Radar data assimilation for WRF Macaé INEA case studies · 3 cases · draft for WRF User Meeting 2026

CONVECT / Project Sharktopus · last updated 2026-09-03 · mirrored from GitHub (migration in progress)

Three end-to-end WRF radar-DA experiments over the INEA Macaé S-band radar. Each case uses objective nest placement (composite convective-index anomaly, swept against a 3-month WRF climatology), hourly 3D-Var cycling of radial velocity and reflectivity, and a free forecast out to 21 h on a 3-domain 9/3/1 km grid via ndown. Every case uses a fair same-lineage control — no cold-start mixing with the DA signal.

The experiment spans two calendar years (2023–2024), covers three convective regimes (organised nocturnal flooding, scattered afternoon, and strong nocturnal line), and includes a full audit of the flagship case (C2).

Nest decision overview — Macaé 2024-01-21 — C2 morning nest decision — d01 9 km composite anomaly with placed d02/d03/d04 boxes. Macaé radar marked in black.

cases

2023-11-30 · 2024-01-21 (2 windows) · 2024-12-16

radar

INEA Macaé

S-band, −22.406°, −41.860°; rv + rf assimilated

DA method

3D-Var

WRFDA hourly cycling, 4 cycles per case, same-lineage control

highlight

C2 d03 dawn

POD ≥2.5 mm/h 0.04→0.24; CSI 0.04→0.20 (1403 gauge-hours)

Cases and synthesis

C2 · 2024-01-21

The audited flagship case

Two windows (morning 00–03 Z / afternoon 06–09 Z). Organised nocturnal flooding event. Full placement + innovation + verification site, with a 104-finding audit. Morning window shows clear, robust DA benefit.

Open case 2

C1 · 2023-11-30

Afternoon weak convection

DA cycles 12–15 Z. Weak event; d03 box in a gauge-sparse region. MODE d02 centroid 55.9→10.9 km (3 matched hours); d03 stations POD 0→0.33 at ≥2.5 mm/h (1 hit of 3 events). A design lesson in observation density.

Open case 1

C3 · 2024-12-16

The nocturnal line the model missed

DA cycles 14–17 Z. Nocturnal convective line, Arraial do Cabo, 64 dBZ. Control: 0 hits at every threshold. Radar DA: POD ≥1 mm/h 0.00→0.077 on d03, a single hit out of 13 observed gauge-hours. Indicative, not statistical.

Open case 3

synthesis

Three cases, one fair baseline

Cross-case tables, key numbers control→radar for all 4 experiment windows, honest reading (5 bullets), and caveats on comparability.

Open synthesis

beam blockage

Where the radar is blind

Does it rain in directions the radar never sees? Found two ways — the radar's own dead sectors and a terrain beam-blockage simulation. ~19% of d03 is blind (W/NW behind the Serra do Mar). Map + WRFDA mask file.

Open beam-blockage study

Precipitable water — C2 morning radar DA

synoptic explorer

Browse the synoptic situation

Pre-rendered d01 (9 km) frames for 8 synoptic fields (MSLP, T2, q850, Z500, jet, PW, CAPE/shear, cref) across 2 runs — radar DA morning and the fair control. Use the run/field/hour selectors.

Open explorer