PMID- 32025455
OWN - NLM
STAT- PubMed-not-MEDLINE
LR  - 20240328
IS  - 2169-9097 (Print)
IS  - 2169-9100 (Electronic)
IS  - 2169-9097 (Linking)
VI  - 124
IP  - 11
DP  - 2019 Nov
TI  - Relative Humidity on Mars: New Results From the Phoenix TECP Sensor.
PG  - 2780-2792
LID - 10.1029/2019JE006080 [doi]
AB  - In situ measurements of relative humidity (RH) on Mars have only been performed 
      by the Phoenix (PHX) and Mars Science Laboratory (MSL) missions. Here we present 
      results of our recalibration of the PHX thermal and electrical conductivity probe 
      (TECP) RH sensor. This recalibration was conducted using a TECP engineering model 
      subjected to the full range of environmental conditions at the PHX landing site 
      in the Michigan Mars Environmental Chamber. The experiments focused on the 
      warmest and driest conditions (daytime) because they were not covered in the 
      original calibration (Zent et al., 2010, https://doi.org/10.1029/2009JE003420) 
      and previous recalibration (Zent et al., 2016, 
      https://doi.org/10.1002/2015JE004933). In nighttime conditions, our results are 
      in excellent agreement with the previous 2016 recalibration, while in daytime 
      conditions, our results show larger water vapor pressure values. We obtain vapor 
      pressure values in the range ~0.005-1.4 Pa, while Zent et al. (2016, 
      https://doi.org/10.1002/2015JE004933) obtain values in the range ~0.004-0.4 Pa. 
      Our higher daytime values are in better agreement with independent estimates from 
      the ground by the PHX Surface Stereo Imager instrument and from orbit by Compact 
      Reconnaissance Imaging Spectrometer for Mars. Our results imply larger 
      day-to-night ratios of water vapor pressure at PHX compared to MSL, suggesting a 
      stronger atmosphere-regolith interchange in the Martian arctic than at lower 
      latitudes. Further, they indicate that brine formation at the PHX landing site 
      via deliquescence can be achieved only temporarily between midnight and 6 a.m. on 
      a few sols. The results from our recalibration are important because they shed 
      light on the near-surface humidity environment on Mars.
CI  - (c)2019. The Authors.
FAU - Fischer, E
AU  - Fischer E
AUID- ORCID: 0000-0002-2098-5295
AD  - Department of Climate and Space Sciences and Engineering University of Michigan 
      Ann Arbor MI USA.
FAU - Martinez, G M
AU  - Martinez GM
AUID- ORCID: 0000-0001-5885-236X
AD  - Department of Climate and Space Sciences and Engineering University of Michigan 
      Ann Arbor MI USA.
AD  - Lunar and Planetary Institute Universities Space Research Association Houston TX 
      USA.
FAU - Renno, N O
AU  - Renno NO
AD  - Department of Climate and Space Sciences and Engineering University of Michigan 
      Ann Arbor MI USA.
FAU - Tamppari, L K
AU  - Tamppari LK
AUID- ORCID: 0000-0001-5124-6375
AD  - Jet Propulsion Laboratory California Institute of Technology Pasadena CA USA.
FAU - Zent, A P
AU  - Zent AP
AD  - NASA Ames Research Center Mountain View CA USA.
LA  - eng
PT  - Journal Article
DEP - 20191106
PL  - United States
TA  - J Geophys Res Planets
JT  - Journal of geophysical research. Planets
JID - 101661797
PMC - PMC6988475
OTO - NOTNLM
OT  - Mars
OT  - Phoenix
OT  - TECP
OT  - relative humidity
OT  - water cycle
OT  - water vapor
EDAT- 2020/02/07 06:00
MHDA- 2020/02/07 06:01
PMCR- 2020/01/29
CRDT- 2020/02/07 06:00
PHST- 2019/06/06 00:00 [received]
PHST- 2019/09/19 00:00 [revised]
PHST- 2019/09/20 00:00 [accepted]
PHST- 2020/02/07 06:00 [entrez]
PHST- 2020/02/07 06:00 [pubmed]
PHST- 2020/02/07 06:01 [medline]
PHST- 2020/01/29 00:00 [pmc-release]
AID - JGRE21230 [pii]
AID - 10.1029/2019JE006080 [doi]
PST - ppublish
SO  - J Geophys Res Planets. 2019 Nov;124(11):2780-2792. doi: 10.1029/2019JE006080. 
      Epub 2019 Nov 6.