# 📐  L2 Spec — Sea Ice Thermodynamic-Dynamic Inversion — Nominal + Mismatch Specs

**ID:** `L2-420-001` · **Status:** ⊙ Testnet (genesis catalog)
**Parents:** ⬆ Principle [`L1-420`](/artifact/l1/L1-420)

> **🎯 Tolerance (ε):** expression
> **⚖ Difficulty score:** 0.38 · **Delta tier:** 5
> **⛓ On-chain block:** 41555241

---

## 1. Domain Ω

**Type:** `range`

| Parameter | Unit | Range |
|---|---|---|
| Snow depth cm | — | 0 – 100 |
| N swath pixels | — | 1000 – 1000000 |
| Melt pond fraction | — | 0.0 – 0.5 |
| Ice concentration percent | — | 0 – 100 |

## 2. Tolerance (ε)

**Type:** `fn`

```
3 + 2 * (melt_pond_fraction / 0.1 + 1) ** 0.5
```

## 3. Difficulty

| Property | Value |
|---|---|
| Difficulty score | 0.38 |
| Delta tier | 5 |

## 4. Fingerprint

`7840fa2a433c7d4a6d5a0fe356531d09848e171c9967c69bba0c7028decb808c`

## 5. On-chain Registration

- **Chain hash:** `0x87113aee1eb3f209e79c544f5fb1cef451a30fa4f9d9ae8b023493a9d8211d44`
- **Chain tx hash:** `0x7ae54449e3671bff2b0c0755a2944ae7ff5537f3d412abf02c63c95d9cac65b7`
- **Chain block:** `41555241`

---

## File Mapping

This bundle consists of: `L2-420-001.md`, `L2-420-001.json`.

| File | Role | How to regenerate |
|------|------|-------------------|
| `L2-420-001.md` | Source of truth — edit this | Human or LLM |
| `L2-420-001.json` | Structured metadata for the registry | LLM regenerates from the sections above |

**Prompt for your LLM after editing this Markdown:**

> Read the attached Markdown. Regenerate the sibling `.json` so every field matches.
> Preserve the schema documented in the rows above.
> Output each file in its own fenced code block tagged with the filename.
> Output only the JSON object.

_This Markdown was auto-synthesized from the catalog row for `L2-420-001`._
_Edit it, regenerate the JSON, and submit at [/submit](/submit) to claim the artifact._