We discovered experimentally the importance of wind variations in influencing both vapordrift downwind and the size of the LNG vapor cloud over the pond. This latter effect was large enough to significantly influence our calculations on spill 4. We had to estimate the vapor source size from Ongoing experiments We are currently performing 40-m° spill experiments at China Lake with a much more extensive acquisition center and the stations, and the need to movestations during the experimental series, it has been impractical to link the instru- sensor array (Fig. 6). These tests began in June and will end in September. Because of the large 250 PUTT TTT TTT photographs, since our otherin- strumentation was not designed to 7 Pig. D Fn Anarad 4 _ ATMAS calculation 200 t- Narad’ i © £& J sensor —j| + 1 . ‘| 150 c 7 & r 5 a —| + “+ “| 3 100 t— Cc mn oO b 3 ments to the acquisition center with | (a) Methane | measure it. Our data and calculations showed that the lower flammable limit of the vapor cloud (33 g/m*) extended farther than expected and that the cloud was warmer than predicted. However, the code calculations were in reasonable - agreement with the concentration data for the individual samplingstations. We believe that this agreement is due mainly to the code’s ability to recreate the time and spatial variations in the wind field. To improve our predictive ability, we will need to consider the effects of the large density difference between the cold gas cloud and the air and to refine our methods of modeling the effects of terrain features such as hills and valleys. number of stations involved, the large distances between the data- — Concentrations of hydrocarbons atsta- tion 4 during the second 5-m’spill, measured with an Anarad infrared sensor that distinquished (a)methane, (b) ethane, and (c)propane. The ethane and propane concentration peaks at about 100s provide the first field evidenceof differential boiloff of the various hydrocarbon fractions released in an LNG spill. = 4 50 ;-— ~~ 0 Be cette BOTT TTY TIT Ty Trt ry F {b) Ethane ° ~ § 30} | 40 — £30t- ~~ c r & 207- ~ = — : & \_ 10 | 1 0 | 50 Jit | 100 Time —s 34 ba 150 4 ma | sf = Cc & 10 L~ 4 1 0 + {c) Propane | 6 % 205c PITT TTT TTT 77 a 0 +t 0 jt fog l | 50 100 Time —s 150