Update seasonal scores from sounding data, document commercial link patterns
Soundings (10,935): October has strongest gradients (-350 N/km) and 65.7% ducting, raised seasonal score 82→88. February ducting (20.2%) exceeds January (14.8%), raised 32→40. Commercial links (12,068 samples): 68 GHz shows 3.9 dB diurnal swing, 11 GHz shows 1.7 dB with inverted multipath pattern, 24 GHz remarkably stable at 0.9 dB. Diurnal sensitivity is non-monotonic with frequency. RAOB gradients avg -265 N/km vs HRRR -107 (2.5x stronger) — confirms HRRR misses thin surface ducts that soundings resolve.
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algo.md
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algo.md
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@ -572,6 +572,12 @@ Binned distance analysis of 37,925 HRRR-matched contacts confirms and refines Pa
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**Mode distance advantage quantified.** CW: 247 km avg, PH (SSB): 191 km avg, FM: 141 km avg at 10 GHz. CW's 29% advantage over SSB is consistent with the ~7 dB bandwidth difference theoretical prediction.
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**RAOB gradients are 2.5x stronger than HRRR.** 10,935 soundings show avg gradient -265 N/km (median -200) vs HRRR avg -107 at contact points. RAOB resolves thin surface ducts (50-100m) that HRRR's ~250m vertical resolution misses. The sharp ducting threshold from RAOB data is -200 to -300 N/km, with 91% ducting at -300 and near-zero below -150. This confirms that HRRR refractivity scoring is inherently limited.
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**October seasonal score raised.** RAOB data shows October has the strongest mean gradient of any month (-350 N/km) and 65.7% ducting (3rd highest behind Jun 70% and Jul 71%). The 10 GHz seasonal score was raised from 82 to 88. February raised from 32 to 40 (20.2% ducting exceeds January's 14.8%).
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**Commercial link diurnal patterns (12,068 samples).** 68 GHz (2.82 km) shows 3.9 dB diurnal swing — morning best (-50.7 dBm at 09 UTC), afternoon worst (-54.6 at 13 UTC). 11 GHz (5.66 km) shows inverted pattern: 1.7 dB swing with more multipath variability at night. 24 GHz (4.36 km) is remarkably stable at only 0.9 dB swing. Diurnal sensitivity is non-monotonic with frequency: 24 GHz is more stable than 11 GHz on LOS paths because H₂O absorption is a constant floor rather than a fluctuating variable.
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---
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## Part 3: Band Configuration
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@ -57,7 +57,7 @@ defmodule Microwaveprop.Propagation.BandConfig do
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rain_alpha: 1.28,
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seasonal_base: %{
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1 => 38,
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2 => 32,
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2 => 40,
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3 => 22,
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4 => 55,
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5 => 68,
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@ -65,7 +65,7 @@ defmodule Microwaveprop.Propagation.BandConfig do
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7 => 95,
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8 => 75,
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9 => 78,
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10 => 82,
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10 => 88,
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11 => 78,
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12 => 25
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},
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updates.md
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updates.md
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@ -99,11 +99,102 @@ The -150 to -75 range (the bulk of HRRR gradients) shows remarkably flat distanc
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All atmospheric correlations in this analysis are effectively summer-only findings. Seasonal scoring curves cannot be validated from this dataset. The physics-based seasonal tables remain the best available approach for non-summer months.
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## Finding 8: Commercial Link Diurnal Patterns (12,068 samples, 7 links)
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Data from March 30 - April 7, 2026. All links in Princeton TX area, LOS paths.
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### 68 GHz (af60, 2.82 km) — Strongest diurnal signal
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| UTC Hour | Avg RX (dBm) | Std Dev | Notes |
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|----------|-------------|---------|-------|
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| 09-10 | **-50.7** | 0.80 | Morning best |
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| 00-08 | -51.2 to -52.2 | 0.6-1.2 | Night — gradual improvement |
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| 11-12 | -52.1 to -52.3 | 4-5 | Weather events (high std) |
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| 13-14 | **-54.3 to -54.6** | 5-6 | Afternoon worst |
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| 15-23 | -52.8 to -53.4 | 0.8-3.7 | Evening recovery |
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**3.9 dB diurnal swing.** Afternoon degradation at 68 GHz is dominated by gaseous absorption increase with daytime heating and humidity rise, plus convective scintillation. The high stddev at 11-15 UTC indicates individual weather events (rain, convection) can cause 10+ dB excursions.
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### 11 GHz (core-new-hope, 5.66 km) — Inverted pattern
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| UTC Hour | Avg RX (dBm) | Std Dev | Notes |
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|----------|-------------|---------|-------|
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| 08-12 | **-49.7 to -49.8** | 2.1-2.5 | Morning best, but variable |
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| 01-07 | -49.8 to -50.1 | 1.7-2.0 | Night — slightly better mean, multipath |
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| 14-21 | -50.8 to -51.4 | 1.2-1.5 | Afternoon/evening — worse mean, less variable |
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**1.7 dB diurnal swing.** At 11 GHz, gaseous absorption is negligible. The diurnal pattern is driven by **multipath fading** from nocturnal inversions (higher stddev at night: 2.0-2.5 vs afternoon: 1.2-1.4). Mean signal is slightly better at night despite the multipath, because the refractivity enhancement aids the direct path.
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### 24 GHz (climax-to-core, 4.36 km) — Remarkably stable
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**Only 0.9 dB diurnal swing** (-63.4 to -64.3). The 22.235 GHz H₂O line creates a constant absorption floor that varies minimally with diurnal moisture changes on short paths. One anomaly at 12 UTC (stddev 2.51) is likely a single rain event.
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### Key insight: Diurnal sensitivity by frequency on LOS paths
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- 11 GHz: 1.7 dB (multipath-dominated)
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- 24 GHz: 0.9 dB (absorption floor, stable)
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- 68 GHz: 3.9 dB (gaseous absorption-dominated)
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This is **non-monotonic** — 24 GHz is more stable than 11 GHz. The H₂O absorption at 24 GHz is a constant penalty that doesn't fluctuate much diurnally, while 11 GHz refractivity effects create multipath that varies with inversion development.
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## Finding 9: RAOB Soundings Resolve Ducting HRRR Cannot (10,935 soundings)
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### RAOB vs HRRR gradient distributions
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| Statistic | RAOB | HRRR (at contacts) |
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|-----------|------|-------------------|
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| Average | -265.4 N/km | -107.2 N/km |
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| P10 | -521.7 | ~-200 |
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| P50 (median) | -199.5 | ~-75 |
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| P90 | -83.3 | ~-50 |
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| Min | -1969.9 | — |
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RAOB gradients are **2.5x stronger** than HRRR because soundings at ~10m vertical resolution capture thin surface ducts (50-100m) that HRRR's 25 hPa pressure level spacing (~250m) cannot resolve.
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### Sharp ducting threshold at -200 to -300 N/km
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| Gradient Bin | n | Ducting % | Avg PWAT (mm) |
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|-------------|---|-----------|---------------|
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| < -500 | 622 | **100%** | 26.6 |
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| -500 to -300 | 967 | **99.9%** | 26.9 |
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| -300 to -200 | 1,168 | **91.2%** | 29.9 |
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| -200 to -150 | 879 | 31.2% | 28.5 |
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| -150 to -100 | 1,061 | 1.8% | 28.7 |
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| -100 to -50 | 683 | 2.2% | 27.0 |
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| >= -50 | 159 | 1.9% | 20.0 |
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The transition from "always ducting" to "rarely ducting" occurs between -200 and -300 N/km. This is consistent with the theoretical ducting threshold of -157 N/km (where k goes negative), with the additional gradient needed to sustain a duct layer of practical depth.
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### Seasonal ducting rates from RAOB
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| Month | Total | Ducting % | Avg Gradient | Avg PWAT (mm) |
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|-------|-------|-----------|-------------|---------------|
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| Jun | 232 | **70.3%** | -339.9 | 28.5 |
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| Jul | 247 | **71.3%** | -308.0 | 28.1 |
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| Oct | 99 | **65.7%** | **-350.0** | 18.9 |
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| Sep | 2,073 | 56.0% | -282.3 | 26.3 |
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| Aug | 2,281 | 53.7% | -258.2 | 34.0 |
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| Nov | 99 | 49.5% | -248.9 | 10.8 |
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| May | 128 | 41.4% | -227.4 | 20.4 |
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| Apr | 86 | 32.6% | -155.1 | 13.7 |
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| Feb | 84 | 20.2% | -135.4 | 6.8 |
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| Jan | 61 | 14.8% | -126.3 | 8.9 |
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| Mar | 54 | 14.8% | -140.9 | 10.5 |
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| Dec | 100 | 12.0% | -138.7 | 8.0 |
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**October is the most underrated month.** It has the strongest average gradients of any month (-350 N/km), 65.7% ducting rate (3rd highest), but was scored only 82/100 in the 10 GHz seasonal table.
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**February was scored below January despite higher ducting.** Feb: 20.2% ducting, was scored 32. Jan: 14.8% ducting, scored 38.
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**Code changes:**
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- 10 GHz February seasonal score: 32 → 40 (now exceeds January, matching its higher ducting rate)
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- 10 GHz October seasonal score: 82 → 88 (3rd highest ducting, strongest gradients)
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## Updated Dataset Statistics
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- **Contacts:** 58,367 total, 58,367 tropo (<3000 km)
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- **HRRR profiles:** 41,071,398 (37,925 matched to contacts, 65% coverage)
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- **Terrain profiles:** 58,361 (56,735 BLOCKED 97.1%, 1,284 CLEAR 2.2%, 342 FRESNEL_PARTIAL 0.6%)
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- **Soundings:** 10,935 (5,539 with gradient data, 2,964 with ducting detected)
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- **Commercial samples:** 12,068 (7 links, March 30 - April 7, 2026)
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- **IEMRE observations:** 15,092
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- **Weather stations:** 3,268
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- **Commercial samples:** 0 locally (available on production only)
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