# 📐  L2 Spec — Ensemble Kalman Filter (EnKF) — Nominal + Mismatch Specs

**ID:** `L2-436-001` · **Status:** ⊙ Testnet (genesis catalog)
**Parents:** ⬆ Principle [`L1-436`](/artifact/l1/L1-436)

> **🎯 Tolerance (ε):** expression
> **⚖ Difficulty score:** 0.38 · **Delta tier:** 5
> **⛓ On-chain block:** 41555261

---

## 1. Domain Ω

**Type:** `range`

| Parameter | Unit | Range |
|---|---|---|
| N e ensemble | — | 10 – 1000 |
| Localization km | km | 50 – 5000 |
| N state million | — | 0.001 – 100 |
| Obs density per gridpt | — | 0.01 – 10.0 |

## 2. Tolerance (ε)

**Type:** `fn`

```
0.03 + 0.02 * (50 / N_e_ensemble) ** 0.5
```

## 3. Difficulty

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

## 4. Fingerprint

`09c853a6e61cf6b39851864e3fc8459def359727a0ad48ed2ea0a3b5c5d4aceb`

## 5. On-chain Registration

- **Chain hash:** `0xe728f3e5ef7e8759fb791e23ed9a6920ccae49b24d28c7e457c754ff6aff0c6f`
- **Chain tx hash:** `0xf52ced7743e521efc8218bf65edd4da4340e4fc02abfadf516783c3e094ffdcb`
- **Chain block:** `41555261`

---

## File Mapping

This bundle consists of: `L2-436-001.md`, `L2-436-001.json`.

| File | Role | How to regenerate |
|------|------|-------------------|
| `L2-436-001.md` | Source of truth — edit this | Human or LLM |
| `L2-436-001.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 `L2-436-001`._
_Edit it, regenerate the JSON, and submit at [/submit](/submit) to claim the artifact._