From 5d3bb23b8716b04cca3c3dc888f1d7d514a98f74 Mon Sep 17 00:00:00 2001
From: Labreo <74888611+Labreo@users.noreply.github.com>
Date: Fri, 30 Jan 2026 08:42:29 +0530
Subject: [PATCH 1/2] feat:Added a simple energy balance check

---
 src/sipnet/sipnet.c | 49 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/src/sipnet/sipnet.c b/src/sipnet/sipnet.c
index 2a67c4a62..7c7fabe7d 100644
--- a/src/sipnet/sipnet.c
+++ b/src/sipnet/sipnet.c
@@ -1760,6 +1760,55 @@ void updateState(void) {
   // All non-event fluxes
   calculateFluxes();
 
+  /*
+   * Energy Balance Sanity Check
+   * ----------------------------------------
+   * Verifies that Latent Energy (LE) flux does not exceed incoming Shortwave
+   * Radiation (SW).
+   *
+   * Physics Definitions:
+   * - LE (Latent Energy): Derived from Total Evapotranspiration * Heat of
+   * Vaporization (LAMBDA).
+   * - SW (Shortwave): Approximated here using PAR (Photosynthetically Active
+   * Radiation).
+   *
+   * Constraints:
+   * - The check is restricted to daylight hours (PAR > 1.0) to prevent
+   * numerical noise at night/dawn/dusk from triggering false positives.
+   */
+  if (climate->par > 1.0) {
+    // Aggregate individual water fluxes to calculate total ET (cm/day).
+    // Note: 'eventEvap' is intentionally excluded as processEvents() has not
+    // yet run.
+    double ET_sum = fluxes.transpiration + fluxes.immedEvap +
+                    fluxes.evaporation + fluxes.sublimation;
+
+    double LE_check = ET_sum * LAMBDA;
+    double SW_check = climate->par;
+
+    // ALPHA represents a conservative estimate of absorbed SW (approx. 1 -
+    // albedo). Values exceeding this threshold warrant investigation but are
+    // not strictly impossible.
+    const double ALPHA = 0.8;
+
+    // Hard Physics Violation (Conservation of Energy)
+    // Latent energy output cannot physically exceed total energy input.
+    if (LE_check > SW_check) {
+      printf("[ERROR] Energy Balance Violation: Year %d Day %d Time %.2f\n",
+             climate->year, climate->day, climate->time);
+      printf("        LE (%f) > SW (%f)\n", LE_check, SW_check);
+      // exit(EXIT_FAILURE); // Uncomment to enforce model termination on error
+    }
+    // Soft Plausibility Warning
+    // Warn if LE consumes an unusually high percentage of available energy.
+    else if (LE_check > (ALPHA * SW_check)) {
+      printf("[WARNING] High Latent Energy: Year %d Day %d Time %.2f\n",
+             climate->year, climate->day, climate->time);
+      printf("          LE (%f) is > %.0f%% of SW (%f)\n", LE_check,
+             ALPHA * 100.0, SW_check);
+    }
+  }
+
   // All event handling, which is modeled as fluxes
   processEvents();
 

From ac77e5014d503bf9effa03d5f46e94923c42a555 Mon Sep 17 00:00:00 2001
From: Labreo <74888611+Labreo@users.noreply.github.com>
Date: Sat, 31 Jan 2026 16:18:37 +0530
Subject: [PATCH 2/2] Fix:Convert PAR to SW energy units for energy balance
 sanity check

---
 src/sipnet/sipnet.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/sipnet/sipnet.c b/src/sipnet/sipnet.c
index 7c7fabe7d..85b116a04 100644
--- a/src/sipnet/sipnet.c
+++ b/src/sipnet/sipnet.c
@@ -1769,8 +1769,10 @@ void updateState(void) {
    * Physics Definitions:
    * - LE (Latent Energy): Derived from Total Evapotranspiration * Heat of
    * Vaporization (LAMBDA).
-   * - SW (Shortwave): Approximated here using PAR (Photosynthetically Active
-   * Radiation).
+   * - SW (Shortwave): Calculated from PAR (Photosynthetically Active
+   * Radiation). PAR is ~48.6% of SW. Conversion: SW (Energy) = (PAR_photons *
+   * EnergyPerPhoton) / 0.486 EnergyPerPhoton ~ 235,000 J/mol (for PAR
+   * wavelengths)
    *
    * Constraints:
    * - The check is restricted to daylight hours (PAR > 1.0) to prevent
@@ -1784,7 +1786,8 @@ void updateState(void) {
                     fluxes.evaporation + fluxes.sublimation;
 
     double LE_check = ET_sum * LAMBDA;
-    double SW_check = climate->par;
+
+    double SW_check = (climate->par * 235000.0) / 0.486;
 
     // ALPHA represents a conservative estimate of absorbed SW (approx. 1 -
     // albedo). Values exceeding this threshold warrant investigation but are