In-situ UT/LS cirrus observations over the Asian Summer Monsoon

The 2017 StratoClim high-altitude aircraft campaign provided measurements of near-tropopause cirrus and tracer measurements in the upper troposphere/lower stratosphere (UT/LS) region over the Asian monsoon region. Because this region had not previously been sampled by in-situ measurements, the StratoClim flights provide a unique perspective on what is perhaps the largest source of water to the stratosphere. Cirrus were frequently present to tropopause level and above, with evidence of convective detrainment to at least 400 K. Flights sampled fresh convective outflow with ages of minutes to hours, as well as probable instances of in-situ dehydration. The dataset thus provides an unprecedented set of case studies on the evolution of near-tropopause cirrus. We show examples of cirrus of multiple types that highlight the diversity of processes controlling ice crystal size distributions and lifetimes and the interaction between convective sources and their environment. Measurements of water isotopic composition from the Chicago Water Isotope Spectrometer (ChiWIS) provide additional insight into these interactions and the influence of cirrus on the large-scale environment.