News

The paper describes some fieldwork we completed as part of SMAPVEX19-21, to demonstrate explicitly (and without a difference in spatial scales) that L-band VOD is sensitive to xylem and leaf water potential variations. The paper is still undergoing typesetting, but the original version can be found here.

Carbon cycle models have become increasingly complex over time, as more and more processes are represented. But as models get more complex, the risk that they are mis-parametrized becomes increasingly large. We used CARDAMOM with a variety of different model structures, data assimilation types and errors, and more to systematically assess whether increasing model complexity always improves forecast performance (including accounting for prediction uncertainty). In fact, intermediate complexity models often perform better than more complex models. Increased complexity only improves forecast skill if net carbon flux data is available to sufficiently constrain the parameters. This suggests terrestrial biosphere models should focus more on constraining parameter uncertainties rather than simply increasing the number of processes represented. A list of other specific recommendations is also included in the paper, which can be read (or commented on!) here.

Check out the virtual AGU presentations from the RSEG members!
B081-0018: Olivia's poster (with Yanlan) on spatial patterns in maximum stomatal conductance, and simple PFT-alternative predictive models
B089-06: Yanlan's talk (with Natan) on estimating global plant hydraulic traits maps using VOD and designing 'hydraulic functional types'
B034-0007: Krishna's poster on using SAR-derived live fuel moisture to understand the relationship between plant hydraulic traits and fire ignition risk
EP042-06: Nathan's talk on characterizing the factors driving soil moisture drying in tropical peatlands using SMAP
B117-06: Caroline's talk (with Greg) on the relationship between carbon cycle model forecast performance and model complexity
B110-0001: Greg's poster (with Nathan and Caroline) using 100-year CARDAMOM simulations to show the surprisingly tight and large
H093-03: Matt's poster on ECOSTRESS and radiation in the Upper Colorado River, his undergraduate work
B090-06: Alex's talk (with Natan, Krishna and Yanlan) on using microwave remote sensing for ecosystem-scale plant drought response studies
H072-01: Alex's talk (with Nathan) on mapping drainage canals in Southeast Asian peatlands and their relationship with carbon fluxes

Natan and Alex contributed to this paper as part of the SMAPVEX19 validation campaign. The paper is available here

Matthew Worden joins the group as a new PhD student. Welcome, Matt!

I am currently looking for a new postdoctoral fellow! If you think our group and your background would be a good fit, please email Alex at konings@stanford.edu with a CV and a description of your research interests. Multiple research topics are available. The postdoc will work to either: a) test newly derived datasets of canopy water content based on microwave radiometry and apply these to a variety of ecological questions or b) use a global carbon cycle data assimilation system constrained by remote sensing (CARDAMOM) to understand the spatial variability of carbon cycle parameters and their implication for global scale modelling. I am, of course, also open to discussing your research ideas. Applicants should have strong, demonstrated quantitative, computational, and communication skills. Experience working with ecological modeling, remote sensing data analysis, and/or microwave remote sensing is preferred. If that sounds like you, please reach out! Applications will be reviewed starting August 17th, until filled. Candidates from underrepresented groups are especially encouraged to apply

Yanlan Liu has accepted an offer as assistant professor at The Ohio State University! She will have a joint appointment in the School of Earth Sciences and in the School of Environment and Natural Resources and will begin her new position in fall 2021. We are excited that Yanlan can stay with us a little longer before then. Congratulations, Yanlan!!

The talk is in Spanish, but can be watched on Youtube here. It discussed the findings of our recent Remote Sensing of Environment paper.

The approach combines Sentinel-1 with in situ LFMC measurements from the National Fuel Moisture Databse using a recurrent neural network. The use of Sentinel-1 SAR provides observations that are directly sensitive to vegetation moisture content, enabling improved accuracy relative to provious optical-data-only approaches. Maps are available at 15-day and 250 m resolution across the Western United States. You can play with the data interactively or download them here. The paper can be read here.

The paper is co-authored by Susan Steele Dunne (TU Delft) and discusses the interpretation of, and possible value for, microwave remote sensing indices of vegetation water content for plant physiological and ecological applications. You can read it here.

A team including Krishna Rao and Natan Holtzman won first prize in the 'Best use of Google Cloud' and 'Most Energy-Efficient Sustainable Energy Hack' categories at the Stanford TreeHacks hackathon. Their project combined Krishna's recently created dataset of live fuel moisture content with data on fuel availability and urban proximity. More information is here. Congratulations, Krishna and Natan!

Here are our presentations:
1) Greg's Monday talk on CARDAMOM historical CO2 attribution: B11B-03
2) Nathan's Monday poster on mapping Southeast Asian peatland canals: H13K-1857
3) Yanlan's Monday talk on the interactions between plant hydraulics and VPD sensitivity: B12A-03
4) Caroline's Tuesday poster on extreme wet vs dry effects on NDVI: B21G-2407
5) Alex's Tuesday talk on Krishna's work predicting mortality with VOD: B22E-02
6) Alex's Thursday panel participation on the past and future of hydrological remote sensing: H41D-07
7) Krishna's talk on SAR-based high-resolution maps of live fuel moisture content: NH52A-03
8) Natan's poster on fieldwork showing the VOD - xylem water potential link: H51M-1657

To find out more about the workshop and see Alex's introductory talk about remote sensing of vegetation water content, click here. Yanlan and Natan were also among the 34 international attendees of the workshop. Thnak you to all the attendees for stimulating discussions!

Caroline presented her work about the effect of pluvials on ecosystem growth, and Greg presented on parameter uncertainty vs. structural uncertainty in CARDAMOM and other models, as well as an attribution of historical CO2 uptake due to climate change. 

Yanlan was previously a visiting student in summer of 2018. Welcome back, Yanlan!

We are working with Alexandre Roy (Université du Québec à Trois Rivières) and others to compare in situ L-band radiometry at Harvard Forest with various measurements of tree water status

Congratulations to Michael Burnett, Nathan Dadap and Krishna Rao for winning the Stanford School of Earth, Energy, and Environmental Sciences Certificate for Outstanding Achievement in Mentoring! 

The article was published in Remote Sensing of Environment and can be found here.

The article is a short Tansley Insight article and will become part of a virtual issue on remote sensing for plant science. You can find it (open access) here.

Greg will be speaking at 12:15 on Tuesday in Session BG2.48 on "Net Biosphere Exchange in the Recent Past: Uncertainty Comparison Between Model-data Fusion and Earth System Models"

We'll be presenting: B33N-2872 (Krishna's work on fire fuel estimation with Sentinel-1), B51G-2013: (Greg's work comparing CARDAMOM, CMIP5, and TRENDY, oh my!), B53D-07 (Yanlan's work on plant hydraulic traits and ET), H44A-04 (Mike's work on using GRACE to estimate ET in the Congo basin), and B31J-2627 (Alex's work on global, data-driven heterotrophic respiration estimates)

In Mike's absence, Alex will present his work on estimating ET in the Congo River Basin via a water balance approach, and trends in the seasonality of ET in the basin.

The flux tower based analysis is supplemented by a global analysis using VOD data that Alex led. The article can be found here.

The paper shows that the photosyntheis of taller Amazon forests is up to tree times less sensitive to precipitation than than of shorter forests. You can find it here

You can find it here

The research will employ model-data fusion in a plant hydraulic model to improve hydrologic modelling

Jackie Fortin (MS student in CEE) and Mike Burnett (senior in Earth Systems) join the group. Welcome!

Our talks and posters:
Nathan:  B13D-1794: Using Remotely Sensed Soil Moisture to Estimate Fire Risk in Tropical Peatlands

Mostafa: B24C-02: Interacting Effects of Leaf Water Potential and Biomass on Vegetation Optical Depth

Krishna: B31D-2009: Vegetation optical depth measured by microwave radiometry as an indicator of tree mortality

Alex: H14A-01: Stomatal and xylem regulation traits control the sensitivity of grassland productivity to aridity

You can find it here

WECANN is a new set of flux predictions based on solar-induced fluorescence based on neural networks. The paper can be found here

You can find it here. 

You can find it here