seawifs views smoke plumes from fires around sydney, australia gene feldman nasa goddard space...
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SeaWiFS Views Smoke Plumes from Fires Around Sydney, Australia
Gene FeldmanNASA Goddard Space Flight Center, Laboratory for Hydrospheric Processes, [email protected]
The smoke plumes from numerous fires surrounding Sydney, Australia— clearly seen in this image—have been sending vast quantities of smoke into the skies over the Pacific Ocean.
SeaWiFS Views Smoke Plumes from FiresAround Sydney, Australia
Sydney
January 2, 2002
Tracking the SeaWiFS Record with a Coupled Physical/Biogeochemical/Radiative Model of the Global Oceans
Watson W. GreggNASA Goddard Space Flight Center, Laboratory for Hydrospheric Processes, [email protected] The Sea-Viewing Wide Field-of-view Sensor (SeaWiFS) has observed multiple years of routine global chlorophyll observations from space. The mission was launched into a record El Niño event, which eventually gave way to one of the most intense and longest-lasting La Niña events ever recorded. The SeaWiFS chlorophyll record captured the response of ocean phytoplankton to these significant events in the tropical Indo-Pacific basins, but also indicated significant interannual variability unrelated to the El Niño/La Niña events. This included large variability in the North Atlantic and Pacific basins, in the North Central and equatorial Atlantic, and milder patterns in the North Central Pacific. This SeaWiFS record was tracked with a coupled physical/biogeochemical/radiative model of the global oceans using near-real-time forcing data such as wind stresses, sea surface temperatures, and sea ice. This provided an opportunity to offer physically and biogeochemically meaningful explanations of the variability observed in the SeaWiFS data set, since the causal mechanisms and interrelationships of the model are completely understood. The coupled model was able to represent the seasonal distributions of chlorophyll during the SeaWiFS era, and was capable of differentiating among the widely different processes and dynamics occurring in the global oceans. The model was also reasonably successful in representing the interannual signal, especially when it was large, such as the El Niño and La Niña events in the tropical Pacific and Indian Oceans. The model provided different phytoplankton group responses for the different events in these regions: diatoms were predominant in the tropical Pacific during the La Niña but other groups were predominant during El Niño. The opposite condition occurred in the tropical Indian Ocean. Both situations were due to the different responses of the basins to El Niño. Interannual variability in the North Pacific was exhibited as an increase in the spring bloom in 1999 and 2000 relative to 1998. This resulted in the model from a shallower and more rapidly shoaling mixed layer, producing more average irradiance in the water column and preventing herbivore populations to keep pace with increasing phytoplankton populations. This model represents the first coupled three-dimensional simulation of interannual variability in global biogeochemical processes. It was published in Deep-Sea Research, Dec. 2001.
This sequence of images illustrates the dramatic effects of El Niño and La Niña in model surface nitrate concentrations. In November 1997 high nitrate values in the eastern equatorial Indian occurred as a result of intense upwelling. Nitrate concentrations continued to diminish through May 1998 in the tropical Pacific, and then began to re-establish upwelling conditions in June 1998 as the La Niña developed. By September 1999 the La Niña was fully established.
Global Land Surface Evaporation and Heat Balance
Bhaskar J. Choudhury
NASA Goddard Space Flight Center, Laboratory for Hydrospheric Processes, [email protected]
A biophysical process-based model has been used, together with 60 consecutive months of geo-coded and synchronous observations, to calculate components to total evaporation (transpiration, soil evaporation, and interception loss) and energy balance over the global land surface. The present results allows one to assess to a limited degree the magnitude of interannual variation of water and energy balance fluxes at regional and global scale.
Annual Total Evaporation (average, 1986-1990)
This figure shows the annual total evaporation (i.e., sum of transpiration, soil evaporation and interception loss), averaged over the five year period. One can see a gradient of evaporation on the eastern U.S. and in the north-south direction over the northern Africa, in response to precipitation.
Fractional Transpiration
This figure shows the ratio of annual total transpiration and total evaporation (averaged over the five years). This ratio is calculated to be maximum over the tropical humid forest areas, and minimum over arid and semi-arid areas.
Evaporative Fraction (averaged, 1986-1990)
This figure shows the ratio of annual total evaporation and net radiation (both expressed in the same units). This ratio is found to maximum over the tropical humid forest areas, and also some areas in the northern latitudes (taiga and tundra).
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Peter H. HildebrandLaboratory for Hydrospheric Processes, Microwave Sensors Branch, [email protected]
The Aquarius approach to radiometric measurement of ocean salinity is being tested using data from aircraft flight tests (Levine, et al, 2001, Wilson, et al, 2001), from ground-based measurements and from laboratory tests. The airborne and ground tests address radiometer design issues that improve measurement accuracy and stability and are demonstrating the needed level of measurement accuracy, thus confirming the Aquarius approach. These figures compare aircraft radiometer and in-situ measurements. The top panel (Levine, et al, 2001) compares Goddard/ESTAR radiometer measurements with ship salinity measurements across the Gulf Stream, and demonstrates good agreement of the airborne and ship-measured salinity. The bottom pair of graphs, (Wilson, et al, 2001) compares JPL/PALS radiometer Tb measurements (red lines) with Tb values (black dashed lines) from ship measurements of SST and salinity (blue). Both measurements illustrate good agreement between the radiometer and the confirmatory measurements. Additional measurements are using measurements of the galactic background to verify radiometer accuracy and stability, are improving the ocean surface roughness algorithm, and other aspects of the salinity retrieval algorithm.
Aquarius Program - Confirmatory Measurements of Sea Surface SalinityNASA/GSFC Codes 971 and 975