摘要 : As already stated by CN09, we agree with P09 thatthere is not enough evidence to unambiguously conclude that NAT-like layers in CN09 are actually composed of NATcrystals. Mixtures of liquid aerosols and ice, as proposed byP09, app... 展开 As already stated by CN09, we agree with P09 thatthere is not enough evidence to unambiguously conclude that NAT-like layers in CN09 are actually composed of NATcrystals. Mixtures of liquid aerosols and ice, as proposed byP09, appear as a convincing possibility. As mentioned byCN09, other potential candidates include very small, non-spherical ice crystals that have been observed in situ insignificant concentrations [Gayet et al., 2007]; it remains tobe seen if such particles are thermodynamically stable in thespecific conditions of the TTL. However, this reply tries toshow why we also think that it is too soon to defmitely ruleout a NAT composition for the non-ice/non-liquid layers inCALIOP TTL observations. More studies, including remotesensing and in-situ observations, are required to fullyresolve these questions. 收起