2011 - Cooperative Institute for Research in Environmental Sciences ...

Earth Science and
Observation Center
CIRES’ Earth Science and Observation Center (ESOC)
provides a focus for the development and application of
modern remote-sensing techniques used in the research
of all aspects of Earth sciences at CU-Boulder. Our aim is
to work on all scales of problems, from technique development
in small test sites to understanding pattern and
process on regional and global scales. A long-term goal of
ESOC research is to investigate problems in global geosciences—questions
of global change, in particular—through
remote-sensing observations. ESOC had seven faculty
associates during FY11, 26 graduate students, eight post
docs and two visiting fellows. Below, ESOC accomplishments
and activities are summarized by topic.
Cryospheric Change
We continued to monitor the climate on the Greenland Ice
Sheet using 18 automatic weather stations and two permanent
research sites (Swiss Camp at the equilibrium line altitude
and Summit Station close to the highest point on the ice
sheet). This data set, initiated during the Program for Arctic
Regional Climate Assessment (PARCA) in 1995, is the longest
in situ meteorological time series capturing the recent climate
warming in the ice sheet. Decadal temperature increases
of 1.0°C in the fall; between 1.5 and 2.0°C in the summer
and spring; and up to 3°C in winter were measured on the
western slope of the ice sheet at Swiss Camp between 1995
and 2009. Other activities within ESOC’s cryospheric-change
research group include the development of an ice model to
study the englacial effect of meltwater, the development of a
glacio-hydrological model and the study of a moulin system
in the ablation region close to Swiss Camp. In the Southern
Hemisphere, we completed our second successful field
campaign on the Larsen C Ice Shelf in the Antarctic Peninsula
by monitoring the shelf-ice thickness using surface-based
ground-penetrating radar along a total of 500 km. We established
an advanced monitoring station at Summit Camp in
Greenland to link the isotopic composition, used to develop
long ice cores, to snow-formation processes and the surface
energy balance. This work uses state-of-the-art laser-imaging
spectrometers to measure the shape falling snow crystals
alongside the measurements of isotopic composition of vapor
to better understand the origin of the isotopic signals in ice
cores and, thereby, improve our understanding of the climate
history of the Greenland Ice Sheet.
Land Surface Effects on Climate
We continue to examine the impact of surface hydrology
on climate, particularly in the massively irrigated
regions of Asia, and have found evidence of substantial
impacts both in observational and model-simulation
studies. We have continued examining minimum tem-
66 CIRES Annual Report 2011
The southern lights at McMurdo, Antarctica.
ZHIBIN YU/CIRES
perature regulation by convection at high latitudes and
are proposing to extend this to maximum temperatures
in future work. We also have been looking into low-level
inversions in the western United States, which we found
to have substantially decreased over the period of record
in six Western cities. This is of interest because air quality
in the U.S. West is a function of inversion frequency and
strength, and because climate models have predicted that
inversions would be more frequent in a warming climate.
Ecology
Future disturbances to forest ecosystems are expected to
be of greater frequency, extent, intensity and variety as a result
of a changing climate. In addition, human-forest interactions
(e.g., forest management and wildland-urban interface)
will increase the complexity of disturbance impacts and forest
recovery. Our ongoing study of several catastrophic disturbances
in a northern Colorado subalpine forest is yielding
interesting insights into disturbance interactions and their
influence on the current and future landscape mosaic. Our
analyses of conifer seedling establishment patterns following
a stand-replacing fire in 2002 show a strong influence of prefire
disturbances (such as 1997 catastrophic blowdown and
salvage logging) on forest recovery rates. MODIS (Moderate-
Resolution Imaging Spectrometer) Normalized Difference
Vegetation Index time-series data indicate that these different
recovery patterns are evident at landscape scales. Importantly,
our recent studies suggest that satellite data can provide
regional information on forest response to disturbance, thus
assisting larger-scale efforts such as forest management and
regional-to-global ecological modeling.
Hydrology
A core hypothesis in a newly developing nonlinear geophysical
theory of floods says that solutions of conservation
equations in self-similar river networks exhibit spatial scaling
(power laws). Our analysis of 26 medium-size river basins
(about 3,000 km 2 ) confirmed the presence of self-similarity
in networks, thus supporting the hypothesis. This is the first
time the theory has been put to the test on medium-size