By Grace Bischof
Over the previous couple of weeks, I’ve been wracking my mind to provide you with a great subject to put in writing about for my spherical of the weblog put up. I spotted I’m now simply shy of my first-year anniversary as a PVL member (the place did the time go!?). With a bit expertise below my belt, I figured it might be a great time to lastly give an replace on the analysis I’ve been doing over the past 12 months – and particularly the previous 8 months. Since I had no courses to fret about, I may dedicate the vast majority of my working hours to my undertaking.
The undertaking I’ve been engaged on was initially assigned to me with a necessity for a undertaking to work on from house. My preliminary undertaking – MAGE – which I briefly talked about in my introductory weblog put up final 12 months, is all lab-based. Clearly, with a number of lock-downs and really restricted entry to campus, I’ve not been capable of work on MAGE. Thus, the Phoenix undertaking was born.
To begin, the Martian ambiance may be very skinny, and has a weak greenhouse impact in comparison with Earth. The each day temperature on Mars is actually mediated by visible-band radiation coming in from the solar, the place it’s absorbed by the floor, then re-radiated again into area as thermal radiation. Aerosols within the ambiance – within the type of mud or water-ice particles – can produce a secondary impact on the temperature. Water-ice particles scatter a portion of the incoming photo voltaic flux and, importantly to this undertaking, soak up and mirror outgoing longwave flux. This will increase the thermal radiation on the floor, which may enhance warming.
This work is dubbed “the Phoenix undertaking” as a result of it’s based mostly on the Phoenix mission, which landed on Mars in 2008. The Phoenix lander was, and nonetheless is, probably the most northern-based lander on Mars, the place it was geared up with devices to check the native meteorology and water cycle within the Martian polar area. Phoenix operated for 150 sols, starting on the finish of northern Spring, and carrying by summer time solstice into the mid-summer. Throughout its mission, Phoenix made many detections of water-ice clouds, fog, and made the primary remark of water-ice precipitation on Mars.
So, how does this all relate? Effectively, whereas the LIDAR and digital camera onboard the lander captured necessary details about the clouds close to Phoenix, these devices may solely function for a small fraction of your complete mission size. However, the temperature sensors on the lander made near-continuous observations for your complete mission, measuring the atmospheric temperature each 2 seconds. Since we all know that clouds can affect the temperature, by modelling the atmospheric temperature on the Phoenix website, we will create a full report of the cloud exercise.
Constructing the cloud report includes utilizing a floor power steadiness on the location of the lander. This contains all power flux parts that may affect the temperature, corresponding to radiative results of mud within the ambiance. The power steadiness comprises one parameter, R, which is solely attributed to the flux mirrored by water-ice clouds. The bottom temperature is modelled utilizing a subsurface conduction scheme involving numerous regolith properties, and the atmospheric temperature is discovered by an equation involving the bottom temperature and the wise warmth flux. R is then decided by evaluating the modeled air temperature to the air temperature collected by the temperature sensor aboard Phoenix. If the temperatures are an ideal match, R = 0 over your complete run, and it’s assumed no clouds are current. In any other case, the temperatures are matched by various R on 2-hour intervals throughout the mannequin.
Finishing this evaluation for each sol of the mission builds up a steady image of the mirrored flux all through the mission. The mirrored flux might be associated to cloud properties corresponding to optical depth and ice-particle radius. That is the portion of the undertaking I’m at present engaged on. I consider this undertaking has helped strengthen my analysis expertise, because the strategies went by a number of iterations to start with and we needed to work by many issues that have been occurring. Whereas this isn’t the undertaking I used to be given initially, I’ve actually loved the time I’ve spent engaged on the Phoenix undertaking and my enthusiasm for Martian meteorology has actually grown.