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Abu Dhabi GFS point profile — handling missing moisture aloft

This example loads the GFS point forecast for Abu Dhabi on 2025-07-15 12Z and shows how LegacyConnectors handles NaN values that appear in the moisture column at very high altitudes (the GFS product does not extend qᵛ into the mesosphere).

using LegacyConnectors
using Breeze
using CairoMakie

sounding = Sounding(:abudhabi_gfs)
Sounding(input_sounding, 33 z-cells, p_sfc=991.11 mb, θ_sfc=315.78 K, qᵛ_sfc=14.57 g/kg)

NaN is a first-class value here

Unlike the other two bundled soundings, this file contains a literal nan token in the qᵛ column at its highest level. The parser preserves it rather than silently filling or dropping the row:

qᵛ_col = [sounding.specific_humidity[1, 1, k] for k in 1:length(sounding)]
zc     = znodes(sounding.specific_humidity)

last_finite = findlast(isfinite, qᵛ_col)
first_nan   = findfirst(isnan,    qᵛ_col)
(last_finite, first_nan,
 z_last_finite = zc[last_finite],
 z_first_nan   = zc[first_nan])
(last_finite = 32, first_nan = 33, z_last_finite = 42554.109375, z_first_nan = 47871.210938)

This is important because the right thing to do with mesospheric missing moisture depends on the downstream consumer — a Breeze simulation that only extends to 30 km doesn't care; one that extends higher will need an extrapolation policy. By preserving NaN we leave that choice to the consumer.

Plot the profile, masking NaN for the qᵛ axis

θ_col = [sounding.potential_temperature[1, 1, k] for k in 1:length(sounding)]
u_col = [sounding.x_momentum[1, 1, k]            for k in 1:length(sounding)]
v_col = [sounding.y_momentum[1, 1, k]            for k in 1:length(sounding)]
finite = isfinite.(qᵛ_col)

fig = Figure(size = (900, 450))
ax_θ  = Axis(fig[1, 1]; xlabel = "θ (K)",      ylabel = "z (m AGL)",
             title = "Abu Dhabi GFS 2025-07-15 12Z")
ax_qᵛ = Axis(fig[1, 2]; xlabel = "qᵛ (g/kg)",  ylabel = "z (m AGL)")
ax_w  = Axis(fig[1, 3]; xlabel = "wind (m/s)", ylabel = "z (m AGL)")
lines!(ax_θ,  θ_col, zc)
lines!(ax_qᵛ, qᵛ_col[finite] .* 1000, zc[finite])
lines!(ax_w,  u_col, zc; label = "u")
lines!(ax_w,  v_col, zc; label = "v")
axislegend(ax_w; position = :rb)
fig

Note the profile reaches ~48 km — well above the tropopause — with strongly easterly winds aloft and a near-isothermal stratosphere (θ rising exponentially in z above the tropopause).