Satellite-based monitoring and prediction of tropical cyclone intensity and movement

ABSTRACT. Capabilities of meteorological satellites have gone a long way in meeting requirements of synoptic analysis and forecasting of tropical cyclones. This paper shows the impact made by the satellite data in the intensity estimation and track prediction of tropical cyclones in the Indian Seas and also reviews the universally applied Dvorak algorithm for performing tropical cyclone intensity analysis. Extensive use of Dvorak's intensity estimation scheme has revealed many of its limitations and elements of subjectivity in the analysis of tropical cyclones over the Arabian Sea and the Bay of Bengal, which, like cyclones in other ocean basins, also exhibit wide structural variability as seen in the satellite imagery. Satellite-based cyclone tracking techniques include: (i) use of satellite-derived mean wind flow, (ii) animation of sequence of satellite images and extrapolation of the apparent motion of the cloud system and (iii) monitoring changes in the upper level moisture patterns in the water vapour absorption channel imagery. Satellite-based techniques on tropical cyclone intensity estimation and track prediction have led to very significant improvement in disaster warning and consequent saving of life and property.

The Impact of Post-Manufacture Treatments on the Surface Characteristics Important for Finishing of OSB and Particleboard

Oriented strand board (OSB) is a commonly used structural wood-based panel for walls and roof siding, but recently the industry has become interested in OSB as a substrate for indoor and outdoor furniture. Particleboard is mainly used in furniture productions and has become popular as a construction material due to its numerous usage possibilities and inexpensive cost. Moisture is one of the most important factors affecting wood-based panel performance and the post-treatment conditions affected their affinity to water. When OSB and particleboard are used as substrates for coatings, their surface characteristics play an important role in determining the quality of the final product. Furthermore, roughness can significantly affect the interfacial phenomena such as adsorption, wetting, and adhesion which may have an impact on the coating performance. In this research particleboard and OSB panels were sanded, re-pressed and IR heated and the influence of surface treatments on hardness, roughness, wetting, water, and water vapour absorption was studied. Results showed that sanding improved the wetting of particleboard and OSB with water. Moreover, studied surface treatments increased water absorption and water penetration depth of OSB panels, and re-pressing had a positive effect on reducing the water vapour absorption of particleboard and OSB panels.

On the structure of instantaneous radiative forcing kernels for greenhouse gases

The SOCRATES offline radiative transfer code is used to investigate the magnitude and structure of the instantaneous radiative forcing kernels (IRFKs) for five major greenhouse gases (GHGs; CO2, CH4, N2O, CFC-11, and O3). All gases produce IRFKs that peak in the tropical upper troposphere. In addition to differences in spectroscopic intensities and the position of absorption features relative to the peak of the Planck function for Earth’s temperature, the variation in current background concentration of gases substantially affects the IRFK magnitudes. When the background concentration of CO2 is reduced from parts per million to parts per trillion levels, the peak magnitude of the IRFK increases by a factor of 642. When all gases are set to parts per trillion concentrations in the troposphere, the peak IRFK magnitudes are 1.0, 3.0, 3.1, 58 and 75 Wm−2 ppmv−1 100 hPa−1 for CH4, CO2, N2O, O3 and CFC-11, respectively. The altitude of the IRFK maximum also differs, with the maximum for CFC-11 and water vapour occurring above 100 hPa while the other gases peak near 150-200 hPa. Overlap with water vapour absorption decreases the magnitude of the IRFKs for all the GHGs, particularly in the low-to-mid troposphere, but it does not strongly affect the peak IRFK altitude. Cloud radiative effects reduce the magnitude of the IRFK for CO2 by around 10-20% in the upper troposphere. The use of IRFKs to estimate IRF is found to be accurate for small amplitude perturbations, but becomes inaccurate for large amplitude changes (e.g. a doubling) for gases with a higher atmospheric optical depth.

Discriminating between hazy and clear hot-Jupiter atmospheres with CARMENES

Context. Relatively large radii of some hot Jupiters observed in the ultraviolet and blue-optical are generally interpreted to be due to Rayleigh scattering by high-altitude haze particles. However, the haze composition and its production mechanisms are not fully understood, and observational information is still limited. Aims. We aim to study the presence of hazes in the atmospheres of HD 209458 b and HD 189733 b with high spectral resolution spectra by analysing the strength of water vapour cross-correlation signals across the red optical and near-infrared wavelength ranges. Methods. A total of seven transits of the two planets were observed with the CARMENES spectrograph at the 3.5 m Calar Alto telescope. Their Doppler-shifted signals were disentangled from the telluric and stellar contributions using the detrending algorithm SYSREM. The residual spectra were subsequently cross-correlated with water vapour templates at 0.70–0.96 μm to measure the strength of the water vapour absorption bands. Results. The optical water vapour bands were detected at 5.2σ in HD 209458 b in one transit, whereas no evidence of them was found in four transits of HD 189733 b. Therefore, the relative strength of the optical water bands compared to those in the near-infrared were found to be larger in HD 209458 b than in HD 189733 b. Conclusions. We interpret the non-detection of optical water bands in the transmission spectra of HD 189733 b, compared to the detection in HD 209458 b, to be due to the presence of high-altitude hazes in the former planet, which are largely absent in the latter. This is consistent with previous measurements with the Hubble Space Telescope. We show that currently available CARMENES observations of hot Jupiters can be used to investigate the presence of haze extinction in their atmospheres.

Improved SIFTER v2 algorithm for long-term GOME-2A satellite retrievals of fluorescence with a correction for instrument degradation

Solar-induced fluorescence (SIF) data from satellites are increasingly used as a proxy for photosynthetic activity by vegetation and as a constraint on gross primary production. Here we report on improvements in the algorithm to retrieve mid-morning (09:30 LT) SIF estimates on the global scale from the GOME-2 sensor on the MetOp-A satellite (GOME-2A) for the period 2007–2019. Our new SIFTER (Sun-Induced Fluorescence of Terrestrial Ecosystems Retrieval) v2 algorithm improves over a previous version by using a narrower spectral window that avoids strong oxygen absorption and being less sensitive to water vapour absorption, by constructing stable reference spectra from a 6-year period (2007–2012) of atmospheric spectra over the Sahara and by applying a latitude-dependent zero-level adjustment that accounts for biases in the data product. We generated stable, good-quality SIF retrievals between January 2007 and June 2013, when GOME-2A degradation in the near infrared was still limited. After the narrowing of the GOME-2A swath in July 2013, we characterised the throughput degradation of the level-1 data in order to derive reflectance corrections and apply these for the SIF retrievals between July 2013 and December 2018. SIFTER v2 data compare well with the independent NASA v2.8 data product. Especially in the evergreen tropics, SIFTER v2 no longer shows the underestimates against other satellite products that were seen in SIFTER v1. The new data product includes uncertainty estimates for individual observations and is best used for mostly clear-sky scenes and when spectral residuals remain below a certain spectral autocorrelation threshold. Our results support the use of SIFTER v2 data being used as an independent constraint on photosynthetic activity on regional to global scales.

Improved SIFTER v2 algorithm for long-term GOME-2A satellite retrievals of fluorescence with a correction for instrument degradation

Solar-induced fluorescence (SIF) data from satellites are increasingly used as a proxy for photosynthetic activity by vegetation, and as a constraint on gross primary production. Here we develop an improved retrieval algorithm to retrieve mid-morning (09:30 hrs local time) SIF estimates on the global scale from GOME-2 sensor on the Metop-A satellite (GOME-2A) for the period 2007–2019. Our new SIFTER v2 algorithm improves over a previous version by using a narrower spectral window that avoids strong oxygen absorption and is less sensitive to water vapour absorption, by constructing stable reference spectra from a 6-year period (2007–2012) of atmospheric spectra over the Sahara, and by applying a latitude-dependent zero-level adjustment that accounts for biases in the data product. We generated stable, good-quality SIF retrievals between January 2007 and June 2013, when GOME-2A degradation in the near infrared was still limited. After the narrowing of the GOME-2A swath in July 2013, we characterized the throughput degradation of the level-1 data in order to derive reflectance corrections and apply these for the SIF retrievals between July 2013 and December 2018. SIFTER v2 data compares well with the independent NASA v2.8 data product. Especially in the evergreen tropics, SIFTER v2 no longer shows the underestimates against other satellite products that were seen in SIFTER v1. The new data product includes uncertainty estimates for individual observations, and is best used for mostly clear-sky scenes, and when spectral residuals remain below a certain spectral autocorrelation threshold. Our results support the use of SIFTER v2 data to be used as an independent constraint on photosynthetic activity on regional to global scales.

Examination of Selected Upper Shoe Materials Based on Bamboo Fabrics

In this paper the authors describe the creation of new material packages based on bamboo textile materials for upper shoe material. These packages were made up of three layers: an inner layer in the foot skin neighbourhood, outer layer – which contacted with the surrounding environment, and a medium layer – polyurethane foam of a thickness of 2 mm. Experimetal tests consisted in the measurement of hygienic parameters (water vapour absorption and permeability) and some mechanical indicators important from the user’s point of view, like the elongation property and maximum force at break. The packages based on bamboo materials were compared with a standard composition: cotton – polyurethane foam – cotton. The results obtained showed, that in a lot of cases, the use of bamboo materials as lining or an outer layer is a good possibility to improve the hygienic and mechanical properties of newly formed material compositions.