly-3-thienylboronic acid at different potentials and pH were studied. Potential cycling leads to a well reversible electrochromic effect. At pH 7.4, the increase of potential leads to the decrease in the absorption band at 480 nm and to the rise in the absorption band at 810 nm with an isosbestic point at 585 nm. Spectroelectrochemical behavior of poly-3-thienylboronic acid and polythiophene was compared. Binding of sorbitol at fixed electrode potential leads to an increase in the absorbance in the shortwave band and to the decrease in the longwave band; the effect depends on the electrode potential and pH. Perspectives of application of poly-3-thienylboronic acid as new chemosensitive material are discussed.

Radiometric Characteristics of the Broadband Radiometer (BBR) Instrument for the EarthCARE Mission

The Broadband Radiometer (BBR) is one of a suite of instruments to be flown on the Earth Clouds, Aerosol and Radiation Explorer (EarthCARE) space mission. Its role is to make broadband measurements of Earth radiance in terms of reflected solar radiation and emitted thermal infrared radiation for use with the other EarthCARE instruments for the study of Earth atmosphere processes. The Broadband Radiometer has its design based on the principles and heritage of previous instruments for studying the earth radiation budget (ERB). The radiometer has common features with those instruments: two measurement bands—shortwave (solar energy of 0.25–4 µm) and total wave (0.25 to >50 µm)—with a longwave band (thermal emission of 4 to >50 µm) being obtained by subtraction of the two measured bands. Multiple simultaneous views of Earth at three different view angles are used to account for angular variations in radiance. The radiometer requires an accuracy of 1% in each band, similar to those of the previous instruments, and detailed calibration measurements on ground and in orbit. This paper describes the instrument calibration algorithms and the corresponding requirements on the ground calibration of the flight instrument prior to launch. It includes a description of the main methods to be used and the error sources to be controlled, based on the design heritage and analysis results of the previous ERB instruments.

Temperature Effect on the Absorption and Fluorescence Spectra of p-Cyano-N,N-dimethylaniline in Dichloroethane and Ethyl Acetate

The effect of temperature (293 ÷ 413 K) upon absorption and fluorescence spectra of p-cyano-N,N-dimethylaniline (CDMA) was investigated in 1,2-dichloroethane and ethyl acetate. Two fluorescence bands, a and b, were already observed at 293 K, with the intensity of band b increasing strongly with temperature in both solvents. The absorption and fluorescence b bands of CDMA were found to be independent of the orientation interaction with the solvent. On the other hand, the longwave band of fluorescence a undergoes a strong hypsochromic shift resulting from the decrease in the permittivity with increasing temperature. Based on these observations, the electric dipole moment μe in the 1Lb state (shortwave band of fluorescence b) was found to be equal to the dipole moment,μg, in the ground state. The electric dipole moment μe in the 1La state (the longwave band of fluorescence a), which is strongly stabilized by the polar solvent, is about 2.5 times as high as μg , amounting to 54 x 10- 0 Cm (16.2 D) for μg = 22.5 x 10 -30 Cm (= 6.75 D).