Vegetation Effects
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Author(s):  
S.A.H. Weisscher ◽  
K. Van den Hoven ◽  
H.J. Pierik ◽  
M.G. Kleinhans
Keyword(s):  

2022 ◽  
Vol 4 ◽  
Author(s):  
Jérôme Laganière ◽  
Laurent Augusto ◽  
Jeff Allen Hatten ◽  
Sandra Spielvogel

2021 ◽  
Author(s):  
Jieun Oh ◽  
Eungul Lee

Abstract Vegetation reduction could affect regional climate by perturbing the surface energy and moisture balances via changes in albedo and evapotranspiration. However, it is unknown whether vegetation effects on climate occur in North Korea, where a severe reduction in forest cover has been observed. This study aimed to identify the biogeophysical processes in vegetation and climate interactions in North Korea, using Normalized Difference Vegetation Index (NDVI) and climate reanalysis data over the period 1982‒2015. As per the NDVI regression trend results, the highest rates of decreasing NDVI were detected in the western region of North Korea during summer. Based on the detrended correlation analysis of NDVI with surface energy variables at each grid point, including solar radiation, sensible and latent heat fluxes, Bowen ratio, and temperature, we identified a cooling effect of vegetation in the western region (with lower NDVI and lower elevation), but a warming effect of vegetation in the northern region (with higher NDVI and higher elevation). The different biogeophysical effects were induced by the increasing and decreasing Bowen ratio with increasing vegetation in the northern and western regions, respectively. In the western region of North Korea, where large-scale human-induced forest loss has been observed, the increasing summer temperature caused by the decreasing cooling effect of vegetation would be up to 1.5 ℃ by the end of this century, if the current rate of deforestation continues. Thus, we urgently suggest that sustainable management and restoration of forests are needed in North Korea, which is among the countries most vulnerable to climate change now and in the future.


2021 ◽  
Vol 13 (20) ◽  
pp. 4023
Author(s):  
Veena Shashikant ◽  
Abdul Rashid Mohamed Shariff ◽  
Aimrun Wayayok ◽  
Md Rowshon Kamal ◽  
Yang Ping Lee ◽  
...  

In oil palm crop, soil fertility is less important than the physical soil characteristics. It is important to have a balance and sufficient soil moisture to sustain high yields in oil palm plantations. However, conventional methods of soil moisture determination are laborious and time-consuming with limited coverage and accuracy. In this research, we evaluated synthetic aperture radar (SAR) and in-situ observations at an oil palm plantation to determine SAR signal sensitivity to oil palm crop by means of water cloud model (WCM) inversion for retrieving soil moisture from L-band HH and HV polarized data. The effects of vegetation on backscattering coefficients were evaluated by comparing Leaf Area Index (LAI), Leaf Water Area Index (LWAI) and Normalized Plant Water Content (NPWC). The results showed that HV polarization effectively simulated backscatter coefficient as compared to HH polarization where the best fit was obtained by taking the LAI as a vegetation descriptor. The HV polarization with the LAI indicator was able to retrieve soil moisture content with an accuracy of at least 80%.


2021 ◽  
Author(s):  
Huiming Lin ◽  
Yindong Tong ◽  
Chenghao Yu ◽  
Long Chen ◽  
Xiufeng Yin ◽  
...  

Abstract. The Tibetan Plateau is generally considered to be a significantly clean area owing to its high altitude; however, the transport of atmospheric pollutants from the Indian subcontinent to the Tibetan Plateau has infected the Tibetan environments. Nyingchi is located at the end of an important water vapor channel. In this study, continuous monitoring of gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), and particle-bound mercury (PBM) was conducted in Nyingchi from March 30 to September 3, 2019, to study the influence of the Indian summer monsoon (ISM) on the origin, transport and behavior of mercury. The atmospheric Hg concentrations during the preceding Indian summer monsoon (PISM) period (1.20 ± 0.35 ng m−3, 13.5 ± 7.3 pg m−3, and 11.4 ± 4.8 pg m−3 for GEM, GOM, and PBM, respectively) were relatively higher than those during the ISM period (0.95 ± 0.21 ng m−3, 12.7 ± 14.3 pg m−3 and 8.8 ± 6.0 pg m−3). The average annual total gaseous mercury concentration in the Nyingchi region was obtained using a passive sampler as 1.12 ± 0.28 ng m−3. The GEM concentration showed that the sampling area was very clean. The GEM has several patterns of daily variation during different periods. Stable high GEM concentrations occur at night during PISM, which may be related to the nocturnal boundary layer. High values occurring in the late afternoon during the ISM may be related to long-range transport. The results of the trajectory model demonstrate that the sources of pollutants at Nyingchi are different under the control of different airflow fields. During westerly circulation, pollutants mainly originate from northeast India or Nepal. During the ISM period, the pollutants mainly originate from northeast India, or the Bay of Bengal, and the Indian Ocean. The strong precipitation and vegetation effects on Hg during the ISM resulted in low Hg concentrations transmitted to Nyingchi during this period. Further, principal component analysis showed that long-distance transport, local emissions, meteorological factors, and snowmelt factors are the main factors affecting the local Hg concentration in Nyingchi.


Water ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 2564
Author(s):  
Francesco Coscarella ◽  
Nadia Penna ◽  
Aldo Pedro Ferrante ◽  
Paola Gualtieri ◽  
Roberto Gaudio

River vegetation radically modifies the flow field and turbulence characteristics. To analyze the vegetation effects on the flow, most scientific studies are based on laboratory tests or numerical simulations with vegetation stems on smooth beds. Nevertheless, in this manner, the effects of bed sediments are neglected. The aim of this paper is to experimentally investigate the effects of bed sediments in a vegetated channel and, in consideration of that, comparative experiments of velocity measures, performed with an Acoustic Doppler Velocimeter (ADV) profiler, were carried out in a laboratory flume with different uniform bed sediment sizes and the same pattern of randomly arranged emergent rigid vegetation. To better comprehend the time-averaged flow conditions, the time-averaged velocity was explored. Subsequently, the analysis was focused on the energetic characteristics of the flow field with the determination of the Turbulent Kinetic Energy (TKE) and its components, as well as of the energy spectra of the velocity components immediately downstream of a vegetation element. The results show that both the vegetation and bed roughness surface deeply affect the turbulence characteristics. Furthermore, it was revealed that the roughness influence becomes predominant as the grain size becomes larger.


2021 ◽  
Vol 11 (18) ◽  
pp. 8429
Author(s):  
Spyridon Mavroulis ◽  
Efthymis Lekkas

The August 1953 seismic sequence comprised the most destructive events in the recent history of Greece. The mainshock on 12 August, and its foreshocks on 9 and 11 August, devastated the southern Ionian Islands. The existing literature emphasized the destructive effects of the earthquakes on buildings, as well as to the emergency response and recovery actions. This resulted in a large gap in capturing the full picture of the earthquake’s environmental effects. The present study aims to fill this gap by reconstructing the most complete picture possible of the primary and secondary effects on the environment of the southern Ionian Islands by the August 1953 earthquakes. This reconstruction is based on all available sources, comprising not only the existing scientific literature, but especially sources that have not been considered to date, including newspapers of local and national circulation. In total, 120 cases of the earthquake’s environmental effects were identified, comprised of 33 cases of primary and 87 cases of secondary effects. In descending order of occurrence, slope failures, co-seismic uplift, hydrological anomalies, ground cracks, tsunami, liquefaction, dust clouds, hydrocarbon-related phenomena, jumping stones and vegetation effects were distributed mainly in Cephalonia Island and secondarily in the Ithaki and Zakythos Islands. The primary effects were mainly detected in eastern Cephalonia, which presented uplift of up to 70 cm, while the majority of the secondary effects were triggered in specific zones with characteristics that made them susceptible to the occurrence of earthquake-related hazards.


2021 ◽  
Vol 13 (16) ◽  
pp. 3293
Author(s):  
Nicola Montaldo ◽  
Laura Fois ◽  
Roberto Corona

The new constellation of synthetic aperture radar (SAR) satellite, Sentinel-1, provides images at a high spatial resolution (up to 10 m) typical of radar sensors, but also at high time resolutions (6–12 revisit days), representing a major advance for the development of operational soil moisture mapping at a plot scale. Our objective was to develop and test an operational approach to assimilate Sentinel 1 observations in a land surface model, and to demonstrate the potential of the use of the new satellite sensors in soil moisture predictions in a grass field. However, for soil moisture retrievals from Sentinel 1 observations in grasslands, there is still the need to identify robust and parsimonious solutions, accounting for the effects of vegetation attenuation and their seasonal variability. In a grass experimental site in Sardinia, where field measurements of soil moisture were available for the 2016–2018 period, three common retrieval methods have been compared to estimate soil moisture from Sentinel 1 data, with increasing complexity and physical interpretation of the processes: the empirical change detection method, the semi-empirical Dubois model, and the physically-based Fung model. In operational approaches for soil moisture mapping from remote sensing, the parameterization simplification of soil moisture retrieval techniques is encouraged, looking for parameter estimates without a priori information. We have proposed a simplified approach for estimating a key parameter of retrieval methods, the surface roughness, from the normalized difference vegetation index (NDVI) derived by simultaneous Sentinel 2 optical observations. Soil moisture was estimated better using the proposed approach and the Dubois model than by using the other methods, which accounted vegetation effects through the common water cloud model. Furthermore, we successfully merged radar-based soil moisture observations and a land surface model, through a data assimilation approach based on the Ensemble Kalman filter, providing robust predictions of soil moisture.


Urban Climate ◽  
2021 ◽  
Vol 39 ◽  
pp. 100939
Author(s):  
Muhammad Omer Mughal ◽  
Aytac Kubilay ◽  
Simone Fatichi ◽  
Naika Meili ◽  
Jan Carmeliet ◽  
...  

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