The spectroscopically selective two-photon laser-induced fluorescence (TP-LIF) technique is used by GIT to simultaneously measure NO and NO2 in the remote atmosphere. Whether measuring NO or NO2, the heart of the system is the ability to detect NO. In this approach laser beams at 226 nm and 1097 nm are used to sequentially excite rotationally resolved transitions in the NO molecule. The measured fluorescence resulting from excited transition occurs in the spectral region near 190 nm that is blue shifted and therefore free from laser generated background noise. The photodynamic scheme enables the TP-LIF approach to be signal limited rather than background limited. The two Nd:YAG lasers that have been deployed on both PEM Tropics A & B will again be used in TRACE-P. On of the Nd:YAG lasers will be used to generate the NO2 photolysis wavelength while the other Nd:YAG is pumping optical parametric oscillators (OPOs). One OPO will produce the infrared wavelength and another the ultraviolet wavelength necessary to excite the NO molecules. New for TRACE-P a more direct way of detected NO2 will be deployed. This involves another OPO which will be used to probe the prompt NO population from the NO2 photolysis in the v=1 vibrationally excited state. In all previous deployments of the Georgia Institute of Technologies Airborne Laser Induced Fluorescence Experiment (GITALIFE) we have waited for all of the NO produced from NO2 photolysis to relax back to the ground state be for probing the NO population (we will be measuring NO2 by this technique during TRACE-P also). When NO2 is photolyzed at 355 nm about 40% of the population comes off vibrationally hot. Detecting these prompt, excited NO molecules, will allow us NOT to do an abient NO subtraction and thus decreasing the error bars on our NO2 measurement. This technique should out preform the older differential technique when the NOx budget is shifted to a high NO concentration. It will not out preform the older differential technique when the NOx budget is shifted to low ambient NO conditions such is after dark. This is driven by the actual population that is being probed. The molecules that do not come off vibrationally hot are available to be probed by the older technique while only ~40% are available in the new more direct technique.

A newer data acquisition system will be deployed for the first time. It’s a far more space and power saving than the old rack and stack HP system we have flown for the last 10 years. I should also quickly state that GITALIFE has been on a very substantial diet since the passing of Dr. John and it will be between 800 - 900 pounds lighter than what we have ever installed on the DC8 in the past. Manpower to include Joe Mastromorino, Drs H. W. Guan, R. E. Stickel, D. K. Tan, and S. T. Sandholm.