<p><span style="color: rgb(80, 80, 80); font-family: NexusSan, Arial, Georgia, sans-serif, serif; font-size: 16px; background-color: rgb(255, 255, 255);">Because of the diurnal thermal cycle and the irregular shape of the nucleus, </span><span class="ScopusTermHighlight" style="box-sizing: border-box; background-color: rgb(252, 243, 142); display: inline-block; padding: 0.2rem 0.1rem; color: rgb(80, 80, 80); font-family: NexusSan, Arial, Georgia, sans-serif, serif; font-size: 16px;">gas</span><span style="color: rgb(80, 80, 80); font-family: NexusSan, Arial, Georgia, sans-serif, serif; font-size: 16px; background-color: rgb(255, 255, 255);"> </span><span class="ScopusTermHighlight" style="box-sizing: border-box; background-color: rgb(252, 243, 142); display: inline-block; padding: 0.2rem 0.1rem; color: rgb(80, 80, 80); font-family: NexusSan, Arial, Georgia, sans-serif, serif; font-size: 16px;">outflow</span><span style="color: rgb(80, 80, 80); font-family: NexusSan, Arial, Georgia, sans-serif, serif; font-size: 16px; background-color: rgb(255, 255, 255);"> of </span><span class="ScopusTermHighlight" style="box-sizing: border-box; background-color: rgb(252, 243, 142); display: inline-block; padding: 0.2rem 0.1rem; color: rgb(80, 80, 80); font-family: NexusSan, Arial, Georgia, sans-serif, serif; font-size: 16px;">comet</span><span style="color: rgb(80, 80, 80); font-family: NexusSan, Arial, Georgia, sans-serif, serif; font-size: 16px; background-color: rgb(255, 255, 255);"> </span><span class="ScopusTermHighlight" style="box-sizing: border-box; background-color: rgb(252, 243, 142); display: inline-block; padding: 0.2rem 0.1rem; color: rgb(80, 80, 80); font-family: NexusSan, Arial, Georgia, sans-serif, serif; font-size: 16px;">67P</span><span style="color: rgb(80, 80, 80); font-family: NexusSan, Arial, Georgia, sans-serif, serif; font-size: 16px; background-color: rgb(255, 255, 255);">/</span><span class="ScopusTermHighlight" style="box-sizing: border-box; background-color: rgb(252, 243, 142); display: inline-block; padding: 0.2rem 0.1rem; color: rgb(80, 80, 80); font-family: NexusSan, Arial, Georgia, sans-serif, serif; font-size: 16px;">Churyumov-Gerasimenko</span><span style="color: rgb(80, 80, 80); font-family: NexusSan, Arial, Georgia, sans-serif, serif; font-size: 16px; background-color: rgb(255, 255, 255);"> could be highly anisotropic as indicated by the colliminated </span><span class="ScopusTermHighlight" style="box-sizing: border-box; background-color: rgb(252, 243, 142); display: inline-block; padding: 0.2rem 0.1rem; color: rgb(80, 80, 80); font-family: NexusSan, Arial, Georgia, sans-serif, serif; font-size: 16px;">dust</span><span style="color: rgb(80, 80, 80); font-family: NexusSan, Arial, Georgia, sans-serif, serif; font-size: 16px; background-color: rgb(255, 255, 255);"> jet structures on the sunlit side. Based on the OSIRIS imaging observations of the outgassing effect, a simple model of surface sublimation can be constructed by taking into account the dependence on the solar insolation. With preliminary information on the time variability of the global </span><span class="ScopusTermHighlight" style="box-sizing: border-box; background-color: rgb(252, 243, 142); display: inline-block; padding: 0.2rem 0.1rem; color: rgb(80, 80, 80); font-family: NexusSan, Arial, Georgia, sans-serif, serif; font-size: 16px;">gas</span><span style="color: rgb(80, 80, 80); font-family: NexusSan, Arial, Georgia, sans-serif, serif; font-size: 16px; background-color: rgb(255, 255, 255);"> production rate, a sequence of </span><span class="ScopusTermHighlight" style="box-sizing: border-box; background-color: rgb(252, 243, 142); display: inline-block; padding: 0.2rem 0.1rem; color: rgb(80, 80, 80); font-family: NexusSan, Arial, Georgia, sans-serif, serif; font-size: 16px;">gas</span><span style="color: rgb(80, 80, 80); font-family: NexusSan, Arial, Georgia, sans-serif, serif; font-size: 16px; background-color: rgb(255, 255, 255);"> coma models can be generated at different epochs before and after perihelion. We also investigate different patterns of </span><span class="ScopusTermHighlight" style="box-sizing: border-box; background-color: rgb(252, 243, 142); display: inline-block; padding: 0.2rem 0.1rem; color: rgb(80, 80, 80); font-family: NexusSan, Arial, Georgia, sans-serif, serif; font-size: 16px;">dust</span><span style="color: rgb(80, 80, 80); font-family: NexusSan, Arial, Georgia, sans-serif, serif; font-size: 16px; background-color: rgb(255, 255, 255);"> particle dynamics under the influences of nuclear rotation and </span><span class="ScopusTermHighlight" style="box-sizing: border-box; background-color: rgb(252, 243, 142); display: inline-block; padding: 0.2rem 0.1rem; color: rgb(80, 80, 80); font-family: NexusSan, Arial, Georgia, sans-serif, serif; font-size: 16px;">gas</span><span style="color: rgb(80, 80, 80); font-family: NexusSan, Arial, Georgia, sans-serif, serif; font-size: 16px; background-color: rgb(255, 255, 255);"> drag. From these considerations, a consistent picture of the spatial distribution of dusty materials across the surface of </span><span class="ScopusTermHighlight" style="box-sizing: border-box; background-color: rgb(252, 243, 142); display: inline-block; padding: 0.2rem 0.1rem; color: rgb(80, 80, 80); font-family: NexusSan, Arial, Georgia, sans-serif, serif; font-size: 16px;">comet</span><span style="color: rgb(80, 80, 80); font-family: NexusSan, Arial, Georgia, sans-serif, serif; font-size: 16px; background-color: rgb(255, 255, 255);"> </span><span class="ScopusTermHighlight" style="box-sizing: border-box; background-color: rgb(252, 243, 142); display: inline-block; padding: 0.2rem 0.1rem; color: rgb(80, 80, 80); font-family: NexusSan, Arial, Georgia, sans-serif, serif; font-size: 16px;">67P</span><span style="color: rgb(80, 80, 80); font-family: NexusSan, Arial, Georgia, sans-serif, serif; font-size: 16px; background-color: rgb(255, 255, 255);"> as it moves around the perihelion can be developed. It is found that because of the redeposition of the ejected </span><span class="ScopusTermHighlight" style="box-sizing: border-box; background-color: rgb(252, 243, 142); display: inline-block; padding: 0.2rem 0.1rem; color: rgb(80, 80, 80); font-family: NexusSan, Arial, Georgia, sans-serif, serif; font-size: 16px;">dust</span><span style="color: rgb(80, 80, 80); font-family: NexusSan, Arial, Georgia, sans-serif, serif; font-size: 16px; background-color: rgb(255, 255, 255);"> from the Southern hemisphere to the Northern hemisphere during the southern summer season the Hapi region could gain up to 0.4 m while the Wosret region would lose up to 1.8 m of </span><span class="ScopusTermHighlight" style="box-sizing: border-box; background-color: rgb(252, 243, 142); display: inline-block; padding: 0.2rem 0.1rem; color: rgb(80, 80, 80); font-family: NexusSan, Arial, Georgia, sans-serif, serif; font-size: 16px;">dust</span><span style="color: rgb(80, 80, 80); font-family: NexusSan, Arial, Georgia, sans-serif, serif; font-size: 16px; background-color: rgb(255, 255, 255);"> mantle per orbit. © 2017 The Authors.</span></p>