Balance incoming and outgoing energy at surfaces. Solve for missing flux using consistent sign conventions. Explore residuals and improve field data interpretation easily now.
The calculator uses the surface energy balance closure:
Rn = H + LE + G + S
where all terms are expressed in W/m².
| Case | Rn (W/m²) | H (W/m²) | LE (W/m²) | G (W/m²) | S (W/m²) | Typical context |
|---|---|---|---|---|---|---|
| Midday, moist vegetation | 450 | 120 | 250 | 60 | 20 | High evapotranspiration dominates available energy |
| Midday, dry bare soil | 520 | 260 | 120 | 110 | 30 | More energy partitions into sensible and ground flux |
| Evening transition | 120 | 40 | 55 | 20 | 5 | Lower net radiation with modest turbulent fluxes |
The surface energy balance links radiation to heat exchange between land, water, vegetation, and air. When the balance is quantified, you can interpret evaporation, warming, and storage processes with fewer assumptions. This is central to micrometeorology, agriculture, hydrology, and urban climate studies.
All terms are flux densities in W/m² (joules per second per square meter). Typical daytime net radiation often ranges from about 100–800 W/m² depending on season, clouds, latitude, and albedo. Sensible heat commonly spans tens to a few hundred W/m², while latent heat can exceed 300 W/m² over well‑watered canopies.
Many datasets treat turbulent fluxes as positive upward, while radiative components are sometimes positive downward. Mixing conventions is the fastest way to obtain unrealistic results. Choose one convention and apply it to Rn, H, LE, G, and S together, then interpret signs in that same framework.
Ground heat flux (G) is often 5–30% of net radiation over bare soil at midday, and smaller under dense vegetation. The storage term (S) captures heat stored in air layers, biomass, built materials, snow, or water. For short averaging windows, S can be non‑negligible and improves closure.
The ratio H/LE (Bowen ratio) summarizes how energy is partitioned between heating the air and evaporating water. Values below 0.5 often indicate moist surfaces with strong evapotranspiration, while values above 1 suggest dry conditions. Use the computed terms to compare sites or seasons objectively.
The residual shown is Rn − (H + LE + G + S). A residual near zero indicates good closure for the chosen averaging period. Persistent non‑zero residuals may reflect instrument biases, footprint mismatch, or neglected storage and advection. Reporting residual percent of Rn helps compare conditions across time.
In practice, you may measure Rn with net radiometers, H and LE with eddy covariance, and G with soil heat flux plates. Enter three or four terms and solve for the missing one to check plausibility. During data cleaning, track residual patterns against wind, stability, and canopy wetness to identify systematic issues.
Use consistent averaging intervals (for example 30 minutes) and ensure all sensors are time‑aligned. Apply standard corrections where applicable and document your convention, height, and footprint. If you routinely see large residuals, test adding S or revisiting sign conventions before drawing physical conclusions.
A positive residual means available energy (Rn) is larger than H + LE + G + S. It suggests unaccounted processes, sign mismatch, or sensor bias, especially if it persists across many periods.
Yes, for longer averages or simple checks, S is often approximated as zero. However, short intervals, forests, snow, and urban surfaces can store substantial heat, so including S improves closure.
Turbulent fluxes (H and LE) can be most uncertain because they depend on turbulence sampling and corrections. Ground heat flux also needs careful soil calibration and spatial representativeness.
Limited moisture, high stomatal resistance, or sealed surfaces reduce evaporation, so more energy shifts to sensible heating and ground storage. This often happens over dry soil or during drought.
Bowen ratio (H/LE) varies widely. Moist vegetation often falls below 0.5, mixed conditions are near 0.5–1, and dry surfaces frequently exceed 1, especially during hot, dry afternoons.
You can use both, but interpretation differs. At night, Rn can be negative and storage can dominate. Ensure your sign convention matches your instruments before comparing day and night periods.
Verify sign conventions, synchronize timestamps, and confirm units. Add a realistic storage term when needed, check instrument maintenance, and compare footprints of radiometers and turbulent flux sensors.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.