scholarly journals Plant gross primary production, plant respiration and carbonyl sulfide emissions over the globe inferred by atmospheric inverse modelling

2021 ◽  
Author(s):  
Marine Remaud ◽  
Frédéric Chevallier ◽  
Fabienne Maignan ◽  
Sauveur Belviso ◽  
Antoine Berchet ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Primary Production ◽  
Gross Primary Production ◽  
Inverse System ◽  
Striking Similarity ◽  
High Latitudes ◽  
The Pacific ◽  
The Pacific Ocean ◽  
The Tropics ◽  
Plant Respiration

Abstract. Carbonyl Sulphide (COS), a trace gas showing striking similarity to CO2 in terms of biochemical diffusion pathway into leaves, has been recognized as a promising indicator of the plant gross primary production (GPP), the amount of carbon dioxide that is absorbed through photosynthesis by terrestrial ecosystems. However, large uncertainties about the other components of its atmospheric budget prevent us from directly relating the atmospheric COS measurements to GPP. The largest uncertainty comes from the closure of its atmospheric budget, with a source component missing. Here, we explore the benefit of assimilating both COS and CO2 measurements into the LMDz atmospheric transport model to obtain consistent information on GPP, plant respiration and COS budget. To this end, we develop an analytical inverse system that optimizes biospheric fluxes for the 15 plant functional types (PFTs) defined in the ORCHIDEE global land surface model. Plant uptake of COS is parameterized as a linear function of GPP of the leaf relative uptake (LRU), which is the ratio of COS to CO2 deposition velocities in plants. A possible scenario for the period 2008–2019 leads to a global biospheric sink of 800 GgS.yr−1, with higher absorption in the high latitudes and higher oceanic emissions between 400 and 600 GgS.yr−1 most of which is located in the tropics. As for the CO2 budget, the inverse system increases GPP in the high latitudes by a few GtC.yr−1 without modifying the respiration compared to the ORCHIDEE fluxes used as a prior. In contrast, in the tropics the system tends to weaken both respiration and GPP. The optimized components of the COS and CO2 have been evaluated against independent measurements over Northern America, the Pacific Ocean, at three sites in Japan and at one site in France. Overall, the posterior COS concentrations are in better agreement with the COS retrievals at 250 hPa from the MIPAS satellite and with airborne measurements made over North America and the Pacific Ocean. The system seems to have rightly corrected the underestimated GPP over the high latitudes. However, the change in seasonality of GPP in the tropics disagrees with Solar Induced Fluorescence (SIF) data. The decline in biospheric sink in the Amazon driven by the inversion also disagrees with MIPAS COS retrievals at 250 hPa, highlighting the lack of observational constraints in this region. Moreover, the comparison with the surface measurements in Japan and France suggests misplaced sources in the prior anthropogenic inventory, emphasizing the need for an improved inventory to better partition oceanic and continental sources in Asia and Europe.

scholarly journals Meridional Extent and Interannual Variability of the Pacific Ocean Tropical–Subtropical Warm Water Exchange

2005 ◽  
Vol 35 (3) ◽  
pp. 323-335 ◽  
Author(s):  
Christopher S. Meinen
Keyword(s):  
Pacific Ocean ◽  
El Niño ◽  
El Nino ◽  
Warm Water ◽  
Height Anomaly ◽  
The South ◽  
El Niño Event ◽  
The Pacific ◽  
The Pacific Ocean ◽  
The Tropics

Abstract Altimetric observations of sea surface height anomaly (SSHA) from the TOPEX/Poseidon and ERS satellites, hydrography, and the ECMWF and Florida State University wind products are used to track warm water (≥20°C) as it is exchanged between the equatorial Pacific Ocean and the higher latitudes during 1993–2003. The large El Niño event of 1997–98 resulted in a significant discharge of warm water toward the higher latitudes within the interior of the Pacific Ocean. The exchange of anomalous warm water volume with the Northern Hemisphere appears to be blocked under the intertropical convergence zone, consistent with most current ideas on the time-mean tropical–subtropical exchange. Little of the warm water discharged northward across 5° and 8°N during the 1997–98 El Niño event could be traced as far as 10°N. To the south, however, these anomalous volumes of warm water were visible at least as far as 20°S, primarily in the longitudes around 130°–160°W. In both hemispheres most of the warm water appeared to flow westward before returning to the Tropics during the recharge phase of the El Niño–La Niña cycle. The buildup of warm water in the Tropics before the 1997–98 El Niño is shown to be fed primarily by warm water drawn from the region in the western Pacific within 5°S–15°N. The exchange cycle between the equatorial band and the higher latitudes north of the equator leads the cycle in the south by 6–8 months. These results are found in all three datasets used herein, hydrography, altimetric observations of SSHA, and Sverdrup transports calculated from multiple wind products, which demonstrates the robustness of the results.

scholarly journals Oceanic Response to Idealized Net Atmospheric Freshwater in the Pacific at the Decadal Time Scale*

2005 ◽  
Vol 35 (12) ◽  
pp. 2467-2486 ◽  
Author(s):  
Boyin Huang ◽  
Vikram M. Mehta ◽  
Niklas Schneider
Keyword(s):  
Pacific Ocean ◽  
South Pacific ◽  
Tropical Pacific ◽  
Temperature Anomalies ◽  
The Pacific ◽  
Basin Scale ◽  
The Pacific Ocean ◽  
The Tropics ◽  
North And South ◽  
The Tropical Pacific

Abstract In the study of decadal variations of the Pacific Ocean circulations and temperature, the role of anomalous net atmospheric freshwater [evaporation minus precipitation minus river runoff (EmP)] has received scant attention even though ocean salinity anomalies are long lived and can be expected to have more variance at low frequencies than at high frequencies. To explore the magnitude of salinity and temperature anomalies and their generation processes, the authors studied the response of the Pacific Ocean to idealized EmP anomalies in the Tropics and subtropics using an ocean general circulation model developed at the Massachusetts Institute of Technology. Simulations showed that salinity anomalies generated by the anomalous EmP were spread throughout the Pacific basin by mean flow advection. This redistribution of salinity anomalies caused adjustments of basin-scale ocean currents, which further resulted in basin-scale temperature anomalies due to changes in heat advection caused by anomalous currents. In this study, the response of the Pacific Ocean to magnitudes and locations of anomalous EmP was linear. When forced with a positive EmP anomaly in the subtropical North (South) Pacific, a cooling occurred in the western North (South) Pacific, which extended to the tropical and South (North) Pacific, and a warming occurred in the eastern North (South) Pacific. When forced with a negative EmP anomaly in the tropical Pacific, a warming occurred in the tropical Pacific and western North and South Pacific and a cooling occurred in the eastern North Pacific near 30°N and the South Pacific near 30°S. The temperature changes (0.2°C) in the tropical Pacific were associated with changes in the South Equatorial Current. The temperature changes (0.8°C) in the subtropical North and South Pacific were associated with changes in the subtropical gyres. The temperature anomalies propagated from the tropical Pacific to the subtropical North and South Pacific via equatorial divergent Ekman flows and poleward western boundary currents, and they propagated from the subtropical North and South Pacific to the western tropical Pacific via equatorward-propagating coastal Kelvin waves and to the eastern tropical Pacific via eastward-propagating equatorial Kelvin waves. The time scale of temperature response was typically much longer than that of salinity response because of slow adjustment times of ocean circulations. These results imply that the slow response of ocean temperature due to anomalous EmP in the Tropics and subtropics may play an important role in the Pacific decadal variability.

On the Slope of Low-pressure Axes as a Criterion for Deepening in the Tropics

1948 ◽  
Vol 29 (1) ◽  
pp. 9-15
Author(s):  
R. H. Simpson
Keyword(s):  
Pacific Ocean ◽  
Tropical Cyclones ◽  
Wind Shear ◽  
Vertical Wind Shear ◽  
Low Pressure ◽  
Vertical Wind ◽  
Vertical Shear ◽  
The Pacific ◽  
The Pacific Ocean ◽  
The Tropics

The relation between the slope of tropical low pressure axes and the tendency for such lows to deepen or fill has been studied during investigations carried on separately in the Atlantic and in the Pacific ocean areas. The preliminary conclusions drawn from each of the two studies differ considerably and are reviewed herein. Limitations upon the use of vertical wind shear computations in determining the slope of such pressure axes are discussed. Questions are raised regarding the assumption in such computations that the vertical shear of the observed wind is a good approximation of the shear of the geostrophic components. Illustrations are given of the fallacies of reasoning that may result from such an assumption in connection with tropical cyclones.

On the Pacific Ocean regime shift

2001 ◽  
Vol 28 (19) ◽  
pp. 3721-3724
Author(s):  
Cathy Stephens
Keyword(s):  
Pacific Ocean ◽  
Regime Shift ◽  
The Pacific ◽  
The Pacific Ocean
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