Mati Kahru | University of California, San Diego (original) (raw)

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Papers by Mati Kahru

Research paper thumbnail of Cetacean biomass, prey consumption, and primary production requirements in the California Current ecosystem

To better understand the role played by cetaceans as top-level predators in the California Curren... more To better understand the role played by cetaceans as top-level predators in the California Current ecosystem, we estimate the fraction of annual net primary production (NPP) required to support the prey consumed by cetaceans, using a simple trophic transfer model. The biomass of cetacean species in the California Current is calculated as the product of their mean summer and fall abundance during 1991 to 2005 and estimates of mean mass ind. -1 . Total prey consumption by cetaceans is estimated from a mass-specific consumption model. NPP is estimated from remote satellite measurements using the Behrenfeld-Falkowski vertically-generalized production model for each of 4 geographic regions. The total biomass of baleen whales exceeds the biomass of toothed whales by a factor of ~2.5; however, the estimated prey consumption by these taxa is nearly equal. Assuming 10% trophic transfer efficiency, cetaceans are estimated to require 32.2 g C m -2 yr -1 of primary production, or ~12% of the NPP in the study area, to sustain the prey that they directly consume. Because they feed at a lower trophic level, the primary production requirement (PPR) of baleen whales is 13% of that of toothed whales, despite their 2.5-fold greater biomass. Uncertainty in trophic transfer efficiency results in the greatest uncertainty in estimating PPR for these upper trophic predators.

Research paper thumbnail of Ocean Color Chlorophyll Algorithms for SeaWiFS

Journal of …, Jan 1, 1998

Research paper thumbnail of Ocean color chlorophyll a algorithms for SeaWiFS, OC2, and OC4: Version 4

SeaWiFS postlaunch …, Jan 1, 2000

This chapter describes the revisions (version 4) to the ocean chlorophyll two-and four-band algor... more This chapter describes the revisions (version 4) to the ocean chlorophyll two-and four-band algorithms as well as the very large in situ data set used to update these algorithms for use in the third reprocessing of SeaWiFS data. The in situ data set is substantially larger (N = 2,853) than was used to develop earlier versions of OC2 and OC4, includes samples from a greater variety of bio-optical provinces, and better represents oligotrophic and eutrophic waters. The correlation between chlorophyll a concentration, C a , estimated using OC4 and in situ C a (C a ) estimated from fluorometric and HPLC analyses was slightly higher than that for OC2. Also, OC4 would be expected to perform better than OC2, when applied to satellite-derived, water-leaving radiances retrieved from oligotrophic and eutrophic areas. Variations of the OC4 algorithm are provided for other ocean color sensors to facilitate comparisons with SeaWiFS.

Research paper thumbnail of Satellite Detection of Increased Cyanobacteria Blooms In the Baltic Sea: Natural Fluctuation or Ecosystem Change?

Ambio. Stockholm, Jan 1, 1994

Research paper thumbnail of Estimation of Particulate Organic Carbon In the Ocean From Satellite Remote Sensing

Research paper thumbnail of Spectral Reflectance and Absorption of a Massive Red Tide Off Southern California

Journal of Geophysical Research, Jan 1, 1998

Research paper thumbnail of Influence of the 1997-98 El Niño on the Surface Chlorophyll In the California Current

Geophysical Research Letters, Jan 1, 2000

Research paper thumbnail of Seasonal and nonseasonal variability of satellite-derived chlorophyll and colored dissolved organic matter concentration in the California Current

Journal of Geophysical Research, Jan 1, 2001

Research paper thumbnail of Using satelites to monitor large-scale environmental changes: a case study of cyanobacterial blooms in the Baltic Sea

Monitoring algal blooms: new techniques for detecting …, Jan 1, 1997

Research paper thumbnail of Algorithms for SeaWiFS Standard Products Developed With the CalCOFI Bio-Optical Data Set

California Cooperative Oceanic Fisheries …, Jan 1, 1998

Research paper thumbnail of Two models for absorption by coloured dissolved organic matter (CDOM)

Research paper thumbnail of Influence of the El Niño-La Niña cycle on satellite-derived primary production in the California Current

Investigaciones marinas, Jan 1, 2002

Research paper thumbnail of New approaches and technologies for observing harmful algal blooms

Research paper thumbnail of Ocean-color variability in the Gulf of California: scales from days to ENSO

Deep Sea Research …, Jan 1, 2004

Research paper thumbnail of Phytoplankton absorption, photosynthetic parameters, and primary production off Baja California: summer and autumn 1998

Deep Sea Research …, Jan 1, 2004

Research paper thumbnail of Ocean color reveals increased blooms in various parts of the world

EOS, Transactions, American Geophysical Union, Jan 1, 2008

Research paper thumbnail of Problems In Assessment of the Ultraviolet Penetration Into Natural Waters From Space-Based Measurements

Research paper thumbnail of Particle(plankton) size structure across the Azores front- Joint Global Ocean Flux Study North Atlantic Bloom Experiment

Journal of Geophysical …, Jan 1, 1991

Research paper thumbnail of Trends in primary production in the California Current detected with satellite data

J. Geophys. Res, Jan 1, 2009

Research paper thumbnail of Assessment of the ultraviolet radiation field in ocean waters from space-based measurements and full radiative-transfer calculations

Applied …, Jan 1, 2005

Quantitative assessment of the UV effects on aquatic ecosystems requires an estimate of the in-wa... more Quantitative assessment of the UV effects on aquatic ecosystems requires an estimate of the in-water radiation field. Actual ocean UV reflectances are needed for improving the total ozone retrievals from the total ozone mapping spectrometer (TOMS) and the ozone monitoring instrument (OMI) flown on NASA's Aura satellite. The estimate of underwater UV radiation can be done on the basis of measurements from the TOMS͞OMI and full models of radiative transfer (RT) in the atmosphere-ocean system. The Hydrolight code, modified for extension to the UV, is used for the generation of look-up tables for in-water irradiances. A look-up table for surface radiances generated with a full RT code is input for the Hydrolight simulations. A model of seawater inherent optical properties (IOPs) is an extension of the Case 1 water model to the UV. A new element of the IOP model is parameterization of particulate matter absorption based on recent in situ data. A chlorophyll product from ocean color sensors is input for the IOP model. Verification of the in-water computational scheme shows that the calculated diffuse attenuation coefficient K d is in good agreement with the measured K d .

Research paper thumbnail of Cetacean biomass, prey consumption, and primary production requirements in the California Current ecosystem

To better understand the role played by cetaceans as top-level predators in the California Curren... more To better understand the role played by cetaceans as top-level predators in the California Current ecosystem, we estimate the fraction of annual net primary production (NPP) required to support the prey consumed by cetaceans, using a simple trophic transfer model. The biomass of cetacean species in the California Current is calculated as the product of their mean summer and fall abundance during 1991 to 2005 and estimates of mean mass ind. -1 . Total prey consumption by cetaceans is estimated from a mass-specific consumption model. NPP is estimated from remote satellite measurements using the Behrenfeld-Falkowski vertically-generalized production model for each of 4 geographic regions. The total biomass of baleen whales exceeds the biomass of toothed whales by a factor of ~2.5; however, the estimated prey consumption by these taxa is nearly equal. Assuming 10% trophic transfer efficiency, cetaceans are estimated to require 32.2 g C m -2 yr -1 of primary production, or ~12% of the NPP in the study area, to sustain the prey that they directly consume. Because they feed at a lower trophic level, the primary production requirement (PPR) of baleen whales is 13% of that of toothed whales, despite their 2.5-fold greater biomass. Uncertainty in trophic transfer efficiency results in the greatest uncertainty in estimating PPR for these upper trophic predators.

Research paper thumbnail of Ocean Color Chlorophyll Algorithms for SeaWiFS

Journal of …, Jan 1, 1998

Research paper thumbnail of Ocean color chlorophyll a algorithms for SeaWiFS, OC2, and OC4: Version 4

SeaWiFS postlaunch …, Jan 1, 2000

This chapter describes the revisions (version 4) to the ocean chlorophyll two-and four-band algor... more This chapter describes the revisions (version 4) to the ocean chlorophyll two-and four-band algorithms as well as the very large in situ data set used to update these algorithms for use in the third reprocessing of SeaWiFS data. The in situ data set is substantially larger (N = 2,853) than was used to develop earlier versions of OC2 and OC4, includes samples from a greater variety of bio-optical provinces, and better represents oligotrophic and eutrophic waters. The correlation between chlorophyll a concentration, C a , estimated using OC4 and in situ C a (C a ) estimated from fluorometric and HPLC analyses was slightly higher than that for OC2. Also, OC4 would be expected to perform better than OC2, when applied to satellite-derived, water-leaving radiances retrieved from oligotrophic and eutrophic areas. Variations of the OC4 algorithm are provided for other ocean color sensors to facilitate comparisons with SeaWiFS.

Research paper thumbnail of Satellite Detection of Increased Cyanobacteria Blooms In the Baltic Sea: Natural Fluctuation or Ecosystem Change?

Ambio. Stockholm, Jan 1, 1994

Research paper thumbnail of Estimation of Particulate Organic Carbon In the Ocean From Satellite Remote Sensing

Research paper thumbnail of Spectral Reflectance and Absorption of a Massive Red Tide Off Southern California

Journal of Geophysical Research, Jan 1, 1998

Research paper thumbnail of Influence of the 1997-98 El Niño on the Surface Chlorophyll In the California Current

Geophysical Research Letters, Jan 1, 2000

Research paper thumbnail of Seasonal and nonseasonal variability of satellite-derived chlorophyll and colored dissolved organic matter concentration in the California Current

Journal of Geophysical Research, Jan 1, 2001

Research paper thumbnail of Using satelites to monitor large-scale environmental changes: a case study of cyanobacterial blooms in the Baltic Sea

Monitoring algal blooms: new techniques for detecting …, Jan 1, 1997

Research paper thumbnail of Algorithms for SeaWiFS Standard Products Developed With the CalCOFI Bio-Optical Data Set

California Cooperative Oceanic Fisheries …, Jan 1, 1998

Research paper thumbnail of Two models for absorption by coloured dissolved organic matter (CDOM)

Research paper thumbnail of Influence of the El Niño-La Niña cycle on satellite-derived primary production in the California Current

Investigaciones marinas, Jan 1, 2002

Research paper thumbnail of New approaches and technologies for observing harmful algal blooms

Research paper thumbnail of Ocean-color variability in the Gulf of California: scales from days to ENSO

Deep Sea Research …, Jan 1, 2004

Research paper thumbnail of Phytoplankton absorption, photosynthetic parameters, and primary production off Baja California: summer and autumn 1998

Deep Sea Research …, Jan 1, 2004

Research paper thumbnail of Ocean color reveals increased blooms in various parts of the world

EOS, Transactions, American Geophysical Union, Jan 1, 2008

Research paper thumbnail of Problems In Assessment of the Ultraviolet Penetration Into Natural Waters From Space-Based Measurements

Research paper thumbnail of Particle(plankton) size structure across the Azores front- Joint Global Ocean Flux Study North Atlantic Bloom Experiment

Journal of Geophysical …, Jan 1, 1991

Research paper thumbnail of Trends in primary production in the California Current detected with satellite data

J. Geophys. Res, Jan 1, 2009

Research paper thumbnail of Assessment of the ultraviolet radiation field in ocean waters from space-based measurements and full radiative-transfer calculations

Applied …, Jan 1, 2005

Quantitative assessment of the UV effects on aquatic ecosystems requires an estimate of the in-wa... more Quantitative assessment of the UV effects on aquatic ecosystems requires an estimate of the in-water radiation field. Actual ocean UV reflectances are needed for improving the total ozone retrievals from the total ozone mapping spectrometer (TOMS) and the ozone monitoring instrument (OMI) flown on NASA's Aura satellite. The estimate of underwater UV radiation can be done on the basis of measurements from the TOMS͞OMI and full models of radiative transfer (RT) in the atmosphere-ocean system. The Hydrolight code, modified for extension to the UV, is used for the generation of look-up tables for in-water irradiances. A look-up table for surface radiances generated with a full RT code is input for the Hydrolight simulations. A model of seawater inherent optical properties (IOPs) is an extension of the Case 1 water model to the UV. A new element of the IOP model is parameterization of particulate matter absorption based on recent in situ data. A chlorophyll product from ocean color sensors is input for the IOP model. Verification of the in-water computational scheme shows that the calculated diffuse attenuation coefficient K d is in good agreement with the measured K d .

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