| 1. |
- André, Mats, et al.
(författare)
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Thin electron-scale layers at the magnetopause
- 2004
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Ingår i: Geophysical Research Letters. - : American Geophysical Union (AGU). - 0094-8276 .- 1944-8007. ; 31, s. L03803-
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Tidskriftsartikel (refereegranskat)
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| 2. |
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| 3. |
- Behlke, Rico, et al.
(författare)
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Solitary structures associated with short large-amplitude magnetic structures (SLAMS) upstream of the Earth's quasi-parallel bow shock
- 2004
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Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 31:16
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Tidskriftsartikel (refereegranskat)abstract
- [1] For the first time, solitary waves (SWs) have been observed within short large-amplitude magnetic structures (SLAMS) upstream of the Earth's quasi-parallel bow shock. The SWs often occur as bipolar pulses in the electric field data and move parallel to the background magnetic field at velocities of v = 400–1200 km/s. They have peak-to-peak amplitudes in the parallel electric field of up to E′∥ = 65 mV/m and parallel scale sizes of L∥ ∼ 10 λD. The bipolar solitary waves exhibit negative potential structures of ∣Φ∥∣ = 0.4–2.2 V, i.e., eΦ∥/kTe ∼ 0.1. None of the theories commonly used to describe SWs adequately address these negative potential structures moving at velocities above the ion thermal speed in a weakly magnetized plasma.
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| 4. |
- Buehler, Stefan, et al.
(författare)
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The impact of temperature errors on perceived humidity supersaturation
- 2003
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Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 30:14, s. 1759-
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Tidskriftsartikel (refereegranskat)abstract
- A Monte Carlo method is used to study the propagation of temperature uncertainties into relative humidity with respect to ice (RH i ) calculated from specific humidity. For a flat specific humidity distribution and Gaussian temperature uncertainties the resulting RH i distribution drops exponentially at high RH i values—much slower than a Gaussian. This agrees well with the RH i distribution measured by the Microwave Limb Sounder (MLS), which means that such remotely measured RH i distributions can be explained, at least partly, by temperature uncertainties.
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| 5. |
- Carbonell, R., et al.
(författare)
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Geophysical Evidence of a Mantle Plume Derived Intrusion Complex
- 2004
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Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 31, s. L11601-
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Deep seismic reflection data acquired as part of the SW-Iberia EUROPROBE project across the transpressional Variscan orogen sample three tectonic terranes: the South Portuguese Zone, the Ossa-Morena Zone, and the Central Iberian Zone. The seismic data reveal the existence of a mid-crustal reflective body 140 km long and of variable thickness (up to 5 km), the Iberian Reflective body. The conductivity image provided by coincident MT soundings, the amplitude characteristics of the seismics, mineralization studies related to magmatic ore deposits, and the surface geology suggest that the IRB is a mantle-derived mafic intrusion. The geophysical, geological and petrological data suggest that the IRB is most probably an Early Carboniferous (approximately at 350–340 Ma) mantle-derived intrusion possibly linked to plume activity that took place in Europe in the Carboniferous and Permian.
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| 6. |
- Christensen, Torben, et al.
(författare)
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Factors controlling large scale variations in methane emissions from wetlands
- 2003
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Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 30:7
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Tidskriftsartikel (refereegranskat)abstract
- [1] Global wetlands are, at estimate ranging 115-237 Tg CH4/yr, the largest single atmospheric source of the greenhouse gas methane (CH4). We present a dataset on CH4 flux rates totaling 12 measurement years at sites from Greenland, Iceland, Scandinavia and Siberia. We find that temperature and microbial substrate availability (expressed as the organic acid concentration in peat water) combined explain almost 100% of the variations in mean annual CH4 emissions. The temperature sensitivity of the CH4 emissions shown suggests a feedback mechanism on climate change that could validate incorporation in further developments of global circulation models.
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| 7. |
- Christensen, Torben, et al.
(författare)
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Thawing sub-arctic permafrost : Effects on vegetation and methane emissions
- 2004
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Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 31:4
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Tidskriftsartikel (refereegranskat)abstract
- Ecosystems along the 0degreesC mean annual isotherm are arguably among the most sensitive to changing climate and mires in these regions emit significant amounts of the important greenhouse gas methane (CH4) to the atmosphere. These CH4 emissions are intimately related to temperature and hydrology, and alterations in permafrost coverage, which affect both of those, could have dramatic impacts on the emissions. Using a variety of data and information sources from the same region in subarctic Sweden we show that mire ecosystems are subject to dramatic recent changes in the distribution of permafrost and vegetation. These changes are most likely caused by a warming, which has been observed during recent decades. A detailed study of one mire show that the permafrost and vegetation changes have been associated with increases in landscape scale CH4 emissions in the range of 22-66% over the period 1970 to 2000.
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| 8. |
- Dupuy, E., et al.
(författare)
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Strato-mesospheric Measurements of Carbon Monoxide with the Odin Sub-millimetre Radiometer: Retrieval and First Results
- 2004
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Ingår i: Geophysical Research Letters. - 1944-8007 .- 0094-8276. ; 31:20
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Tidskriftsartikel (refereegranskat)abstract
- The Sub-Millimetre Radiometer (SMR) aboard the Odin satellite has been measuring vertical profiles of atmospheric trace gases since August 2001. We present the inversion methodology developed for CO measurements and the first retrieval results. CO can be retrieved from a single scan measurement throughout the middle atmosphere, with a typical resolution of similar to3 km and a relative error of similar to10% to similar to25%. Retrieval results are evaluated through comparison with data from the Whole Atmosphere Community Climate Model (WACCM) and observations of the Improved Stratospheric and Mesospheric Sounder (ISAMS) on board the Upper Atmospheric Research Satellite (UARS). Considering the large natural variability of CO, the SMR retrievals give good confirmation of the WACCM results, with an overall agreement within a factor of 2. ISAMS abundances are higher than SMR mixing ratios by a factor of 5-10 above 0.5 hPa from similar to80degreesS to similar to50degreesN.
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| 9. |
- Forkman, Peter, 1959, et al.
(författare)
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Longest continous ground-based measurements of mesospheric CO
- 2003
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Ingår i: Geophysical Research Letters. - 1944-8007 .- 0094-8276. ; 30:10
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Tidskriftsartikel (refereegranskat)abstract
- The longest continuous series of ground-based measurements of mesospheric CO is presented. The continuous data cover the period September 2000 to September 2002. Sporadic measurements from 1988 and 1989 are also reported. The results show a large CO accumulation in the winter mesosphere, which is consistent with generally accepted ideas about the seasonally-varying mean meridional circulation. Comparison of the observations with simulations by the Whole Atmosphere Community Climate Model (WACCM) indicate that the model can reproduce the observed seasonal cycle as well as much of its variability, although calculated columns amounts are smaller than the largest values seen in the data.
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| 10. |
- Gradinarsky, Lubomir, 1970, et al.
(författare)
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Horizontal gradients in the wet path delay derived from four years of microwave radiometer data
- 2000
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Ingår i: Geophysical Research Letters. - 1944-8007 .- 0094-8276. ; 27:16, s. 2521-2524
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Tidskriftsartikel (refereegranskat)abstract
- We have analyzed four years of inferred wet path delay data from a microwave radiometer operating at 21.0 and 31.4 GHz. We have applied a four parameter gradient model to the wet delays, using different lengths of the time series for the gradient estimation. The mean gradient, averaged over 15 to 1440 minutes, varies between 0.9 and 0.4 mm End has a preferred direction towards the north-east. Increasing the averaging time causes the estimated gradient to decrease. The 15 minutes mean gradient is 1.3 mm for the summer months and 0.7 mm for the winter months. Structure function results are also presented.
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