Sunday, December 8, 2013
And yet more snow!
Monday, November 25, 2013
More snow
Saturday, November 23, 2013
2013 Fieldwork Images
A gallery of images depicting our recent fieldwork is posted here.
(Viewing these requires the freely-available Adobe Flash Player web
browser plug-in, which usually works consistently across browsers
on a broad range of devices.)
The objectives of our work all pertain to climate and glacier research at the summit: recovering climate data from automated weather station instrumentation; inspecting, servicing, repairing and replacing equipment; and making both observations and measurements of the summit glaciers. However, other aspects of the fieldwork are disproportionately represented by the gallery - primarily because carrying out the research objectives requires staying alive and functional for several days at an elevation of 6,000 meters (19,000 feet). Doing this necessitates ascending slowly to allow both our bodies and those of our Tanzanian helpers to acclimatize (~6 days). Once on the summit glaciers we then become too busy and/or cold to spend much time taking photos!
For 2013 work - as the images illustrate - we began in Arusha, traveled to West Kilimanjaro, ascended the Lemosho Route, slept 3 nights at the summit, and descended via Millennium Camp to Mweka. Logistical support is required of all groups on the mountain, even with research permits, and ours was provided by SENE (Summit Expeditions and Nomadic Experience). This support allows us to maximize our time preparing for and carrying out the research.
As always, we would like to thank everyone at SENE for another safe and productive round of fieldwork - and for the two-way transfer of knowledge that characterizes these experiences. We would also like to acknowledge invaluable assistance from the staff at Tanzania Wildlife Research Institute (TAWIRI) who oversee and manage all wildlife and environmental research in Tanzania, the staff at Tanzania National Parks (TANAPA), and the many wardens and other staff at Kilimanjaro National Park. Asanteni!
The objectives of our work all pertain to climate and glacier research at the summit: recovering climate data from automated weather station instrumentation; inspecting, servicing, repairing and replacing equipment; and making both observations and measurements of the summit glaciers. However, other aspects of the fieldwork are disproportionately represented by the gallery - primarily because carrying out the research objectives requires staying alive and functional for several days at an elevation of 6,000 meters (19,000 feet). Doing this necessitates ascending slowly to allow both our bodies and those of our Tanzanian helpers to acclimatize (~6 days). Once on the summit glaciers we then become too busy and/or cold to spend much time taking photos!
For 2013 work - as the images illustrate - we began in Arusha, traveled to West Kilimanjaro, ascended the Lemosho Route, slept 3 nights at the summit, and descended via Millennium Camp to Mweka. Logistical support is required of all groups on the mountain, even with research permits, and ours was provided by SENE (Summit Expeditions and Nomadic Experience). This support allows us to maximize our time preparing for and carrying out the research.
As always, we would like to thank everyone at SENE for another safe and productive round of fieldwork - and for the two-way transfer of knowledge that characterizes these experiences. We would also like to acknowledge invaluable assistance from the staff at Tanzania Wildlife Research Institute (TAWIRI) who oversee and manage all wildlife and environmental research in Tanzania, the staff at Tanzania National Parks (TANAPA), and the many wardens and other staff at Kilimanjaro National Park. Asanteni!
Wednesday, November 20, 2013
Snow!
In an early-October entry I mentioned a late-September snowfall event which resulted in ~10 cm of accumulation on the Northern Ice Field, ending 4+ months of ablation. Prior to the September snow, surface albedo had dropped below 0.5 and net radiation receipt was increasing with the seasonal increase in solar irradiance.
Brightening of the glacier surface with the September snow prevented any further mass loss for at least 2 weeks. During this time the snow was transformed by melting and re-freezing to create the bright, icy surface we encountered upon our visit beginning 24 October, as shown in the photo above. Simultaneously, as demonstrated by other evidence, sublimation was removing some of the mass added by September snow.
The next snowfall occurred during our descent (27 October), although we received no rain low on the mountain and were not aware of the snow until the mountain emerged from clouds in the evening.
Today we received a note from Timba at Ahsante Tours & Safaris that more continuous precipitation has begun on the mountain, with fresh snow visible at the summit, and heavy rain occurring during afternoons at lower elevations. Our telemetry data confirm Timba's information, with higher humidity and snowfall especially during the interval 5-9 November. Snowfall was especially heavy on the Northern Ice Field late on 8 November into the next morning, with an average of 14 cm recorded by our 2 sensors. So the glacier-surface albedo has increased yet again, and this event may have been enough to bring thin snowcover to the crater.
As always, we welcome and encourage sharing of any photographs and/or snowcover observations!
Wednesday, November 6, 2013
Monthly weather synopsis
A monthly summary of summit weather has been available here for many years. Beginning with October 2013 the mean values for air temperature and relative humidity will be from a different sensor, and thus are not strictly comparable with those from prior months. Although the difference is likely to be only a few tenths of a degree, users should be aware of the change.
The reason for the change is that we decided to remove the fan-aspirated sensor during October fieldwork. The radiation shield housing this sensor had known systematic errors, and our technique of intermittent aspiration created additional problems. So, after 3 years of overlap with the CRN-compatible shield and sensors (T and RH), the time had come to remove this instrument.
The reason for the change is that we decided to remove the fan-aspirated sensor during October fieldwork. The radiation shield housing this sensor had known systematic errors, and our technique of intermittent aspiration created additional problems. So, after 3 years of overlap with the CRN-compatible shield and sensors (T and RH), the time had come to remove this instrument.
Friday, November 1, 2013
Fieldwork!
Fieldwork this year was conducted late - as the dry season to short-rains transition was underway. Conditions were dry and dusty on trails and in the caldera; relatively high wind speeds at temperatures below freezing made servicing the weather station difficult.
The images below provide an initial perspective on our 2013 work. Note the smooth, icy glacier surface which facilitated glacier travel and accurate ablation stake measurements, while requiring fixed ropes for those without crampons. Thanks to the hard-working crew of SENE (Summit Expeditions and Nomadic Experience) for helping us achieve our objectives while keeping everyone safe!
The images below provide an initial perspective on our 2013 work. Note the smooth, icy glacier surface which facilitated glacier travel and accurate ablation stake measurements, while requiring fixed ropes for those without crampons. Thanks to the hard-working crew of SENE (Summit Expeditions and Nomadic Experience) for helping us achieve our objectives while keeping everyone safe!
 |
| Ascending toward the southern glaciers; view to southwest |
 |
| Heading back to camp across the dry crater |
 |
| Ben enjoying the exceptionally flat surface of superimposed ice on the Northern Ice Field |
 |
| AWS serviced and ready to continue autonomous operation |
 |
| The October 2013 SENE team (w/o Doug; Ben barely visible) |
Wednesday, October 9, 2013
First snow accumulation since May
Telemetry from the Northern Ice Field shows a snowfall event last month, likely associated with the seasonal increase in humidity, the transition from dry
season to the short rains. This was the first noteworthy, accumulating
snow since early May.
Snow sensors indicate that the event began on 19 September and continued through the 27th. Averaging two series of measurements suggests 9-10 cm of accumulation. This snow isn't likely to persist, due to densification (settling) and ablation. The climate at this time of year remains quite dry and sunny, and several centimeters of surface lowering occurred on a single day, 5 October. Nonetheless, a 10 cm snowfall is sufficient to dramatically increase albedo and thus reduce the amount of solar radiation absorbed. The net effect is a reduction in the rate of ablation - for a period of perhaps weeks.
At the Northern Ice Field site where our measurements are concentrated, there has been effectively no net change in glacier thickness (mass balance) for 2 years; accumulation has balanced ablation. This will change if the 2013 short rains are delayed, as ablation can be rapid during October - November. We will visit the glaciers later this month, and are looking forward to seeing surface conditions and assessing the spatial variability of mass balance over the past year.
Snow sensors indicate that the event began on 19 September and continued through the 27th. Averaging two series of measurements suggests 9-10 cm of accumulation. This snow isn't likely to persist, due to densification (settling) and ablation. The climate at this time of year remains quite dry and sunny, and several centimeters of surface lowering occurred on a single day, 5 October. Nonetheless, a 10 cm snowfall is sufficient to dramatically increase albedo and thus reduce the amount of solar radiation absorbed. The net effect is a reduction in the rate of ablation - for a period of perhaps weeks.
At the Northern Ice Field site where our measurements are concentrated, there has been effectively no net change in glacier thickness (mass balance) for 2 years; accumulation has balanced ablation. This will change if the 2013 short rains are delayed, as ablation can be rapid during October - November. We will visit the glaciers later this month, and are looking forward to seeing surface conditions and assessing the spatial variability of mass balance over the past year.
Subscribe to:
Posts (Atom)
