Asa Rennermalm
Posted: Dec 8, 2008
I am giving two talks at the American Geophysical Union Fall meeting in San Francisco this December. First, I am giving an invited talk on Monday, December 15 in Moscone West 3016 at noon. The title of this talk is: The Influence of Hydrologic Variability on Peatland Dynamics. Second, I am giving a talk on Friday, December 19 in Moscone West 2006 at 3.25pm. The title of this talk is: Local sea-ice influence on Greenland surface melt.
Posted: Dec 8, 2008
The UCLA Writing group is in full swing. We meet bi-weekly on Fridays at 2pm. Send me an email if you want to join us. The week before AGU we will be discussing our AGU posters and presentations. Colin Purrington at Swarthmore has made a great website with tips on how to make an effective poster presentation (find it here).
Posted: Dec 8, 2008
Ellen Mosely-Thompson gave a talk at UCLA Geography on November 5. She and her research group at Ohio State University, the Ice core paleoclimatology group, reconstruct earth's climate history by collecting and analyzing ice cores from glaciers and ice sheet from all over the world. They have made some remarkable findings. For example, although global warming is expected to first be noticed in the high northern latitudes, global warming can already be detected in tropical glaciers (read more here). Furthermore, a Himalayan glacier at very high elevation has not accumulated mass since the 1950's (read more here). Thus, tropical glaciers seem to be affected by global warming, and the fact that Himalayan high elevation glaciers are losing mass is of great concern because x million people depend on the water from this region.
Posted: August 26, 2008
In recent years the Greenland ice-sheet melt has accelerated. Further acceleration of ice-sheet melt could increase global sea levels with huge global socio-economic costs. However, it is unknown how much of the melt water from the Greenland ice-sheet reaches the ocean. To help quantify how much melt water that reaches the ocean, myself, Vena Chu, and Professors Laurence Smith and Rick Forester has established field observations of river discharge in the Kangerlussuaq area on Greenland's south west coast this summer. We hope our measurements will further the understanding of Greenland's present and future role in governing global sea levels.
Posted: Saturday, June 14, 2008
I got hooded in Princeton on June 2, and was awarded my PhD degree in latin by the always inspirational University president Shirley Tilghman on June 3. Good times.
Posted: Saturday, June 14, 2008
Steve Frolking from University of New Hampshire gave at the UCLA Geography Department on Friday May 16. Frolking studies peatland, which is a carbon rich ecosystem that is widespread in the high northern latitudes. The processes controlling uptake and release of greenhouse gases from these ecosystems are highly temperature dependent, and could possibly enhance future anthropogenic warming. However, the climate impact of peatland greenhouse gas release is dependent on the relative importance of two greenhouse gases, carbon dioxide and methane. Frolking developed a model to evaluate the climate impact from peatland exchange of carbon dioxide and methane. While the future climate impact of peatlands in unknown, Frolking showed in his talk that historically these ecosystems have acted as a net cooler on the global climate.
Posted: Saturday, June 14, 2008
During the week May 4-12 I participated in a symposium called "New Generation Polar Researchers". At the symposium about 30 early career scientists working on polar topics were present. We discussed our research, how to conduct outreach, deal with media, and the past, present and future of polar research. The best thing besides meeting the other early career scientist was the interactions with the ~10 mentors. The mentors had experience from both inside and outside academia and were generous in sharing their thoughts and advice. The symposium was held at La Foret in Colorado Springs - a very nice place.
Posted: Saturday, June 14, 2008
Between April 14-18 the European Geoscience Union (EGU) had its annual meeting in Vienna. I was awarded a conference fee waiver to attend the meeting to present my work about hydrologic variability and peatland functioning. The EGU meeting, just like the American Geophysical Union's annual meeting, are always great fun and interesting. Thousands of scientist from all over the worlds participate in discussion about everthing between heaven and earth and beyond.
Posted: Wednesday, May 21, 2008
I spent the summers of 1998 and 1999 at Zackenberg research station in North East Greenland. There I did field work quantifying the exchange of greenhouse gases between the tundra and the atmosphere. That work is presented in my master thesis and in this paper. Recently a book in Advances of Ecological Research book series came out that synthesizes the research that has been made at Zackenberg since the start in 1995. In this issue, my work is featured in a synthesis paper by Louise Groendal and others.(paper is here). Check it out.
Posted: Thursday, March 27, 2008
On March 25 I attended a talk organized by the UCLA Society of Postdoctoral Scholars on how to improve academic productivity and writing. The talk was give by Gina Hiatt from Academic Ladder. Her talk was very inspiring. She pointed out common misconceptions about academic writing such as: long time blocks is needed, and that you have to be in the mood to write. She also presented strategies to improve academic writing productivity. For example, write regularly, write in short sessions, use a timer and take breaks.
Posted: Thursday, March 27, 2008
March 16 to18 I attended a workhop of the NEESPI Focus Research Center for Biogeochemical Cycles at the Max-Planck Insititute for Biogeochemistry in Jena, Germany. Northern Eurasia is undergoing large scale changes potentially in response to global warming. These changes could trigger feedbacks with global and regional implications (find an example on how Eurasian snow extent anomalies influence the hydrology of eastern Canada here). At the workshop we discussed what we know, and don't know about biogeochemical cycles in Northern Eurasia, and what research areas we should pursue.
Posted: Tuesday, March 4
Dar Roberts, professor of geography at UC Santa Barbara, gave a talk at UCLA on March 4th about remote sensing of urban environments. Urban environments around the world are experiencing rapid development. The rapid change quickly outdates maps of urban land cover types. To produces current urban maps Dar Roberts uses remotely sensed data. By combining high resolution hyper spectral (AVRIS) and high resolution elevation data (LIDAR) his group is able to distinguish between different types of urban land surface types such as roads, roofs, vegetated, and bare soil surfaces. His group is also able to map different types of roof material. Such information may be used to locate houses with wood shingle roofs, which may be useful for urban fire mitigation since wood shingle roofs are prone to spread fires.
Posted: Tuesday, March 4
I gave a talk at the UCLA Geography Department EOS seminar series on Monday February 25th. My talk was titled : Pan- arctic change; trends in 20th century cold season river discharge". I showed that most of the 20th century pan-arctic (high northern latitudes), with the exception of late 20th century eastern Canada, is dominated by increasing cold-season river discharge. I speculate that the increase could be due to earlier timing of spring, and/or thickening of the snow pack which results in soil warming. Although the increased river discharge is modest in terms of volume of water, it indicates that the soil hydrology of the pan-arctic is in transition and taking place over large scales.
Posted: Friday, February 22
Today I received my PhD diploma from Princeton.
Posted: Friday, February 22
In south west USA a large fraction of the water supply come from snow spring melt. Water from snow melt fills up water reservoirs that are managed to provide water throughout the year. In the late 20th century water management is complicated by trends of earlier snow melt. While the earlier snow melt may be caused by global warming, the earlier snow melt may also be influenced by increased dust deposition. At a talk at the UCLA Geography department on February 8th, Thomas Painter from University of Utah presented research showing how enhanced dust deposition in the 20th century has shifted snow melt with about a month. Although enhanced dust deposition might be driven by global warming, dust deposition is also highly dependent on land use practices.
Posted: Tuesday, January 29
On January 29 Paul Levin gave a talk at the Geography Department about rainfall-runoff modeling. These models can predict river discharge from watersheds using inputs of precipitation, which is especially useful for watershed without gauges for river discharge measurements. However, the model needs parameters, and these tend to be calibrated for watershed with gauges by using river discharge measurements. This is not possible in ungauged basins, therefore, techniques has been developed to estimate parameters in ungauged basins. Paul presented how model parameters for ungauged basins can be estimated by using the model parameters from surrounding gauged basins.
Posted: Tuesday, January 29
At the AGU Fall meeting in San Francisco I presented the talk "Hydrologic Variability and its Influence on Peatland Dynamics".
Posted: Tuesday, January 29
After many wonderful years in Princeton I have moved to Los Angeles. I am now working as a postdoctoral scholar at UCLA. I am working with Professor Larry Smith at the Geography Department. My research topics are still related to Arctic hydroclimatology, but with a stronger focus on Greenland.
Posted: Tuesday, January 29
I attended a workshop at IARC in Fairbanks Alaska lead by IARC Jessie Cherry. The topic was Eurasian hydroclimatology, and the goal to understand trends and what causes these trends.
Posted: Tuesday, January 29
On November 5 I successfully defended my thesis "Pan-arctic land surface hydrology: patterns of change and global implication".
Posted: Thursday, October 11
A fellow CEE student, Sujata Ray defended her thesis on October 5th and was awarded the Ph.D degree. She studied the stress response of microbes at a metabolic level. Her work shows that microbes exposed to high stress multiple times develop resilience to stress. Her findings are useful for waste-water treatment-plant managers who use microbes to clean water.
Posted: Thursday, October 11
Snow depth information is desirable for water management, and for climate change assessment. However, snow depth measurements are sparse. In contrast satellite provides data of snow extent and snow grain size with great spatial coverage. Steve Margulies at UCLA gave a talk on September 28th where he described how he combines information from satellites with land surface hydrology modeling to estimate snow depth.
Posted: Friday, August 10
Fellow CEE Ph.d Student Alexandros Ntelekos work on thunderstorms is being featured on
Eureka News Alert. His work shows that the structures of a city enhance atmospheric turbulence. Enhanced turbulence can trigger the thunderstorm's massive rainfall. Compared to rural and natural areas, rainstorms in urban area have severe consequences. Flash floods and flooding are more frequent where there are urban structures such as pavements and bridges, and can result in massive damages and loss of life. It is ironical that cities, which may suffer severely from rainstorms, also may enhance the formation of the same rainstorms.
Posted: Saturday, August 4
I have written a paper examining the AMOC (Atlantic Meridional Overturning Circulation) sensitivity to river discharge into Hudson Bay and the Arctic Ocean. The paper is accepted to be part of a special issue on the Arctic freshwater budget in the Journal of Geophysical Research - Biogeoscience. Currently, the paper is in press. Find the latest version here. It will probably take some time before it gets in print because all the paper for the special issue has to get through the reviews.
Posted: Monday June 25
Over the summer, Me and Kate, Sujata and RE are meeting weekly to give feedback on our manuscripts. Anyone in the EEWR program or related field is welcome to join us. Contact me if you are interested.
Thursday June 7
Check out BBC's coverage of climate change, and how global warming may affect the different continents, water, ecosystem and food supplies. Are scientist being to cautious about their predictions of consequences of climate change? James Hansen from NASA thinks so. In a recent paper he writes: "Concern about the danger of `crying wolf' is more immediate than concern about the danger of `fiddling while Rome burns'". Is Rome burning?
Wednesday June 6
To mark the national day of my home country Sweden I will take the opportunity to present some of the interesting Swedish scientists and explorers. Carl von Linne (Linneaus) who laid the foundations for the present system of naming, and classifying organisms. Svante Arrhenius who came up with the idea that atmospheric carbon dioxide concentrations could influence the earth's surface temperature through a greenhouse effect. Salomon August Andre who in 1897 tried to travel to the North Pole with a hot air balloon and paid with his life as many of the early polar explorers.
Wednesday May 23 - Thursday May 24
I got a student travel award to attended the ARCUS Annual Meeting and the Arctic Forum in Washington D.C. I presented the poster "Identification of dominant pan Arctic river discharge trends". Two days of interesting talks covered topics as diverse as greenhouse gas release from the Arctic landscape to the form and function of the narwhal tooth. More information about the meeting is here.
Tuesday May 15, 2007
Professor Andrea Rinaldo from University of Padova gave a talk about scaling in nature. He is trying to understand how nature works on a very fundamental level. Many complex systems in nature show power law behavior. For example: ecosystems population density is a function of population body mass raised to a power. Such power law behavior indicate that the system is self organizing, which implies that if we knew the governing equations at any scale they could be applied at all scales (analog to Hamilton's equations). Of course...we don't know these equations, but there are other discoveries to be made...
In a recent paper professor Rinaldo and collaborators show how a set of different ecological power-law relationship commonly treated as independent in fact are dependent. They were also able to derive the ideal value for the power law exponents. Their values exactly match empirical observations!
Friday May 4, 2007
Robert Harley from Berkeley gave a talk about Sustainable Transportation. His group is performing in situ measurements of automobile emissions at highway tunnel in the Bay area. Part of the tunnel system only allows personal vehicles, as a consequence the emissions contributions from personal vehicles can be separated out from that of truck vehicles. Robert suggested that main problem with automobile emissions comes from few high emitting vehicles. The high emitting vehicles have increased their share of emissions. In 1997 10% of the cars emitted ~50% of the CO2 emission. In 2006 10% of the cars emitted ~70% of the CO2 emissions. These cars should theoretically be caught by vehicles inspections, but the owners of these cars slip through the cracks by registering their car elsewhere, doing quick fix repairs etc. Robert was skeptical about the potential of corn based ethanol as an alternative fuel. Corn requires a lot of agricultural land. and the use of corn for fuel directly compete with the use of corn for food. Furthermore, compared to petroleum corn based ethanol has lower fuel efficiency, requires more energy to produce and contributes with as much greenhouse gases (read more here). It seems as the strongest argument for using corn based ethanol instead of petroleum is reduced the US dependence on foreign fuel imports. More thoughts on biofuels are here.
Tuesday May 1, 2007
I went to a great colloquium featuring a few short presentations by faculty members. Professor Ingrid Daubechies, the woman behind wavelets, introduced us to her recent work of analyzing spatial patterns in fMRI scans.
Professor Fei-Fei talked about how humans create meaning of the visual world, and her work of trying to describe that quantitively. Check out this recent paper in PNAS that brings us one step closer to making the blind see!
Professor Claire Gmachl talked about the MIRTHE project that aims to develop mid-infra red lasers for monitoring indicators of individual health and the state of the environment. Mid infra red lasers are particularly suitable for measuring concentration of compounds that are in gaseous form in room temperature. It turns out that the absorptivity of most room temperature gases is strongest in the mid infra red spectrum. Cascading quantum lasers is the tool to do the measurement with. Challenges with the developing this technology are to figure out what materials to use, how to layer the material, and finally how to shape the material into lasers.
Professor Olga Troyanskaya described her work to help making meaning out of descriptive genome data. This type of data is piling up in huge amounts with out us getting much wiser about the functioning of genomes. Her group has done some very exciting work. For example they have come up with hypothesis of protein function that was later shown to be correct.
President of Princeton University Shirley Tilghman also came by the colloquium. She contrasted the evolution of her field, molecular biology, with that of computer science. The two fields show many similarities, they emerged after the Second World War from established disciplines etc.. However, molecular biology has a lot more women scientist than computer science. In fact, the number of graduating women in computer science has fallen from 1984 to 2005 (more info here). This is a big problem because US companies have to look abroad for people with computational skills. If women and minorities could fill the people deficit lots of money and resources could be saved. Why are there so few women in the computational sciences? The colloquium participants were not sure, but a common feeling was that many women may benefit from mentoring and encouragement to get the confidence to tackle computational science. An interesting perspective on the issue of gender in science can be found in this paper by Ben Barres. Ben has a unique perspective since he, as a transgender person, has seen it from both sides. Read his paper today!
Monday April 30, 2007
I went to a talk by Wolfang Kinzelbach from the Swiss Federal Institute of Technology in Zurich titled "Sustainable Water Management in the Yanqi Basin, China". The Yanqi basin has some of the best agricultural lands in China thanks to the irrigation provided by the Kaidu river. Extraction of river water for irrigation has had several bad consequences in the Yanqi region. Irrigation has lead to elevated groundwater levels leading to soil salinization, which ultimately may result in irreversible loss of soil fertility. The reduced river discharge into the Bostan sea has lowered the sea level and increased the lake salinity, as a consequence fish die off. Further down stream, the river Kongque has dried up and threaten the forest in the Konque river basins. This forest is important in stabilizing the land which eases keeping the roads Yanqi open.
Wolfgang and his research group investigated if the Yanqi’s water resources could be managed more sustainable by building a surface ground water model. They found that extracting part of the irrigation water from the ground water instead of river water, and applying drip irrigation would improve the situation. However, using ground water is costly and will probably not be feasible unless food prices go up. Food prices have tended to fall leaving the future of the Yanqi basin uncertain.
Thursday, April 26, 2007
Trenton Franz, a fellow graduate student, defended his Master thesis today. He has been studying the Ecohydrology of the Upper Ewaso Nigro Basin in Kenya. This region of the world has limited water resources. Further strain of the water is expected in the future due to climate change and population growth. Among other things, Trenton showed that the 20th century low river flows have decreased. If this trend continues it may severely limit the livelihood of the local population. Stay tuned for more research..Trenton is continuing his work at a Ph.D student in the CEE department.
Monday April 23, 2007
I attended a workshop on the use of Arc GIS model builder and scripts lead by Princeton's grandmasters of Geographic Information System (GIS): Bill Guthe and Wangyal Shawa. The things you can do with ArcGIS these days! Great GIS resources can be found at the Digital Map and Geospatial Information Center/
Monday April 23, 2007
Fellow graduate student Chot had his Final Public Oral examination. He gave the talk: "Biodiversity in River Networks: Theoretical and Empirical Perspectives" and now have the honorable tite Dr. Muneepeerakul! Biodiversity pattern along rivers are strongly controlled by the structure and directionality set by river networks. Read more here.
Thursday April 19, 2007
I am attending a six weeks course in scientific writing offered by the Princeton Writing Program and taught by Dr. Judith Swan. Dr. Swan is an exceptional teacher! I recommend her courses to everyone.
Wednesday April 11, 2007:
I attended a talk by Stephen Long, professor in Plant Biology & Crop Sciences at University of Illinois at the Princeton Environmental Institute. In his talk, Dr. Long presented how the crop Miscanthus could be attractive for biofuel production. Biofuel is an alternative to conventional fossil fuel. However, biofuel production needs biomass input that may compete with food production. The crop Miscanthus is favorable compared to other biofuels plants because of its high yield, thus requiring less land. Recently, I read a paper by Tilman et al. that shows how Low-impact-high-diversity also is an attractive biofuel crop because it is carbon neutral and can be grown without nitrogen fertilization. Either of these methods could probably take care of one of Pacala and Socolow's wedges. The future is saved! At present it seems as the bottle neck problem with biofuel is to efficiently break down the lignin and cellulose from the biofuel plans.
04.19.07:I gave a talk at University of New Hampshire at the Institute for the study of Earth, Ocean and Space. The talk was titled: Arctic land surface hydrology and global climate.
04.04.07: I gave a talk at Dennis Lettenmaier’s Land surface hydrology group at University of Washington. My talk was titled: Seeking dominant patterns in high latitude river discharge.
04.02.07:I attended the Arctic System Synthesis Workshop: Overview New Perspectives through Data Discovery and Modeling that took place in Seattle April 2-4.
03.14.07:Attended a talk by Miroslav Dudik, Princeton University, on estimating specices distribution with maximum entropy method. The methods compares favorably to other methods that predict species distribution when you are limited by only having a few and biased samples.
03.13.07: Attended a talk by John Albertson, Duke University. He presented his work in the water limited ecosystems of Southern Africa. It turns out that drought recovery of grasses is dependent on the amount of woody biomass. If a regime has low precipitation and large woody biomass grasses may not recover after drought. Read more here.
02.27.07: Attended a talk by Victor Li, University of Michigan, about sustainable infrastructure engineering. A very interesting talk. America's infrastructure is in decay. Long term/life cycle perspective and on green materials are necessary. There is such a thing as "bendable" concrete!
01.09.07: Volunteered as a judge in the New Jersey's Science Olympiad Regional Tournament for middle school students. I judged the Awesome Aquifer competition designed to teach groundwater hydrology concepts
12.11.06: I gave the talk "Regional Patterns of Trends and Multi-decadal Variability in Pan Arctic River Runoff" at the American Geophysical Union's fall meeting in San Francisco, 11 - 15 December, in the Union Session: "Polar Regions: Past, Present, and Future Changes and Synthesis of Their Role in the Modern Earth System"
11.17.06: Attended part of the conference Food, ethics and the environment at Princeton University
11.15.06: Attended Professor Brian Kernighan's workshop "Good Programming Practices in Scientific Computing" offered by Picasso.
10.27.06: The symposium "Towards an environmental balance" took place. Organized by me, Sarah, Kate and Junu.
10.23.06: I gave the talk "Peatland dynamics" at the meeting between students from Princeton University and Bergen University
10.20.06: I gave the talk "Arctic land surface hydrology and global climate" at the CEE's Brownbag seminar.