Broadband radiative quantities for the EarthCARE mission: the ACM-COM and ACM-RT products

The EarthCARE satellite mission's objective is to retrieve profiles of aerosol and water cloud physical properties from measurements made by its cloud-profiling radar, backscattering lidar, and passive multi-spectral imager. These retrievals, together with other geophysical properties, are input into broadband (BB) radiative transfer (RT) models that predict radiances and fluxes commensurate with measurements made and inferred from EarthCARE's BB radiometer (BBR). The scientific goal is that modelled and “observed” BB top-of-atmosphere (TOA) fluxes differ, on average, by less than ±10 W m−2. When sound synergistic retrievals from the ACM-CAP process (ACM: ATLID – backscattering lidar, CPR – cloud-profiling radar, and MSI – multi-spectral imager; CAP: clouds, aerosols, and precipitation) are available, they are acted on by the RT models. When they are not available, the RT models act on “composite” profiles of properties retrieved from measurements made by individual sensors. Compositing is performed in the ACM-COM (COM: composite) process. The majority of this report describes the RT models – and their products – that make up EarthCARE's ACM-RT process. Profiles of BB shortwave (SW) and longwave (LW) fluxes and heating rates (HRs) are computed by 1D RT models for each ∼ 1 km nadir column of inferred properties. Three-dimensional RT models compute radiances for the BBR's three viewing directions, with the SW model also computing flux and HR profiles; the 3D LW model produces upwelling flux at just one level. All 3D RT products are averages over 5×21 km “assessment domains” that are constructed using MSI data. Some of ACM-RT's products are passed forward to the “radiative closure assessment” process that quantifies, for each assessment domain, the likelihood that EarthCARE's goal has been achieved. As EarthCARE represents the first mission to make “operational” use of 3D RT models, emphasis is placed on differences between 1D and 3D RT results. For upwelling SW flux at 20 km altitude, 1D and 3D values can be expected to differ by more than EarthCARE's scientific goal of ±10 W m−2 at least 50 % of the time.</p

A Functionalized Monte Carlo 3D Radiative Transfer Model: Radiative Effects of Clouds Over Reflecting Surfaces

International audienceAbstract In the Earth Sciences, the 3D radiative transfer equation is often solved for by Monte Carlo (MC) methods. They can, however, be computationally taxing, and that can narrow their range of application and limit their use in explorations of model parameter spaces. A novel family of MC algorithms is investigated here in which single simulations provide estimates of both radiative quantities A for a set of parameters , as usual, as well as the overarching functional ( x ) that can be evaluated, extremely efficiently, at any x . One such algorithm is developed and demonstrated for horizontally averaged broadband solar radiative fluxes as functions of surface albedo for uniform Lambertian surfaces beneath inhomogeneous cloudy atmospheres. Simulations for a high‐resolution synthetic cloud field, at various solar zenith angles, illustrate the potential of the method to gain insights into the nature of 3D radiative effects for complicated atmosphere‐surface conditions using information specially derived from the MC simulation. For simulations performed with a single surface albedo it is found that as surface albedo increases, 3D radiative effects increase, too, with maxima occurring at middling to large values, and then decrease. By utilizing the derived coefficients that describe it was established that these 3D effects stem from differences in fractions of radiation entrapped at successive orders of internal multiple reflections for 1D and 3D transfer

Null-collision meshless Monte-Carlo - A new reverse Monte-Carlo algorithm designed for laser-source emission in absorbing/scattering inhomogeneous media

International audienceOver recent decades, numerous studies in a myriad of research fields have improved the efficiency of the Monte-Carlo method to solve radiative transfers in heterogeneous media. The formalization of the concept of path integral formulation on which the construction of the random trajectories is based has made it possible to lay down a convenient framework to investigate sampling strategies and to design adapted low-variance algorithms. Our study focuses on the particular case of laser emission, which corresponds to a spatially-localized source emitting in a low solid angle, which partially illuminates the environment. In this case, the intrinsic characteristics of the laser emission cause problems of convergence with a Monte-Carlo method due to the difficulty in statistically linking sensors (probe points) to sources. This paper proposes, using integral formulation and a Null-Collision Algorithm (NCA), a practicable and simply implementable method to avoid such constraints. The intensity is broken down into a direct and a scattered term (local estimate technique). Then, a reworking of the various integral terms makes it possible to propose a complete algorithm adapted to a collimated source partially illuminating the studied scene. Non-zero contributions are brought more continuously to the Monte-Carlo weight and variance is strongly reduced. The entire methodology, from integral formulation to algorithmic interpretation, is presented step by step. For validation purposes, a new reverse and optimized Monte-Carlo algorithm is compared with an analogous Monte-Carlo for estimation of flux absorbed by a wall in an academic configuration, which ensures benchmark results. As the current proposed algorithm is highly suitable for building computer-generated images (probe calculation), the propagation of light due to laser emission through inhomogeneous environments is then illustrated by the construction of such images. This new tool provides useful support for experimental characterization of the radiative behaviour of particles

Broadband radiative quantities for the EarthCARE mission: the ACM-COM and ACM-RT products

International audienceAbstract. The EarthCARE satellite mission's objective is to retrieve profiles of aerosol and water cloud physical properties from measurements made by its cloud-profiling radar, backscattering lidar, and passive multi-spectral imager. These retrievals, together with other geophysical properties, are input into broadband (BB) radiative transfer (RT) models that predict radiances and fluxes commensurate with measurements made and inferred from EarthCARE's BB radiometer (BBR). The scientific goal is that modelled and “observed” BB top-of-atmosphere (TOA) fluxes differ, on average, by less than ±10 W m−2. When sound synergistic retrievals from the ACM-CAP process (ACM: ATLID – backscattering lidar, CPR – cloud-profiling radar, and MSI – multi-spectral imager; CAP: clouds, aerosols, and precipitation) are available, they are acted on by the RT models. When they are not available, the RT models act on “composite” profiles of properties retrieved from measurements made by individual sensors. Compositing is performed in the ACM-COM (COM: composite) process. The majority of this report describes the RT models – and their products – that make up EarthCARE's ACM-RT process. Profiles of BB shortwave (SW) and longwave (LW) fluxes and heating rates (HRs) are computed by 1D RT models for each ∼ 1 km nadir column of inferred properties. Three-dimensional RT models compute radiances for the BBR's three viewing directions, with the SW model also computing flux and HR profiles; the 3D LW model produces upwelling flux at just one level. All 3D RT products are averages over 5×21 km “assessment domains” that are constructed using MSI data. Some of ACM-RT's products are passed forward to the “radiative closure assessment” process that quantifies, for each assessment domain, the likelihood that EarthCARE's goal has been achieved. As EarthCARE represents the first mission to make “operational” use of 3D RT models, emphasis is placed on differences between 1D and 3D RT results. For upwelling SW flux at 20 km altitude, 1D and 3D values can be expected to differ by more than EarthCARE's scientific goal of ±10 W m−2 at least 50 % of the time

Accounting for Vertical Subgrid‐Scale Heterogeneity in Low‐Level Cloud Fraction Parameterizations

International audienc

Women and health professionals’ perspectives on a conditional cash transfer programme to improve pregnancy follow-up: a qualitative analysis of the NAITRE randomised controlled study

Objectives Women of low socioeconomic status have been described as having suboptimal prenatal care, which in turn has been associated with poor pregnancy outcomes. Many types of conditional cash transfer (CCT) programmes have been developed, including programmes to improve prenatal care or smoking cessation during pregnancy, and their effects demonstrated. However, ethical critiques have included paternalism and lack of informed choice. Our objective was to determine if women and healthcare professionals (HPs) shared these concerns.Design Prospective qualitative research.Setting We included economically disadvantaged women, as defined by health insurance data, who participated in the French NAITRE randomised trial assessing a CCT programme during prenatal follow-up to improve pregnancy outcomes. The HP worked in some maternities participating in this trial.Participants 26 women, 14 who received CCT and 12 who did not, mostly unemployed (20/26), and - 7 HPs.Interventions We conducted a multicentre cross-sectional qualitative study among women and HPs who participated in the NAITRE Study to assess their views on CCT. The women were interviewed after childbirth.Results Women did not perceive CCT negatively. They did not mention feeling stigmatised. They described CCT as a significant source of aid for women with limited financial resources. HP described the CCT in less positive terms, for example, expressing concern about discussing cash transfer at their first medical consultation with women. Though they emphasised ethical concerns about the basis of the trial, they recognised the importance of evaluating CCT.Conclusions In France, a high-income country where prenatal follow-up is free, HPs were concerned that the CCT programme would change their relationship with patients and wondered if it was the best use of funding. However, women who received a cash incentive said they did not feel stigmatised and indicated that these payments helped them prepare for their baby’s birth.Trial registration number NCT0240285