Search results for " technology"

Understanding the Origins of Problem Geomagnetic Storms Associated with "Stealth" Coronal Mass Ejections.

2021

Geomagnetic storms are an important aspect of space weather and can result in significant impacts on space- and ground-based assets. The majority of strong storms are associated with the passage of interplanetary coronal mass ejections (ICMEs) in the near-Earth environment. In many cases, these ICMEs can be traced back unambiguously to a specific coronal mass ejection (CME) and solar activity on the frontside of the Sun. Hence, predicting the arrival of ICMEs at Earth from routine observations of CMEs and solar activity currently makes a major contribution to the forecasting of geomagnetic storms. However, it is clear that some ICMEs, which may also cause enhanced geomagnetic activity, cann…

High‐resolution stimulated Raman spectroscopy and analysis of line positions and assignments for the ν 2 and ν 3 bands of 13 C 2 H 4

2016

High-resolution stimulated Raman spectra of13C2H4 in the regions of the ν2 and ν3 Raman active modes have been recorded at two temperatures (145 and 296 K) based on the quasi continuous-wave (cw) stimulated Raman spectrometer at Instituto de Estructura de la Materia IEM-CSIC in Madrid. A tensorial formalism adapted to X2Y4 planar asymmetric tops with D2h symmetry (developed in Dijon) and a program suite called D2hTDS (now part of the XTDS/SPVIEW spectroscopic software) were proposed to analyze and calculate the high-resolution spectra. A total of 103 and 51 lines corresponding to ν2 and ν3 Raman active modes have been assigned and fitted in wavenumber with a global root mean square deviatio…

Very high spectral resolution imaging spectroscopy: The Fluorescence Explorer (FLEX) mission

2016

The Fluorescence Explorer (FLEX) mission has been recently selected as the 8th Earth Explorer by the European Space Agency (ESA). It will be the first mission specifically designed to measure from space vegetation fluorescence emission, by making use of very high spectral resolution imaging spectroscopy techniques. Vegetation fluorescence is the best proxy to actual vegetation photosynthesis which can be measurable from space, allowing an improved quantification of vegetation carbon assimilation and vegetation stress conditions, thus having key relevance for global mapping of ecosystems dynamics and aspects related with agricultural production and food security. The FLEX mission carries the…

Vicarious Calibration of Landsat-8 Thermal Data Collections and its Influence on Split-Window Algorithm Validation

2018

Landsat 8 (L8) satellite was launched on February 11, 2013 with two thermal bands located in the atmospheric window between $10-12\ \mu \mathrm{m}$ . Continuous monitoring of the Thermal Infrared Sensor (TIRS) onboard of L8 was performed over two Spanish test sites – Barrax and Donana – in order to contribute to the quality of TIRS data. In this work, a Vicarious Calibration (VC) of the TIRS bands was performed between years 2013–2016 in order to assess the new Stray Light (SL) data correction. The results of VC show us that band 10 and 11 provide accurate results (bias near to zero, and precision around 0.8 K) which is an improvement – especially for band 11 – in comparison to preprocessed…

Effect of soil management on soil erosion on sloping farmland during crop growth stages under a large-scale rainfall simulation experiment

2018

Soil erosion on farmland is a critical environmental issue and the main source of sediment in the Yellow River, China. Thus, great efforts have been made to reduce runoff and soil loss by restoring vegetation on abandoned farmland. However, few studies have investigated runoff and soil loss from sloping farmland during crop growth season. The objective of this study was to investigate the effects of soil management on runoff and soil loss on sloping farmland during crop growth season. We tested different soybean growth stages (i.e., seedling stage (R1), initial blossoming stage (R2), full flowering stage (R3), pod bearing stage (R4), and initial filling stage (R5)) and soil management pract…

FLEX/S3 Tandem Mission Performance Assessment: Evolution of the End-to-End Simulator Flex-E

2018

An End-to-end simulator (E2ES) is a tool to evaluate the performance of a satellite mission. Once a mission is approved for operation, E2ES evolves during Phase C/D to become a supporting tool for the development and validation of the ground data processor, as well as for simulating data sets to test the Prototype and Operational Processors. FLEX-E is the E2ES of the FLEX/Sentinel-3 tandem mission, which was selected in 2015 as ESA's eighth Earth Explorer. The FLEX-E evolution implies the consolidation of all the retrieval algorithms (e.g. fluorescence, reflectance, biophysical variables), the implementation of new scientific developments, as well the improvement of the co-registration proc…

Raindrop size distribution and terminal velocity for rainfall erosivity studies. A review

2019

Abstract The knowledge of the rainfall drop size distribution (DSD) at the land surface is essential for understanding precipitation mechanisms affecting soil erosion processes. Rainfall erosivity is defined as the potential of rain to cause erosion and it can be evaluated by rainfall kinetic power, which is determined by DSD and raindrop terminal velocity. This paper firstly deals with the raindrop terminal velocity estimate. Then the most widely used DSD are reviewed highlighting the difference between the raindrop size distribution per unit volume of air and that per unit area and time. The reliability of the available kinetic power-rainfall intensity relationships and their application …

Sun-Induced Chlorophyll Fluorescence I: Instrumental Considerations for Proximal Spectroradiometers

2019

Growing interest in the proximal sensing of sun-induced chlorophyll fluorescence (SIF) has been boosted by space-based retrievals and up-coming missions such as the FLuorescence EXplorer (FLEX). The European COST Action ES1309 “Innovative optical tools for proximal sensing of ecophysiological processes” (OPTIMISE, ES1309; https://optimise.dcs.aber.ac.uk/) has produced three manuscripts addressing the main current challenges in this field. This article provides a framework to model the impact of different instrument noise and bias on the retrieval of SIF; and to assess uncertainty requirements for the calibration and characterization of state-of-the-art SIF-oriented spectroradiom…

Preface to theHydrological processes in urban environments: Updates on urbanization, naturalization and climate changeSpecial Issue

2018

Analysis of drought and vulnerability in the North Darfur region of Sudan

2018

North Darfur of Sudan is located on the edge of the Sahara Desert and endures frequent droughts due to water shortages and high summer temperatures. Monitoring and understanding drought characteristics are essential for integrated drought risk mitigation and prevetion of land degradation. This study evaluates drought conditions in North Darfur by analyzing the spatiotemporal distribution of drought using three drought indices (Standardized Precipitation Index, Vegetation Condition Index, and Soil Moisture Content Index) and their combined drought index (CDI) from 2004 to 2013. Biophysical and socioeconomic indicators are further used to measure vulnerability to drought risk and its three co…