Source: https://guthlabs.ai/docs/instruments/cape-estimator-simplified/implementation/

instrument implementation / implementation-contract

# CAPE Estimator (simplified) implementation

A source-bound implementation contract for CAPE Estimator (simplified); deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-clean

**Evidence ID**: t7-055

**Effect**: Computation or source lookup only

## Input and validation requirements

The zero-environment-virtual-temperature vector makes the required denominator vanish, so an implementation that accepts it without validation produces an undefined result. The specification also leaves positive-buoyancy clipping, height sign, and temperature-unit conventions insufficiently explicit.

## Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "inputs": {
    "layers": [
      {
        "z_bottom_m": 0,
        "z_top_m": 1000,
        "Tv_parcel_K": 301,
        "Tv_env_K": 300
      },
      {
        "z_bottom_m": 1000,
        "z_top_m": 2000,
        "Tv_parcel_K": 300,
        "Tv_env_K": 300
      }
    ],
    "height_unit": "m",
    "category_convention": "provisional: weak <100, moderate 100-250, strong 250-2000, extreme >=2000",
    "saturation_vapor_pressure_lookup": {
      "temperature_C": 0
    }
  },
  "expected_outputs": {
    "cape_J_per_kg": 32.688833,
    "instability_category": "weak",
    "saturation_vapor_pressure_kPa": 0.6113
  },
  "reference_data": {
    "standard_gravity_m_s2": 9.80665,
    "standard_gravity_source_convention": "widely tabulated standard value (CGPM standard gravity)",
    "saturation_vapor_pressure_0C_kPa": 0.6113,
    "saturation_vapor_pressure_source_convention": "widely tabulated standard value (IAPWS/CRC convention)"
  },
  "working": "Layer 1 buoyancy ratio = (301−300)/300 = 1/300. Layer 1 contribution = 9.80665 × (1/300) × (1000−0) = 32.688833 J/kg. Layer 2 ratio = (300−300)/300 = 0, so its contribution is 0. CAPE = 32.688833 + 0 = 32.688833 J/kg. This is below 100 J/kg, hence provisional category weak. The lookup fragment gives e_s(0 °C) = 0.6113 kPa exactly."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/cape-estimator-simplified/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/cape-estimator-simplified/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/cape-estimator-simplified/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche7/tranche7-results.json`