Zonal Wind

Author: CislunarSpace
Site: https://cislunarspace.cn

Definition

Zonal wind is atmospheric horizontal motion blowing along latitude lines (east-west direction). In meteorology: eastward flow is westerly (positive), westward flow is easterly (negative). Zonal wind is a key input parameter for stratospheric airship trajectory planning and energy consumption estimation.

Atmospheric Circulation Framework

Three-cell Circulation Model

Circulation Cell	Latitude Range	Zonal Wind Characteristic
Hadley Cell	0-30°	NE/SE trade winds (Easterly)
Ferrel Cell	30-60°	Temperate westerlies
Polar Cell	60-90°	Polar Easterlies

Seasonal Variation

Typical High-altitude Zonal Wind (@30°N)

Season	20 km	25 km	30 km
Winter	-20 m/s	-40 m/s	-60 m/s
Spring	0 m/s	-10 m/s	-30 m/s
Summer	+20 m/s	+30 m/s	+50 m/s
Autumn	0 m/s	+10 m/s	+20 m/s

Note: Negative = Westerly, Positive = Easterly

Effects on Stratospheric Airships

Trajectory Planning

Impact	Description
Position drift	Wind-induced drift rate = $v_{wind} \times t$
Propulsion energy	Headwind navigation requires extra energy
Station-keeping radius	Larger wind speed increases radius maintenance difficulty

Wind Field Modeling

Statistical Model

Based on historical data:

\bar{u}(h, \phi, t) = u_0(h) + \sum_{i=1}^{N} A_i(h) \cos(\omega_i t + \phi_i)

Numerical Weather Prediction (NWP)

Modern wind field forecasting uses:

WRF (Weather Research and Forecasting)
ECMWF Global Model
GFS Global Forecast System

References

Wallace J M, Hobbs P V. Atmospheric Science: An Introductory Survey[M]. Academic Press, 2023.
NOAA. US Standard Atmosphere 1976[M]. US Government Printing Office, 1976.