Evaluation of SHADOZ sondes, HALOE and SAGE II ozone profiles at the tropics from SAOZ UV-Vis remote measurements onboard long duration balloons
[摘要] Ozone profiles from 10 to 26km have been obtained at almost constantlatitude (20 ± 5° S) in the tropics using SAOZ UV-vis spectrometersflown onboard long duration balloons in 2001 and 2003. The precision of themeasurements is estimate to be better than 2% in the stratosphere(3.5% accuracy) and 5-6% in the troposphere (12% and 25%accuracy at 15km and 10km respectively) with an altitude uncertainty of-30 ± 25m. The variability of ozone concentration along a latitudinalcircle at 20° S in the SH summer is found smaller than 3-4% above 20km,but increasing rapidly below in the Tropical Tropopause Layer (TTL). Thehigh correlation between PV and ozone suggests that most of this variabilitycan be attributed to quasi-horizontal exchange with the mid-latitudestratosphere.
The performances of the SHADOZ ozonesonde network, HALOE and SAGE II in thetropics have been studied by comparison with SAOZ measurements. In thestratosphere, the main discrepancies arise from differences in altituderegistration, particularly sensitive between 20 and 26km in the tropicsbecause of the strong gradient of ozone concentration. In the uppertroposphere, the SAOZ measurements are consistent with those of the sondesand the lidar in cloud free conditions, but biased high by 60% on averagecompared to ozonesondes over the Western Pacific, at American Samoa andFiji. The likely explanation is the frequent occurrence of near zero ozonelayers in the convective clouds of the South Pacific Convergence Zone whichcannot be seen by SAOZ as well as all ground-based and space borne remotesensing instruments. Compared to SAOZ, SAGE II displays a 50-60% low biassimilar to that already known with the ozonesondes, and a larger zonalvariability. However, the significant correlation with PV suggests thatuseful information on tropospheric ozone could be derived from SAGE II.Finally, the unrealistic large offsets and variability in the HALOE datacompared to all others, indicates that the measurements of this instrumentare of limited use below 17km.
