How Do We Define Climate Change? Considering the Temporal Resolution of Niveo-Meteorological Data

Abstract

Historically, snowpack trends have been assessed using one fixed date to represent peak snow accumulation prior to the onset of melt. Subsequent trend analyses have considered the peak snow water equivalent (SWE), but the date of peak SWE can vary by several months due to inter-annual variability in snow accumulation and melt patterns. A 2018 assessment evaluated monthly SWE trends. However, since the month is a societal construct, this current work examines daily trends in SWE, cumulative precipitation, and temperature. The method was applied to 13 snow telemetry stations in Northern Colorado, USA for the period from 1981 to 2018. Temperature trends were consistent among all the stations; warming trends occurred 63% of the time from 1 October through 24 May, with the trends oscillating from warming to cooling over about a 10-day period. From 25 May to 30 September, a similar oscillation was observed, but warming trends occurred 86% of the time. SWE and precipitation trends illustrate temporal patterns that are scaled based on location. Specifically, lower elevations stations are tending to record more snowfall while higher elevation stations are recording less. The largest SWE, cumulative precipitation, and temperature trends were +30 to −70 mm/decade, +30 to −30 mm/decade, and +4 to −2.8 °C/decade, respectively. Trends were statistically significance an average of 25.8, 4.5, and 29.4% of the days for SWE, cumulative precipitation, and temperature, respectively. The trend in precipitation as snow ranged from +/−2%/decade, but was not significant at any station.

Intra‐day variability of temperature and its near‐surface gradient with elevation over mountainous terrain: Comparing MODIS land surface temperature data with coarse and fine scale near‐surface measurements

“…The NFRC is a semi‐arid region that is cool at night and warm during the day in spring, summer and fall, and cold in the winter (Goble, 2017). Total annual precipitation varies from 500 to 1,100 mm at the SNOTEL stations, with only 120 to 300 mm coming when there is no snow cover (Fassnacht et al ., 2020). Snow is intermittent below about 2000 m a.s.l.…”

Drivers of Dust-Enhanced Snowpack Melt-Out and Streamflow Timing

“…The snowpack (Figure 3a) [61,62], snowfall (Figure 3b) [63], the quantity of dust deposited onto the snowpack (Figure 3c) [16], and the number of dust events (Figure 3d) all vary inter-annually [21]. After peak SWE, the timing of dust events (Figure 3) and snowfall events influence melt characteristics (Figure 4) [15].…”

Snow Water Equivalent Accumulation Patterns from a Trajectory Approach over the U.S. Southern Rocky Mountains

“…The elevation data are the U.S. Geological Survey National Map at https: //nationalmap.gov/ (date accessed on 16 August 2021). Data were taken from Fassnacht and Records [11].…”

“…Drought conditions have been identified over the southern portions of the SRM (Figure 1) since the early 2000s [7], and these have persisted for the past two decades [8]. As well, a decline in the snowpack has occurred over the past few decades across most of the SRM [9][10][11]. The changing climate may not influence the snowpack accumulation, melt and subsequent runoff uniformly [12].…”