A Remote Sensing Water Information Extraction Method Based on Unsupervised Form Using Probability Function to Describe the Frequency Histogram of NDWI: A Case Study of Qinghai Lake in China

Water, Journal Year: 2024, Volume and Issue: 16(12), P. 1755 - 1755

Published: June 20, 2024

With escalating human activities and the substantial emissions of greenhouse gases, global warming intensifies. This phenomenon has led to increased occurrences various extreme hydrological events, precipitating significant changes in lakes rivers across Qinghai Tibet Plateau. Therefore, accurate information extraction about delineation water bodies are crucial for lake monitoring. paper proposes a methodology based on Normalized Difference Water Index (NDWI) Gumbel distribution determine optimal segmentation thresholds. Focusing Lake, this study utilizes multispectral characteristics from US Landsat satellite analysis. Comparative assessments with seven alternative methods conducted evaluate accuracy. Employing proposed approach, Lake is extracted over 38 years, 1986 2023, revealing trends area variation. Analysis indicates rising trend Lake’s following turning point 2004. To investigate phenomenon, Pearson correlation analysis temperature precipitation past years used unveils fact that slight impacts there positive between area. In conclusion, employs remote sensing data statistical comprehensively mechanisms driving surface area, providing insights into ecological shifts systems against backdrop warming, thereby offering valuable references understanding addressing these changes.

Language: Английский

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Time-lag effects of NEP and NPP to meteorological factors in the source regions of the Yangtze and Yellow Rivers

Frontiers in Plant Science, Journal Year: 2025, Volume and Issue: 15

Published: Jan. 10, 2025

Vegetation productivity and ecosystem carbon sink capacity are significantly influenced by seasonal weather patterns. The time lags between changes in these patterns (including vegetation) responses is a critical aspect vegetation-climate ecosystem-climate interactions. These can vary considerably due to the spatial heterogeneity of vegetation ecosystems. In this study focused on source regions Yangtze Yellow Rivers (SCRYR), we utilized long-term datasets Net Primary Productivity (NPP) model-estimated Ecosystem (NEP) from2015 2020, combined with reconstructed 8-day scale climate sequences, conduct partial correlation regression analysis (isolating influence individual meteorological factors lag effects). found that length effects varies depending regional topography, types, sensitivity their ecological environments factors. region River (SCR), times for NPP NEP response temperature (Tem) longer, compared (SYR), where generally less than 10 days. long precipitation (Pre), ranging from 50 60 days, were primarily concentrated northwestern part SCR, while precipitation, 34 48 covered broad western area. exhibits least solar radiation (SR), exceeding 54 days 99.30% region. contrast, showed varying respect SR: short (ranging 0 15 days) observed areas, 55 64 evident areas. highest SVL, followed C3A, PW, BDS, C3 descending order. This examined spatiotemporal impacts climatic drivers both perspectives. findings crucial enhancing sequestration at important water sources China.

Language: Английский

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Phenology-Optimized Drought Index Reveals the Spatio-Temporal Patterns of Vegetation Health and Its Attribution on the Loess Plateau

Remote Sensing, Journal Year: 2025, Volume and Issue: 17(5), P. 891 - 891

Published: March 3, 2025

Frequent droughts pose a severe threat to the ecological health and sustainable development of Loess Plateau (LP). The accurate assessment impact drought on vegetation is crucial for diagnosing health. Traditional methods often rely coarse estimations based averages indices, overlooking spatial differentiation complex phenology. This study proposes vegetative method that considers phenological characteristics using MODIS EVI LST data products. First, start end growing season timepoints were extracted from Enhanced Vegetation Index (EVI) Savitzky–Golay (S–G) filtering dynamic threshold method, determining growing-time window each pixel. Next, Health (VHI) series was calculated pixel within season. mean value VHI then used construct Growing Season (GSHI). Based GSHI, long-term at LP revealed. Finally, we integrated Optimal Parameters-based Geographical Detector (OPGD) identify quantify multiple driving forces drought. results showed that: (1) spatio-temporal difference phenology significant, exhibiting distinct zonal characteristics; (2) distribution presented “humid southeast, arid northwest” pattern, with early 21st century being period high occurrence; (3) has been alleviated in large-scale natural areas, but local effect under urbanization intensifying; (4) meteorology topography influence by regulating water redistribution, while human activities intensifying.

Language: Английский

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Spatiotemporal Pattern of Soil Moisture and Its Association with Vegetation in the Yellow River Basin

Water, Journal Year: 2025, Volume and Issue: 17(7), P. 1028 - 1028

Published: March 31, 2025

Soil moisture (SM) plays a crucial role in the hydrological and ecological processes of Yellow River Basin (YRB), with its spatiotemporal distribution variability serving as key factors for understanding ecosystem responses to environmental changes. However, previous research has often overlooked variation SM across different soil layers complex bidirectional interactions between vegetation, particularly indicated by Normalized Difference Vegetation Index (NDVI), within vegetation zones layers. Widely used fields such agriculture water cycle research, GLDAS dataset been applied analyze patterns at four depths (0–10 cm, 10–40 40–100 100–200 cm) YRB from 1948 2022, revealing continuous increase over time, more pronounced changes after identified breakpoints (1985 cm layer, 1986 other layers). Granger causality tests show that interaction NDVI dominates all regions, far surpassing unidirectional effects on or vice versa. Regardless whether is primary variable, Temperate Evergreen Broadleaf Forest (TEBF) region consistently exhibits strongest lag layers, followed Qinghai-Tibet Plateau Alpine (QTPAV) Desert Region (TDR). The Subtropical Warm Deciduous (SWTDF) Grassland (TGR) weakest effects. This offers new insights into mutual feedback hydrology provides scientific basis effective resource management.

Language: Английский

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A Phenology-Dependent Analysis for Identifying Key Drought Indicators for Crop Yield based on Causal Inference and Information Theory

EarthArXiv (California Digital Library), Journal Year: 2024, Volume and Issue: unknown

Published: Aug. 29, 2024

Drought indicators, which are quantitative measurements of drought severity and duration, used to monitor predict the risk effects drought, particularly in relation sustainability agriculture water supplies. This research uses causal inference information theory discover index, is most efficient indicator for agricultural productivity a valuable metric estimating predicting crop yield. The connection between precipitation, maximum air temperature, indices corn soybean yield ascertained by cross convergent mapping (CCM), while transfer them determined through entropy (TE). conducted on rainfed lands Iowa, considering phenological stages crops. Based nonlinearity analysis using S-map, it that causality could not be carried out CCM due absence data. results intriguing as they uncover both precipitation temperature indices. analysis, with strongest relationship production SPEI-9m SPI-6m during silking period, SPI-9m doughing period. Therefore, these may considered effective predictors prediction models. study highlights need periods when production, differs two periods.

Language: Английский

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Causes of Increased Compound Temperature and Precipitation Extreme Events in the Arid Region of Northwest China from 1961 to 2100

Remote Sensing, Journal Year: 2024, Volume and Issue: 16(17), P. 3111 - 3111

Published: Aug. 23, 2024

Compound extreme events pose more grave threats to human health, the natural environment, and socioeconomic systems than do individual events. However, drivers spatiotemporal change characteristics of compound under climate transition remain poorly understood, especially in arid region Northwest China. This study examined driving mechanisms temperature precipitation China based on data from 86 national meteorological stations 11 models Coupled Model Intercomparison Project, Phase 6. The results indicated that (1) frequency values heat extremity–dry (1.60/10a) extremity–heavy (0.60/10a) increased 1961 2020, showed a faster uptrend after 1990 before. (2) Under four shared pathway scenarios, there is also likelihood an upward trend by end 21 century, SSP585, with probability 1.70/10a 1.00/10a, respectively. (3) A soil moisture deficit leads decreased evaporation sensible reduction soil–atmosphere exchange; non-adiabatic heating process higher hot days. land–air interaction feedback mechanism significant driver (4) In region, warmer surpasses wetter trend, contributing specific humidity, vapor pressure may lead increasing precipitation, consequently These provide new insights for understanding events, order cope their risks.

Language: Английский

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The Impact of Seasonal Climate on Dryland Vegetation NPP: The Mediating Role of Phenology

Sustainability, Journal Year: 2024, Volume and Issue: 16(22), P. 9835 - 9835

Published: Nov. 11, 2024

Dryland ecosystems are highly sensitive to climate change, making vegetation monitoring crucial for understanding ecological dynamics in these regions. In recent years, combined with large-scale restoration efforts, has led significant greening China’s arid areas. However, the mechanisms through which seasonal variations regulate growth not yet fully understood. This study hypothesizes that change affects net primary productivity (NPP) of by influencing phenology. We focused on Windbreak and Sand-Fixation Ecological Function Conservation Areas (WSEFCAs) as representative regions dryland vegetation. The Carnegie–Ames–Stanford Approach (CASA) model was used estimate NPP from 2000 2020. To extract phenological information, NDVI data were processed using Savitzky–Golay (S–G) filtering threshold methods determine start season (SOS) end (EOS). structural equation (SEM) constructed quantitatively assess contributions (temperature precipitation) phenology NPP, identifying pathways influence. results indicate average annual WSEFCAs increased 55.55 gC/(m2·a) 75.01 gC/(m2·a), exhibiting uneven spatial distribution. more complex uneven. Summer precipitation directly promoted (direct effect = 0.243, p < 0.001) while also indirectly enhancing significantly advancing SOS (0.433, delaying EOS (−0.271, 0.001), an indirect 0.133. finding highlights critical role growth, particularly substantial fluctuations. Although overall environment improved, regional disparities remain, especially northwestern China. introduces causal mediation analysis systematically explore impacts WSEFCAs, providing new insights into broader implications offering scientific support management strategies

Language: Английский

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