Patterns and Drivers of Surface Energy Flux in the Alpine Meadow Ecosystem in the Qilian Mountains, Northwest China
Abstract
:1. Introduction
2. Results
2.1. The Environmental Variables
2.2. Daily Variations in the Characteristics of Energy
2.3. Seasonal Distribution and Proportional Characteristics of Energy Fluxes
2.4. Factors Influencing Energy Fluxes
3. Discussion
3.1. Seasonal Variations in Energy Components
3.2. Factors Influencing Energy Fluxes in Alpine Meadow Ecosystems
4. Materials and Methods
4.1. Study Site
4.2. Instruments and Measurements
4.3. Bowen Ratio Energy Balance (BREB) Method
4.4. Exclusion of Outliers and Imputation
4.5. Energy Closure Calculation
4.6. Data Analysis
5. Conclusions
Author Contributions
Funding
Data Availability Statement
Conflicts of Interest
References
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Item | Growing Season (May–September) | Non-Growing Season (October–April) | Entire Year |
---|---|---|---|
Ta (°C) | 7.12 | −7.77 | −1.53 |
Ts (°C) | 6.41 | −6.89 | −1.31 |
VPD (kPa) | 0.47 | 0.24 | 0.33 |
U (m s−1) | 2.19 | 2.24 | 2.22 |
SWC (m3 m−3) | 0.32 | 0.16 | 0.23 |
Rn (W m−2) | 133.70 | 50.35 | 85.29 |
H (W m−2) | 21.36 | 29.79 | 26.25 |
LE (W m−2) | 100.47 | 28.22 | 58.50 |
G (W m−2) | 6.41 | −7.99 | −1.95 |
H/Rn | 0.17 | 0.84 | 0.56 |
LE/Rn | 0.75 | 0.67 | 0.71 |
G/Rn | 0.04 | −0.57 | −0.32 |
β | 0.25 | 1.42 | 0.93 |
Variable | Sensor | Manufacturer | Accuracy | Height (m) |
---|---|---|---|---|
Net radiation (Rn) | CNR1 | Kipp & Zonen Kipp & Zonen (Delft, The Netherlands) | ±1% | 1.5 |
Air temperature (Ta) | 41382VC; HMP 155A | R. M. Young (Traverse City, MI, USA); Vaisala (Helsinki, Finland) | ±0.05 and ±0.2 °C | 1.5, 7.7 |
Relative humidity (RH) | 41382VC; HMP 155A | R. M. Young (Traverse City, MI, USA); Vaisala (Helsinki, Finland) | ±1 and ±2% | 1.5, 7.7 |
Wind speed and direction (U) | Wind Sonic; Young05103 | Gill (Lymington, Hampshire, UK); R.M. Young (Traverse City, MI, USA) | ±0.01 and ±0.3 m·s−1 | 1.5, 7.7 |
Surface temperature (Ts) | SI-111 | Apogee (Logan, UT, USA) | ±0.2 °C | 1.5 |
Soil heat flux (G) | HFP01SC | Hukseflux(Delft, The Netherlands) | ±3% | −0.05 −0.20 |
Soil water content (SWC) | Enviro SMART | Sentek (Adelaide, Australia) | ±0.1% | −0.05 −0.20 |
Soil temperature (TS5, TS20) | 109SS-L | Campbell Scientific (Logan, UT, USA) | ±0.2 °C | −0.05 −0.20 |
Rn | Net radiation, W m−2 | Kh | Heat exchange coefficient |
Sd | Downward shortwave radiation, W m−2 | Kv | Water vapor exchange coefficient |
Su | Upward shortwave radiation, W m−2 | T1 | Air temperature at Z1, K |
Ld | Downward longwave radiation, W m−2 | T2 | Air temperature at Z2, K |
Lu | Upward longwave radiation, W m−2 | e1 | Vapor pressure at Z1, kPa |
G | Soil heat flux, W m−2 | e2 | Vapor pressure at Z2, kPa |
Δz | Soil layer thickness, m | ρa | Mean air density at constant pressure, kg m−3 |
Gp | Energy measured by the embedded soil heat flux plates, W m−2 | Cp | Specific heat capacity of air at constant pressure, J kg−1 K−1 |
Cs | The volumetric heat capacity of the soil layer (J m−3 K−1) | τ | Adiabatic lapse rate, which is normally taken as 0.01 K m−1 |
β | Bowen ratio | Δe | Vapor pressure difference between the lower and the upper measurement levels, kPa |
∂T/∂t | Rate of variation in the mean temperature of the soil layer | SWC | Soil water content at a depth of 5 cm, m3 m−3 |
Ta | Air temperature at a height of 2 m above the ground, °C | VPD | Vapor pressure deficit, kPa |
U | Wind speed at a height of 2 m above the ground, m s−1 | BREB | Bowen ratio energy balance |
Ts | Soil temperature at a depth of 5 cm, °C | GS | Growing season |
H | Sensible heat flux, W m−2 | NGS | Non-growing season |
LE | Latent heat flux, W m−2 | δ1 | The absolute error limit of vapor pressure difference Δe |
γ | Psychorometric constant, (kPa K−1) | δ2 | The absolute error limit of vapor pressure difference ΔT |
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Tian, Y.; Liu, Z.; Fan, Y.; Li, Y.; Tao, H.; Han, C.; Ao, X.; Chen, R. Patterns and Drivers of Surface Energy Flux in the Alpine Meadow Ecosystem in the Qilian Mountains, Northwest China. Plants 2025, 14, 155. https://doi.org/10.3390/plants14020155
Tian Y, Liu Z, Fan Y, Li Y, Tao H, Han C, Ao X, Chen R. Patterns and Drivers of Surface Energy Flux in the Alpine Meadow Ecosystem in the Qilian Mountains, Northwest China. Plants. 2025; 14(2):155. https://doi.org/10.3390/plants14020155
Chicago/Turabian StyleTian, Yongxin, Zhangwen Liu, Yanwei Fan, Yongyuan Li, Hu Tao, Chuntan Han, Xinmao Ao, and Rensheng Chen. 2025. "Patterns and Drivers of Surface Energy Flux in the Alpine Meadow Ecosystem in the Qilian Mountains, Northwest China" Plants 14, no. 2: 155. https://doi.org/10.3390/plants14020155
APA StyleTian, Y., Liu, Z., Fan, Y., Li, Y., Tao, H., Han, C., Ao, X., & Chen, R. (2025). Patterns and Drivers of Surface Energy Flux in the Alpine Meadow Ecosystem in the Qilian Mountains, Northwest China. Plants, 14(2), 155. https://doi.org/10.3390/plants14020155