Thursday, May 23, 2013
Today was an unusual day in terms of snowmelt. Although rainfall in May was once a rare occurrence, it seems to be occurring more frequently. It started to drizzle just before noon local time, and never stopped. It was a fine warm rain, and just kept coming. I am not sure how much water fell as precipitation; I suspect it was less than 0.1 inches of rain, but it had a big impact on the snow. The entire snowpack is now saturated. The hoar crystals at the base of the snowpack are now rounded meaning water is leaving the snowpack and entering the soil. If it keeps up like this, we could have runoff in a few days.
Having worked in the Arctic for many years, I still think it is likely that our weather will cool and temperatures fall back below the freezing point. However, the forecast calls for cooler evenings, but nothing substantial, so I suppose we should expect that melt is on its way. Around Toolik Lake, we would expect the slopes to by 75% snow free before the stream started to flow. Not sure what will happen here. Vegetation is increasingly obvious, and there was standing water on the ground in some places. We won't be able to use snowmachines for much longer.
Hiroki has done a wonderful job this week. Patrick arrives tomorrow. Everything else is good. I depart tonight for Fairbanks with others arriving in Barrow within a few days. It will be interesting to see how snowmelt progresses in the coming days.
Wednesday, May 22, 2013
Spring is slowly finding its way to Barrow. We’ve seen several flocks of ducks and heard some geese. It has been quite warm during the day, but still freezing at night. I saw one duck in a melt pond just outside Barrow. He was paddling like crazy to keep the pond from freezing.
It has been a very late spring across most of Alaska, but Barrow is right on time. Snowmelt is just starting to kick in. Today was warm, 36 - 38 F and quite windy, up to 25mph for most of the day. The top few inches of snow are already ripe, that is liquid water on the snow crystals. The whole snowpack is isothermal at 0°C, but the whole snowpack must be saturated with liquid water before we start worrying about runoff. There is no water at the base of the snowpack yet, so runoff is certainly not imminent. If the weather continues like this, it could be soon. But coastal Alaska usually bounces back and forth between warm and cold for several weeks before the snow finally disappears. Snowmelt on the Coastal Plain is typically a long slow process, but the snowpack is pretty thin, so I suspect it will be a short fast melt, if it stays warm. Yesterday it was almost 100% snow cover, but the number of bare spots really increased throughout the day today. Our measurements have shown the snowpack has about 3.5” to 5.1” (about 8 or 9 cm) of water equivalent. That means if all the snow suddenly melted, we’d have a layer water about 4 inches deep, which isn’t very much water when one considers this is the total winter accumulation. We don’t get mid-winter melts here. Some of the snow does sublimate but most accumulates all winter to melt in a brief spring. Summer rainfall is quite low, so this snowmelt is the major source of water to replenish lakes, streams and depleted soil moisture.
Hiroki Ikawa and I have come up to get ready for snowmelt. This is the biggest hydrologic event of the year in the Arctic, well maybe the biggest biological and cultural event too. Winter ends quickly and everything goes from frozen to wet. We have been repeating extensive measurements of the snowpack every day. The difference from one day to the next tells us how much snow has melted. This is very useful information for calibrating hydrological and thermal models. It takes over half the day to complete the snow surveys. We have an efficient process, but it is still a big job. After we finish the snow surveys, we have been removing the snow from several of the polygon troughs. We want to document the direction the water is flowing, again for calibration of hydrological models. The terrain here is so flat, a snow drift can influence the direction of flow. We want to determine how the terrain controls runoff, so we must eliminate any snow damming. It is a big job. Although the snow is not deep, we need to dig a long distance in this flat area to avoid backing up from a snow dam.
The Coastal Plain will be an amazing place in a few weeks. Migratory birds that spent the winter in more temperate climes will be back for their annual reunion. It is always spectacular. The numbers and sizes of the flocks are incredible. I hope everyone gets to experience snowmelt in Barrow some time.
Monday, May 6, 2013
This past week I traveled to a snowy Lincoln, Nebraska to take part in LI-COR’s training course on the LI-6400XT. Alistair and I will be taking four LI-6400XTs up to Barrow this summer to measure gas exchange. At the three day course I learned the basics of the 6400, took the entire instrument apart (and then put it back together) and took my first measurements. The course taught me a lot about the things we can achieve this summer in Barrow and with some more practice over the next two months I will be ready to clamp on to my first Arctic plant and start collecting data.
Posted by Unknown at 10:48 AM
We knew from previous experience that collection of permafrost cores from our tundra sites on the Barrow Environmental Observatory (BEO) would be challenging. David alerted us to this fact based on his trip to Barrow several weeks ago. One of our two crews spent the day retrieving a new, and solidly stuck, four foot, 2” diameter SIPRE core barrel from the unforgiving frozen tundra while the other crew managed to collect 6 shallow cores with the three foot 2”core barrel. Over the last few days our crew from LANL and UAF picked up the pace a bit and collected an additional 25 cores, 7 for Janet’s microbiology research and 18 multi-use (hydrologic properties, thermal properties, carbon content, isotopes) cores from Drained Thaw Lake Basins, DTLBs, of medium and old ages.
David kindly lent us his 3” SIPRE core barrel for today’s work, so we mobilized both crews again, comprised of Joel, Andy, Sasha, and Garrett, and attempted some tandem drilling in a rather unyielding high-centered polygon. None of this would have been possible without the great DGPS support from John who laid out the core locations in the field for the LANL-UAF drill team.
The LBNL team stopped by the Herman House for dinner and we spent time selecting sites from collection of cores from high-centered polygons. Tomorrow both the geophysics and coring teams head south to the DTLB transect where we will attempt to collect cores in the ancient and young DTLBs.
|Sasha with bent core barrel.|
Friday, May 3, 2013
Spring brings with it many changes for the North Slope of Alaska, longer days, rising air temperatures and, eventually, the melting of snow that has accumulated over the winter. While snow depth does not seem to be what it was last year, there will still be lots of water moving across the landscape – in and among the ice-wedge polygons – once snow melt gets underway in just a few weeks.
Because understanding the distribution of water is an important goal of the NGEE Arctic project, several teams will be in Barrow in the next few weeks to install sensors and to monitor snow melt, run-off, and water table depth at our field site on the Barrow Environmental Observatory. The first of these teams arrived this past Monday. Cathy (LANL), Anna, Sasha and Andy (all three from UAF) landed in Barrow on Monday night on the flight from Fairbanks. They were picked up by staff from our logistics provider, UMIAQ, and then taken to their offices east of town for orientation and a safety briefing with Michael and Brower. It was then off to Osaka’s for udons and bento boxes. Cathy, Anna, and the others then met up with the LBNL geophysical characterization team at midnight to move core and runoff well locations onto the DGPS unit. The LBNL team (John, Craig, and Baptiste) have been in Barrow for a few days characterizing subsurface properties using GPR, EM, and electrical resistivity.
On Tuesday morning, John helped the LANL and UAF teams by laying out snow grid and shallow well positions. Anna, Sasha and Andy augered runoff wells, while Cathy picked-up Joel, Garrett and the new 2 inch diameter SIPRE corer from the airport. We have been using a standard SIPRE for several years now, but had reason to believe that a smaller diameter core would facilitate collection of some deeper permafrost samples. Coring began mid-afternoon and the new corer worked very well; punching 6 cores in a few hours. We will meet up again with the LBNL group this evening to prepare for laying out additional coring locations tomorrow.
|Photo: Transition between organic-rich soil and an underlying ice wedge in a polygon trough core.|
|Photo: Joel and Andy pulling a 4 foot core.|