Ready to check in on El Niño

Snow and sampling tools are packed and ready to help assess 2015-16 El Niño event impact to date at Quelccaya. We will be at the glacier until early May, playing in the snow and recovering frozen samples, Also planned are retrieval of AWS measurements, servicing the station, and doing a geodetic mass balance survey. Some exciting ecology research is part of the program; stay tuned for further details!

AWS moonshadow

The image above isn't likely to win any contests; the beauty of this shot is that it captures a night-time moment at the automated weather station, when we were thousands of kilometers away. This is one of over 7,000 images acquired during a 15 month interval at the Quelccaya AWS by a Pentax K100D Super camera, in an early version of a Harbortronics Time-Lapse system. It nicely demonstrates one of the ways that modern automated stations can include more than sensors making basic weather measurements.

The enclosure is installed looking toward the west, with a fixed field of view. About half of each scene shows the sky (i.e., clouds and all the information they convey about the atmospheric state), while the lower half illustrates the glacier surface, providing information such as snowfall timing, magnitude, subsequent wind re-distribution, and surface texture (see above). In addition, the foreground - only 75 cm from the camera - depicts sections of the tower, a guy cable, the GOES antenna, and a solar panel. Rime ice is easily observed here, during conditions when it develops. Remarkably, both distant and nearby elements of the image are almost always in focus!

This particular photo from 19:05 on 11 July is noteworthy because the only source of light was from a nearly-full moon, rising through clear sky to the east behind the camera. Faintly visible in the western background is a band of clouds; on the right-hand side a mountain in the Cordillera Vilcanota can be seen, ~50 km distant. On the foreground snow is a shadow of the AWS, clearly showing (left to right) an ultrasonic snow sensor, the big Met One T/RH radiation shield, and the RM Young Wind Monitor. EXIF data indicate the shutter speed was 6 seconds, with the aperture at f/4.

Our initial use for this set of hourly images is in aiding quality-control of snowfall measurements. Thanks to two different ultrasonic sensors on this station, raw measurements are usually unambiguous after adjusting for air-path temperature. But sometimes, it can be difficult to assess whether measurements recording a surface height increase are due to a snowfall event, re-distribution of previously-fallen snow, or something rare and unrelated to climate (e.g., jiggling of the tower as accumulation settles).

Getting the time-lapse system to this point hasn't been without frustration, but the result is proving both useful and interesting!

Mean daily air temperature [updated]

Here is the annual cycle of air temperature at Quelccaya (5,680 m), based upon the best dataset available. Each mean daily value is based upon ~4 years of measurements, which are not contiguous due to a power problem in 2010-12; the record has been smoothed slightly for clarity. A previous post (available here) provides some background, and the data will be available here shortly.

Analyses of these and other Quelccaya data are gearing up, working towards publication of a Quelccaya climatology. As illustrated by this graph, some interesting patterns are emerging.

[UPDATE 3/25:  A complete record of quality-controlled hourly air temperatures for July 2007-June 2009 are available here, as well as the accompanying metadata.]

Air temperature series [updated]!

In June of 2007 the Quelccaya AWS was supplemented by instrumentation compatible with NOAA’s Climate Reference Network (CRN). As nicely documented on the CRN website, several highly-accurate air temperature sensors housed within a continuously-ventilated radiation shield provide what is likely the best air temperature measurement possible in the extreme environment of the ice cap. (The link above now has comprehensive access to all CRN publications.)

Further information on Quelccaya temperature measurements is available here, along with access to the first 3 years of measurements.

Processing of the full 2007-13 temperature record from these sensors has just been completed, and access will be provided early next month. This record was assembled from 5-min averages based on 3-4 PRT sensors, quality controlled following CRN protocols (see Palecki & Groisman, 2011).

[UPDATE 3/25:  A complete record of quality-controlled hourly air temperatures for July 2007-June 2009 are available here, as well as the accompanying metadata. The full 2007-13 period has been processed, yet these are not yet available due to insufficient fan speed during early-morning hours through a portion of this period. Maximum daily temperatures were largely unaffected and this series will be available soon. Thanks for your patience.]

A sneak preview of one aspect of the new record is provided above, illustrating how melt energy is far from uniform through the year, or even through the accumulation season. The bar chart shows the number of hours each day in which the hourly mean temperature was above freezing, for each of the 6 years; also shown (as symbols) are the total number of hours above freezing - over 6 years - for each date. Although air temperature rises above freezing during only 0.42% of all hours, the associated melt is having a profound impact on the ice core record!

Failures, breaks, and solutions

During almost every venture into the field, something inevitably breaks. Try as we may to bring the most appropriate and robust gear with us, and to use it carefully, equipment fails during fieldwork in extreme environments for a variety of reasons: (a) it isn't quite up to what we ask of it, (b) it is simply worn out, and/or (c) it fails due to unforeseen stresses - such as getting dropped.

One of the challenges of gear problems during fieldwork is... solving them! Such tasks span the full spectrum from exasperating to fun, yet their outcomes influence the extent to which fieldwork objectives are met. A few approaches for mitigating gear and equipment failures include: (a) redundancy, in which multiple methods are planned - or equipment brought along - to accomplish the same task, (b) repair, usually requiring supplies and tools, and (c) substitution of a different piece of gear or a different approach.

During fieldwork on Quelccaya in July we were presented with an unusual number of equipment challenges, minor and major, solvable and not. Upon return we pondered, investigated, and resolved them in a variety of ways. Below are our 2013 gear challenges and their solutions or outcomes, in no particular order. In cases where the original manufacturer was contacted, note the variety of support (customer service) we received!

• After more than a decade of faithful service, a Black Diamond Gemini headlamp must have been damaged during travel, for it was unresponsive when needed the first night at base camp. Neither changing batteries nor disassembling it revealed the problem, which may have been a broken wire within the insulation. A spare headlamp was borrowed from one of our guides, and ironically the Gemini was found on within a duffel late in the trip. The headlamp continues to function fine, but has been replaced and is now relegated to use closer to home.
• An apparently faulty switch on one of the dual-frequency GPS receivers resulted in loss of some data from one of the base stations. This well-used unit has only LED lights to indicate functionality. Suspecting a potential power problem when the unit was deployed, we bypassed all connections between the GPS and power supply. This initially appeared to solve the problem, which we later learned did not. Although data were lost spanning several days, power was continuous through the most critical period when multiple base stations operated.
  
• Continuing with power problems, a "powergorilla" portable power supply station (Powertraveller, Ltd.) came along to supplement aging laptop batteries. Although the unit had worked well on several previous trips within the past 2 years, it appeared dead upon plugging in the laptop. Strangely, it appeared to take a charge just fine via a "solargorilla," yet when disconnected it had no power. Powertraveller was contacted about the problem and agreed to replace the unit, despite expiration of the warranty. A new powergorilla will power a laptop and recharge mobile phone batteries on Kilimanjaro, later this month!
• At the AWS, three problems developed in the year of autonomous operation. One was the complete failure of the transducer within one of the station's Campbell Scientific SR50 Sonic Ranging Sensors, a relatively uncommon event. These transducers are replaced annually, both to prevent such failures and to yield the cleanest possible measurements; without replacement however, the transducers sometimes last years. When one failed on Quelccaya in mid-May this year, 55 days before our field visit, almost all data were lost. This is why 2 sensors are used on all UMass stations, and replacement sensors with new transducers and desiccant are brought in each year, following careful lab testing. 
  
• A second sensor problem at the AWS involved one of the Rotronic MP101A temperature and humidity probes. This was not a new issue and the equipment is not to blame, but is likely due to a combination of the technology used, intermittent ventilation of the radiation shield, and a relatively humid environment during the Quelccaya wet season. The probe which develops problems has been housed within a radiation shield which is intermittently ventilated by fan (2 of every 10 minutes), and under certain conditions ice crystals are hypothesized to grow during ventilation and then melt during the subsequent unventilated 8 minutes. Despite microscopic analysis of several probes by both Rotronic and Vaisala - which clearly reveals damage to the thin-film polymer - the problem with the humidity sensor has never been satisfactorily explained. So, during this field season the probe and shield were both eliminated!
  
• The third AWS problem in 2013 was due to the fan motor on the shield referenced above, which allowed measurement of the fan revolutions. This ceased functioning at the end of March. The decision to remove the shield was not difficult, due to known radiation-loading errors with this shield design.
  
• A new batch of "harsh-environment" cable ties was purchased for this fieldwork, in an effort to economize on well-proven Tefzel ties. In every attempted installation, the tooth which allows only one-way motion immediately broke; they may have been a defective batch. McMaster-Carr promptly refunded the cost of these.
• To measure snowpit stratigraphy and sample depth, we have been using a Lufkin brand tape measure with a powerful spring to retract the tape into a housing. When blowing snow accumulated in the pit and buried the tape cartridge, a bit-too-much pulling caused the tape to detach, creating 8 meters of chaos. Replacing the tape was not possible in the field or lab, and an e-mail to Lufkin was unanswered.
  
• Lastly, at some point during travel to or from Cusco the airlines broke the frame of a Mountain Hardwear rolling duffel (Juggernaut) - one which had endured numerous prior trips. This has always been a crucial piece of luggage, as it offers more protection for items than a soft duffel and rolls exceptionally well. Mountain Hardwear inspected the break - which was considered unusual - and quickly provided a new Juggernaut.

For forthcoming fieldwork on Kilimanjaro we will be ready for breakages and failures, as always, but we are hoping for considerably fewer than at Quelccaya. After all, there are always other types of gear issues, such as forgetting and loosing things, even though we try to avoid these as well!

Preparing for fieldwork!

A component of our forthcoming 2013 fieldwork will involve high-accuracy GPS measurements, uploading data to Scripps for processing, downloading calculated coordinates, and then re-occupying dozens of points comprising a strain net on the glacier which was established and surveyed in 1983. In preparation, Dave Chadwell & Carsten Braun are in San Diego this week testing GPS receivers, a BGAN terminal, laptops, charging systems, and Iridium phones. Multiple redundancies will hopefully insure that things go smoothly on the ice cap!

Fieldwork photos

Photos from this year's fieldwork are in 3 different galleries:

1. At the summit our efforts were focused on the weather station (AWS), and in a snowpit as time permitted. Photos here. 
2. Working at an elevation of nearly 6,000 meters requires adapting to less oxygen (lower partial pressure), providing time to make other observations. Photos from travel to the ice cap and at the margin are here. For several locations - including outlet glacier Qori Kalis - photos from previous years have been mixed in to illustrate ice recession and thinning.
3. Among other observations possible while acclimatizing is documenting the elevation and habitats of various bird species living at this high elevation; the Quelccaya margin (~5,200 m or 17,000 ft) represents the upper end of most species' range. Photos of birds seen in 2012 are here (Additional Vilcanota birds can be seen here and here, or this link for more on Diuca speculifera.)

Please get in touch with any questions or comments!

AWS GigaPan

This image of the weather station is tiled composite which allows you to zoom in and explore the station in detail. In this case, 54 images from a robotic camera were stitched together to form a 43° field of view comprised of 24,128 x 12,048 pixels. GigaPan is a development of the Global Connection Project; read more and find links to images and equipment here, and click here or "GigaPan" on the image below to open a fullsize version in another tab.

The GigaPan page for this image has a series of "snapshots" which provide detail on each of the AWS components and sensors. If we missed any, please let us know!