Remote sensing and hydrogeophysics give a new impetus to integrated hydrological models: a review

Integrated Hydrological Models (IHMs) dynamically couple surface and groundwater processes across the unsaturated zone domain. IHMs are data intensive and computationally demanding but can provide physically realistic output, particularly if sufficient input data of high quality is available. In-situ observations often have a small footprint and are time and cost-demanding. Satellite remote sensing observations, with their long time series archives and spatially semi-continuous gridded format, as well as hydrogeophysical observations with their flexible, ‘on-demand’ high-resolution data coverage, perfectly complement in-situ observations. We review the contribution of various satellite remote sensing products for IHM: (1) climate forcings, (2) parameters, (3) boundary conditions and (4) observations for constraining model calibration and data assimilation. Our review of hydrogeophysics focuses on the four mentioned IHM contributions, but we analyze them per data acquisition platform, i.e., surface, drone-borne and airborne hydrogeophysics. Finally, the review includes a discussion on the optimal use of satellite remote sensing and hydrogeophysical data in IHMs, as well as a vision for further improvements of data-driven, integrated hydrological modelling

Sodium recycling at Europa: what do we learn from the sodium cloud variability ?

International audienceWe study the ejection of sodium atoms from Europa's surface by both magnetospheric ion and electron sputtering and desorption stimulated by UV solar photons. The depletion of the surface by ejection and its enrichment by redeposition of sodium atoms are described. The redistribution of sodium atoms at the surface induced by photo-stimulated desorption from the dayside and by sputtering ejection from the trailing hemisphere cannot explain the observed variation of the Na emission brightness. However, a transient increase of the sputtering rate due to a plasma injection may explain such an increase. The relationship between the sodium surface content and the sodium exosphere are also discussed

Fluctuation diagnostics of the electron self-energy: Origin of the pseudogap physics

We demonstrate how to identify which physical processes dominate the low-energy spectral functions of correlated electron systems. We obtain an unambiguous classification through an analysis of the equation of motion for the electron self-energy in its charge, spin and particle-particle representations. Our procedure is then employed to clarify the controversial physics responsible for the appearance of the pseudogap in correlated systems. We illustrate our method by examining the attractive and repulsive Hubbard model in two-dimensions. In the latter, spin fluctuations are identified as the origin of the pseudogap, and we also explain why $d-$wave pairing fluctuations play a marginal role in suppressing the low-energy spectral weight, independent of their actual strength.Comment: 6 pages, 2 figures + 4 pages supplementar

Three\u27s Company: Collaborative Instructional Design on a Librarian-Instructor Team

This session will describe a unique collaboration that resulted in development of a strategic research assignment design supported by relevant information literacy sessions. This effort stems from an existing relationship between research librarians and an instructor who was previously a graduate assistant in Research & Instruction Services and became an instructor of a general education course in Communication Sciences and Disorders. Through this collective, a synergistic arrangement developed where librarians contribute to research assignment design and the instructor contributes to developing the information literacy sessions to prepare students for finding, evaluating, and understanding relevant scholarly articles early in their college career. We will provide suggestions for developing librarian-instructor relationships that help identify student pain points as well as guide the development of customized classroom assignments relevant to beginning a student’s research path. We will also introduce strategies we have found successful in helping students locate and synthesize relevant scholarly articles, in the classroom and online, for more effective information literacy session activities

Structure of the Effective Potential in Nonrelativistic Chern-Simons Field Theory

We present the scalar field effective potential for nonrelativistic self-interacting scalar and fermion fields coupled to an Abelian Chern-Simons gauge field. Fermions are non-minimally coupled to the gauge field via a Pauli interaction. Gauss's law linearly relates the magnetic field to the matter field densities; hence, we also include radiative effects from the background gauge field. However, the scalar field effective potential is transparent to the presence of the background gauge field to leading order in the perturbative expansion. We compute the scalar field effective potential in two gauge families. We perform the calculation in a gauge reminiscent of the $R_\xi$-gauge in the limit $\xi\rightarrow 0$ and in the Coulomb family gauges. The scalar field effective potential is the same in both gauge-fixings and is independent of the gauge-fixing parameter in the Coulomb family gauge. The conformal symmetry is spontaneously broken except for two values of the coupling constant, one of which is the self-dual value. To leading order in the perturbative expansion, the structure of the classical potential is deeply distorted by radiative corrections and shows a stable minimum around the origin, which could be of interest when searching for vortex solutions. We regularize the theory with operator regularization and a cutoff to demonstrate that the results are independent of the regularization scheme.Comment: 24 pages, UdeM-LPN-TH-93-185, CRM-192

Basin-scale, integrated observations of the early 21st century multiyear drought in southeast Australia

The Murray-Darling Basin in southeast Australia is experiencing one of the most severe droughts observed recently in the world, driven by several years of rainfall deficits and record high temperatures. This paper provides new basin‐scale observations of the multiyear drought, integrated to a degree rarely achieved on such a large scale, to assess the response of water resources and the severity of the drought. A combination of Gravity Recovery and Climate Experiment (GRACE) data with in situ and modeled hydrological data shows the propagation of the water deficit through the hydrological cycle and the rise of different types of drought. Our observations show the rapid drying of soil moisture and surface water storages, which reached near‐stationary low levels only ∼2 years after the onset of the drought in 2001, with a loss of ∼80 and ∼12 km3 between January 2001 and January 2003, respectively. The multiyear drought has led to the almost complete drying of surface water resources which account for most of the water used for irrigation and domestic purposes. High correlation between observed groundwater variations and GRACE data substantiates the persistent reduction in groundwater storage, with groundwater levels still declining 6 years after the onset of the drought (groundwater loss of ∼104 km3 between 2001 and 2007). The hydrological drought continues even though the region returned to average annual rainfall during 2007