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Satellite Remote Sensing for Water Resources in a Changing Climate

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A special issue of Remote Sensing (ISSN 2072-4292).

Deadline for manuscript submissions: closed (31 October 2018) | Viewed by 70417

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Special Issue Editors

Dr. George P. Petropoulos

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Guest Editor

Department of Geography, Harokopio University of Athens, 176 71 Moschato, Greece
Interests: earth observation; modeling; land surface interactions; soil moisture; evapotrasnpiration; land use/cover mapping; change detection; natural hazards; floods; wildfires; sensitivity analysis; soil vegetation atmosphere transfer modeling; operational products benchmarking
Special Issues, Collections and Topics in MDPI journals

Dr. Simonetta Paloscia

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Guest Editor

Consiglio Nazionale delle Ricerche, Institute of Applied Physics, Florence, Italy
Interests: microwave remote sensing; soil moisture; vegetation biomass; snow water equivalent; SAR; microwave radiometry
Special Issues, Collections and Topics in MDPI journals

Dr. Prashant K Srivastava

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Guest Editor

Institute of Environment and Sustainable Development, Banaras Hindu University, Varanasi, India
Interests: hyperspectral remote sensing; soft computing
Special Issues, Collections and Topics in MDPI journals

Prof. Dr. Guangsheng Zhou

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Guest Editor

State Key Laboratory of Vegetation and Environmental Change (LVEC), The Institute of Botany, the Chinese Academy of Sciences, No.20 Nanxincun, Xiangshan, No.46, Zhongguancun South Street, Beijing 100093, China
Interests: plant and crop ecology; crop drought and irrigation; vegetation water stress; net primary productivity; plant biodiversity; multi-temporal remote sensing; multi-spectral; hyper-spectral

Special Issue Information

Dear Colleagues,

Water is one of the most important substances on Earth. It is a key variable in Earth’s hydrological cycle for water and energy exchanges that occur at the land–surface/atmosphere interface, and is responsible for the evolution of weather and climate over continental regions. Information on our planet’s water resources is indispensable to a number of practical applications related to both society and ecosystems. Globally, the monitoring of the Earth’s water resources has developed into a very important and urgent research direction, especially in the face of climate change.

However, the amount of water available throughout the world is already limited, and demand will continue to rise as population grows. In this context, there is a growing need to monitor and obtain a better understanding of its use, which will provide information that can assist towards the development of effective water management strategies and infrastructures. This can be of crucial importance, particularly to regions on which the amount of water available is limited.

Water resource modeling and management includes the activity of planning, developing, distributing and managing the optimum use of water resources in a simplistic manner. As compared to other natural resources, modeling and management of water is complicated in practice. The use of satellites for the management of water can play an important role in the future of water resources. The launch of Earth Observation (EO) sensors from advanced satellites, such as SMOS, Landsat 8, Sentinel-2/3, GCOM-W1, SMAP, GPM, TRMM, etc. has the potential to reshape the water world. These instruments provide necessary data that can make up for the lack of on-the-ground monitoring of water resources around the world.

Therefore, the main aim of this Special Issue is to foster advances in EO technology for water resources management with the scope of flood, drought, irrigation, soil moisture retrieval, algorithms development, operational products benchmarking, precipitation, modelling and applications. In particular, submission of article exploring the use of New Earth Observation missions providing data at all the different regions of the electromagnetic spectrum are highly encouraged. Both applied EO technology to water resources management implementation and models’ or algorithms’ related scientific investigations are encouraged.

Consequently, topics of interest to the Special Issue may include, but are not limited to, the following:

Keywords:

Multi-spectral imagery
Hyper-spectral imagery
Thermal infrared imagery
SAR processing
Time series analysis
Soil moisture mapping
Vegetation Water stress
Crop Drought and irrigation
Water Use Efficiency
Yield mapping
Decision support systems
Meteorological disaster risk management
Early warning systems for agrometerological hazards.
Agro-informatics and agricultural water management
Groundwater level monitoring
Geo-informatic
Natural disasters management, e.g., floods and droughts

Authors are required to check and follow the specific Instructions to Authors, https://www.mdpi.com/journal/remotesensing/instructions.

Dr. George P. Petropoulos
Dr. Guangsheng Zhou
Dr. Prashant Srivastava
Dr. Simonetta Paloscia
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Remote Sensing is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (11 papers)

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Research

17 pages, 6499 KiB

Open AccessArticle

Integration of Microwave and Optical/Infrared Derived Datasets for a Drought Hazard Inventory in a Sub-Tropical Region of India

by Varsha Pandey and Prashant K. Srivastava

Remote Sens. 2019, 11(4), 439; https://doi.org/10.3390/rs11040439 - 20 Feb 2019

Cited by 17 | Viewed by 3999

Abstract

Drought is an intricate phenomenon assessed by analyzing several hydro-meteorological factors such as rainfall, soil moisture, temperature, evapotranspiration, vegetation cover, etc. For effective drought hazard management and preparedness, the monitoring of drought requires the evaluation of influencing factors via the Drought Hazard Inventory (DHI). The main objective of this study is to compare spatial occurrences of drought hazard with the help of microwave and Optical/Infrared datasets obtained from multiple satellites. The long-term climatology of the Tropical Rainfall Measuring Mission (TRMM) Rainfall, Climate Change Initiative soil moisture (CCI-SM) and Moderate Resolution Imaging Spectroradiometer (MODIS) derived Land Surface Temperature (LST), Evapotranspiration (ET) and Normalized Difference Vegetation Index (NDVI) were used in this study for drought hazard assessment. This study was carried out in the Bundelkhand region of Uttar Pradesh, considered as one of the most frequent and dominant drought-prone areas of India. The current study includes the Analytical Hierarchy Process (AHP) technique based on Multi-Criteria Decision Making Analysis (MCDM) for weighting assignment and decision making, while the geospatial platform was used for data layer standardization, integration, and drought assessment. The results indicate that a large percentage of area (38.05% and 27.54%, respectively) lying in the central part of Bundelkhand region is under high to extreme drought conditions, where precautionary measures are needed. To demonstrate the robustness of our results, we compare them with the long-term in-situ ground water depletion as a proxy. Finally, based on the findings of this study, we recommend the methodology for drought assessment at a larger scale, as well as in the remote areas where ground based measurements are limited. Full article

(This article belongs to the Special Issue Satellite Remote Sensing for Water Resources in a Changing Climate)

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22 pages, 2317 KiB

Open AccessFeature PaperArticle

An Appraisal of the Potential of Landsat 8 in Estimating Chlorophyll-a, Ammonium Concentrations and Other Water Quality Indicators

by Vassiliki Markogianni, Dionissios Kalivas, George P. Petropoulos and Elias Dimitriou

Remote Sens. 2018, 10(7), 1018; https://doi.org/10.3390/rs10071018 - 26 Jun 2018

Cited by 41 | Viewed by 6380

Abstract

In-situ monitoring of lake water quality in synergy with satellite remote sensing represents the latest scientific trend in many water quality monitoring programs worldwide. This study investigated the suitability of the Operational Land Imager (OLI) instrument onboard the Landsat 8 satellite platform in accurately estimating key water quality parameters such as chlorophyll-a and nutrient concentrations. As a case study the largest freshwater body of Greece (Trichonis Lake) was used. Two Landsat 8 images covering the study site were acquired on 30 October 2013 and 30 August 2014 respectively. Near concurrent in-situ observations from two water sampling campaigns were also acquired from 22 stations across the lake under study. In-situ measurements (nutrients and chlorophyll-a concentrations) were statistically correlated with various spectral band combinations derived from the Landsat imagery of year 2014. Subsequently, the most statistically promising predictive models were applied to the satellite image of 2013 and validation was conducted using in-situ data of 2013 as reference. Results showed a relatively variable statistical relationship between the in-situ and reflectances (R logchl-a: 0.58, R NH₄⁺: 0.26, R chl-a: 0.44). Correlation coefficient (R) values reported of up to 0.7 for ammonium concentrations and also up to 0.5 and up to 0.4 for chl-a concentration and chl-a concentrations respectively. These results represent a higher accuracy of Landsat 8 in comparison to its predecessors in the Landsat satellites series, as evidenced in the literature. Our findings suggest that Landsat 8 has a promising capability in estimating water quality components in an oligotrophic freshwater body characterized by a complete absence of any quantitative, temporal and spatial variance, as is the case of Trichonis lake. Yet, even with the presence of a lot of ground information as was the case in our study, a quantitatively accurate estimation of water quality constituents in coastal/inland waters remains a great challenge. The launch of sophisticated spaceborne sensing systems, such as that of Landsat 8, can assist in improving our ability to estimate freshwater lake properties from space. Full article

(This article belongs to the Special Issue Satellite Remote Sensing for Water Resources in a Changing Climate)

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25 pages, 10325 KiB

Open AccessArticle

Lake Surface Water Temperature Derived from 35 Years of AVHRR Sensor Data for European Lakes

by Gian Lieberherr and Stefan Wunderle

Remote Sens. 2018, 10(7), 990; https://doi.org/10.3390/rs10070990 - 22 Jun 2018

Cited by 37 | Viewed by 5856

Abstract

Lake surface water temperature (LSWT) is an important parameter with which to assess aquatic ecosystems and to study the lake’s response to climate change. The AVHRR archive of the University of Bern offers great potential to derive consistent LSWT data suited for the study of climate change and lake dynamics. To derive such a dataset, challenges such as orbit drift correction, non-water pixel detection, and homogenization had to be solved. The result is a dataset covering over 3.5 decades of spatial LSWT data for 26 European lakes. The validation against in-situ temperature data at 19 locations showed an uncertainty between ±0.8 K and ±2.0 K (standard deviation), depending on locations of the lakes. The long-term robustness of the dataset was confirmed by comparing in-situ and satellite derived temperature trends, which showed no significant difference. The final trend analysis showed significant LSWT warming trends at all locations (0.2 K/decade to 0.8 K/decade). A gradient of increasing trends from south-west to north-east of Europe was revealed. The strong intra-annual variability of trends indicates that single seasonal trends do not well represent the response of a lake to climate change, e.g., autumn trends are dominant in the north of Europe, whereas winter trends are dominant in the south. Intra-lake variability of trends indicates that trends at single in-situ stations do not necessarily represent the lake’s response. The LSWT dataset generated for this study gives some new and interesting insights into the response of European lakes to climate change during the last 36 years (1981–2016). Full article

(This article belongs to the Special Issue Satellite Remote Sensing for Water Resources in a Changing Climate)

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22 pages, 35992 KiB

Open AccessArticle

Discrimination of Algal-Bloom Using Spaceborne SAR Observations of Great Lakes in China

by Lin Wu, Le Wang, Lin Min, Wei Hou, Zhengwei Guo, Jianhui Zhao and Ning Li

Remote Sens. 2018, 10(5), 767; https://doi.org/10.3390/rs10050767 - 16 May 2018

Cited by 25 | Viewed by 6672

Abstract

Although optical remote sensing can intuitively detect algal bloom, it is limited by the weather conditions. Synthetic aperture radar (SAR) is not affected by inadequate weather conditions. According to visual interpretation of SAR images and comparisons of quasi-synchronized optical images, the gathering areas of algal bloom present as “dark regions” on SAR images. It is shown that using SAR to monitor the water surface is workable. However, dark regions may also be caused by other factors, such as low wind speeds. This challenges with SAR monitoring of algal bloom on the water surface. In this study, an improved K-means algorithm, combined with multi-Otsu thresholding algorithm, was proposed to segment the dark regions. After feature analysis and extraction of Sentinel-1A images, an algal bloom recognition model with a support vector machine (SVM) was applied to discriminate the algal bloom dark regions from the low wind dark regions. According the experimental results, the overall accuracy achieved 74.00% in Taihu Lake. Additionally, this method was also validated in Chaohu Lake and Danjiangkou Reservoir. Therefore, it can be concluded that SAR can provide a new technical means for monitoring algal bloom of inland lakes, particularly when it is cloudy and unsuitable for optical remote sensing. To obtain more information about algal bloom, multi-band and multi-polarization SAR images can be considered for future. Full article

(This article belongs to the Special Issue Satellite Remote Sensing for Water Resources in a Changing Climate)

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19 pages, 9972 KiB

Open AccessArticle

Improving the Regional Applicability of Satellite Precipitation Products by Ensemble Algorithm

by Waseem Muhammad, Hanbo Yang, Huimin Lei, Ajmal Muhammad and Dawen Yang

Remote Sens. 2018, 10(4), 577; https://doi.org/10.3390/rs10040577 - 09 Apr 2018

Cited by 25 | Viewed by 3945

Abstract

Satellite-based precipitation products (e.g., Integrated Multi-Satellite Retrievals for Global Precipitation Measurement (IMERG) and its predecessor, Tropical Rainfall Measuring Mission (TRMM)) are a critical source of precipitation estimation, particularly for a region with less, or no, hydrometric networking. However, the inconsistency in the performance of these products has been observed in different climatic and topographic diverse regions, timescales, and precipitation intensities and there is still room for improvement. Hence, using a projected ensemble algorithm, the regional precipitation estimate (RP) is introduced here. The RP concept is mainly based on the regional performance weights derived from the Mean Square Error (MSE) and the precipitation estimate from the TRMM product, that is, TRMM 3B42 (TR), real-time (late) (IT) and the research (post-real-time) (IR) products of IMERG. The overall results of the selected contingency table (e.g., Probability of detection (POD)) and statistical indices (e.g., Correlation Coefficient (CC)) signposted that the proposed RP product has shown an overall better potential to capture the gauge observations compared with the TR, IR, and IT in five different climatic regions of Pakistan from January 2015 to December 2016, at a diurnal time scale. The current study could be the first research providing preliminary feedback from Pakistan for global precipitation measurement researchers by highlighting the need for refinement in the IMERG. Full article

(This article belongs to the Special Issue Satellite Remote Sensing for Water Resources in a Changing Climate)

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23 pages, 7883 KiB

Open AccessEditor’s ChoiceArticle

Assessment of Water Management Changes in the Italian Rice Paddies from 2000 to 2016 Using Satellite Data: A Contribution to Agro-Ecological Studies

by Luigi Ranghetti, Elisa Cardarelli, Mirco Boschetti, Lorenzo Busetto and Mauro Fasola

Remote Sens. 2018, 10(3), 416; https://doi.org/10.3390/rs10030416 - 08 Mar 2018

Cited by 20 | Viewed by 5623

Abstract

The intensive rice cultivation area in northwestern Italy hosts the largest surface of rice paddies in Europe, and it is valued as a substantial habitat for aquatic biodiversity, with the paddies acting as a surrogate for the lost natural wetlands. The extent of submerged paddies strictly depends on crop management practices: in this framework, the recent diffusion of rice seeding in dry conditions has led to a reduction of flooded surfaces during spring and could have contributed to the observed decline of the populations of some waterbird species that exploit rice fields as foraging habitat. In order to test the existence and magnitude of a decreasing trend in the extent of submerged rice paddies during the rice-sowing period, MODIS remotely-sensed data were used to estimate the extent of the average flooded surface and the proportion of flooded rice fields in the years 2000–2016 during the nesting period of waterbirds. A general reduction of flooded rice fields during the rice-sowing season was observed, averaging

- 0.86 \pm 0.20

% per year (p-value < 0.01). Overall, the loss in submerged surface area during the sowing season reached

44 %

of the original extent in 2016, with a peak of

78 %

in the sub-districts to the east of the Ticino River. Results highlight the usefulness of remote sensing data and techniques to map and monitor water dynamics within rice cropping systems. These techniques could be of key importance to analyze the effects at the regional scale of the recent increase of dry-seeded rice cultivations on watershed recharge and water runoff and to interpret the decline of breeding waterbirds via a loss of foraging habitat. Full article

(This article belongs to the Special Issue Satellite Remote Sensing for Water Resources in a Changing Climate)

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4490 KiB

Open AccessArticle

Response of Grassland Degradation to Drought at Different Time-Scales in Qinghai Province: Spatio-Temporal Characteristics, Correlation, and Implications

by Shiliang Liu, Yueqiu Zhang, Fangyan Cheng, Xiaoyun Hou and Shuang Zhao

Remote Sens. 2017, 9(12), 1329; https://doi.org/10.3390/rs9121329 - 19 Dec 2017

Cited by 41 | Viewed by 5211

Abstract

Grassland, as the primary vegetation on the Qinghai-Tibet Plateau, has been increasingly influenced by water availability due to climate change in last decades. Therefore, identifying the evolution of drought becomes crucial to the efficient management of grassland. However, it is not yet well understood as to the quantitative relationship between vegetation variations and drought at different time scales. Taking Qinghai Province as a case, the effects of meteorological drought on vegetation were investigated. Multi-scale Standardized Precipitation Evapotranspiration Index (SPEI) considering evapotranspiration variables was used to indicate drought, and time series Normal Difference Vegetation Index (NDVI) to indicate the vegetation response. The results showed that SPEI values at different time scales reflected a complex dry and wet variation in this region. On a seasonal scale, more droughts occurred in summer and autumn. In general, the NDVI presented a rising trend in the east and southwest part and a decreasing trend in the northwest part of Qinghai Province from 1998 to 2012. Hurst indexes of NDVI revealed that 69.2% of the total vegetation was positively persistent (64.1% of persistent improvement and 5.1% of persistent degradation). Significant correlations were found for most of the SPEI values and the one year lagged NDVI, indicating vegetation made a time-lag response to drought. In addition, one month lagged NDVI made an obvious response to SPEI values at annual and biennial scales. Further analysis showed that all multiscale SPEI values have positive relationships with the NDVI trend and corresponding grassland degradation. The study highlighted the response of vegetation to meteorological drought at different time scales, which is available to predict vegetation change and further help to improve the utilization efficiency of water resources in the study region. Full article

(This article belongs to the Special Issue Satellite Remote Sensing for Water Resources in a Changing Climate)

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5448 KiB

Open AccessEditor’s ChoiceArticle

Co-Orbital Sentinel 1 and 2 for LULC Mapping with Emphasis on Wetlands in a Mediterranean Setting Based on Machine Learning

by Andromachi Chatziantoniou, Emmanouil Psomiadis and George P. Petropoulos

Remote Sens. 2017, 9(12), 1259; https://doi.org/10.3390/rs9121259 - 04 Dec 2017

Cited by 129 | Viewed by 9366

Abstract

This study aimed at evaluating the synergistic use of Sentinel-1 and Sentinel-2 data combined with the Support Vector Machines (SVMs) machine learning classifier for mapping land use and land cover (LULC) with emphasis on wetlands. In this context, the added value of spectral information derived from the Principal Component Analysis (PCA), Minimum Noise Fraction (MNF) and Grey Level Co-occurrence Matrix (GLCM) to the classification accuracy was also evaluated. As a case study, the National Park of Koronia and Volvi Lakes (NPKV) located in Greece was selected. LULC accuracy assessment was based on the computation of the classification error statistics and kappa coefficient. Findings of our study exemplified the appropriateness of the spatial and spectral resolution of Sentinel data in obtaining a rapid and cost-effective LULC cartography, and for wetlands in particular. The most accurate classification results were obtained when the additional spectral information was included to assist the classification implementation, increasing overall accuracy from 90.83% to 93.85% and kappa from 0.894 to 0.928. A post-classification correction (PCC) using knowledge-based logic rules further improved the overall accuracy to 94.82% and kappa to 0.936. This study provides further supporting evidence on the suitability of the Sentinels 1 and 2 data for improving our ability to map a complex area containing wetland and non-wetland LULC classes. Full article

(This article belongs to the Special Issue Satellite Remote Sensing for Water Resources in a Changing Climate)

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4323 KiB

Open AccessArticle

Spatial-Temporal Simulation of LAI on Basis of Rainfall and Growing Degree Days

by Elham Davoodi, Hoda Ghasemieh, Okke Batelaan and Khodayar Abdollahi

Remote Sens. 2017, 9(12), 1207; https://doi.org/10.3390/rs9121207 - 23 Nov 2017

Cited by 4 | Viewed by 4552

Abstract

The dimensionless Leaf Area Index (LAI) is widely used to characterize vegetation cover. With recent remote sensing developments LAI is available for large areas, although not continuous. However, in practice, continuous spatial-temporal LAI datasets are required for many environmental models. We investigate the relationship between LAI and climatic variable rainfall and Growing Degree Days (GDD) on the basis of data of a cold semi-arid region in Southwest Iran. For this purpose, monthly rainfall and temperature data were collected from ground stations between 2003 and 2015; LAI data were obtained from MODIS for the same period. The best relationship for predicting the monthly LAI values was selected from a set of single- and two-variable candidate models by considering their statistical goodness of fit (correlation coefficients, Nash-Sutcliffe coefficients, Root Mean Square Error and mean absolute error). Although various forms of linear and nonlinear relationships were tested, none showed a statistically meaningful relationship between LAI and rainfall for the study area. However, a two-variable nonlinear function was selected based on an iterative procedure linking rainfall and GDD to the expected LAI. By taking advantage of map algebra tools, this relationship can be used to predict missing LAI data for time series simulations. It is also concluded that the relationship between MODIS LAI and modeled LAI on basis of climatic variables shows a higher correlation for the wet season than for dry season. Full article

(This article belongs to the Special Issue Satellite Remote Sensing for Water Resources in a Changing Climate)

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6289 KiB

Open AccessArticle

Temporal and Spatial Comparison of Agricultural Drought Indices from Moderate Resolution Satellite Soil Moisture Data over Northwest Spain

by Miriam Pablos, José Martínez-Fernández, Nilda Sánchez and Ángel González-Zamora

Remote Sens. 2017, 9(11), 1168; https://doi.org/10.3390/rs9111168 - 14 Nov 2017

Cited by 58 | Viewed by 8473

Abstract

During the last decade, a variety of agricultural drought indices have been developed using soil moisture (SM), or any of its surrogates, as the primary drought indicator. In this study, a comprehensive study of four innovative SM-based indices, the Soil Water Deficit Index (SWDI), the Soil Moisture Agricultural Drought Index (SMADI), the Soil Moisture Deficit Index (SMDI) and the Soil Wetness Deficit Index (SWetDI), is conducted over a large semi-arid crop region in northwest Spain. The indices were computed on a weekly basis from June 2010 to December 2016 using 1-km satellite SM estimations from Soil Moisture and Ocean Salinity (SMOS) and/or Moderate Resolution Imaging Spectroradiometer (MODIS) data. The temporal dynamics of the indices were compared to two well-known agricultural drought indices, the atmospheric water deficit (AWD) and the crop moisture index (CMI), to analyze the levels of similarity, correlation, seasonality and number of weeks with drought. In addition, the spatial distribution and intensities of the indices were assessed under dry and wet SM conditions at the beginning of the growing season. The results showed that the SWDI and SMADI were the appropriate indices for developing an efficient drought monitoring system, with higher significant correlation coefficients (R ≈ 0.5–0.8) when comparing with the AWD and CMI, whereas lower values (R ≤ 0.3) were obtained for the SMDI and SWetDI. Full article

(This article belongs to the Special Issue Satellite Remote Sensing for Water Resources in a Changing Climate)

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53630 KiB

Open AccessArticle

A Study of Spatial Soil Moisture Estimation Using a Multiple Linear Regression Model and MODIS Land Surface Temperature Data Corrected by Conditional Merging

by Chunggil Jung, Yonggwan Lee, Younghyun Cho and Seongjoon Kim

Remote Sens. 2017, 9(8), 870; https://doi.org/10.3390/rs9080870 - 22 Aug 2017

Cited by 34 | Viewed by 8142

Abstract

This study attempts to estimate spatial soil moisture in South Korea (99,000 km²) from January 2013 to December 2015 using a multiple linear regression (MLR) model and the Terra moderate-resolution imaging spectroradiometer (MODIS) land surface temperature (LST) and normalized distribution vegetation index (NDVI) data. The MODIS NDVI was used to reflect vegetation variations. Observed precipitation was measured using the automatic weather stations (AWSs) of the Korea Meteorological Administration (KMA), and soil moisture data were recorded at 58 stations operated by various institutions. Prior to MLR analysis, satellite LST data were corrected by applying the conditional merging (CM) technique and observed LST data from 71 KMA stations. The coefficient of determination (R²) of the original LST and observed LST was 0.71, and the R² of corrected LST and observed LST was 0.95 for 3 selected LST stations. The R² values of all corrected LSTs were greater than 0.83 for total 71 LST stations. The regression coefficients of the MLR model were estimated seasonally considering the five-day antecedent precipitation. The p-values of all the regression coefficients were less than 0.05, and the R² values were between 0.28 and 0.67. The reason for R² values less than 0.5 is that the soil classification at each observation site was not completely accurate. Additionally, the observations at most of the soil moisture monitoring stations used in this study started in December 2014, and the soil moisture measurements did not stabilize. Notably, R² and root mean square error (RMSE) in winter were poor, as reflected by the many missing values, and uncertainty existed in observations due to freezing and mechanical errors in the soil. Thus, the prediction accuracy is low in winter due to the difficulty of establishing an appropriate regression model. Specifically, the estimated map of the soil moisture index (SMI) can be used to better understand the severity of droughts with the variability of soil moisture. Full article

(This article belongs to the Special Issue Satellite Remote Sensing for Water Resources in a Changing Climate)

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