scholarly journals Trends of land surface phenology derived from passive microwave and optical remote sensing systems and associated drivers across the dry tropics 1992–2012

2019 ◽  
Vol 232 ◽  
pp. 111307 ◽  
Author(s):  
Xiaoye Tong ◽  
Feng Tian ◽  
Martin Brandt ◽  
Yi Liu ◽  
Wenmin Zhang ◽  
...  
2021 ◽  
pp. 1-12
Author(s):  
Iulian-Horia Holobâcă ◽  
Levan G. Tielidze ◽  
Kinga Ivan ◽  
Mariam Elizbarashvili ◽  
Mircea Alexe ◽  
...  

Abstract Global warming is causing glaciers in the Caucasus Mountains and around the world to lose mass at an accelerated pace. As a result of this rapid retreat, significant parts of the glacierized surface area can be covered with debris deposits, often making them indistinguishable from the surrounding land surface by optical remote-sensing systems. Here, we present the DebCovG-carto toolbox to delineate debris-covered and debris-free glacier surfaces from non-glacierized regions. The algorithm uses synthetic aperture radar-derived coherence images and the normalized difference snow index applied to optical satellite data. Validating the remotely-sensed boundaries of Ushba and Chalaati glaciers using field GPS data demonstrates that the use of pairs of Sentinel-1 images (2019) from identical ascending and descending orbits can substantially improve debris-covered glacier surface detection. The DebCovG-carto toolbox leverages multiple orbits to automate the mapping of debris-covered glacier surfaces. This new automatic method offers the possibility of quickly correcting glacier mapping errors caused by the presence of debris and makes automatic mapping of glacierized surfaces considerably faster than the use of other subjective methods.


2018 ◽  
Vol 176 ◽  
pp. 06010
Author(s):  
Gregori de A. Moreira ◽  
Juan L. Guerrero-Rascado ◽  
Jose A. Benavent-Oltra ◽  
Pablo Ortiz-Amezcua ◽  
Roberto Róman ◽  
...  

The Planetary Boundary Layer (PBL) is the lowermost part of the troposphere. In this work, we analysed some high order moments and PBL height detected continuously by three remote sensing systems: an elastic lidar, a Doppler lidar and a passive Microwave Radiometer, during the SLOPE-2016 campaign, which was held in Granada from May to August 2016. This study confirms the feasibility of these systems for the characterization of the PBL, helping us to justify and understand its behaviour along the day.


2021 ◽  
Author(s):  
Volker Wulfmeyer ◽  
David D. Turner

<p>The Land-Atmosphere Feedback Experiment (LAFE) deployed several state-of-the-art scanning lidar and remote sensing systems to the Atmospheric Radiation Measurement (ARM) Program Southern Great Plains (SPG) site during August 2017. A novel synergy of remote sensing systems was applied for simultaneous measurements of land-surface fluxes and horizontal and vertical transport processes in the atmospheric boundary layer (ABL). The impact of spatial inhomogeneities of the soil-vegetation continuum on L-A feedback was studied using the scanning capability of the instrumentation as well as soil, vegetation, and surface flux measurements. Thus, both the variability of surface fluxes and ABL dynamics and thermodynamics over the SGP site was studied for the first time. The objectives of LAFE are as follows:</p><p>I. Determine turbulence profiles and investigate new relationships among  gradients, variances, and fluxes<br>II. Map surface momentum, sensible heat, and latent heat fluxes using a synergy of scanning wind, humidity, and temperature lidar systems<br>III. Characterize land-atmosphere feedback and the moisture budget at the SGP site via the new LAFE sensor synergy<br>IV: Verify large-eddy simulation model runs and improve turbulence representations in mesoscale models.</p><p>In this presentation, the status of LAFE research and recent achievements of the science objectives are presented and discussed. Concerning I., long-term profiling capabilities of turbulent properties have been developed and will be presented such as continuous measurements of latent heat flux profiles for a duration of one month. Concerning II., we present a combination of tower and remote sensing measurements to study surface layer profiles of wind, temperature, and humidity. A first evaluation of the results demonstrates significant deviations from Monin-Obukhov similarity theory. Concerning III., Convective Triggering Potential (CTP)-Humidity Index (HIlow) metrics are presented at the SGP site to characterize L-A feedback and a new technique for determination of water-vapor advection, as important part of its budget. Last but not least, concerning IV., we present an advanced ensemble model design with turbulence permitting resolution for case studies and model verification from the convection-permitting to the turbulent scales in a realistic mesoscale environment. Using this framework, we introduce a strategy to apply the observations for the test and development of turbulence parameterizations. These results confirm that LAFE will make significant contributions to process understanding and the parameterization of the next generation of high-resolution weather forecast, climate, and earth system models.</p>


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