Research Highlights


GRACE Arctic Water Mass Changes  - R. Muskett
GRACE
We are processing geoid data from the joint NASA-German Aerospace Center Gravity Recovery and Climate Experiment (GRACE) mission for terrestrial and ocean water mass changes. Click here for more information. The revolving GRACE Geoid 01 is courtesy of the Center for Space Research, Univ. of Texas Austin.

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SeaWiFS+MODIS chlorophyll-a cocentration in the Arctic/Subarctic Seas  - K. Mizobata
Click to activate Google Earth
The NASA Godard Space Flight Center Ocean Color team recenlty released sea surface chlorophyll-a (Chl-a) images derived from ocean color sensors (the SeaWiFS and MODIS;http://seadas.gsfc.nasa.gov/). Here you can see chl-a images using Google Earth (before browsing, you need to install Google Earth!).

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Net ecosystem productivity over Alaska black spruce forests  - M.Ueyama

We evaluated gross primary production (GPP), net ecosystem productivity (NPP), and autotrophic respiration over Alaska black spruce forests by combining a field-observed dataset and a newly developed satellite-based model. A three-year continuous dataset derived from the eddy covariance technique at a black spruce forest was used to link the MODIS products of NDVI and land surface temperature (LST) to the tower-based GPP. In order to determine NPP and autotrophic respiration (RES), BIOME-BGC was tuned and validated for Alaska black spruce forests. Using simulation results from a sensitivity analysis, ratios, NPP/GPP and RES/GPP, were determined as functions of LST, and then applied to calculate NPP and RES.

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A terrain corrected ERS-1/2 mosaic SAR backscatter image - R.Muskett
The image on the left is a terrain corrected ERS-1/2 C-band SAR mosaic of the Bering, Malaspina Glacier systems and the glaciers of Icy Bay, south-central Alaska. The SAR images were acquired in the summer of 1995. The calibrated sigma-0 values have been scaled in an 8-bit range with a color table applied. The sigma-0 values correspond to surface roughness and changes in the material dielectric constant.
The colors as seen correspond closely to C-band SAR glacier facies. 
Dark orange is the glacier ice faciers and blue colors are the
wet snow / firn facies.

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Low chl-a area in the western Arctic Ocean (Chukchi/Beaufort Seas) - K.Mizobata
Since 2002, extremely low chl-a has been idintified by using SeaWiFS MLAC dataset. This low chl-a is probably related to the Pacific Summer Water. Now we are investigating the ice-ocean circulation and phytoplankton dynamics in the western Arctic Ocean by using the Coupled Ice-Ocean Model and satellite dataset (SeaWiFS chl-a and MODIS SST).
See also IARC Arctic Modeling Group website

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Hokkaido University Oshoro-maru cruise in the Bering Sea 2006 - K.Mizobata
From June 21-28, Hokkaido University Training Ship Oshoro-maru conducted summer hydrographic survey in the Bering Sea. Our observation covered the southeastern continental shelf and a part of the basin area.
A cruise report is here.


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Eddy field and Primary productivity in the Bering Sea shelf break - K.Mizobata
A left figure shows the 2003 summer primary productivity (PP) in the Bering Sea derived from AVHRR sea surface temperature, SeaWiFS chlorophyll-a and SeaWiFS PAR. The interannual variability of PP in the Bering Sea shelf break area is consistent with the variability of mesoscale eddy field (Mizobata and Saitoh, 2004). Mesoscale eddies along the shelf break 1) contributes on-shelf nutrient flux resulting the high primary productivity at the shelf break and 2) transport the high productive waters to offshore (Mizobata et al.
accepted to JGR-Ocean; Mizobata et al. submitted to DSR-2).

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High productive area along the Bering Sea shelf break - K.Mizobata
Towed CTD (Conductivity, Temperature and Depth sensor) observation were carried outby the Hokkaido University Training Ship Oshoro-maru in the Bering Sea in 2003 July (Mizobata et al., submitted to DSR2). High fluorescence area were found from 200m to 1000m isobaths (i.e., shelf break area) in the surface layer. We visulalized 3-D isotherms (5-7oC) and high fluorescence water using AVS/Express (left, gary:Bathymetry, 4 cross sections:fuluorescence). Left 3-D image allows us to infer that vertical structure of high fluorescence is determined by the thermocline structure.

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