Not SAIL-ing Into Spring 2023

Published: 20 April 2023

Editor’s note: Daniel Feldman, the principal investigator for the Surface Atmosphere Integrated Field Laboratory (SAIL) campaign in Colorado, provided the following blog post.

The SAIL campaign has just entered spring 2023, its final season of data collection. But so far, the winter of 2022/2023 won’t quit. The conditions across the Western United States have been very wet and cold, with snowpack peaking at 160% of normal.

For the Colorado River Watershed, this is most welcome news.

Two years ago, 100% of the Western Slope of Colorado was at least abnormally dry, 92% was at least in moderate drought, 62% was in severe drought, 32% was in extreme drought and 15% was in exceptional drought. Now, 100% of the Western Slope is drought-free.

Three maps that show, left to right, how the drought in Colorado has been busted. The 2023 map shows a drought-free western part of the state.
In these U.S. Drought Monitor snapshots from March 2021, March 2022, and March 2023, the blue star indicates SAIL’s study area. White is no drought, yellow is abnormally dry, light orange is moderate drought, dark orange is severe drought, red is extreme drought, and dark red is exceptional drought.

The SAIL campaign has been fortunate to collect data on the details of how a Western drought is busted in the Upper Colorado River Basin. A parade of storms, including atmospheric rivers, has brought near-record levels of precipitation, unseasonably cold surface conditions, lower surface radiation, and, of course, a very deep snowpack. The winter continues to significantly exceed both expectations and historical patterns.

Three pictures show different wintery views of the SAIL main site and Rocky Mountain Biological Laboratory
Reality outruns expectations. The top picture shows the same iconic view of the SAIL instruments collected at the start of the campaign but covered in snow. The bottom photos show that SAIL is measuring snow, so much so that signs about the campaign continue to be buried in it! Photos are courtesy of SAIL technician Travis Guy.

Plot shows four different lines: 1991-2020 Median Pr, WY2023 Pr, 1991-2020 Median SWE, and WY2023 SWE
This plot shows water year 2023 snowpack and precipitation at the Butte SNOTEL station (~1 kilometer from the SAIL S2 site at Crested Butte Mountain) relative to the 30-year mean climatology from 1991 through 2020. Water year 2023 extends from October 1, 2022, to September 30, 2023.

A Bounty of Winter Data

The high-spectral-resolution lidar with its vertically pointing green laser beam shooting up into the night sky
The SAIL campaign never sleeps: Most SAIL instruments collect data all day and night, including the high-spectral-resolution lidar with its vertically pointing green laser beam shown here. The long winter nights provided opportunities to measure atmospheric dynamics, thermodynamics, radiation, clouds, and aerosols under very cold (< minus 20 degrees Celsius), generally stable nighttime conditions. Photo is courtesy of SAIL technician Thomas Day.

In spite of the inclement conditions, the SAIL campaign is going smoothly. Data continue to be collected, with 145 current data products and counting. Measurements of precipitation, aerosols, winds, radiation, and atmospheric thermodynamics show exactly how large-scale circulation translates to local precipitation and down to the snowpack. In addition, ARM twice deployed the tethered balloon system this winter, in spite of the snowdrifts.

Clearly, the scientific community has no shortage of precipitation events to explore. Also, researchers Allison Aiken and Maria Zawadowicz are leading the science for aerosol data collection and will unpack these data to understand not just aerosols at the surface, but also their vertical distribution and what that means for aerosol processes in complex terrain.

There is a growing number of scientists looking at SAIL data. The late fall and early winter featured several opportunities for SAIL researchers to connect with the scientific community and share data and preliminary findings. They included:

Meanwhile, DOE Office of Science Director Asmeret Berhe wrote a blog about SAIL and related DOE fieldwork in Colorado, and Atmospheric System Research (ASR) promoted a call to fund SAIL science.

In addition, the SAIL campaign continues to advance and also benefit from current partnerships.

SAIL is hosting over a dozen guest instruments to complement data from ARM’s instruments.

The Watershed Function Scientific Focus Area works very closely with the SAIL campaign, which has been important for this winter’s science-enabling activities such as shoveling snow and validating precipitation observations.

Personnel from the SAIL and Sublimation of Snow (SOS) campaigns fill in a snow pit at Kettle Ponds (SAIL S3 site and SOS main site) in March 2023.
Personnel from the SAIL and Sublimation of Snow (SOS) campaigns fill in a snow pit at Kettle Ponds (SAIL S3 site and SOS main site) in March 2023. Photo is courtesy of Daniel Feldman.

Near the SAIL instruments, the Study of Precipitation, the Lower Atmosphere and Surface for Hydrometeorology (SPLASH) and the Sublimation of Snow (SOS) campaign continue to collect complementary atmospheric and surface state measurements.

SOS is also using SAIL data: Wind fields measured by SAIL have been critical for constraining mountain-valley circulations to contextualize the SOS observations.

But the icy grip of winter may start to loosen in the next few weeks.

On the horizon, the changing of the seasons looms. There are forecasts of major dust storms and hints that the albedo of the snow will drop dramatically as aerosols. SAIL’s Aerosol Observing System, for example, recorded an epic dust event April 4, just after the Geostationary Operational Environmental Satellite (GOES) showed major dust plumes across the Rockies.

A plot of aerosol total light scattering coefficients and aerosol light backscattering coefficients shows a peak on April 4, 2023, indicating a dust event at the site.
The nephelometer measuring light scattered by aerosols at SAIL’s S2 site records a major dust event April 4, 2023.

So stay tuned, but if you’re heading to SAIL, don’t forget your ski gear. Based on April 1 snowpack, the current estimate is that you will still have to ski to SAIL in early June! And melt-out could be pretty wild, but welcome as the melt fills the parched reservoirs of the West!