From 2eefe64c9bef0dc5e0ba446ff2cad25b7eb40db2 Mon Sep 17 00:00:00 2001 From: Graham McIntire Date: Tue, 7 Apr 2026 11:45:37 -0500 Subject: [PATCH] Update seasonal scores from sounding data, document commercial link patterns MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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. --- algo.md | 6 ++ lib/microwaveprop/propagation/band_config.ex | 4 +- updates.md | 93 +++++++++++++++++++- 3 files changed, 100 insertions(+), 3 deletions(-) diff --git a/algo.md b/algo.md index 3ef4b833..f4c29fe4 100644 --- a/algo.md +++ b/algo.md @@ -572,6 +572,12 @@ Binned distance analysis of 37,925 HRRR-matched contacts confirms and refines Pa **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. +**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. + +**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%). + +**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. + --- ## Part 3: Band Configuration diff --git a/lib/microwaveprop/propagation/band_config.ex b/lib/microwaveprop/propagation/band_config.ex index d9d216ac..e0d7c144 100644 --- a/lib/microwaveprop/propagation/band_config.ex +++ b/lib/microwaveprop/propagation/band_config.ex @@ -57,7 +57,7 @@ defmodule Microwaveprop.Propagation.BandConfig do rain_alpha: 1.28, seasonal_base: %{ 1 => 38, - 2 => 32, + 2 => 40, 3 => 22, 4 => 55, 5 => 68, @@ -65,7 +65,7 @@ defmodule Microwaveprop.Propagation.BandConfig do 7 => 95, 8 => 75, 9 => 78, - 10 => 82, + 10 => 88, 11 => 78, 12 => 25 }, diff --git a/updates.md b/updates.md index 1027cf70..9ccaecf7 100644 --- a/updates.md +++ b/updates.md @@ -99,11 +99,102 @@ The -150 to -75 range (the bulk of HRRR gradients) shows remarkably flat distanc 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. +## Finding 8: Commercial Link Diurnal Patterns (12,068 samples, 7 links) + +Data from March 30 - April 7, 2026. All links in Princeton TX area, LOS paths. + +### 68 GHz (af60, 2.82 km) — Strongest diurnal signal + +| UTC Hour | Avg RX (dBm) | Std Dev | Notes | +|----------|-------------|---------|-------| +| 09-10 | **-50.7** | 0.80 | Morning best | +| 00-08 | -51.2 to -52.2 | 0.6-1.2 | Night — gradual improvement | +| 11-12 | -52.1 to -52.3 | 4-5 | Weather events (high std) | +| 13-14 | **-54.3 to -54.6** | 5-6 | Afternoon worst | +| 15-23 | -52.8 to -53.4 | 0.8-3.7 | Evening recovery | + +**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. + +### 11 GHz (core-new-hope, 5.66 km) — Inverted pattern + +| UTC Hour | Avg RX (dBm) | Std Dev | Notes | +|----------|-------------|---------|-------| +| 08-12 | **-49.7 to -49.8** | 2.1-2.5 | Morning best, but variable | +| 01-07 | -49.8 to -50.1 | 1.7-2.0 | Night — slightly better mean, multipath | +| 14-21 | -50.8 to -51.4 | 1.2-1.5 | Afternoon/evening — worse mean, less variable | + +**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. + +### 24 GHz (climax-to-core, 4.36 km) — Remarkably stable + +**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. + +### Key insight: Diurnal sensitivity by frequency on LOS paths +- 11 GHz: 1.7 dB (multipath-dominated) +- 24 GHz: 0.9 dB (absorption floor, stable) +- 68 GHz: 3.9 dB (gaseous absorption-dominated) + +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. + +## Finding 9: RAOB Soundings Resolve Ducting HRRR Cannot (10,935 soundings) + +### RAOB vs HRRR gradient distributions + +| Statistic | RAOB | HRRR (at contacts) | +|-----------|------|-------------------| +| Average | -265.4 N/km | -107.2 N/km | +| P10 | -521.7 | ~-200 | +| P50 (median) | -199.5 | ~-75 | +| P90 | -83.3 | ~-50 | +| Min | -1969.9 | — | + +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. + +### Sharp ducting threshold at -200 to -300 N/km + +| Gradient Bin | n | Ducting % | Avg PWAT (mm) | +|-------------|---|-----------|---------------| +| < -500 | 622 | **100%** | 26.6 | +| -500 to -300 | 967 | **99.9%** | 26.9 | +| -300 to -200 | 1,168 | **91.2%** | 29.9 | +| -200 to -150 | 879 | 31.2% | 28.5 | +| -150 to -100 | 1,061 | 1.8% | 28.7 | +| -100 to -50 | 683 | 2.2% | 27.0 | +| >= -50 | 159 | 1.9% | 20.0 | + +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. + +### Seasonal ducting rates from RAOB + +| Month | Total | Ducting % | Avg Gradient | Avg PWAT (mm) | +|-------|-------|-----------|-------------|---------------| +| Jun | 232 | **70.3%** | -339.9 | 28.5 | +| Jul | 247 | **71.3%** | -308.0 | 28.1 | +| Oct | 99 | **65.7%** | **-350.0** | 18.9 | +| Sep | 2,073 | 56.0% | -282.3 | 26.3 | +| Aug | 2,281 | 53.7% | -258.2 | 34.0 | +| Nov | 99 | 49.5% | -248.9 | 10.8 | +| May | 128 | 41.4% | -227.4 | 20.4 | +| Apr | 86 | 32.6% | -155.1 | 13.7 | +| Feb | 84 | 20.2% | -135.4 | 6.8 | +| Jan | 61 | 14.8% | -126.3 | 8.9 | +| Mar | 54 | 14.8% | -140.9 | 10.5 | +| Dec | 100 | 12.0% | -138.7 | 8.0 | + +**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. + +**February was scored below January despite higher ducting.** Feb: 20.2% ducting, was scored 32. Jan: 14.8% ducting, scored 38. + +**Code changes:** +- 10 GHz February seasonal score: 32 → 40 (now exceeds January, matching its higher ducting rate) +- 10 GHz October seasonal score: 82 → 88 (3rd highest ducting, strongest gradients) + ## Updated Dataset Statistics - **Contacts:** 58,367 total, 58,367 tropo (<3000 km) - **HRRR profiles:** 41,071,398 (37,925 matched to contacts, 65% coverage) - **Terrain profiles:** 58,361 (56,735 BLOCKED 97.1%, 1,284 CLEAR 2.2%, 342 FRESNEL_PARTIAL 0.6%) +- **Soundings:** 10,935 (5,539 with gradient data, 2,964 with ducting detected) +- **Commercial samples:** 12,068 (7 links, March 30 - April 7, 2026) - **IEMRE observations:** 15,092 - **Weather stations:** 3,268 -- **Commercial samples:** 0 locally (available on production only)