Progress in water vapour spectroscopy at RAL Dr Robert McPheat CAVIAR Progress Meeting Cambridge, 19/02/2011
Plan for mid-IR measurements 800 – 2100 cm -1, 12.5 – 4.8 µm Saturated P H2O (mb) ! T (K)P (mb) ? 10 F , 15 F (F) 10, 15 F, (F) No Argon steps are needed for LPAC measurements (F) , 150, , 150, 200, 350 Resolution (cm -1 ): N of scans: | ? (to ensure good S/N) | SPAC, 20m | LPAC, 512m (F) Only foreign measurement: H 2 O + Air( 1.5atm) F Foreign measurement: H 2 O + Air( 1.5atm), in addition to the pure one
LPAC measurements 512 m path length, 31 images High accuracy Baratrons & PRTs Room kept at 297 K Initial problems stable WV pressure
LPAC Window problems
LPAC Measurements New water vapour injection system Sample Gauge Air
LPAC Measurements Wavenumber / cm hPa water vapour
LPAC Temperature Calibration T = T prt T SPRT / °C
LPAC Temperature Calibration T LPAC = × T SPRT Days LPAC PRTs Std. Dev. Corrected LPAC temperature - T SPRT
LPAC Humidity Calibration