record. The first 3 years of the mission captured the peak of the El Niño event and
the following transition to an equally large La Niña (Behrenfeld et al. 2001). The
peak to peak change in ocean NPP across this transition (*6 Pg C) exceeds any
other anomaly since observed in the satellite ocean color record (Arndt et al. 2010;
Blunden et al. 2011). El Niño is accompanied by higher than normal SST
throughout much of the tropical Pacific Ocean and interrupts the normal upwelling
pattern which supports significantly elevated NPP in the eastern tropical Pacific.
Field studies have estimated reductions in nutrient supply and NPP of *80 %
during El Niño (Barber and Chavez 1983; Chavez et al. 2002). A similar relationship was reported by Behrenfeld et al. (2006a) over the entire stratified surface
ocean (*40°N to 40°S) based on remote sensing estimates of NPP.
A central objective underlying the development of a long-term, climate-quality
satellite ocean color data record is to improve understanding of climate-ocean
ecology interactions. It has been estimated that 50 or more years of continuous
satellite observations will be necessary in many ocean regions to clearly detect the
signature of anthropogenic impacts from natural variability (Henson et al. 2009).
Clearly, this is far too long to wait. However, over much shorter time scales,
natural forms of climate variation can provide critical insights on NPP and phytoplankton biomass variability. To this end, Behrenfeld et al. (2006a) showed that
over the first 10 years of SeaWiFS observations, anomalies in water column
integrated chlorophyll and modeled NPP (VGPM and CbPM) integrated over the
permanently stratified oceans (i.e., annual average SST [15 °C) were highly
correlated with variations in SST and surface mixing depths. Furthermore, the
spatial distribution of NPP anomalies mirrored those of SST anomalies.
The Behrenfeld et al. (2006a) study has been followed by a series of similar
analyses. In Behrenfeld et al. (2008), the strong correlation between chlorophyll
and SST anomalies was also shown to occur at higher northern latitudes, but no
significant trends were found for the Southern Ocean. This latter conclusion was
repeated by Arrigo et al. (2008b) who reported no significant trend in Southern
Ocean NPP between 1998 and 2006. Annual totals for the domain south of 50°S
were *2 ± 0.07 Pg C year
-1 , nearly half of previous remote sensing based
estimates for this region. Martinez et al. (2009) significantly expanded the time
period of evaluation by combining SeaWiFS data with the earlier CZCS record.
Their study again reported significant inverse relationships between global ocean
SST and chlorophyll anomalies, both in regionally integrated data and spatiallyresolved fields. With this expanded data set, these authors were also able to clearly
identify impacts of the longer time-scale climate fluctuations associated with
ocean basin decadal oscillations. Additional analyses of temporal ocean color data
employing both SeaWiFS and MODIS measurements were provided in reports by
(Arndt et al. 2010; Blunden et al. 2011). Interestingly, several recent studies
addressing temporal changes using in situ measured NPP have reported conflicting
results from those found using satellite data (Dave and Lozier 2010; Lozier et al.
2011; Saba et al. 2010; Chavez et al. 2011). These differences highlight the difficulty in comparing quantities and trends derived from singular locations representing small spatial scales to integrated signals over entire ocean basins.
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T. K. Westberry and M. J. Behrenfeld
the following transition to an equally large La Niña (Behrenfeld et al. 2001). The
peak to peak change in ocean NPP across this transition (*6 Pg C) exceeds any
other anomaly since observed in the satellite ocean color record (Arndt et al. 2010;
Blunden et al. 2011). El Niño is accompanied by higher than normal SST
throughout much of the tropical Pacific Ocean and interrupts the normal upwelling
pattern which supports significantly elevated NPP in the eastern tropical Pacific.
Field studies have estimated reductions in nutrient supply and NPP of *80 %
during El Niño (Barber and Chavez 1983; Chavez et al. 2002). A similar relationship was reported by Behrenfeld et al. (2006a) over the entire stratified surface
ocean (*40°N to 40°S) based on remote sensing estimates of NPP.
A central objective underlying the development of a long-term, climate-quality
satellite ocean color data record is to improve understanding of climate-ocean
ecology interactions. It has been estimated that 50 or more years of continuous
satellite observations will be necessary in many ocean regions to clearly detect the
signature of anthropogenic impacts from natural variability (Henson et al. 2009).
Clearly, this is far too long to wait. However, over much shorter time scales,
natural forms of climate variation can provide critical insights on NPP and phytoplankton biomass variability. To this end, Behrenfeld et al. (2006a) showed that
over the first 10 years of SeaWiFS observations, anomalies in water column
integrated chlorophyll and modeled NPP (VGPM and CbPM) integrated over the
permanently stratified oceans (i.e., annual average SST [15 °C) were highly
correlated with variations in SST and surface mixing depths. Furthermore, the
spatial distribution of NPP anomalies mirrored those of SST anomalies.
The Behrenfeld et al. (2006a) study has been followed by a series of similar
analyses. In Behrenfeld et al. (2008), the strong correlation between chlorophyll
and SST anomalies was also shown to occur at higher northern latitudes, but no
significant trends were found for the Southern Ocean. This latter conclusion was
repeated by Arrigo et al. (2008b) who reported no significant trend in Southern
Ocean NPP between 1998 and 2006. Annual totals for the domain south of 50°S
were *2 ± 0.07 Pg C year
-1 , nearly half of previous remote sensing based
estimates for this region. Martinez et al. (2009) significantly expanded the time
period of evaluation by combining SeaWiFS data with the earlier CZCS record.
Their study again reported significant inverse relationships between global ocean
SST and chlorophyll anomalies, both in regionally integrated data and spatiallyresolved fields. With this expanded data set, these authors were also able to clearly
identify impacts of the longer time-scale climate fluctuations associated with
ocean basin decadal oscillations. Additional analyses of temporal ocean color data
employing both SeaWiFS and MODIS measurements were provided in reports by
(Arndt et al. 2010; Blunden et al. 2011). Interestingly, several recent studies
addressing temporal changes using in situ measured NPP have reported conflicting
results from those found using satellite data (Dave and Lozier 2010; Lozier et al.
2011; Saba et al. 2010; Chavez et al. 2011). These differences highlight the difficulty in comparing quantities and trends derived from singular locations representing small spatial scales to integrated signals over entire ocean basins.
214
T. K. Westberry and M. J. Behrenfeld