scholarly journals Using Long-Term Earth Observation Data to Reveal the Factors Contributing to the Early 2020 Desert Locust Upsurge and the Resulting Vegetation Loss

2021 ◽  
Vol 13 (4) ◽  
pp. 680
Author(s):  
Lei Wang ◽  
Wen Zhuo ◽  
Zhifang Pei ◽  
Xingyuan Tong ◽  
Wei Han ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Land Surface ◽  
Arabian Peninsula ◽  
Vegetation Coverage ◽  
Observation Data ◽  
Desert Locust ◽  
Meteorological Observations ◽  
Earth Observation Data ◽  
Vegetation Loss

Massive desert locust swarms have been threatening and devouring natural vegetation and agricultural crops in East Africa and West Asia since 2019, and the event developed into a rare and globally concerning locust upsurge in early 2020. The breeding, maturation, concentration and migration of locusts rely on appropriate environmental factors, mainly precipitation, temperature, vegetation coverage and land-surface soil moisture. Remotely sensed images and long-term meteorological observations across the desert locust invasion area were analyzed to explore the complex drivers, vegetation losses and growing trends during the locust upsurge in this study. The results revealed that (1) the intense precipitation events in the Arabian Peninsula during 2018 provided suitable soil moisture and lush vegetation, thus promoting locust breeding, multiplication and gregarization; (2) the regions affected by the heavy rainfall in 2019 shifted from the Arabian Peninsula to West Asia and Northeast Africa, thus driving the vast locust swarms migrating into those regions and causing enormous vegetation loss; (3) the soil moisture and NDVI anomalies corresponded well with the locust swarm movements; and (4) there was a low chance the eastwardly migrating locust swarms would fly into the Indochina Peninsula and Southwest China.

scholarly journals A Cuboid Model for Assessing Surface Soil Moisture

2019 ◽  
Vol 11 (24) ◽  
pp. 3034 ◽  
Author(s):  
Xiufang Zhu ◽  
Yaozhong Pan ◽  
Junxia Wang ◽  
Ying Liu
Keyword(s):  
Soil Moisture ◽  
Land Surface ◽  
Vegetation Index ◽  
Vegetation Coverage ◽  
Observation Data ◽  
Optical Remote Sensing ◽  
Moisture Index ◽  
Significance Level ◽  
Feature Parameters ◽  
Soil Moisture Inversion

This study proposes a cuboid model for soil moisture assessment. In the model, the three edges were the meteorological, soil, and vegetation feature parameters highly related to soil moisture, and the edge lengths represented the degree of influence of each feature parameter on soil moisture. Soil moisture is assessed by the cuboid diagonal, which is referred to as the cuboid soil moisture index (CSMI) in this paper. The model was applied and validated in the Huang-Huai-Hai Plain. The results showed that (1) the difference in land surface temperature between day and night (ΔLST), land surface water index (LSWI), and accumulated precipitation (AP) were most closely correlated with soil moisture observation data in our study area, and were therefore selected as soil, crop, and meteorological system parameters to participate in CSMI calculations, respectively. (2) CSMI-1, with a cuboid length coefficient of 2/1/2, was the best model. The correlation of soil moisture derived from CSMI-1 with observed values was 0.64, 0.60, and 0.52 at depths of 10 cm, 20 cm, and 50 cm, respectively. (3) CSMI-1 had good applicability to the evaluation of soil moisture under different vegetation coverage. When the normalized difference vegetation index (NDVI)was 0–0.7, CSMI-1 was highly correlated with soil moisture at a significance level of 0.01. (4) The three-dimensional (3D) CSMI model can be easily converted to a two-dimensional (2D) model to adapt to different surface conditions (as long as the weight coefficient of one parameter is set to 0). Irrigation information (if available) can be considered as artificial recharge precipitation added in the AP to improve the accuracy of soil moisture inversion. This study provides a reference for soil moisture inversion using optical remote sensing images by integrating soil, vegetation, and meteorological feature parameters.

scholarly journals Quantifying Tree Cover Loss in Urban Forests within Nairobi City Metropolitan Area from Earth Observation Data

2020 ◽  
Vol 3 (1) ◽  
pp. 78
Author(s):  
Francis Oloo ◽  
Godwin Murithi ◽  
Charlynne Jepkosgei
Keyword(s):  
Land Cover ◽  
Metropolitan Area ◽  
Land Surface ◽  
Urban Forest ◽  
Urban Forests ◽  
Earth Observation ◽  
Tree Cover ◽  
Observation Data ◽  
Vegetation Health ◽  
Earth Observation Data

Urban forests contribute significantly to the ecological integrity of urban areas and the quality of life of urban dwellers through air quality control, energy conservation, improving urban hydrology, and regulation of land surface temperatures (LST). However, urban forests are under threat due to human activities, natural calamities, and bioinvasion continually decimating forest cover. Few studies have used fine-scaled Earth observation data to understand the dynamics of tree cover loss in urban forests and the sustainability of such forests in the face of increasing urban population. The aim of this work was to quantify the spatial and temporal changes in urban forest characteristics and to assess the potential drivers of such changes. We used data on tree cover, normalized difference vegetation index (NDVI), and land cover change to quantify tree cover loss and changes in vegetation health in urban forests within the Nairobi metropolitan area in Kenya. We also used land cover data to visualize the potential link between tree cover loss and changes in land use characteristics. From approximately 6600 hectares (ha) of forest land, 720 ha have been lost between 2000 and 2019, representing about 11% loss in 20 years. In six of the urban forests, the trend of loss was positive, indicating a continuing disturbance of urban forests around Nairobi. Conversely, there was a negative trend in the annual mean NDVI values for each of the forests, indicating a potential deterioration of the vegetation health in the forests. A preliminary, visual inspection of high-resolution imagery in sample areas of tree cover loss showed that the main drivers of loss are the conversion of forest lands to residential areas and farmlands, implementation of big infrastructure projects that pass through the forests, and extraction of timber and other resources to support urban developments. The outcome of this study reveals the value of Earth observation data in monitoring urban forest resources.

Operational Delivery of Customized Earth Observation Data Using Web Coverage Service

2011 ◽  
pp. 385-400
Author(s):  
Wenli Yang
Keyword(s):  
Web Service ◽  
Earth Observation ◽  
Observation Data ◽  
Data Systems ◽  
On Demand ◽  
Promising Solution ◽  
Open Geospatial Consortium ◽  
Earth Observation Data ◽  
Operational Data

Global long term Earth Observation (EO) provides valuable information about the land, ocean, and atmosphere of the Earth. EO data are often archived in specialized data systems managed by the data collector’s system. For the data to be fully utilized, one of the most important aspects is to adopt technologies that will enable users to easily find and obtain needed data in a form that can be readily used with little or no manipulation. Many efforts have been made in this direction but few, if any, data providers can deliver on-demand and operational data to users in customized form. Geospatial Web Service has been considered a promising solution to this problem. This chapter discusses the potential for operational and scalable delivery of on-demand personalized EO data using the interoperable Web Coverage Service (WCS) developed by the Open Geospatial Consortium (OGC).

scholarly journals The Influence of Atlantic Tropical Cyclones on Drought over the Eastern United States (1980–2007)

2013 ◽  
Vol 26 (10) ◽  
pp. 3067-3086 ◽  
Author(s):  
Jonghun Kam ◽  
Justin Sheffield ◽  
Xing Yuan ◽  
Eric F. Wood
Keyword(s):  
United States ◽  
Soil Moisture ◽  
Tropical Cyclones ◽  
Land Surface ◽  
Hydrologic Model ◽  
Eastern United States ◽  
Short Term ◽  
Drought Duration ◽  
Study Region

Abstract To assess the influence of Atlantic tropical cyclones (TCs) on the eastern U.S. drought regime, the Variable Infiltration Capacity (VIC) land surface hydrologic model was run over the eastern United States forced by the North American Land Data Assimilation System phase 2 (NLDAS-2) analysis with and without TC-related precipitation for the period 1980–2007. A drought was defined in terms of soil moisture as a prolonged period below a percentile threshold. Different duration droughts were analyzed—short term (longer than 30 days) and long term (longer than 90 days)—as well as different drought severities corresponding to the 10th, 15th, and 20th percentiles of soil moisture depth. With TCs, droughts are shorter in duration and of a lesser spatial extent. Tropical cyclones variously impact soil moisture droughts via late drought initiation, weakened drought intensity, and early drought recovery. At regional scales, TCs decreased the average duration of moderately severe short-term and long-term droughts by less than 4 (10% of average drought duration per year) and more than 5 (15%) days yr−1, respectively. Also, they removed at least two short-term and one long-term drought events over 50% of the study region. Despite the damage inflicted directly by TCs, they play a crucial role in the alleviation and removal of drought for some years and seasons, with important implications for water resources and agriculture.

Long-Term Climate and Derived Surface Hydrology and Energy Flux Data for Mexico: 1925–2004

2007 ◽  
Vol 20 (9) ◽  
pp. 1936-1946 ◽  
Author(s):  
Chunmei Zhu ◽  
Dennis P. Lettenmaier
Keyword(s):  
Soil Moisture ◽  
North American ◽  
Land Surface ◽  
Surface Fluxes ◽  
The Other ◽  
Shortwave Radiation ◽  
Infiltration Capacity ◽  
Time Step ◽  
Downward Longwave Radiation

Abstract Studying the role of land surface conditions in the Mexican portion of the North American monsoon system (NAMS) region has been a challenge due to the paucity of long-term observations. A long-term gridded observation-based climate dataset suitable for forcing land surface models, as well as model-derived land surface states and fluxes for a domain consisting of all of Mexico, is described. The datasets span the period of January 1925–October 2004 at 1/8° spatial resolution at a subdaily (3 h) time step. The simulated runoff matches the observations plausibly over most of the 14 small river basins spanning all of Mexico, which suggests that long-term mean evapotranspiration is realistically reproduced. On this basis, and given the physically based model parameterizations of soil moisture and energy fluxes, the other surface fluxes and state variables such as soil moisture should be represented reasonably. In addition, a comparison of the surface fluxes from this study is performed with North American Regional Reanalysis (NARR) data on a seasonal mean basis. The results indicate that downward shortwave radiation is generally smaller than in the NARR data, especially in summer. Net radiation, on the other hand, is somewhat larger in the Variable Infiltration Capacity (VIC) hydrological model than in the NARR data for much of the year over much of the domain. The differences in radiative and turbulent fluxes are attributed to (i) the parameterization used in the VIC forcings for solar and downward longwave radiation, which links them to the daily temperature and temperature range, and (ii) differences in the land surface parameterizations used in VIC and the NCEP–Oregon State University–U.S. Air Force–NWS/Hydrologic Research Lab (Noah) land scheme used in NARR.

Extension of the regional climate model REMO by a 5-layer soil scheme

2020 ◽  
Author(s):  
Daniel Abel ◽  
Felix Pollinger ◽  
Katrin Ziegler ◽  
Heiko Paeth
Keyword(s):  
Soil Moisture ◽  
Land Surface ◽  
Soil Depth ◽  
Regional Climate ◽  
Capillary Rise ◽  
Rooting Depth ◽  
Climate Projections ◽  
Observation Data ◽  
Soil Hydrology ◽  
Spatiotemporal Resolution

<p>The EFRE-Project BigData@Geo, founded by the European Union, aims to create highly resolved climate projections for the model region of Lower Franconia in Bavaria, Germany. These projections are analyzed and made available to local stakeholders of agriculture, forestry, and viniculture as well as the public. As recent regional climate models are not dealing with the necessary spatiotemporal resolution the model REMO will be developed in the project‘s frame in cooperation with the Climate Service Center Germany (GERICS).</p><p>For these very high resolutions, besides improvements like the non-hydrostatic atmosphere, higher resolved static land surface parameters, and land use land cover changes, etc., realistic modeling of the soil hydrology becomes absolutely necessary. Therefore, REMO is extended by a 5-layer soil scheme which is a first step to overcome restrictions of the recently used soil hydrology scheme due to the included vertical water flow. Furthermore, the current work also aims to implement lateral water flows between grid cells because this is the only way to model the soil hydrology appropriate to the project‘s question.</p><p>The current model version of REMO includes a bucket scheme that treats the soil hydrology as a single layer. The soil depth is equal to the rooting depth and, thus, depends on the overlying vegetation class. Consequently, the whole soil moisture of the soil is available for transpiration. Evaporation only occurs if the soil moisture reaches at least 90 % of the field capacity.</p><p>The 5-layer scheme has 5 layers with increasing thicknesses for deeper layers. The maximum depth of the soil is at approximately 10 m or the depth of the bedrock. Due to the existence of water below the rooting zone and the processes of capillary rise and percolation more water becomes available for transpiration compared to the bucket scheme. Furthermore, evaporation only occurs if the uppermost layer contains soil moisture which is a more realistic process representation as well.</p><p>First results of the comparison of the two schemes and with observation data in the EURO-CORDEX region and a german subregion are presented. We also show some sensitivity studies of the current improvements to the parameterizations of the 5-layer scheme which are necessary for the goal of incorporation of the lateral flow.</p>

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