A5066503271- Atmospheric and Environmental Gas Dynamics
- Plant Water Relations and Carbon Dynamics
- Climate variability and models
- Remote Sensing in Agriculture
- Cryospheric studies and observations
- Plant responses to elevated CO2
- Tree-ring climate responses
- Meteorological Phenomena and Simulations
- Climate change and permafrost
- Forest ecology and management
- Hydrology and Watershed Management Studies
- Fire effects on ecosystems
- Species Distribution and Climate Change
- Soil Moisture and Remote Sensing
- Remote Sensing and LiDAR Applications
- Atmospheric chemistry and aerosols
- Plant and Fungal Interactions Research
- Nuts composition and effects
- Hydrology and Drought Analysis
- Soil and Unsaturated Flow
- Hydrology and Sediment Transport Processes
- Hydrological Forecasting Using AI
- Environmental Impact and Sustainability
- Atmospheric Ozone and Climate
- Precipitation Measurement and Analysis
NSF National Center for Atmospheric Research
2021-2025
Computational & Information Systems Laboratory
2025
University of Colorado System
2024
Auburn University
2024
University of Utah
2015-2021
Noveltis (France)
2020
Pennsylvania State University
2011-2018
Walker (United States)
2013-2014
Abstract Phenology, by controlling the seasonal activity of vegetation on land surface, plays a fundamental role in regulating photosynthesis and other ecosystem processes, as well competitive interactions feedbacks to climate system. We conducted an analysis evaluate representation phenology, associated seasonality ecosystem‐scale CO 2 exchange, 14 models participating N orth A merican C arbon P rogram S ite ynthesis. Model predictions were evaluated using long‐term measurements...
Northern hemisphere evergreen forests assimilate a significant fraction of global atmospheric CO2 but monitoring large-scale changes in gross primary production (GPP) these systems is challenging. Recent advances remote sensing allow the detection solar-induced chlorophyll fluorescence (SIF) emission from vegetation, which has been empirically linked to GPP at large spatial scales. This particularly important forests, where traditional remote-sensing techniques and terrestrial biosphere...
Accurately simulating gross primary productivity (GPP) in terrestrial ecosystem models is critical because errors simulated GPP propagate through the model to introduce additional biomass and other fluxes. We evaluated simulated, daily average from 26 against estimated at 39 eddy covariance flux tower sites across United States Canada. None of this study match within observed uncertainty. On average, overestimate winter, spring, fall, underestimate summer. Models overpredicted under dry...
Abstract Interannual variability in biosphere‐atmosphere exchange of CO 2 is driven by a diverse range biotic and abiotic factors. Replicating this thus represents the ‘acid test’ for terrestrial biosphere models. Although such models are commonly used to project responses both normal anomalous climate, they rarely tested explicitly against inter‐annual observations. Herein, using standardized data from N orth A merican Carbon Program, we assess performance 16 3 remote sensing products...
Terrestrial biosphere models can help identify physical processes that control carbon dynamics, including land–atmosphere CO 2 fluxes, and have great potential to predict the terrestrial ecosystem response changing climate. The skill of provide continental‐scale flux estimates, however, remains largely untested. This paper evaluates performance estimates from 17 against observations 36 North American towers. Fluxes extracted regional model simulations were compared with co‐located tower at...
Abstract. Droughts in the western United States are expected to intensify with climate change. Thus, an adequate representation of ecosystem response water stress land models is critical for predicting carbon dynamics. The goal this study was evaluate performance Community Land Model (CLM) version 4.5 against observations at old-growth coniferous forest site Pacific Northwest region (Wind River AmeriFlux site), characterized by a Mediterranean that subjects trees each summer. CLM driven...
Abstract. Land surface models are useful tools to quantify contemporary and future climate impact on terrestrial carbon cycle processes, provided they can be appropriately constrained tested with observations. Stable isotopes of CO2 offer the potential improve model representation coupled water cycles because strongly influenced by stomatal function. Recently, a stable isotope discrimination was incorporated into Community Model component Earth System Model. Here, we model's capability...
Abstract Traditional methods of carbon monitoring in mountainous regions are challenged by complex terrain. Recently, solar‐induced fluorescence (SIF) has been found to be an indicator gross primary production (GPP), and the increased availability remotely sensed SIF provides opportunity estimate GPP across Western United States. Although empirical linkage between is strong, current mechanistic understanding this incomplete depends upon changes leaf biochemical processes which absorbed...
Abstract. Recent successes in passive remote sensing of far-red solar-induced chlorophyll fluorescence (SIF) have spurred the development and integration canopy-level models global terrestrial biosphere (TBMs) for climate carbon cycle research. The interaction with photochemistry at leaf canopy scales provides opportunities to diagnose constrain model simulations photosynthesis related processes, through direct comparison assimilation tower, airborne, satellite data. TBMs describe key...
Abstract The Western United States is dominated by natural lands that play a critical role for carbon balance, water quality, and timber reserves. This region also particularly vulnerable to forest mortality from drought, insect attack, wildfires, thus requiring constant monitoring assess ecosystem health. Carbon techniques are challenged the complex mountainous terrain, there an opportunity data assimilation systems combine land surface models satellite‐derived observations provide improved...
Abstract Terrestrial biosphere models can help identify physical processes that control carbon dynamics, including land‐atmosphere CO 2 fluxes, and have the potential to project terrestrial ecosystem response changing climate. It is important most responsible for model predictive uncertainty design improved representation observational system studies reduce uncertainty. Here we identified parameters contribute long‐term (~100 years) projections of net exchange, primary production,...
Drought, a recurring extreme climate event caused by prolonged below-average precipitation, results in significant water deficits and poses substantial threat to India's economy, which is heavily reliant on agriculture. Despite notable monsoon rainfall, drought remains persistent annual phenomenon, underscoring the need for accurate estimation continuous monitoring mitigate its adverse socio-economic impacts. Real-time monitoring, including spatial temporal characterization, critical guiding...
Abstract. Summer droughts in the western United States are expected to intensify with climate change. Thus, an adequate representation of ecosystem drought response land models is critical for predicting carbon dynamics. The goal this study was assess performance Community Land Model, Version 4.5 (CLM) old-growth coniferous forest Pacific Northwest region (Wind River AmeriFlux site), characterized by a that has heavy winter precipitation followed summer drought. Particular attention given...
Abstract. The flow of carbon through terrestrial ecosystems and the response to climate are critical but highly uncertain processes in global cycle. However, with a rapidly expanding array situ satellite data, there is an opportunity improve our mechanistic understanding (C) cycle's land use change. Uncertainty temperature limitation on productivity poses significant challenge predicting ecosystem fluxes changing climate. Here we diagnose quantitatively resolve environmental limitations...
Abstract Model representation of carbon uptake and storage is essential for accurate projection the response arctic‐boreal zone to a rapidly changing climate. Land model estimates LAI aboveground biomass that can have marked influence on projections vary substantially in arctic boreal zone, making it challenging correctly evaluate Gross Primary Productivity (GPP). To understand correct bias Community (CLM), we assimilated 8‐day Moderate Resolution Imaging Spectroradiometer (MODIS)...
Abstract. Land surface models are useful tools to quantify contemporary and future climate impact on terrestrial carbon cycle processes, provided they can be appropriately constrained tested with observations. Stable isotopes of CO2 offer the potential improve model representation coupled water cycles because strongly influenced by stomatal function. Recently, a stable isotope discrimination was incorporated into Community Model component Earth System Model. Here, we model's capability...
Abstract The seasonal pattern of the carbon isotope content (δ 13 C) atmospheric CO 2 depends on local and nonlocal land‐atmosphere exchange transport. Previous studies suggested that δ C net flux ( source ) varies seasonally as stomatal conductance plants responds to vapor pressure deficit air (VPD). We studied variation at seven sites across United States representing forests, grasslands, an urban center. Using a two‐part mixing model, we calculated for each site after removing background...
The Western US accounts for a significant amount of the forested biomass and carbon uptake within conterminous United States. Warming drying climate trends combined with legacy fire suppression have left forests particularly vulnerable to disturbance from insects, drought mortality. These challenging conditions may significantly weaken this region’s ability atmosphere warrant continued monitoring. Traditional methods monitoring are limited by complex terrain Rocky Mountains that lead...