Dataset Information

Evaluation of a MetOp ASCAT-Derived Surface Soil Moisture Product in Tundra Environments.

ABSTRACT: Satellite-derived surface soil moisture data are available for the Arctic, but detailed validation is still lacking. Previous studies have shown low correlations between in situ and modeled data. It is hypothesized that soil temperature variations after soil thaw impact MetOp ASCAT satellite-derived surface soil moisture (SSM) measurements in wet tundra environments, as C band backscatter is sensitive to changes in dielectric properties. We compare in situ measurements of water content within the active layer at four sites across the Arctic in Alaska (Barrow, Sagwon, Toolik) and Siberia (Tiksi), taken in the spring after thawing and in autumn prior to freezing. In addition to the long-term measurement fields, where sensors are installed deeper in the ground, we designed a monitoring setup for measuring moisture very close to the surface in the Lena River Delta, Siberia. The volumetric water content (VWC) and soil temperature sensors were placed in the moss organic layer in order to account for the limited penetration depth of the radar signal. ASCAT SSM variations are generally very small, in line with the low variability of in situ VWC. Short-term changes after complete thawing of the upper organic layer, however, seem to be mostly influenced by soil temperature. Correlations between SSM and in situ VWC are generally very low, or even negative. Mean standard deviation matching results in a comparably high root-mean-square error (on average 11%) for predictions of VWC. Further investigations and measurement networks are needed to clarify factors causing temporal variation of C band backscatter in tundra regions.

SUBMITTER: Hogstrom E

PROVIDER: S-EPMC6472635 | biostudies-literature | 2018 Dec

REPOSITORIES: biostudies-literature

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Evaluation of a MetOp ASCAT-Derived Surface Soil Moisture Product in Tundra Environments.

Högström Elin E Heim Birgit B Bartsch Annett A Bergstedt Helena H Pointner Georg G

Journal of geophysical research. Earth surface 20181206 12

Satellite-derived surface soil moisture data are available for the Arctic, but detailed validation is still lacking. Previous studies have shown low correlations between in situ and modeled data. It is hypothesized that soil temperature variations after soil thaw impact MetOp ASCAT satellite-derived surface soil moisture (SSM) measurements in wet tundra environments, as C band backscatter is sensitive to changes in dielectric properties. We compare in situ measurements of water content within th ...[more]

PMID: 31007990

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Project description:Understanding the patterns and processes driving natural genetic variation in gene expression is of fundamental importance to biology. In this study, we examined genetic variation in gene transcription through expression QTL (eQTL) analysis in the Tsu-1 x Kas-1 recombinant inbred line (RIL) mapping population of Arabidopsis thaliana. To understand how natural variation in transcription responds to abiotic stress, we conducted eQTL in both well watered and soil drying conditions. Further, we evaluated whether elements of genome structure were associated with eQTL occurance and genes responding to treatment conditions. Overall, we identified thousands of genes that responded to soil moisture availability and hundreds of eQTLs. However, we identified very few interactions between eQTLs and environmental conditions, and both treatment conditions were enriched for similar gene ontology (GO) categories. We did find strong evidence for associations between genome structure and natural variation in transcription. In general, genes with eQTLs were positively associated with local recombination rates and levels of polymorphism while genes responding to the treatment were negatively correlated with these factors. Our study provides further insight into the origin and maintenance of natural variation in transcription and how that variation responds to environmental conditions. Expression analysis by hybridization to atSNPTILE array (Affymetrix). Seed of the 104 RILs from reciprocal crosses between A. thaliana (L.) Heynh. accessions Kas-1 (CS903) and Tsu-1 (CS1640) were sown on fritted clay (Profile Products LLC, Buffalo Grove, IL) in 2.5-inch pots. Plants were arranged in a randomized complete block design consisting of 4 blocks, and then the pots were refrigerated at 4Â°C in darkness for 6 d to cold-stratify the seeds prior to commencement of a 12 h photoperiod in Conviron ATC60 growth chambers (Controlled Environments, Winnipeg, MB), at 23Â°C and 40% humidity during the day and 20Â°C and 50% humidity during the dark period. Light intensity was approximately 330 Âµmol m-2 s-1. After four weeks of growth, half of the plants were given a drought treatment, while the others remained fully watered. The drought treatment was randomly assigned to 2 of the 4 blocks and consisted of a slow decrease in soil moisture content over the course of one week. Each day, all pots assigned to the drought treatment were weighed, and water was added to individual pots to bring them to the target gravimetric water content. The target water content decreased each day, in the following series: 100%, 90%, 80%, 70%, 60%, 45%, and 40% of field capacity. At the end of the treatment, leaf tissue was collected from both treatments for RNA extraction.

Dataset Information

Evaluation of a MetOp ASCAT-Derived Surface Soil Moisture Product in Tundra Environments.

Publications

Evaluation of a MetOp ASCAT-Derived Surface Soil Moisture Product in Tundra Environments.

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