Relation between sea level and barometric pressure determined from altimeter data and model simulations

1997 ◽  
Vol 102 (C1) ◽  
pp. 961-971 ◽  
Author(s):  
Philippe Gaspar ◽  
Rui M. Ponte
Keyword(s):  
Sea Level ◽  
Barometric Pressure ◽  
Altimeter Data ◽  
Model Simulations

scholarly journals Validating and improving elevation data of a satellite-image map of Filchner,Ronne Ice Shelf, Antarctica, with Results from ERS-1

1994 ◽  
Vol 20 ◽  
pp. 347-352 ◽  
Author(s):  
J. Sievers ◽  
C.S.M. Doake ◽  
J. Ihde ◽  
D.R. Mantripp ◽  
V.S. Pozdeev ◽  
...  
Keyword(s):  
Sea Level ◽  
Satellite Image ◽  
Barometric Pressure ◽  
Lower Surface ◽  
Radar Data ◽  
Altimeter Data ◽  
Topographic Map ◽  
Radar Altimeter ◽  
Ice Shelf ◽  
Noaa Avhrr

A satellite-image map with surface-elevation contours of Filchner Ronne Ice Shelf has been published previously as a topographic map. The image map was constructed from a mosaic of 69 Landsat Multispectral Scanner (MSS) images and NOAA AVHRR data. The standard deviation in position in the central part of the mosaic is ±125m. Topographic-glaciologic features were taken from Landsat scenes and represent the best coastline of this region. Surface elevations have been calculated from airborne and ground measurements of either ice thickness (by assuming hydrostatic equilibrium) or barometric pressure. Accuracies vary from ±2 to ±7 m, Oversnow trigonometric levelling in the northeastern part of the ice shelf, tied to sea level at the ice front, has given accuracies of ± 1m. Accuracies reduce to about ±20 m in the grounded ice areas, ERS-I radar-altimeter data over the ice shelf have been processed to give ellipsoidal heights elevation above the ellipsoid), Geoidal reductions have been used to convert these to orthometric heights (elevation above sea level). No tidal corrections have been applied. The overall accuracy of the radar-altimeter-derived elevations is estimated to be better than ±5m. There are noticeable differences from the topographic map in the central part where the radar data indicate a lower surface. However, the maps agree to within the stated error figures.

scholarly journals Validating and improving elevation data of a satellite-image map of Filchner,Ronne Ice Shelf, Antarctica, with Results from ERS-1

1994 ◽  
Vol 20 ◽  
pp. 347-352 ◽  
Author(s):  
J. Sievers ◽  
C.S.M. Doake ◽  
J. Ihde ◽  
D.R. Mantripp ◽  
V.S. Pozdeev ◽  
...  
Keyword(s):  
Sea Level ◽  
Satellite Image ◽  
Barometric Pressure ◽  
Lower Surface ◽  
Radar Data ◽  
Altimeter Data ◽  
Topographic Map ◽  
Radar Altimeter ◽  
Ice Shelf ◽  
Noaa Avhrr

A satellite-image map with surface-elevation contours of Filchner Ronne Ice Shelf has been published previously as a topographic map. The image map was constructed from a mosaic of 69 Landsat Multispectral Scanner (MSS) images and NOAA AVHRR data. The standard deviation in position in the central part of the mosaic is ±125m. Topographic-glaciologic features were taken from Landsat scenes and represent the best coastline of this region. Surface elevations have been calculated from airborne and ground measurements of either ice thickness (by assuming hydrostatic equilibrium) or barometric pressure. Accuracies vary from ±2 to ±7 m, Oversnow trigonometric levelling in the northeastern part of the ice shelf, tied to sea level at the ice front, has given accuracies of ± 1m. Accuracies reduce to about ±20 m in the grounded ice areas,ERS-I radar-altimeter data over the ice shelf have been processed to give ellipsoidal heights elevation above the ellipsoid), Geoidal reductions have been used to convert these to orthometric heights (elevation above sea level). No tidal corrections have been applied. The overall accuracy of the radar-altimeter-derived elevations is estimated to be better than ±5m. There are noticeable differences from the topographic map in the central part where the radar data indicate a lower surface. However, the maps agree to within the stated error figures.

Contributions of Wind Forcing and Surface Heating to Interannual Sea Level Variations in the Atlantic Ocean

2006 ◽  
Vol 36 (9) ◽  
pp. 1739-1750 ◽  
Author(s):  
Cécile Cabanes ◽  
Thierry Huck ◽  
Alain Colin de Verdière
Keyword(s):  
Atlantic Ocean ◽  
Sea Level ◽  
Wind Stress ◽  
Large Scale ◽  
Sea Surface Height ◽  
Sea Surface ◽  
Altimeter Data ◽  
Local Response ◽  
Sea Level Variability ◽  
Sea Level Variations

Abstract Interannual sea surface height variations in the Atlantic Ocean are examined from 10 years of high-precision altimeter data in light of simple mechanisms that describe the ocean response to atmospheric forcing: 1) local steric changes due to surface buoyancy forcing and a local response to wind stress via Ekman pumping and 2) baroclinic and barotropic oceanic adjustment via propagating Rossby waves and quasi-steady Sverdrup balance, respectively. The relevance of these simple mechanisms in explaining interannual sea level variability in the whole Atlantic Ocean is investigated. It is shown that, in various regions, a large part of the interannual sea level variability is related to local response to heat flux changes (more than 50% in the eastern North Atlantic). Except in a few places, a local response to wind stress forcing is less successful in explaining sea surface height observations. In this case, it is necessary to consider large-scale oceanic adjustments: the first baroclinic mode forced by wind stress explains about 70% of interannual sea level variations in the latitude band 18°–20°N. A quasi-steady barotropic Sverdrup response is observed between 40° and 50°N.

Improvement in lung diffusion by endothelin A receptor blockade at high altitude

2012 ◽  
Vol 112 (1) ◽  
pp. 20-25 ◽  
Author(s):  
Claire de Bisschop ◽  
Jean-Benoit Martinot ◽  
Gil Leurquin-Sterk ◽  
Vitalie Faoro ◽  
Hervé Guénard ◽  
...  
Keyword(s):  
High Altitude ◽  
Sea Level ◽  
Exercise Capacity ◽  
Barometric Pressure ◽  
Membrane Component ◽  
Alveolar Volume ◽  
Double Blind ◽  
Lung Diffusion ◽  
Endothelin A Receptor ◽  
Endothelin A

Lung diffusing capacity has been reported variably in high-altitude newcomers and may be in relation to different pulmonary vascular resistance (PVR). Twenty-two healthy volunteers were investigated at sea level and at 5,050 m before and after random double-blind intake of the endothelin A receptor blocker sitaxsentan (100 mg/day) vs. a placebo during 1 wk. PVR was estimated by Doppler echocardiography, and exercise capacity by maximal oxygen uptake (V̇o2 max). The diffusing capacities for nitric oxide (DLNO) and carbon monoxide (DLCO) were measured using a single-breath method before and 30 min after maximal exercise. The membrane component of DLCO (Dm) and capillary volume (Vc) was calculated with corrections for hemoglobin, alveolar volume, and barometric pressure. Altitude exposure was associated with unchanged DLCO, DLNO, and Dm but a slight decrease in Vc. Exercise at altitude decreased DLNO and Dm. Sitaxsentan intake improved V̇o2 max together with an increase in resting and postexercise DLNO and Dm. Sitaxsentan-induced decrease in PVR was inversely correlated to DLNO. Both DLCO and DLNO were correlated to V̇o2 max at sea level ( r = 0.41–0.42, P < 0.1) and more so at altitude ( r = 0.56–0.59, P < 0.05). Pharmacological pulmonary vasodilation improves the membrane component of lung diffusion in high-altitude newcomers, which may contribute to exercise capacity.

Global mapping of seasonal variations in tides from tide gauge and satellite altimeter data

2021 ◽  
Author(s):  
Inger Bij de Vaate ◽  
Henrique Guarneri ◽  
Cornelis Slobbe ◽  
Martin Verlaan
Keyword(s):  
Seasonal Variation ◽  
Sea Level ◽  
Seasonal Variations ◽  
Large Scale ◽  
Arctic Region ◽  
The Arctic ◽  
Altimeter Data ◽  
Tide Gauges ◽  
Tidal Constituents ◽  
The Arctic Region

&lt;p&gt;The existence of seasonal variations in major tides has been recognized since decades. Where Corkan (1934) was the first to describe the seasonal perturbation of the M2 tide, many others have studied seasonal variations in the main tidal constituents since. However, most of these studies are based on sea level observations from tide gauges and are often restricted to coastal and shelf regions. Hence, observed seasonal variations are typically dominated by local processes and the large-scale patterns cannot be clearly distinguished. Moreover, most tide models still perceive tides as annually constant and seasonal variation in tides is ignored in the correction process of satellite altimetry. This results in reduced accuracy of obtained sea level anomalies. &lt;/p&gt;&lt;p&gt;To gain more insight in the large-scale seasonal variations in tides, we supplemented the clustered and sparsely distributed sea level observations from tide gauges by the wealth of data from satellite altimeters. Although altimeter-derived water levels are being widely used to obtain tidal constants, only few of these implementations consider seasonal variation in tides. For that reason, we have set out to explore the opportunities provided by altimeter data for deriving seasonal modulation of the main tidal constituents. Different methods were implemented and compared for the principal tidal constituents and a range of geographical domains, using data from a selection of satellite altimeters. Specific attention was paid to the Arctic region where seasonal variation in tides was expected to be significant as a result of the seasonal sea ice cycle, yet data availability is particularly limited. Our study demonstrates the potential of satellite altimetry for the quantification of seasonal modulation of tides and suggests the seasonal modulation to be considerable. Already for M2 we observed changes in tidal amplitude of the order of decimeters for the Arctic region, and centimeters for lower latitude regions.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;div&gt;Corkan, R. H. (1934). An annual perturbation in the range of tide. &lt;em&gt;Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character&lt;/em&gt;, &lt;em&gt;144&lt;/em&gt;(853), 537-559.&lt;/div&gt;

Oxygen transport to exercising leg in chronic hypoxia

1988 ◽  
Vol 65 (6) ◽  
pp. 2592-2597 ◽  
Author(s):  
P. R. Bender ◽  
B. M. Groves ◽  
R. E. McCullough ◽  
R. G. McCullough ◽  
S. Y. Huang ◽  
...  
Keyword(s):  
Blood Flow ◽  
Sea Level ◽  
Chronic Hypoxia ◽  
Peripheral Resistance ◽  
Hemoglobin Concentration ◽  
Barometric Pressure ◽  
Ambient Air ◽  
Leg Blood Flow ◽  
State Cycle ◽  
O2 Delivery

Residence at high altitude could be accompanied by adaptations that alter the mechanisms of O2 delivery to exercising muscle. Seven sea level resident males, aged 22 +/- 1 yr, performed moderate to near-maximal steady-state cycle exercise at sea level in normoxia [inspired PO2 (PIO2) 150 Torr] and acute hypobaric hypoxia (barometric pressure, 445 Torr; PIO2, 83 Torr), and after 18 days' residence on Pikes Peak (4,300 m) while breathing ambient air (PIO2, 86 Torr) and air similar to that at sea level (35% O2, PIO2, 144 Torr). In both hypoxia and normoxia, after acclimatization the femoral arterial-iliac venous O2 content difference, hemoglobin concentration, and arterial O2 content, were higher than before acclimatization, but the venous PO2 (PVO2) was unchanged. Thermodilution leg blood flow was lower but calculated arterial O2 delivery and leg VO2 similar in hypoxia after vs. before acclimatization. Mean arterial pressure (MAP) and total peripheral resistance in hypoxia were greater after, than before, acclimatization. We concluded that acclimatization did not increase O2 delivery but rather maintained delivery via increased arterial oxygenation and decreased leg blood flow. The maintenance of PVO2 and the higher MAP after acclimatization suggested matching of O2 delivery to tissue O2 demands, with vasoconstriction possibly contributing to the decreased flow.

Cardiovascular adaptations in Andean natives after 6 wk of exposure to sea level

1991 ◽  
Vol 70 (6) ◽  
pp. 2650-2655 ◽  
Author(s):  
D. C. McKenzie ◽  
L. S. Goodman ◽  
C. Nath ◽  
B. Davidson ◽  
G. O. Matheson ◽  
...  
Keyword(s):  
Sea Level ◽  
Barometric Pressure ◽  
Cycle Ergometer ◽  
Left Ventricular ◽  
Structure And Function ◽  
Left Ventricular Ejection ◽  
Noninvasive Methods ◽  
Functional Changes ◽  
And Function ◽  
Quechua Indians

Six male Quechua Indians (34.0 +/- 1.1 yr, 159.5 +/- 2.1 cm, 60.5 +/- 1.6 kg), life-long residents of La Raya, Peru (4,350-m altitude with an average barometric pressure of 460 Torr), were studied using noninvasive methods to determine the structural and functional changes in the cardiovascular system in response to a 6-wk deacclimation period at sea level. Cardiac output, stroke volume, and left ventricular ejection fractions were determined using radionuclide angiographic techniques at rest and during exercise on a cycle ergometer at 40, 60, and 90% of a previously determined maximal O2 consumption. Subjects at rest were subjected to two-dimensional and M-mode echocardiograms and a standard 12-lead electrocardiogram. Hemoglobin and hematocrit were measured on arrival at sea level by use of a Coulter Stacker S+ analyzer. After a 6-wk deacclimation period, all variables were remeasured using the identical methodology. Hemoglobin values decreased significantly over the deacclimation period (15.7 +/- 1.1 to 13.5 +/- 1.2 g/dl; P less than 0.01). The results indicate that the removal of these high-altitude-adapted natives from 4,300 m to sea level for 6 wk results in only minor changes to the cardiac structure and function as measured by these noninvasive techniques.

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