Evaluation of the Relationship between Air and Land Surface Temperature under Clear- and Cloudy-Sky Conditions

Abstract

Clear and cloudy daytime comparisons of land surface temperature (LST) and air temperature (Tair) were made for 14 stations included in the U.S. Climate Reference Network (USCRN) of stations from observations made from 2003 through 2008. Generally, LST was greater than Tair for both the clear and cloudy conditions; however, the differences between LST and Tair were significantly less for the cloudy-sky conditions. In addition, the relationships between LST and Tair displayed less variability under the cloudy-sky conditions than under clear-sky conditions. Wind speed, time of the observation of Tair and LST, season, the occurrence of precipitation at the time of observation, and normalized difference vegetation index values were all considered in the evaluation of the relationship between Tair and LST. Mean differences between LST and Tair of less than 28C were observed under cloudy conditions for the stations, as compared with a minimum difference of greater than 28C (and as great as 718C) for the clear-sky conditions. Under cloudy conditions, Tair alone explained over 94%-and as great as 98%-of the variance observed in LST for the stations included in this analysis, as compared with a range of 81%-93% for clear-sky conditions. Because of the relatively homogeneous land surface characteristics encouraged in the immediate vicinity of USCRN stations, and potential regional differences in surface features that might influence the observed relationships, additional analyses of the relationships between LST and Tair for additional regions and land surface conditions are recommended.

Transient modeling of the ground thermal conditions using satellite data in the Lena River delta, Siberia

“…In essence, gaps in the MODIS LST record due to cloud cover are filled by the reanalysis data, which creates a data record with homogeneous data density and has the potential to moderate the cold bias of temporal averages of surface temperatures computed from clear-sky MODIS LST . During cloudy skies, differences between air and surface temperatures are strongly reduced compared to clear-sky conditions (e.g., Gallo et al, 2011), so air temperatures can be regarded as an adequate proxy when MODIS LST is not available due to cloud cover. Note that this gap-filling procedure assumes that air temperatures from the ERA-Interim reanalysis are not strongly biased.…”

“…In this study, we therefore employ a gap-filling procedure with ERA-Interim nearsurface air temperatures. During cloudy periods, reanalysisderived air temperatures may indeed facilitate an adequate representation of surface temperatures, as the near-surface temperature gradient is smaller compared to clear-sky conditions (e.g., Hudson and Brandt, 2005;Gallo et al, 2011;Westermann et al, 2012). As demonstrated by Westermann et al (2015) for the N Atlantic region, the composite product features a considerably reduced bias and is significantly better suited as input for permafrost modeling than the original MODIS LST record.…”

Growth performance and resistance to ground late frosts of Fagus sylvatica L. plantation treated with a brassinosteroid compound

“…extraordinary temperature extremes are primarily reached during clear (cloudless) nights and days (e.g. oke 1970; Gallo et al 2011;leslie et al 2014). The spatial distribution of low temperatures corresponds well with local terrain forms, and frost events are more frequent in so called frost hollows, i.e.…”

The Urban Heat Island Effect in the City of Valencia: A Case Study for Hot Summer Days

“…During daytime the differences between AT and LST at the Airport reached more than 10 °C, however during the night the difference was not greater than 2.5 °C. This discrepancy was due to the different physical nature of AT and LST as it has been studied in several settings [53][54][55]. At Viveros the difference between AT and LST was more moderated, during daylight less than 6 °C, and during nighttime less than 2 °C.…”

“…The point LST values were obtained from the nearest pixel to the stations to compare them directly with the air temperature measurements. During daytime the differences between AT and LST at the Airport reached more than 10 • C, however during the night the difference was not greater than 2.5 • C. This discrepancy was due to the different physical nature of AT and LST as it has been studied in several settings [53][54][55]. At Viveros the difference between AT and LST was more moderated, during daylight less than 6 • C, and during nighttime less than 2 • C. This is a consequence of the altered surface-atmosphere interaction resulting in the urban canopy layer (UCL, the lower atmosphere from the surface until the mean building height) and the urban boundary layer (UBL, the lower atmosphere above UCL) that function as "buffer" layers over the surface of the city [24].…”