Reconstructing the photometric light curves of Earth as a planet along its history

By utilizing satellite-based estimations of the distribution of clouds, we have studied the Earth's large-scale cloudiness behavior according to latitude and surface types (ice, water, vegetation and desert). These empirical relationships are used here to reconstruct the possible cloud distribution of historical epochs of the Earth's history such as the Late Cretaceous (90 Ma ago), the Late Triassic (230 Ma ago), the Mississippian (340 Ma ago), and the Late Cambrian (500 Ma ago), when the landmass distributions were different from today's. With this information, we have been able to simulate the globally-integrated photometric variability of the planet at these epochs. We find that our simple model reproduces well the observed cloud distribution and albedo variability of the modern Earth. Moreover, the model suggests that the photometric variability of the Earth was probably much larger in past epochs. This enhanced photometric variability could improve the chances for the difficult determination of the rotational period and the identification of continental landmasses for a distant planets.Comment: 12 pages, 4 figures. Accepted in ApJ. Latest version for publicatio

Artritis séptica de rodilla por Pantoea agglomerans: caso clínico

Presentamos un caso clínico de artritis séptica de rodilla causado por Pantoea agglomerans, inoculado en la articulación mediante un pinchazo con cuerpo vegetal. Este bacilo gram (-) se ha asociado a la producción de artritis séptica en algunas ocasiones, pero nunca en nuestro país hasta la fecha y según nuestro conocimiento. Artritis originadas por punciones con vegetales y etiquetadas como asépticas, enmascaran en nuestra opinión verdaderos cuadros infecciosos. Como el tratamiento de cualquier artritis purulenta, deben combinarse el drenaje (en este caso mediante artroscopia) y antibioterapia, lo que en nuestro caso consiguió la curación del paciente.We report a case of septic arthritis of the knee caused by Pantoea agglomerans, that gained access into the joint by a puncture with a vegetal body. This gram –ve bacillus has been occasionally linked to cases of septic arthritis, but never in our country up to date and to our know- ledge. We think that arthritis related to punctures with plants and labelled as “aseptic”, mask in fact septic processes. As in any pyogenic arthritis, adequate drainage of joint fluid (through arthroscopy in this case) and antimicrobial therapy must be used together; this approach allowed the healing of our patient

Impact of instrumental line shape characterization on ozone monitoring by FTIR spectrometry

Retrieving high-precision concentrations of atmospheric trace gases from FTIR (Fourier transform infrared) spectrometry requires a precise knowledge of the instrumental performance. In this context, this paper examines the impact on the ozone (O$_{3}$) retrievals of several approaches used to characterize the instrumental line shape (ILS) function of ground-based FTIR spectrometers within NDACC (Network for the Detection of Atmospheric Composition Change). The analysis has been carried out at the subtropical Izaña Observatory (IZO, Spain) by using the 20-year time series of the high-resolution FTIR solar absorption spectra acquired between 1999 and 2018. The theoretical quality assessment and the comparison to independent O$_{3}$ observations available at IZO (Brewer O$_{3}$ total columns and electrochemical concentration cell, ECC, sondes) reveal consistent findings. The inclusion of a simultaneous retrieval of the ILS parameters in the O$_{3}$ retrieval strategy allows, on the one hand, a rough instrumental characterization to be obtained and, on the other hand, the precision of the FTIR O$_{3}$ products to be slightly improved. The improvement is of special relevance above the lower stratosphere, where the cross-interference between the O$_{3}$ vertical distribution and the instrumental performance is more significant. However, it has been found that the simultaneous ILS retrieval leads to a misinterpretation of the O$_{3}$ variations on daily and seasonal scales. Therefore, in order to ensure the independence of the O$_{3}$ retrievals and the instrumental response, the optimal approach to deal with the FTIR instrumental characterization is found to be the continuous monitoring of the ILS function by means of independent observations, such as gas cell measurements

Twenty years of ground-based NDACC FTIR spectrometry at Izaña Observatory-overview and long-term comparison to other techniques

High-resolution Fourier transform infrared (FTIR) solar observations are particularly relevant for climate studies, as they allow atmospheric gaseous composition and multiple climate processes to be monitored in detail. In this context, the present paper provides an overview of 20 years of FTIR measurements taken in the framework of the NDACC (Network for the Detection of Atmospheric Composition Change) from 1999 to 2018 at the subtropical Izaña Observatory (IZO, Spain). Firstly, long-term instrumental performance is comprehensively assessed, corroborating the temporal stability and reliable instrumental characterization of the two FTIR spectrometers installed at IZO since 1999. Then, the time series of all trace gases contributing to NDACC at IZO are presented (i.e. C$_{2}$H$_{6}$, CH$_{4}$, ClONO$_{2}$, CO, HCl, HCN, H$_{2}$CO, HF, HNO$_{3}$, N$_{2}$O, NO$_{2}$, NO, O$_{3}$, carbonyl sulfide (OCS), and water vapour isotopologues H$_{2}$$^{16}$O, H$_{2}$$^{18}$O, and HD$^{16}$O), reviewing the major accomplishments drawn from these observations. In order to examine the quality and long-term consistency of the IZO FTIR observations, a comparison of those NDACC products for which other high-quality measurement techniques are available at IZO has been performed (i.e. CH$_{4}$, CO, H$_{2}$O, NO$_{2}$, N$_{2}$O, and O$_{3}$). This quality assessment was carried out on different timescales to examine what temporal signals are captured by the FTIR records, and to what extent. After 20 years of operation, the IZO NDACC FTIR observations have been found to be very consistent and reliable over time, demonstrating great potential for climate research. Long-term NDACC FTIR data sets, such as IZO, are indispensable tools for the investigation of atmospheric composition trends, multi-year phenomena, and complex climate feedback processes, as well as for the validation of past and present space-based missions and chemistry climate models

Surface and Temporal Biosignatures

Recent discoveries of potentially habitable exoplanets have ignited the prospect of spectroscopic investigations of exoplanet surfaces and atmospheres for signs of life. This chapter provides an overview of potential surface and temporal exoplanet biosignatures, reviewing Earth analogues and proposed applications based on observations and models. The vegetation red-edge (VRE) remains the most well-studied surface biosignature. Extensions of the VRE, spectral "edges" produced in part by photosynthetic or nonphotosynthetic pigments, may likewise present potential evidence of life. Polarization signatures have the capacity to discriminate between biotic and abiotic "edge" features in the face of false positives from band-gap generating material. Temporal biosignatures -- modulations in measurable quantities such as gas abundances (e.g., CO2), surface features, or emission of light (e.g., fluorescence, bioluminescence) that can be directly linked to the actions of a biosphere -- are in general less well studied than surface or gaseous biosignatures. However, remote observations of Earth's biosphere nonetheless provide proofs of concept for these techniques and are reviewed here. Surface and temporal biosignatures provide complementary information to gaseous biosignatures, and while likely more challenging to observe, would contribute information inaccessible from study of the time-averaged atmospheric composition alone.Comment: 26 pages, 9 figures, review to appear in Handbook of Exoplanets. Fixed figure conversion error

The Detectability of Earth's Biosignatures Across Time

Over the past two decades, enormous advances in the detection of exoplanets have taken place. Currently, we have discovered hundreds of earth-sized planets, several of them within the habitable zone of their star. In the coming years, the efforts will concentrate in the characterization of these planets and their atmospheres to try to detect the presence of biosignatures. However, even if we discovered a second Earth, it is very unlikely that it would present a stage of evolution similar to the present-day Earth. Our planet has been far from static since its formation about 4.5 Ga ago; on the contrary, during this time, it has undergone multiple changes in it's atmospheric composition, it's temperature structure, it's continental distribution, and even changes in the forms of life that inhabit it. All these changes have affected the global properties of Earth as seen from an astronomical distance. Thus, it is of interest not only to characterize the observables of the Earth as it is today, but also at different epochs. Here we review the detectability of the Earth's globally-averaged properties over time. This includes atmospheric composition and biosignatures, and surface properties that can be interpreted as sings of habitability (bioclues). The resulting picture is that truly unambiguous biosignatures are only detectable for about 1/4 of the Earth's history. The rest of the time we rely on detectable bioclues that can only establish an statistical likelihood for the presence of life on a given planet.Comment: To appear in "Handbook of Exoplanets", eds. Deeg, H.J. & Belmonte, J.A, Springer (2018). arXiv admin note: text overlap with arXiv:astro-ph/0609398 by other author

Izaña Atmospheric Research Center. Activity Report 2015-2016

This report is a summary of the many activities at the Izaña Atmospheric Research Center to the broader community. The combination of operational activities, research and development in state-of-the-art measurement techniques, calibration and validation and international cooperation encompass the vision of WMO to provide world leadership in expertise and international cooperation in weather, climate, hydrology and related environmental issues