Assessment of five different methods for the estimation of surface photosynthetically active radiation from satellite imagery at three sites – application to the monitoring of indoor soft fruit crops in southern UK

International audienceThis paper assesses several methods for the retrieval of Photosynthetically Active Radiation (PAR) from satellite imagery. The results of five different methods are compared to coincident in-situ measurements collected at three sites in southern UK. PAR retrieval methods are separated into two distinct groups. The first group comprises three methods that compute PAR by multiplying the satellite-retrieved solar broadband irra-diance at the surface (SSI) by a constant coefficient. The two methods in the second group are based on more sophisticated modelling of the radiative transfer in the atmosphere involving advanced global aerosol property analyses and physically consistent total column water vapour and ozone produced by the Copernicus Atmosphere Monitoring Service (CAMS). Both methods compute a cloud modification factor from satellite-retrieved SSI. The five methods have been applied to two satellite-retrieved SSI datasets: HelioClim-3 version 5 (HC3v5) and CAMS Radiation Service (CAMS-Rad). Except at the seashore site, Group 2 methods combined with the cloud extinction from the HC3v5 dataset deliver the best results with small biases of − 5 to 0 µmol m−2 s−1 (−1 % to 0 % relative to the mean of the measurements), root mean square errors of 130 µmol m−2 s−1 (28 %) and correlation coefficients exceeding 0.945. For all methods, best results are attained with the HC3v5 data set. These results demonstrate that all methods capture the temporal and spatial variability of the PAR irradiation field well, although several methods require a posteriori bias adjustments for reliable results. Combined with such an adjustment, the Udo et Aro method is a good compromise for this geographical area in terms of reliability , tractability and its ability to run in real-time. Overall, the method performing a spectral discretization in cloud-free conditions, combined with the HC3v5 dataset, outperforms other methods and has great potential for supporting an operational system

Brain functions : the challenges to integrate and assimilate climate information

International audienceThe general public expects relevant, comprehensible and acceptable communication on climate change. Many efforts have been, and are still, being made to make the message clear and comprehensible. The key point is the acceptability of the message by the audience, which is seldom discussed in the literature. This presentation investigates the brain mechanisms, which allow it to understand, integrate and assimilate climate information. The brain faces challenges to integrate this information. We will tackle six of them here. Cognitive dissonance is one major factor. When receiving climate information, one understands that a change will occur. However, the consequences are so important that it is difficult to assimilate and project ourselves into this future reality. The future cannot be connected to something that is already known, and so it is challenging to construct meaning. In order to keep the system coherent, the brain distances itself from the information. The information that is heard will seem distant despite all efforts from the individual to assimilate it. A better understanding of cognitive biases in communication on climate change allows building acceptable talks, such as increasing the integration of the information by non-specialists, which, in turn, will help to transfer individuals knowledge into concrete action

Your collective timeline of climate science history

International audience<p>EGU General Assembly is one of the world’s biggest conferences dedicated to geosciences. It gathers experts from all science fields connected to the study of past, present and future climates. Many of them have an historic perspective on their area of expertise: such knowledge is useful to develop an integrated view of the history of climate sciences.</p><p>We propose EGU2020 attendees to help building a collective timeline of the history of climate science. Everyone is invited to come to our poster to add to the printed timeline a scientific breakthrough in her/his field of expertise. This will be an opportunity to come to chat on climate science history and to construct together a wider picture of climate sciences.</p><p>The final cut of the timeline produced during EGU2020 will be available on our web page EarthBreath (https://www.sophia.mines-paristech.fr/earthbreath/), and our Twitter english (@eb_climate_data) and french (@eb_climat_fr) accounts.</p><p>EarthBreath is a non-profit initiative that we develop for promoting climate and Earth sciences to diverse publics.</p>PARTNERS If you are a climate scientist, send us a mail with 1 to 3 dates with scientific breakthroughs in your area of expertise! Discover the interactive timeline online! Benoît Tournadre (O.I.E) Mélodie Trolliet (O.I.E) A collective timeline of climate science history EGU General Assembly 2020 (2020/05/07) The cancellation of EGU2020 physical conference forced us to slightly modify the content of our presentation. Instead of fully building a timeline of the history of climate sciences during the event, we chose to ask for prior contributions from climate scientists. Finally, instead of a poster filled by handwritten contributions, the timeline is developed on an interactive web page with illustrations. Our contributing experts Various expertises → Climate modeling → Paleoclimatology → Space oceanography Find the timeline and more visual resources on our Earthbreath webpage Eumetsat www.sophia.mines-paristech.fr/earthbreat

Influence of speaker involvement and own personal actions in assimilation and appropriation of climate information by the audience

International audienceIn this presentation, two main speaker involvements are investigated. Firstly : the speaker is not deeply convinced by his message or is deeply convinced but not involved into personal actions yet. In the first case, he would communicate few emotions during his speech. In the second case, the gap between what the speaker wants to do and what he will really do, will lead to a cognitive dissonance. The information will be stressfully perceived. In any case, even if the talk is given in a way to be persuasive, the mirror neuron system, responsible among other of empathy, will capture the real involvement of the speaker in his message through his own actions. Among others, the unappropriate emotional data medium (nonexistent or stressful), involved in memorization process, lead to a possible partial or short term assimilation of the information, and so to a partial or short term changes in the audience's life. Finally, this presentation highlights the case where speaker combine both personal involvement and actions in accordance with the message. This leads to efficient communication thanks to good assimilation and appropriation. By reconciling theory, methodology and practice, the speaker can generate sustainable behavioral changes in the audience's personal life

Monthly solar radiation in the tropical Atlantic Ocean: Can its spatial variations be captured by the current configuration of the PIRATA moorings?

International audienceThe present work aims at contributing to the proper design of networks of measuring moorings with regard to the downwelling solar irradiance at surface (DSIS). Considering the yearly profiles of the monthly DSIS, this article studies whether the 17 moorings within the existing PIRATA network are well geographically distributed so that they capture the spatial variations of the yearly profiles in the tropical Atlantic Ocean. A clustering technique is performed onto the HelioClim-3v5 satellite-derived gridded dataset of DSIS spanning 12 years, thus yielding 17 zones of similar yearly profiles. It was found that the mean yearly profiles of several zones are similar to the measured ones at the three moorings having enough measurements to perform the comparison. Zones have clear connections with the climatology of the region and circulation regimes. The geographical distribution of the moorings has been analysed with regard to the zoning. In the northern region of the tropical basin, each zone contains at least one PIRATA mooring. Hence, the configuration of the PIRATA network is appropriate to reflect the spatial variations of the yearly profiles in this northern part. In the southern basin, the coverage is less complete; several zones do not contain any PIRATA mooring. Thus, the network does not capture the spatial variations of the yearly profiles and this may induce misinterpretation of the PIRATA measurements at synoptic scales. It was also found that the computation of latitudinal or longitudinal averages of irradiance may be wrong if based solely on measurements from moorings without taking into account the spatial representativeness of a mooring

Interface between climate and energy communities: assessing long term variability of the surface solar irradiance for solar energy projects

International audienceAssessing the future surface solar irradiance (SSI) is important for both energy and climate community : it is a way to understand the solar resource characteristics and SSI is an essential climate variable. In a way to develop concrete mitigation projects taking into account a changing climate, communication between the two communities can bring out promising approaches mixing both statistical and physical methodologies, especially in SSI assessment. In solar energy conversion projects, the method used by developers to take into account the interannual variability of SSI during the lifetime of the projects is essentially applied on 10+ years of historical SSI datasets. This work proposes a review of the different statistical methods accessing the on-site solar resource and its inter-annual variability. Among others, we show that most of statistical methods suppose the data are independent and identically distributed. This hypothesis is questionable because of the climate long term variability. In climate community, assessing the future SSI is essentially based on physical approaches with related climate scenarios. Finding a common way to assess the climate variability could allow learning from past estimations in order to have a more accurate approach to predict resource variations in the future

Where to get visual climate data that suit education and outreach?

International audienceFrom our own climate outreach experiences, we have observed key elements that make an efficient outreach work. They include interactivity, exclusivity, fun and surprising content, intuitive explanations, connection between data and the audience lives, and the use of beautiful illustrations. Geosciences continuously produce highly esthetical and novel material that can be much appreciated, even by people who are not familiar with environmental issues. Data like satellite imagery and its derived products are thus a strong educational means for intuitively apprehending climate and other environmental topics. They have strong artistic power, as well as a strong ability to capture phenomena occurring on spatiotemporal scales stranger to the human eye (e.g. glacier flow, desiccation of lakes, sea level rise, surface air temperature changes, etc.). For non-experts however, the way to find these data may be quite tortuous. One of the main issues to access to the many free online visual resources is the multiplicity of sources where to get the information. This is challenging for journalists, teachers and other interested people, as well as for geoscience researchers who develop outreach materials with content wider than their own specific field. On the other hand, when it comes to their own field of expertise, climate scientists are the best placed to find the relevant resources. We call the scientific community to promote the visual data they produce to the large public. To catalyze this process, we are continuously gathering a selection of websites with scientific content easily understandable to non-experts. This catalog can be freely read on our EarthBreath webpage at http://www.sophia.mines-paristech.fr/earthbreath/. EarthBreath aims at being enriched by scientific and non-scientific people aware of additional state-of-the-art high-quality online contents. We therefore enjoin all to help us building this box of precious outreach tools, by notifying to us via email such websites. The objectives of the EarthBreath tool will be presented along with two detailed examples of workshops leaning on contents from indexed websites

Comparison of several databases of downward solar daily irradiation data at ocean surface with PIRATA measurements

International audienceThe solar radiation impinging at sea surface is an essential variable in climate system. There are several means to assess the daily irradiation at surface, such as pyranometers aboard ship or on buoys, meteorological re-analyses and satellite-derived databases. Among the latter, assessments made from the series of geostationary Meteosat satellites offer synoptic views of the tropical and equatorial Atlantic Ocean every 15 min with a spatial resolution of approximately 5 km. Such Meteosat-derived databases are fairly recent and the quality of the estimates of the daily irradiation must be established. Efforts have been made for the land masses and must be repeated for the Atlantic Ocean. The Prediction and Research Moored Array in the Tropical Atlantic (PIRATA) network of moorings in the Tropical Atlantic Ocean is considered as a reference for oceanographic data. It consists in 17 long-term Autonomous Temperature Line Acquisition System (ATLAS) buoys equipped with sensors tomeasure near-surface meteorological and subsurface oceanic parameters, including downward solar irradiation. Corrected downward solar daily irradiation from PIRATA were downloaded from the NOAA web site and were compared to several databases: CAMS RAD, HelioClim-1, HelioClim-3 v4 and HelioClim-3 v5. CAMS-RAD, the CAMS radiation service, combines products of the Copernicus Atmosphere Monitoring Service (CAMS) ongaseous content and aerosols in the atmosphere together with cloud optical properties deduced every 15 min from Meteosat imagery to supply estimates of the solar irradiation. Part of this service is the McClear clear sky model that provides estimates of the solar irradiation that should be observed in cloud-free conditions. The second and third databases are HelioClim-1 and HelioClim-3 v4 that are derived from Meteosat images using the Heliosat-2 method and the ESRA clear sky model, based on the Linke turbidity factor. HelioClim-3 v5 is the fourth database and differs from v4 by the partial use of McClear and CAMS products. HelioClim-1 covers the period 1985-2005, while the others start in 2004 and are updated daily. Deviations between PIRATA measurements and estimates were computed and summarized by usual statistics. Biases and root mean square errors differ from one database to the other. As a whole, the correlation coefficients are large, meaning that each database reproduces the day-to-daychanges in irradiation well. These good results will support the development of a satellite-derived database of daily irradiation created by MINES ParisTech within the HelioClim project. The size of the cells will be 0.25°. HelioClim-1 and HelioClim-3v5 will be combined yielding a period coverage of 32 years, from 1985 to 2016, thus allowing analyses of long term variability of downward shortwave solar radiation over the Atlantic Ocean

Solar radiation map on the Atlantic ocean

International audienceThe work adresses the zonation of the Atlantic Ocean based on typical yearly profiles of the downwelling solarradiation at ocean surface and its inter-annual variability. Solar radiation climatic zoning is of large importancefor preliminary assessment and modeling of systems natural systems, e.g., heat fluxes or radiation balance. Zoningcan also guide the selection of appropriate measuring stations for a given geographical location. Satellite dataoffers archives of synoptic views of the Atlantic Ocean and its cloud cover. The surface solar radiation may bederived from such images. The HelioClim3v5 data set originates from a proper processing of Meteosat imagesusing Heliosat-2 method. It offers estimates of the surface solar radiation over the tropical and equatorial AtlanticOcean every 15 min with a spatial resolution of approximately 5 km. HelioClim3v5 has been validated against theThe Prediction and Research Moored Array in the Tropical Atlantic (PIRATA) network of moorings in the TropicalAtlantic Ocean, considered as a reference for oceanographic data. This work is a first attempt to propose a map ofthe solar radiation on the Atlantic ocean. The Atlantic ocean has been discretized in the form of a structured gridof uniform resolution of 0.25 degree. A data set of monthly means of the global irradiance has been constructedfor each cell and is available at MINES ParisTech. For each calendar month, the monthly means were averagedover the years and the inter-annual variability was computed. A cluster analysis was applied at each cell with these24 values as inputs to create classes that were reported into a map of the Atlantic ocean. The zonation exhibitslatitudinal trends. Noticeable anomalies are observed at South of equator. Interactions between Angola-Benguelacurrent and atmospheric dynamic through global irradiance in this area are discussed

Evaluating the validity of the stationarity hypothesis of yearly solar irradiation data using long-term time series from the GEBA network

International audienceThe solar radiation impinging at ground level is an essential variable for climate but also for solar photovoltaic (PV) systems as it directly impacts its economic viability. As a consequence, estimating solar irradiation on a long-term time scale, up to 30 years, is a critical issue in the planning of a solar system. The amount of solar irradiation expected for the future is usually computed from yearly irradiation data measured on the site of interest by pyranometers, satellite-derived data, meteorological reanalysis products or a combination of them over the past years. In other words, the amount of radiation expected for the future is computed from the amount of radiation measured on the past. Doing this, it is implicitly assumed that the temporal evolution of the solar irradiation is stationary: the yearly irradiation is assumed to be the stochastic realization of the same distribution. However, it is well known that solar radiation reaching the ground is strongly dependent of the atmospheric constituents and their variability. Some constituent knows short term variations, as some types of clouds, when others knows long term variations, influenced for example by long term aerosols anthropic emissions. The observed dimming and brightening reported in several locations are good example of such effects. Theses variations can lead on a non-stationarity if the irradiation. With this in mind, we have explored the temporal stationarity hypothesis for a large number of in-situ measurements. The Global Energy Balance Archive (GEBA) network with more than 2500 measurement sites is considered as a reference for solar radiation data. For our study, a stringent quality check has been applied to the data. At the end, we selected 164 sites worldwide with long-term monthly time series with a high availability (more than 30 consecutive years, less than 2 consecutive month missing). The uncertainty of these stations is estimated to be lower than 5% for monthly irradiation data. We have tested the stationarity hypothesis on theses data, thanks to standard statistical methods: some of them are meant to test the stationarity hypothesis (e.g. KPSS, CUSUM, Man Kendell, Spearman-rho tests), others are meant to test the non-stationary hypothesis (e.g. Dickey Fuller, Phillips-Perron tests). The results of these tests as well as the use of time-frequency decomposition to analyze the stationarity of the different characteristics timescales variability are presented, compared and discussed