Radiative flux measurements in the troposphere

Area of Science:

• Atmospheric Science
• Radiative Transfer
• Aerosol Science

Background:

• Accurate measurement of radiative flux density in the troposphere is crucial for understanding atmospheric processes.
• Previous methods may have limitations in precision and scope.

Purpose of the Study:

• To report results from radiative flux-density measurements in the troposphere using a novel aircraft-mounted radiometer.
• To calculate heating rates for atmospheric gases and aerosols.
• To verify instrument performance by determining the solar constant.

Main Methods:

• Utilized a specially designed radiometer mounted on a Cessna 402B aircraft for in-situ measurements.
• Calculated atmospheric heating rates using measured radiative flux densities and radiosonde data.
• Verified instrument accuracy by calculating the solar constant from tropospheric flux density data.

Main Results:

• Determined total atmospheric heating rates of 0.175 K h⁻¹ for hazy and 0.377 K h⁻¹ for foggy conditions.
• Deduced aerosol heating rates of 0.065 K h⁻¹ (hazy) and 0.235 K h⁻¹ (foggy).
• Derived a solar constant of 1387 ± 21 W m⁻², agreeing within 4% of the standard value.

Conclusions:

• The specialized radiometer provides highly accurate atmospheric radiative flux determinations.
• The study quantifies significant aerosol contributions to atmospheric heating.
• Instrument performance is validated, demonstrating its capability for precise solar constant calculation.