title: Validating satellite-derived land surface temperature with in situ measurements: a public health perspective.
abstract: BACKGROUND
  Land surface temperature (LST) and percent surface imperviousness (SI), both derived from satellite imagery, have been used to characterize the urban heat island effect, a phenomenon in which urban areas are warmer than non-urban areas.
  
  
  OBJECTIVE
  We aimed to assess the correlations between LSTs and SI images with actual temperature readings from a ground-based network of outdoor monitors.
  
  
  METHODS
  We evaluated the relationships among a) LST calculated from a 2009 summertime satellite image of the Detroit metropolitan region, Michigan; b) SI from the 2006 National Land Cover Data Set; and c) ground-based temperature measurements monitored during the same time period at 19 residences throughout the Detroit metropolitan region. Associations between these ground-based temperatures and the average LSTs and SI at different radii around the point of the ground-based temperature measurement were evaluated at different time intervals. Spearman correlation coefficients and corresponding p-values were calculated.
  
  
  RESULTS
  Satellite-derived LST and SI values were significantly correlated with 24-hr average and August monthly average ground temperatures at all but two of the radii examined (100 m for LST and 0 m for SI). Correlations were also significant for temperatures measured between 0400 and 0500 hours for SI, except at 0 m, but not LST. Statistically significant correlations ranging from 0.49 to 0.91 were observed between LST and SI.
  
  
  CONCLUSIONS
  Both SI and LST could be used to better understand spatial variation in heat exposures over longer time frames but are less useful for estimating shorter-term, actual temperature exposures, which can be useful for public health preparedness during extreme heat events.
authors.affiliation: School of Public Health, University of Michigan, Ann Arbor, Michigan, USA. Jalonne@weact.org
authors.forename: Jalonne L
authors.initials: JL
authors.lastname: White-Newsome
authors.forename: Shannon J
authors.initials: SJ
authors.lastname: Brines
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Brown
authors.forename: J Timothy
authors.initials: JT
authors.lastname: Dvonch
authors.forename: Carina J
authors.initials: CJ
authors.lastname: Gronlund
authors.forename: Kai
authors.initials: K
authors.lastname: Zhang
authors.forename: Evan M
authors.initials: EM
authors.lastname: Oswald
authors.forename: Marie S
authors.initials: MS
authors.lastname: O'Neill
mesh_terms: D004784:Environmental Monitoring / Q000379:methods*; D040362:Geographic Information Systems / Q000295:instrumentation; D011634:Public Health; D018531:Spacecraft / Q000295:instrumentation; D013696:Temperature