Atmospheric Gas Absorption at DF Laser Wavelengths

Area of Science:

• Atmospheric spectroscopy
• Laser-based gas analysis

Background:

• Accurate atmospheric gas absorption data is crucial for climate modeling and remote sensing.
• Previous models may not fully capture absorption across specific DF laser wavelengths.

Purpose of the Study:

• To measure and calculate the absorption of specific DF laser wavelengths by key atmospheric gases.
• To evaluate atmospheric transmission for vertical and horizontal paths.
• To compare experimental data with existing theoretical predictions.

Main Methods:

• Measured absorption spectra for CH(4), N(2)O, CO(2), and HDO vapor using 24 DF laser wavelengths.
• Calculated total absorption for individual gases and continua (N(2), H(2)O).
• Modeled transmission for a vertical (2.93 cm precipitable water) and a horizontal (11.2 cm precipitable water) atmospheric path.

Main Results:

• Transmission exceeded 90% for 12 lines in the vertical path.
• Transmission exceeded 65% for 13 lines in the horizontal path.
• Measured absorption coefficients showed good agreement (within a factor of ~2) with McClatchey and Selby's calculated values for most lines.

Conclusions:

• The study provides valuable experimental data for DF laser absorption by atmospheric gases.
• Experimental results validate existing models for many wavelengths, with minor discrepancies noted.
• Findings support the use of DF lasers for atmospheric monitoring and analysis.