Thursday, December 13, 2012

Ten years for the US Climate Reference Network

Congratulations to the USCRN program on the first decade of operations!

Some of the equipment on the UMass Kilimanjaro weather station is compatible with that of the U.S. Climate Reference Network (USCRN), which NOAA's National Climatic Data Center (NCDC) began 10 years ago. We chose to incorporate elements of their system at our site as a result of the extensive testing and characterization they carried out. A nice overview of all USCRN aspects and prospects is contained in the Early Online Release of a paper titled "U.S. Climate Reference Network after One Decade of Operations: Status and Assessment." The paper will appear in a future issue of the Bulletin of the American Meteorological Society, and is freely available now from this link.

To stay updated on further developments of the USCRN, follow NCDC on Twitter:  @NOAANCDC

Tuesday, November 13, 2012

Media communication: no margin for error

Yesterday, the website Live Science - a "trusted and provocative source for highly accessible science... news" - re-published scrambled elements of a NASA Earth Observatory article about Kilimanjaro glaciers. The result is anything but trustworthy, and provocative only in the sense that the information is confusing and only partially accurate. How did this happen?

The story begins innocently enough. Kimberly Casey from NASA Goddard Space Flight Center collaborated on recent Kilimanjaro fieldwork. We all enjoyed having her along, she adapted well to the altitude and proved physically strong, and at the summit she independently undertook a number of different measurements. Once back at Goddard, she took the initiative to request a new NASA EO-1 image of the mountain, which was acquired with perfect timing (see previous blog entry). With such a cool image, the Earth Observatory office reached out to her about featuring it as an Image of the Day. Great!

The EO article took shape over a couple days last week. Kimberly was provided with considerable information regarding what I, as project PI, felt was most important and valuable about the new satellite image, and this material was passed along to EO editors. Following one opportunity to review a draft, the article then went live:  Kilimanjaro's Shrinking Ice Fields.

To the credit of EO, the image provides a timely update on Kilimanjaro ice retreat. The text is interesting, and more-or-less consistent with published understandings. However, the article missed an opportunity to present evidence for recent and important changes in the pattern of ice extent, which we provided. Instead, the piece closes with an observation that the Northern Ice Field has (finally) divided into 2 parts -- a process underway since sometime between 1976 and 1989, and of no physical significance.

In summary, the concluding emphasis of the EO article is not what us as scientists felt was most noteworthy, but is instead an easy-to-grasp bit of trivia.

In the first 5 days, the article has had over 20,000 views. As a NASA product, the EO website has considerable credibility and deservedly so; EO images provide fascinating, timely glimpses of our dynamic planet.

Enter Live Science, a brand of the TechMediaNetwork. With a monthly visitation of 5.3 million and 250,000 FaceBook likes, one might expect the company to insure that their content is accurate and helpful. Apparently not though, for this new story is chock-full of mistakes and confusion. Indeed, the article mentions glaciers that do not even exist!

Most distressing about such over-simplified blurbs by Popular Media is that they confuse the public, while undermining the credibility of hard-working scientists eager to get their results disseminated accurately. In this case, with their large readership and the iconic status of Kilimanjaro, statements such as "The major cause of the ice loss is a matter of debate" are sure to fan the flames of climate-change denialism and obscure what we've learned about Kilimanjaro's glaciers in the past decade of observations, measurements and modeling. No, the proximal causes of ice loss on Kilimanjaro are not still in dispute; lack of snowfall is the problem!

For scientists, the message here is to insist that journalists get the details and the emphasis of your original story exactly correct. Thereafter, expect any errors, omissions, or ambiguities to propagate.

Anyone wishing to read an overview on Kilimanjaro glaciers can start here, and for a synopsis of a decade's worth of research this document will be essential; within it are all the references needed to better understand the processes and uncertainties.

- Doug Hardy

Thursday, November 8, 2012

Glacier images - September 2012

A visual update on the status of Kibo's glaciers is provided in this gallery of recent images. Although mass balance was slightly positive on most horizontal surfaces last year, their steep margins continue retreating.

Two additional GigaPans are also now posted. One provides a perspective on the Kersten Glacier upper margin, which is the view climbers to Uhuru Peak are most familiar with. The other is a wide-angle view of the Reusch Crater. These compliment 2012 GigaPans of the Furtwängler Glacier and Northern Ice Field.

In conjunction with these glacier images, have a look at a valuable new satellite image of the mountain. This was acquired by the Advanced Land Imager (ALI) on the EO-1 mission, just 4 weeks after our fieldwork, at the request of NASA collaborator Kimberly Casey. The timing of this acquisition is quite fortuitous, showing less seasonal snow present than during our fieldwork, yet prior to an early-November snowfall event as the Short Rains got underway.

Previous Earth Observatory stories illustrate patterns of decreasing ice extent, and this latest image reveals that the most dramatic changes are occurring on the south side. Compare, for example, this new image with the 2004 ISS image provided by EO here. Although the Northern Ice Field split has been underway since the 1980s, fragmentation of the Southern Ice Field has been most pronounced in the past year or two. Thanks to Kimberly for arranging acquisition of this latest satellite image!

Monday, November 5, 2012

Seasonal change

Kilimanjaro's extended dry season appears to be coming to a close, based on AWS measurements via telemetry. About 20 cm of horizontal glacier surface ablation occurred between the time of our fieldwork visit at the end of September, terminated by a couple days of snowfall on 11 and 12 October. This event brought ~6 cm of accumulation; after mid-October there was essentially no change in the surface height.

The monthly mean weather for October is available here. As expected going into November, mean air temperature is increasing, along with humidity. A snowfall event during the first few days of November suggests that the short rains will be underway soon.

Friday, October 26, 2012

AWS fieldwork images

A small selection of weather station images have been posted here, illustrating current instrumentation, the atmospheric conditions during fieldwork, and the glacier surface at the end of September. Mass balance for horizontal surfaces of the Northern Ice Field was positive this year (Oct. 2011 - Sept. 2012).

Additional fieldwork images will be posted soon. Credit for above photo:  K. Casey, NASA

Thursday, October 18, 2012

Furtwängler Glacier update

Furtwängler Glacier (foreground) and the Northern Ice Field on 27 September 2012, as seen from just west of Uhuru Peak. Although the mass balance on Furtwängler's horizontal surfaces was slightly positive for 2011/12, shrinkage of the glacier continues due to recession of the vertical walls.

Recent recession of the Furtwängler is well documented by annual GPS surveys. These reveal that although continuous, the rate of recession is not constant. For example, with an extended period of snowcover in the crater during the past year, area only decreased by ~3%. However, over the past 5 years, ice extent has decreased ~35%, and since the Feb. 2000 air photos renewed interest in Kilimanjaro's glaciers, 59% of the ice area has disappeared. In conjunction with ~6-7 meters of thinning since 2000, the loss of ice volume is considerably greater!

To view the Furtwängler Glacier in greater detail, two GigaPan panoramas are available. The western portion is here and embedded below, and clicking through will provide a link to another GigaPan of the eastern portion (also available here).

Wednesday, October 3, 2012

Five days at the summit

We are just back from fieldwork on the summit glaciers, concentrating on the Northern Ice Field. After 4 nights on top for some of us, we accomplished most of our objectives. Thermal imaging was unfortunately postponed yet again, due insufficient time for export control paperwork. Nonetheless, this was a fun group and everyone adapted well to the altitude. Fieldwork did present a few surprises which will be detailed later.

Below are a couple images from the trip. The first illustrates a small portion of the mountain's largest glacier, showing automated weather stations on the upper surface and our camp in the foreground. For late in September, considerable snowcover was present on the glacier and patchy elsewhere within the crater.

The lower image demonstrates why high-elevation observations are so valuable in helping to understand tropical, mid-tropospheric climate. The stratification visible in the image - sharp, spatially uniform, and persistent - is often present in northern Tanzania at a varying altitude. For reference, the distant peak (Mt. Meru) reaches over 4,500m -- and on this day was still not within the free atmosphere! Virtually all climate stations in the region are yet another 2,000 to 3,000m lower in elevation; they simply cannot accurately represent conditions high on the mountain. Two AWS currently operate on the Northern Ice Field, as shown. During this trip a 4-component net radiometer was added to the left-hand station, which will improve the accuracy of our radiation measurements. Also shown (within red circles) are 3 of the NIF ablation stakes, installed to help track gains and losses of mass at the glacier surface.

Saturday, September 8, 2012

August ablation - mostly

Ablation of the snow-covered Northern Ice Field during August proceeded more-or-less at the July pace, with a net surface lowering of ~20 cm. One small snowfall event on ~27 August (~3 cm) brightened the surface and retarded ablation for about a week. For the 11 months since our last fieldwork, ~40 cm of accumulation remains, which could result in a positive balance for 2011-12 at the AWS site.

We depart for fieldwork next week. One of our tasks will be to assess the spatial variability of last year's accumulation on the summit glaciers. This promises to be a fun trip, as we will be a group of 6 interesting people - representing 4 different countries - and accompanied by the-one-and-only Simon Mtuy. Discussions in the dining tent will likely continue each night until our teeth are chattering from the cold!

Sunday, August 12, 2012

Remembering Emmanuel Mtui

The Kilimanjaro community lost a kind person and a strong leader on July 31st, when Emmanuel Mtui was tragically killed in a vehicle accident on the Marangu-Rombo road. He lived in Mbahe, not far from Park Headquarters and the Marangu Gate, and leaves behind his wife and 5 children. Emmanuel worked for years as a Senior Guide at Summit Expeditions & Nomadic Experience (SENE). His leadership style was subtle, yet tremendously effective - orchestrating his trips almost as if by remote control. With pride, attention to detail, and a sense of humor, Emmanuel carefully looked after his staff and clients alike. He will be missed by all who had the good fortune to know him.

Anyone wishing to make a donation to Emmanuel's family may send a personal check made out to Summit Expeditions and Nomadic Experience with "Emmanuel Mtui" in the "for" line. The SENE US office is at: 1808 Riverside Ave S. Suite 208 Minneapolis, MN 55454. More photos of Emmanuel are posted here, and comments may be made on the SENE facebook page.

Friday, August 10, 2012

Summit snowcover - late July

Recent posts have detailed the extent of snowfall during the 2012 Long Rains, which included a couple atypical events during June. Below are some images from the summit taken at the very end of July, snowing snowcover on the crater rim and within the crater.  Imagine the effect of this snowcover on energy exchanges at the crater surface, when perhaps only 30% of the intense incoming solar radiation is absorbed rather than roughly 80% without snow. The effect on people climbing the mountain is likewise severe, exposing skin to radiation from all directions; big sunhats offer protection only from incoming sun!

These images were shot by Peter Greig during a reconnaissance climb for the project Wings Of Kilimanjaro (WoK). In early 2013 a large number of pilots will paraglide and hang-glide off the top while raising a substantial amount of money for Tanzanian charities. Additionally, their goal is to "reinforce the universal need for humanity, compassion and generosity inherent in all of us". More photos from the reconnaissance are available on facebook.

Image captions:
  1. late afternoon in the crater, with Uhuru Peak to the left and the Furtwängler Glacier to the right
  2. nearing Uhuru Peak, showing snowcover on the ridge above the southern glaciers
  3. morning within the crater, walking East between Furtwängler Glacier and the descent from Stella Point; note some topographic shading here
  4. looking North across the crater from high on Uhuru Peak; "crater camp" is visible in the foreground by the Furtwängler Glacier fragments, with the Northern Ice Field in the distance. At this time of year, when the sun is in the northern hemisphere, north-facing slopes such as those above crater camp are the first to become snow free.
Peter Greig photo, Wings Of Kilimanjaro

Peter Greig photo, Wings Of Kilimanjaro
Peter Greig photo, Wings Of Kilimanjaro
Peter Greig photo, Wings Of Kilimanjaro

Thursday, August 2, 2012

June & July weather

A summary of the previous month's weather at Kilimanjaro's summit is typically posted (here) within the first few days of each month. This year the June synopsis didn't make it in time, due to travel for other fieldwork. As usual though, the temperature fell slightly and the average humidity dropped relative to May, but two other reasons made the month noteworthy. First, June saw a net increase in the glacier surface height. Although the net change was only +4 cm, this was the first June in which accumulation was greater than ablation. In comparison - now that the dry season is underway - lowering during July amounted to ~16cm.

Also in June 2012, the daily maximum of incoming solar radiation was on average lower than in any month of the past 10 years. June irradiance is always relatively low of course, being at 3°S latitude, yet the new record this year is likely due to both greater cloud cover than normal - and to snow on the radiometer dome.

Thursday, July 5, 2012

June snowfall

Don't expect to see bare glacier ice on Kilimanjaro's glaciers anytime soon - at least not on horizontal surfaces at the summit. Higher than normal snowfall has continued into June, with ~7 cm accumulation on the Northern Ice Field June 9th and 10th and another event beginning June 22nd. Snowfall this late is quite unusual, as the long rains typically finish by the end of May.

For the glaciers, additional new snow will keep albedo high and reduce the absorption of incoming solar radiation. Less absorption will result in less ablation during the forthcoming dry season. No, this does not mean that recession of Kilimanjaro glaciers has ended; 2011-12 snowfall merely demonstrates the expected interannual variability (which our measurements seek to quantify and understand). For travel on the glaciers, the amount of accumulation since November (~75 cm) will likely result in extensive penitentes towards the end of the dry season (i.e., Sep - Oct).

Telemetry data from Kilimanjaro have been examined only to June 24th due to other fieldwork obligations. Stay tuned for an update towards the end of July!

Tuesday, June 5, 2012

A Fairy Tale comes true!

After more than 12 years of meteorological measurements on Kibo's Northern Ice Field, the most-recent period October through May has - for the first time - followed the expected pattern:  'short rains' during November and December, a brief dry interval into February, substantial and prolonged 'long rains' in March-April-May, and then commencement of an extended dry season by June. The figure above details this pattern through increases in glacier surface height (snowfall) as well as decreases (ablation).

Typically, only a June beginning of the dry season has been reliable, as noted in an entry yesterday. In some years Masika brings only minimal accumulation to the glaciers (e.g., 2001, 2005, 2009 or 2011), sometimes it is Vuli which fails (e.g., 2005 or 2010), sometimes Vuli snowfall exceeds that of Masika (e.g. 2006-07), and sometimes nearly-constant-yet-modest accumulation occurs from November to June (e.g., 2009-10).

Variability in the seasonal timing and magnitude of precipitation at Kilimanjaro's summit is the norm, despite an annual cycle of humidity which follows the 'expected' pattern rather closely. Both small- and large-scale aspects of atmospheric circulation modulate the humidity pattern and influence snowfall, and the timing and amount of snowfall is hugely important to glacier mass balance there. Documenting the inter-annual variability of precipitation on Kilimanjaro and measuring the impact on glaciers is why we keep the AWS going!

Monday, June 4, 2012

2012 dry season begins

One of the most consistent elements of climate on the Northern Ice Field has been cessation of Masika (long rains) by the beginning of June. This year was no exception, with accumulation of snow ending ~17 May. Another extended dry season has begun on Kilimanjaro.

Don't expect to see glacier ice exposed at the surface anytime soon however, as considerable snowfall occurred in the 6+ weeks prior. This followed a notable event in early March, and a snowy short rains (especially November). Indeed, there has been 75 cm of net snow accumulation on the glacier surface since early-October fieldwork! During the forthcoming dry season this clean, relatively-bright snowcover will reflect much more solar radiation than the underlying, decades-old ice surface would, effectively reducing ablation of horizontal surfaces. As a result, large areas of the glaciers are likely to remain snow covered through the dry season.

By September, penitentes could be well developed on the glaciers. Although both beautiful and fascinating, these will render glacier travel more difficult during September fieldwork.

Tuesday, May 15, 2012

More on April precipitation

"The rains this year began promptly on the 1st of April." So begins a column by Gareth Jones on 11 May, titled "Kenya:  Wet in the Wild" and published by AllAfrica Global Media.

At the summit of Kilimanjaro, seasonal precipitation in the form of snow began at exactly the same time, as the screen shot below illustrates. Four-hourly data by telemetry are shown here as circles, from 2 different sensors. The red line simply smooths out a diurnal cycle, and y-axes units are meters of snow accumulation.

If snowfall on the mountain continues through the rest of May, as the Kenya Meteorological Department is forecasting for rains to the north, the 2012 long rains will be one of the snowiest on the Northern Ice Field since our measurements began in 2000.

Tuesday, May 1, 2012

Snowy, calm April 2012

 Snowfall continued through the final week of April, bringing total accumulation to 44 cm. This is the most snow for any April since our records began in 2000. Humidity was high, incoming solar radiation was low, and April 2012 established a new record for the lowest mean monthly wind speed, at only 10.2 km/hr! All monthly values are provided here.
[UPDATE 5/7: The photo above was taken on 1 May, clearly illustrating the late-April snow (courtesy Simon Mtuy).]

Saturday, April 28, 2012

Archival video

Here is a clip produced by New York Times Science Times. The feature was filmed in June 2001 for broadcast on the National Geographic Channel, and recently turned up on YouTube. Director of Photography John Hazard was fun to have along, joining Georg Kaser, Tharsis Hyera, Erick Masawe and others!

Wednesday, April 25, 2012

Snowy April

As of yesterday, 30 cm of snow has accumulated on the Northern Ice Field this month. Not since 2006 has there been this much during April.

Any photographs of snowcover in the crater or at the summit would be appreciated!

 [UPDATE 5/1:  See above... snowfall continued.]

Wednesday, April 4, 2012

6 March snowfall

For the month of March, telemetry data indicate net snow accumulation of a paltry 2.7 cm. However, a detailed examination reveals a more interesting situation.

Telemetry shows only 2 snowfall events occurring at the summit during March. Establishing the magnitude of snowfall from telemetry data is sometimes tricky because: 1) telemetry data are only 4-hourly, 2) measurements by the 2 acoustic sensors often differ due spatial variability of accumulation, and 3) acoustic sensors sometimes yield noisy data during snowfall events. However, for the event on 6 March both acoustic sensors recorded 15-20 cm of accumulation, placing this event among the top 3 in the one-day snowfall rankings since 2000. More typically, snowfall events tend to occur over longer time periods.

The weather on 6 March contrasts sharply with that of other days last month. For example, the 4 AM and 8 AM 4-hourly mean values of temperature and humidity were the highest for both times during the month, suggesting cloud cover and moisture advection. Likewise, the temperature at noon was the lowest for any day of the month, humidity was the second highest, and 12 PM minima of both incoming and reflected solar irradiance were recorded.

Through the balance of March, lowering of the glacier surface was nearly linear, suggesting a near-constant, combined rate of ~7mm/day for settling, sublimation and melt.

Sunday, March 18, 2012

February weather variability

Below are four sets of graphs and time-lapse video clips which illustrate the interannual variability of weather and snowcover at Kilimanjaro summit during February. The graph shows the average change in snow or ice surface height on the Northern Ice Field (black line) and that relative to a height datum on January 31st for the year illustrated (in color). The video provides a daily view of the glacier, crater, and Uhuru Peak - in addition to the weather each morning through the month.

To see the camera system installation, click here, or here for an annotation of what the scene illustrates.

February 2006, with images from 10:58 AM each day:

February 2007, with images from 10:19 AM each day. The month began with the greatest crater snow depth of the decade:

February 2008, with images from 12:24 AM each day:

February 2010 (partial), with images from 10:02 AM each day:

Wednesday, February 29, 2012

Seasonal change

Most years, there is a short dry season on the mountain in between the short and long rains, typically centered on February. In addition to lower humidity, this interval is identifiable in AWS measurements as lowering of the glacier surface, due to both ablation and settling of any snow accumulating during the short rains.

This year the Northern Ice Field surface began lowering on 31 December and continued until 19 February, dropping a total of 27 cm. Very little if any snowfall occurred during this interval. Then, 3 days of meager snowfall suggested that a seasonal change was beginning. Precipitation began accumulating again on the 25th, and by the 27th it appears that a more significant snowfall was underway. However, this is our most recent telemetry. Stay tuned to learn whether the long rains are beginning a bit early this year.

Wednesday, February 8, 2012

January ablation

The 2011 short rains on Kilimanjaro summit continued until the very end of December, with most snowfall occurring during the second half of November. For the season, net snow accumulation on the Northern Ice Field amounted to ~30 cm.

The image above shows an easterly view across the crater on 28 December, just prior to the year’s final snowfall event; snowcover in the crater is often “patchier” than that on the glaciers (credit:  Rohun Gholkar). On the graph, the timing of this photograph is indicated by the light blue star. After departing the summit, Rohun’s team encountered sleet and rain, which was likely associated with 3 days and ~10 cm of snowfall on the glacier (see graph; dashed line indicates midnight on New Year’s Eve).

Very little snowfall occurred during January 2012, as shown in the lower figure, resulting in a net surface height lowering of 19 cm. Two 48-hour intervals of rapid lowering are highlighted by red lines on the graph. Based on weather station measurements received by satellite telemetry, these seem to have been intervals of enhanced sublimation. We cannot be certain, but this interpretation is based on the following, which pertains to both intervals:  air temperature was 2.0 – 2.5° C lower than normal for January, the sky remained mostly clear, wind speed was ~50% higher than normal (directly from the east), and relative humidity averaged a very low 20-25% instead of ~60% as on a typical January day. Together, these are perfect conditions for sublimation.

Any first-hand observations and/or photos from the summit area during these dry intervals (Jan. 1 & 2, Jan. 22 & 23) would be greatly appreciated!