Papers by Valentina Sagris
High-resolution thermal exposure and shade maps for cool corridor planning
Sustainable Cities and Society
Remotely sensed land surface temperature is a proxy of ecosystem respiration in intact and disturbed northern peatlands
CO2 and CH4 gas fluxes in disturbed and intact northern peatlands
The data were collected in seven Estonian peatlands (5 disturbed and 2 intact) during three to fo... more The data were collected in seven Estonian peatlands (5 disturbed and 2 intact) during three to four (2017–2020) years with closed chamber technique. Table 1 (see CO2_CH4_fluxes_README.docx) shows the variables presented in this dataset.
Kaugseire jätkusuutliku rakendamise kava
Kaugseire jätkusuutliku rakendamise kava koostamise eesmärgiks oli võimaluste pakkumine kaugseire... more Kaugseire jätkusuutliku rakendamise kava koostamise eesmärgiks oli võimaluste pakkumine kaugseireandmete kasutamise ja uute rakenduste väljatöötamise abil kaasa aidata avaliku sektori asutuste ees seisvate ülesannete efektiivsele lahendamisele ning nende funktsionaalsuse tõstmisele. Kava aitab kaasa kaugseire süsteemsele rakendamisele Eestis.
IEEE Geoscience and Remote Sensing Letters, 2022
Gap-Filling Satellite Land Surface Temperature Over Heatwave Periods With Machine Learning
IEEE Geoscience and Remote Sensing Letters, 2022
The frequency of heatwave events has increased in recent decades because of global warming. Satel... more The frequency of heatwave events has increased in recent decades because of global warming. Satellite observed land surface temperature (LST) is a widely used parameter for assessing heatwaves. It provides a wide spatial coverage compared to surface air temperature measured at weather stations. However, LST quality is limited by cloud contamination. Because heatwaves have a limited temporal frame, having a full and cloud-free complement of LST for that period is necessary. In this letter, we explore gap filling of LST using spatial features such as land cover, elevation, and vegetation indices in a machine learning approach. We use a seamless open and free daily vegetation index product that is paramount to the success of our study. We create a random forest model that provides a ranking of features relevant for predicting LST. We compare the output of our model to an established spatiotemporal gap-filling algorithm to validate the predictive capability of our model. This study validates machine learning as a suitable tool for filling gaps in satellite LST. In addition, we acknowledge that while time is an important factor in predicting LST, additional information on vegetation can improve the predictions of a model.
Remote Sensing, 2020
The OPtical TRApezoid Model (OPTRAM) is a physically-based approach for remote soil moisture esti... more The OPtical TRApezoid Model (OPTRAM) is a physically-based approach for remote soil moisture estimation. OPTRAM is based on the response of short-wave infrared (SWIR) reflectance to vegetation water status, which in turn responds to changes of root-zone soil moisture. In peatlands, the latter is tightly coupled to water table depth (WTD). Therefore, in theory, the OPTRAM index might be a useful tool to monitor WTD dynamics in peatlands, although the sensitivity of OPTRAM index to WTD changes will likely depend on vegetation cover and related rooting depth. In this study, we aim at identifying those locations (further called ‘best pixels’) where the OPTRAM index is most representative of overall peatland WTD dynamics. In peatlands, the high saturated hydraulic conductivity of the upper layer largely synchronizes the temporal WTD fluctuations over several kilometers, i.e., even though the mean and amplitude of the WTD dynamics may vary in space. Therefore, it can be assumed that the W...
This discussion paper is a continuation of the MARS-PAC efforts to ensure the implementation of b... more This discussion paper is a continuation of the MARS-PAC efforts to ensure the implementation of basic geographic information (GI) concepts into the LPIS and to follow-up the development of geomatics. It addresses the recent challenges on GI, such as establishing of a Spatial Data Infrastructure (SDI), and the requirements for standardisation and interoperability of geographic data. The main outcome of this development is a standardized framework for the LPIS specifications, that records compliance with the Regulation requirements. How to obtain EU publications Our priced publications are available from EU Bookshop (http://bookshop.europa.eu), where you can place an order with the sales agent of your choice. The Publications Office has a worldwide network of sales agents. You can obtain their contact details by sending a fax to (352) 29 29-42758. The mission of the JRC is to provide customer-driven scientific and technical support for the conception, development, implementation and m...
The Institute for the Protection and Security of the Citizen provides research-based, systemsorie... more The Institute for the Protection and Security of the Citizen provides research-based, systemsoriented support to EU policies so as to protect the citizen against economic and technological risk. The Institute maintains and develops its expertise and networks in information, communication, space and engineering technologies in support of its mission. The strong crossfertilisation between its nuclear and non-nuclear activities strengthens the expertise it can bring to the benefit of customers in both domains.
Fire Weather Index (FWI) for Estonia for growing seasons 2018 and 2019
The Canadian Forest Fire Weather Index (FWI) System (Van Wagner 1987) is a weather-based means of... more The Canadian Forest Fire Weather Index (FWI) System (Van Wagner 1987) is a weather-based means of calculating potential fire conditions. Canadian research on forest fire danger rating was started in the 1920s, but in recent decades, FWI is widely used in Europe. The FWI System depends solely on weather measurements taken each day at noon local time. Daily inputs to the system consist of temperature (°C), relative humidity (%), wind speed (km/h), and precipitation (mm) over the past 24 hours. The FWI System outputs three moisture codes: the Fine Fuel Moisture Code (FFMC), the Duff Moisture Code (DMC), and the Drought Code (DC), with higher values indicating drier conditions and greater fire danger. The FWI System also generates three fire behavior outputs based on the above indices: the Initial Spread Index (ISI), the Build-Up Index (BUI), and the Fire Weather Index (FWI), with higher values indicating elevated fire danger (Van Wagner 1987). This dataset creation was a part of RITA1/02-52 "Use of remote sensing data for elaboration and development of public services (1.01.2019−31.12.2020)" and its work-package "Prevention and suppression of wildfires". Project adopted Canadian methodology and investigated possibility of FWI in Estonian meteorological service for wild fire prevention routings. C. E. Van Wagner (1987). Development and Structure of the Canadian Forest Fire Weather Index System. Canadian forest service, Forestery Technical report 35, Ottawa
Metsa- ja maastikutulekahjude ennetamine ja likvideerimine
Põllumajandusmaade kasutuse seire
Feature database of Estonian agricultural parcels for crop classification (years 2018-2019)
Feature database of Estonian agricultural parcels for crop classification (years 2018-2019). Sent... more Feature database of Estonian agricultural parcels for crop classification (years 2018-2019). Sentinel-1 and -2 and additional geospatial feature set time series about Estonian agricultural parcels 2018-2019. The time series was used for neural networks model for crop classification purposed, but could in principle be used also with other models and other purposes
Remotely Sensed Land Surface Temperature Can Be Used to Estimate Ecosystem Respiration in Intact and Disturbed Northern Peatlands
Journal of Geophysical Research: Biogeosciences, 2021
Remotely sensed land surface temperature (LST) enables global modeling and monitoring of CO2 flux... more Remotely sensed land surface temperature (LST) enables global modeling and monitoring of CO2 fluxes from peatlands. We aimed to provide the first overview of the potential for using LST to monitor ecosystem respiration (Reco) in disturbed (drained and extracted) peatlands. We used chamber‐measured data (2017–2020) from five disturbed and two intact northern peatlands and LST data from Landsat 7, 8, and MODIS missions. First, we studied the strength of the relationships between fluxes and their in situ drivers (i.e., thermal and moisture conditions). Second, we examined the association between LST and in situ temperatures. Third, we compared chamber‐measured Reco with the modeled Reco driven by in situ measured water table depth and (a) in situ measured surface temperature and (b) remotely sensed MODIS LST data. In situ temperatures were a stronger driver of CO2 fluxes in disturbed sites (repeated measures correlation rmR = 0.8–0.9) than in intact ones (rmR = 0.5–0.8). LST had a higher association with in situ measured temperatures in disturbed sites (mean rmR = 0.79 for MODIS) and weaker in the intact (hummocks and hollows) peatlands (mean rmR = 0.38 for Landsat and 0.48 for MODIS). Reco models driven by MODIS LST and in situ surface temperature yielded similar accuracy: R2 was 0.27, 0.66, and 0.67 and 0.29, 0.70, and 0.66 for intact and for drained and extracted sites, respectively. Overall, these findings suggest the applicability of LST as a proxy of the thermal regime in Reco models, particularly for disturbed peatlands.
International Journal of Applied Earth Observation and Geoinformation, 2019
Temperature regime is one of the main controlling factors of greenhouse gas (GHG) emissions from ... more Temperature regime is one of the main controlling factors of greenhouse gas (GHG) emissions from peat bogs. Remotely sensed land surface temperature (LST) has a potential to become an efficient instrument in environmental monitoring of carbon dioxide and methane emissions from peat bogs. This paper examines the relationships between field-measured hydrometeorological variables and MODIS LST data in a hemiboreal raised bog for a period from May to September (2008-2016). The Pearson product-moment correlation was used to reveal the relationship between the field-measured parameters and LST over years and months. A multiple linear regression was chosen to model relationships between the hydrometeorological variables and LST by month. It was found that the relationships between the studied parameters and LST were year-and month-dependent. The main factor of LST was air temperature, and the correlation between LST and air temperature was the strongest during the entire period of study. This study has shown that the hydrometeorological factors of LST can explain 67%-81 % of the variance in LST in a hemiboreal raised bog. The relationships between the hydrometeorological variables and LST may be implemented in more accurate GHG emissions estimation from bogs.
The harmonised data model for assessing land parcel identification systems compliance with requir... more The harmonised data model for assessing land parcel identification systems compliance with requirements of direct aid and agri-environmental schemes of the CAP.
International Journal of Spatial Data Infrastructures Research, ,, Jun 19, 2011
This article presents an SDI-based approach to implement selected web services within the Land Pa... more This article presents an SDI-based approach to implement selected web services within the Land Parcel Identification System (LPIS) Quality Assurance framework, according to the Commission Regulation 1122/2009. The Test Bed uses OGC conforming web services allowing for: (1) agricultural data transformation from national data schemas to the common LPIS Core Model, (2) transferring, validating and storing spatial and non-spatial observations of the quality inspections. The OGC Web Processing Service (WPS) interface specification is used as a basis to allow for interoperable accessing the schema transformation and content validation functionalities of the realised services. The implemented solutions demonstrate the feasibility of the proposed concepts and fit in with current INSPIRE activities.
In this paper we focus on urban growth dynamics of Eastern European cities and regions in the pas... more In this paper we focus on urban growth dynamics of Eastern European cities and regions in the past and in the new Europe. This work is a part of on-going research in the field of urban and regional development, carried out in Joint Research Centre (JRC) of the European Commission. Eastern European cities experienced similar and very turbulent historical and
Väitekirja elektrooniline versioon ei sisalda publikatsioone.Käesolevas doktoritöös käsitletakse ... more Väitekirja elektrooniline versioon ei sisalda publikatsioone.Käesolevas doktoritöös käsitletakse Põllumassiivide identifitseerimissüsteemi (Land Parcel Identification System, LPIS) Kontseptuaalse Mudeli (LPIS Conceptual Model, LCM) loomist ja selle kasutamist ruumiandmete standardiseerimisel, kvaliteedi hindamisel ja koostoimimisel teiste valdkondade ruumiandmetega. Mudelis käsitletud ruumiandmeid kasutatakse põllumajandustoetuste haldamise ja kontrolli eesmärgil ELi Ühise Põllumajanduspoliitika (ÜPP) raames. ÜPP raames makstavate toetuste haldamiseks on igas EL liikmesriigis asutatud Ühtne haldus-ja kontrollisüsteem (Eestis Põllumajandusregistrite amet, PRIA), mille ruumiandmeid haldav komponent on põllumassiivide register ehk identifitseerimissüsteem. Nõue kaardistada ja registreerida toetuskõlbulik maa on viinud olukorrani, kus põllumajandussektoris on tekkinud suur hulk ruumiandmeid. Viimase aastakümne jooksul on kasvanud ÜPP-ga seotud geoinformaatika sektor Euroopas. ÜPP-ga seo...
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Papers by Valentina Sagris