Search NASA⌕ Search

Engineering topics

Chen, Jiquan

Publications and source records attributed to Chen, Jiquan.

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Water loss through evapotranspiration after precipitation events in bioenergy crops grown in similar climatic conditions

The relationship between precipitation and evapotranspiration (ET) is critical to understanding water cycle related dynamics in ecosystems, including crops. Existing studies of bioenergy crops have primarily focused on annual or seasonal ET rates, with less attention given to the immediate ET response following precipitation events. This study examines the variation in ET rates in the days subsequent to precipitation events across various bioenergy crops—corn, switchgrass, and prairies—utilizing 13 years (2010–2022) of growing season data. Meteorological and eddy covariance flux data were collected from seven eddy covariance flux towers as part of the GLBRC scale-up experiment at the Kellogg Biological Station Long Term Ecological Research sites. The analysis revealed that average ET peaked the day after precipitation and declined linearly over the following days, with a statistically significant relationship (p-value = 0.00027, R2 = 0.96). Neither the type of biofuel vegetation nor the historical land use significantly influenced ET post-precipitation events (p-values = 0.53 and 0.153, respectively). Key predictors of ET following precipitation events include shortwave radiation, season, day of the year, ambient temperature, vapor pressure deficit (VPD), long-wave radiation, precipitation amount, soil moisture, and annual variability. These findings enhance our comprehension of ET responses in bioenergy crop systems, with implications for water management in sustainable agriculture.

09 BIOMASS FUELS↗
DOE OSTI2024

Overlooked cooling effects of albedo in terrestrial ecosystems

Radiative forcing (RF) resulting from changes in surface albedo is increasingly recognized as a significant driver of global climate change but has not been adequately estimated, including by Intergovernmental Panel on Climate Change (IPCC) assessment reports, compared with other warming agents. Here, we first present the physical foundation for modeling albedo-induced RF and the consequent global warming impact (GWI Δα ). We then highlight the shortcomings of available current databases and methodologies for calculating GWI Δα at multiple temporal scales. There is a clear lack of comprehensive in situ measurements of albedo due to sparse geographic coverage of ground-based stations, whereas estimates from satellites suffer from biases due to the limited frequency of image collection, and estimates from earth system models (ESMs) suffer from very coarse spatial resolution land cover maps and associated albedo values in pre-determined lookup tables. Field measurements of albedo show large differences by ecosystem type and large diurnal and seasonal changes. As indicated from our findings in southwest Michigan, GWI Δα is substantial, exceeding the RF Δα values of IPCC reports. Inclusion of GWI Δα to landowners and carbon credit markets for specific management practices are needed in future policies. We further identify four pressing research priorities: developing a comprehensive albedo database, pinpointing accurate reference sites within managed landscapes, refining algorithms for remote sensing of albedo by integrating geostationary and other orbital satellites, and integrating the GWI Δα component into future ESMs.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

The contributions of microclimatic information in advancing ecosystem science

Drawing upon over 100 years of scholarly work on microclimate, we first present an overview of the history, key references, and critical issues surrounding the collection and utilization of microclimate records in ecosystem studies. We place particular emphasis on addressing specific and pressing issues related to the applications of microclimate at the community-ecosystem-landscape level, excluding those of controlled experiment such as growth chambers and greenhouses. Specifically, we: (1) highlight some key issues concerning the collection, quality assurance/quality control (QA/QC), and utilization of microclimatic data in ecosystem studies; (2) revisit microclimatic responses to the structural changes of ecosystems and landscapes; and (3) emphasize the significance of microclimate in understanding major ecosystem/landscape processes and functions. Vapor pressure deficit (VPD) is particularly emphasized for its calculation and use because of its burgeoning applications in the literature. Case studies for each of the three thematic topics are provided with selected references to demonstrate challenges and solutions. As the scientific community gears up to enhance microclimatic stations, we envision significant increases in the use of smart sensors, wireless access, networking, open databases, and computational capabilities. Understanding and addressing some of the issues raised in this synthesis paper may help advance microclimate research and foster collaboration with other relevant disciplines, such as ecosystem science.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

AmeriFlux FLUXNET-1F US-Oho Oak Openings

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-Oho Oak Openings. This is the FLUXNET version of the carbon flux data for the site US-Oho Oak Openings produced by applying the standard ONEFlux (1F) software. Site Description - The Ohio Oak Openings site is located within the Oak Openings Preserve Metropark of northwest Ohio, one of the few remaining oak woodlands/savanna/prairie complexes in the Midwest. Declared one of the "One of America's Last Great Places" by the Nature Conservancy the area consists of four main vegetation types: Oak Woodlands, Oak Savanna, Floodplain Forests and Wet Prairies. The stand surrounding the tower is mainly Oak Woodlands dominated by red, white and black oaks with a relatively abundant population of red maples indicating high soil moisture retention and a history of limited fire disturbances. Most of the area was cleared for agriculture at the time of Euro-American settlements in the mid to late-19th century. A large fraction of the cleared land was later abandoned due to the poor sandy soils. These areas reverted to Oak Savannas and in cases where fire was limited progressively made the transition to Oak Woodlands. Today patches of the forest are burned every few years as part of prescribed burning cycle to control stand density.

Chen, Jiquan↗
DOE OSTI2023

AmeriFlux FLUXNET-1F US-Wi0 Young red pine (YRP)

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-Wi0 Young red pine (YRP). This is the FLUXNET version of the carbon flux data for the site US-Wi0 Young red pine (YRP) produced by applying the standard ONEFlux (1F) software. Site Description - The Wisconsin Young Red Pine site is located in the Washburn Ranger District of the northeastern section of Chequamegon National Forest. A member of the northern coniferous-deciduous biome, surveys from the mid-19th century indicate the region consisted of a mixed stand of red, white, and jack pines. After extensive timber harvesting, wildfires, and farming activity, the region turned into a fragmented mosaic of stands of various ages and composition. As an assemblage, the ten Wisconsin sites are indicative of the successional stages of development in the predominant stand types of a physically homogeneous landscape. Thinned every 7 years until they reach 100 to 150 years of age, the red pine plantations of all ages occupy approximately 25% of the region.

Chen, Jiquan↗
DOE OSTI2023

AmeriFlux FLUXNET-1F US-Wi1 Intermediate hardwood (IHW)

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-Wi1 Intermediate hardwood (IHW). This is the FLUXNET version of the carbon flux data for the site US-Wi1 Intermediate hardwood (IHW) produced by applying the standard ONEFlux (1F) software. Site Description - The Wisconsin Intermediate Hardwoods site is located in the Washburn Ranger District of the Chequamegon National Forest. A member of the northern coniferous-deciduous biome, surveys from the mid-19th century indicate the region consisted of a mixed stand of red, white, and jack pines. After extensive timber harvesting, wildfires, and farming activity, the region turned into a fragmented mosaic of stands of various ages and composition. The intermediate hardwoods site is one of ten sites that collectively represent the successional stages of development in the predominant stand types of a physically homogeneous landscape. In 2001, northern hardwood stands of all ages occupied 45% of the region.

Chen, Jiquan↗
DOE OSTI2023

AmeriFlux FLUXNET-1F US-Wi3 Mature hardwood (MHW)

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-Wi3 Mature hardwood (MHW). This is the FLUXNET version of the carbon flux data for the site US-Wi3 Mature hardwood (MHW) produced by applying the standard ONEFlux (1F) software. Site Description - The Wisconsin Mature Hardwood site is located in the Washburn Ranger District of the northeastern section of Chequamegon National Forest. A member of the northern coniferous-deciduous biome, surveys from the mid-19th century indicate the region consisted of a mixed stand of red, white, and jack pines. After extensive timber harvesting, wildfires, and farming activity, the region turned into a fragmented mosaic of stands of various ages and composition. As an assemblage, the ten Wisconsin sites are indicative of the successional stages of development in the predominant stand types of a physically homogeneous landscape. The mature hardwood stand represents a typical naturally regenerated second-growth forest, free of anthropogenic disturbances for at least 70 years.

Chen, Jiquan↗
DOE OSTI2023

AmeriFlux FLUXNET-1F US-Wi4 Mature red pine (MRP)

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-Wi4 Mature red pine (MRP). This is the FLUXNET version of the carbon flux data for the site US-Wi4 Mature red pine (MRP) produced by applying the standard ONEFlux (1F) software. Site Description - The Wisconsin Mature Red Pine site is located in the Washburn Ranger District of the northeastern section of Chequamegon National Forest. A member of the northern coniferous-deciduous biome, surveys from the mid-19th century indicate the region consisted of a mixed stand of red, white, and jack pines. After extensive timber harvesting, wildfires, and farming activity, the region turned into a fragmented mosaic of stands of various ages and composition. As an assemblage, the ten Wisconsin sites are indicative of the successional stages of development in the predominant stand types of a physically homogeneous landscape. Thinned every 7 years until they reach 100 to 150 years of age, the red pine plantations of all ages occupy approximately 25% of the region.

Chen, Jiquan↗
DOE OSTI2023

AmeriFlux FLUXNET-1F US-Wi5 Mixed young jack pine (MYJP)

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-Wi5 Mixed young jack pine (MYJP). This is the FLUXNET version of the carbon flux data for the site US-Wi5 Mixed young jack pine (MYJP) produced by applying the standard ONEFlux (1F) software. Site Description - The Wisconsin Mixed Young Jack Pine site is located in the Washburn Ranger District of the northeastern section of Chequamegon National Forest. A member of the northern coniferous-deciduous biome, surveys from the mid-19th century indicate the region consisted of a mixed stand of red, white, and jack pines. After extensive timber harvesting, wildfires, and farming activity, the region turned into a fragmented mosaic of stands of various ages and composition. As an assemblage, the ten Wisconsin sites are indicative of the successional stages of development in the predominant stand types of a physically homogeneous landscape. Clearcut on 40 to 70 year intervals, jack pine stands occupy approximately 13% of the region.

Chen, Jiquan↗
DOE OSTI2023

AmeriFlux FLUXNET-1F US-Wi6 Pine barrens #1 (PB1)

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-Wi6 Pine barrens #1 (PB1). This is the FLUXNET version of the carbon flux data for the site US-Wi6 Pine barrens #1 (PB1) produced by applying the standard ONEFlux (1F) software. Site Description - The Wisconsin Pine Barrens site is located in the Washburn Ranger District of the northeastern section of Chequamegon National Forest. A member of the northern coniferous-deciduous biome, surveys from the mid-19th century indicate the region consisted of a mixed stand of red, white, and jack pines. After extensive timber harvesting, wildfires, and farming activity, the region turned into a fragmented mosaic of stands of various ages and composition. As an assemblage, the ten Wisconsin sites are indicative of the successional stages of development in the predominant stand types of a physically homogeneous landscape. In order to establish and maintain both natural and plantation jack pine stands, pine barrens undergo prescribed burns and harvesting rotations. Pine Barrens occupy 17% of the region in 2001.

Chen, Jiquan↗
DOE OSTI2023

AmeriFlux FLUXNET-1F US-Wi7 Red pine clearcut (RPCC)

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-Wi7 Red pine clearcut (RPCC). This is the FLUXNET version of the carbon flux data for the site US-Wi7 Red pine clearcut (RPCC) produced by applying the standard ONEFlux (1F) software. Site Description - The Wisconsin Clearcut Red Pine site is located in the Washburn Ranger District of the northeastern section of Chequamegon National Forest. A member of the northern coniferous-deciduous biome, surveys from the mid-19th century indicate the region consisted of a mixed stand of red, white, and jack pines. After extensive timber harvesting, wildfires, and farming activity, the region turned into a fragmented mosaic of stands of various ages and composition. The red pine clearcut site is one of ten sites that collectively represent the successional stages of development in the predominant stand types of a physically homogeneous landscape. Thinned every 7 years until they reach 100 to 150 years of age, the red pine plantations or all ages occupy approximately 25% of the region.

Chen, Jiquan↗
DOE OSTI2023

AmeriFlux FLUXNET-1F US-Wi8 Young hardwood clearcut (YHW)

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-Wi8 Young hardwood clearcut (YHW). This is the FLUXNET version of the carbon flux data for the site US-Wi8 Young hardwood clearcut (YHW) produced by applying the standard ONEFlux (1F) software. Site Description - The Wisconsin Clearcut Young Hardwood site is located in the Washburn Ranger District of the northeastern section of Chequamegon National Forest. A member of the northern coniferous-deciduous biome, surveys from the mid-19th century indicate the region consisted of a mixed stand of red, white, and jack pines. After extensive timber harvesting, wildfires, and farming activity, the region turned into a fragmented mosaic of stands of various ages and composition. The young hardwood clearcut site is one of ten sites that collectively represent the successional stages of development in the predominant stand types of a physically homogeneous landscape. In 2001, northern hardwood stands of all ages occupied 45% of the region.

Chen, Jiquan↗
DOE OSTI2023

AmeriFlux FLUXNET-1F US-Wi9 Young Jack pine (YJP)

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-Wi9 Young Jack pine (YJP). This is the FLUXNET version of the carbon flux data for the site US-Wi9 Young Jack pine (YJP) produced by applying the standard ONEFlux (1F) software. Site Description - The Wisconsin Young Jack Pine site is located in the Washburn Ranger District of the northeastern section of Chequamegon National Forest. A member of the northern coniferous-deciduous biome, surveys from the mid-19th century indicate the region consisted of a mixed stand of red, white, and jack pines. After extensive timber harvesting, wildfires, and farming activity, the region turned into a fragmented mosaic of stands of various ages and composition. As an assemblage, the ten Wisconsin sites are indicative of the successional stages of development in the predominant stand types of a physically homogeneous landscape. Clearcut on 40 to 70 year intervals, jack pine stands occupy approximately 13% of the region.

Chen, Jiquan↗
DOE OSTI2023

AmeriFlux FLUXNET-1F US-WPT Winous Point North Marsh

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-WPT Winous Point North Marsh. This is the FLUXNET version of the carbon flux data for the site US-WPT Winous Point North Marsh produced by applying the standard ONEFlux (1F) software. Site Description - The marsh site has been owned by the Winous Point Shooting Club since 1856 and has been managed by wildlife biologists since 1946. The hydrology of the marsh is relatively isolated by the surrounding dikes and drainages and only receives drainage from nearby croplands through three connecting ditches. Since 2001, the marsh has been managed to maintain year-round inundation with the lowest water levels in September. Within the 0–250 m fetch of the tower, the marsh comprises 42.9% of floating-leaved vegetation, 52.7% of emergent vegetation, and 4.4% of dike and upland during the growing season. Dominant emergent plants include narrow-leaved cattail (Typha angustifolia), rose mallow (Hibiscus moscheutos), and bur reed (Sparganium americanum). Common floating-leaved species are water lily (Nymphaea odorata) and American lotus (Nelumbo lutea) with foliage usually covering the water surface from late May to early October.

Chen, Jiquan↗
DOE OSTI2023

AmeriFlux FLUXNET-1F US-CRT Curtice Walter-Berger cropland

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-CRT Curtice Walter-Berger cropland. This is the FLUXNET version of the carbon flux data for the site US-CRT Curtice Walter-Berger cropland produced by applying the standard ONEFlux (1F) software. Site Description - The conventional cropland site is rain fed and no irrigation is applied. As it is located in a part of the historic Great Black Swamp, drainage tiles are deployed around 0.5–1.0 m beneath the ground surface in order to draw down the water level. The soil is classified as silty clay and silty clay loam. The cultivation practices include minimum tillage and both insect and weed control. During the study period, the cropland was planted with soybean and winter wheat.

Chen, Jiquan↗
DOE OSTI2023

Climate cooling benefits of cellulosic bioenergy crops from elevated albedo

Abstract Changes in land surface albedo can alter ecosystem energy balance and potentially influence climate. We examined the albedo of six bioenergy cropping systems in southwest Michigan USA: monocultures of energy sorghum ( Sorghum bicolor ), switchgrass ( Panicum virgatum L.), and giant miscanthus ( Miscanthus × giganteus) , and polycultures of native grasses, early successional vegetation, and restored prairie. Direct field measurements of surface albedo ( α s ) from May 2018 through December 2020 at half‐hourly intervals in each system quantified the magnitudes and seasonal differences in albedo (∆ α ) and albedo‐induced radiative forcing (RF ∆ α ). We used a nearby forest as a historical native cover type to estimate reference albedo and RF ∆ α change upon original land use conversion, and a continuous no‐till maize ( Zea mays L .) system as a contemporary reference to estimate change upon conversion from annual row crops. Annually, α s differed significantly ( p < 0.05) among crops in the order: early successional (0.288 ± 0.012SE) >> miscanthus (0.271 ± 0.009) ≈ energy sorghum (0.270 ± 0.010) ≥ switchgrass (0.265 ± 0.009) ≈ restored prairie (0.264 ± 0.012) > native grasses (0.259 ± 0.010) > maize (0.247 ± 0.010). Reference forest had the lowest annual α s (0.134 ± 0.003). Albedo differences among crops during the growing season were also statistically significant, with growing season α s in perennial crops and energy sorghum on average ~20% higher (0.206 ± 0.003) than in no‐till maize (0.184 ± 0.002). Average non‐growing season (NGS) α s (0.370 ± 0.020) was much higher than growing season α s (0.203 ± 0.003) but these NGS differences were not significant. Overall, the original conversion of reference forest and maize landscapes to perennials provided a cooling effect on the local climate (RF αMAIZE : −3.83 ± 1.00 W m −2 ; RF αFOREST : −16.75 ± 3.01 W m −2 ). Significant differences among cropping systems suggest an additional management intervention for maximizing the positive climate benefit of bioenergy crops, with cellulosic crops on average ~9.1% more reflective than no‐till maize, which itself was about twice as reflective as the reference forest.

Lei, Cheyenne↗
DOE OSTI2023

Upscaling Wetland Methane Emissions From the FLUXNET–CH4 Eddy Covariance Network (UpCH4 v1.0): Model Development, Network Assessment, and Budget Comparison

Wetlands are responsible for 20%–31% of global methane (CH 4 ) emissions and account for a large source of uncertainty in the global CH 4 budget. Data-driven upscaling of CH 4 fluxes from eddy covariance measurements can provide new and independent bottom-up estimates of wetland CH 4 emissions. Here, we develop a six-predictor random forest upscaling model (UpCH4), trained on 119 site-years of eddy covariance CH 4 flux data from 43 freshwater wetland sites in the FLUXNET-CH4 Community Product. Network patterns in site-level annual means and mean seasonal cycles of CH 4 fluxes were reproduced accurately in tundra, boreal, and temperate regions (Nash-Sutcliffe Efficiency ~0.52–0.63 and 0.53). UpCH4 estimated annual global wetland CH 4 emissions of 146 ± 43 TgCH 4 y –1 for 2001–2018 which agrees closely with current bottom-up land surface models (102–181 TgCH 4 y –1 ) and overlaps with top-down atmospheric inversion models (155–200 TgCH 4 y –1 ). However, UpCH4 diverged from both types of models in the spatial pattern and seasonal dynamics of tropical wetland emissions. We conclude that upscaling of eddy covariance CH 4 fluxes has the potential to produce realistic extra-tropical wetland CH 4 emissions estimates which will improve with more flux data. To reduce uncertainty in upscaled estimates, researchers could prioritize new wetland flux sites along humid-to-arid tropical climate gradients, from major rainforest basins (Congo, Amazon, and SE Asia), into monsoon (Bangladesh and India) and savannah regions (African Sahel) and be paired with improved knowledge of wetland extent seasonal dynamics in these regions.

54 ENVIRONMENTAL SCIENCES↗