Modeling Pluto’s minimum pressure: Implications for haze production

Pluto has a heterogeneous surface, despite global haze deposition rate of ~1 micrometer per orbit (Cheng et al., 2017; Grundy 2018). While there could be spatial variation in the rate, this not yet been rigorously quantified, and naively should coat surface more uniformly than was observed. One way (among many) to explain contradiction is for atmospheric pressure at drop low enough interrupt production stop particles onto part driving heterogeneity. If drops less 10^-3 - 10^-4 microbar CH4 mixing ratio remains nearly constant observed 2015 value, atmosphere becomes transparent ultraviolet radiation (Young 2018), which would shut off its source. falls below 0.06 microbar, ceases global, instead localized over only warmest restricting location (Spencer 1997). In Pluto's current atmosphere, monomers collect together into aggregate beginning 0.5 microbar; if limit, appearance deposited different times year locations different. We use VT3D, an energy balance model (Young, 2017), on past orbital configurations four possible static N2 ice distributions: northern hemisphere distribution with (1) bare southern hemisphere, (2) south polar cap, (3) zonal band, finally (4) that everywhere except inside boundary Sputnik Planitia. also present sensitivity study showing effect mobile ice...(cont.)