The intracratonic Ogaden Basin, which covers one‐third of the Democratic Republic of Ethiopia, developed in response to a tri‐radial rift system which was active during Late Palaeozoic to Mesozoic times. Thick Permian to Cretaceous sequences, which principally occur in the SW and central parts of the basin, have proved petroleum potential. Reservoir rocks are mainly Permian to Lower Jurassic sandstones (the Calub and Adigrat Formations), and Callovian limestones (the Upper Hamanlei Formation). Source rocks are organic‐rich Permian, Lower Jurassic and Callovian‐Oxfordian lacustrine and marine shales. This paper reviews the petroleum geology of the Ogaden Basin and assesses potential exploration targets. Successful exploration can be expected in view of the recent discovery of the Calub gas and gas/condensate field, and the occurrence of significant shows in the centre of the basin together with seeps along the margin.

of seasonal signals becomes less important, and the powerlaw character of the residuals starts to play a crucial role in the determined velocity uncertainties. With reference frame and sea level applications in mind, we argue that 7 and 9 years of continuous observations is the threshold for white and flicker noise, respectively, while 17 years are required for random-walk to decrease GDP below 5% and to omit periodic oscillations in the GNSS-derived time series taking only the noise model into consideration.

In the Nordic seas, we combine a computation of absolute surface current flow derived from geodetic data with in situ historical hydrographic data to estimate the absolute volume, heat, and salt transports as a function of depth. Our mean dynamic topography (MDT) is calculated from marine, airborne and satellite gravimetry, combined with satellite altimetry, using a new algorithm called the iterative combination method (ICM). Residual noise in the gravimetric geoid is the limit on MDT resolution and is suppressed using a Gaussian filter with a width at half‐peak amplitude of 59 km. Detailed and coherent flow paths for surface geostrophic currents are clearly identified. ICM MDT was used as fixed boundary condition to transform historical hydrography into absolute estimates of volume, heat, and salt transport, replacing the assumption of an isobaric surface at a predetermined depth. For the inflow of Atlantic Water (potential temperature Θ > 6°C) through the Faroe‐Shetland Channel into the Nordic seas, we obtain time‐averaged fluxes between 1993 and 1996 of 3.5 Sv (volume), 121 TW (heat), and 124 × 106 kg s−1 (salt), very close to reported observations from acoustic Doppler current profiler moorings and conductivity‐temperature‐depth data. For the Svinøy section, we obtain a northward transport of Atlantic Water (S > 35.0, T > 5.0°C) of 3.9 Sv in the eastern branch of the Norwegian Atlantic Current comparable with reported measurements of 4.2 Sv. Similarly good agreement is found for the Hornbanki and Iceland‐Faroe Ridge sections and for monitoring Atlantic Water outflow across the Barents Sea Opening to the Arctic shelf.

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Long series of Zenith Wet Delay (ZWD) obtained as part of a homogeneous re-processing of Global Positioning System solutions constitute a reliable set of data to be assimilated into climate models. The correct stochastic properties, i.e. the noise model of these data, have to be identified to assess the real value of ZWD trend uncertainties since assuming an inappropriate noise model may lead to over-or underestimated error bounds leading to statistically insignificant trends. We present the ZWD time series for 1995-2017 for 120 selected globally distributed stations. The deterministic model in the form of a trend and significant seasonal signals were removed prior to the noise analysis. We examined different stochastic models and compared them to widely assumed white noise (WN). A combination of the autoregressive process of first-order plus WN (AR(1) + WN) was proven to be the preferred stochastic representation of the ZWD time series over the generally assumed white-noise-only approach. We found that for 103 out of 120 considered stations, the AR(1) process contributed to the AR(1) + WN model in more than 50% with noise amplitudes between 9 and 68 mm. As soon as the AR(1) + WN model was employed, 43 trend estimates became statistically insignificant, compared to 5 insignificant trend estimates for a white-noise-only model. We also found that the ZWD trend uncertainty may be underestimated by 5-14 times with median value of 8 using the white-noise-only assumption. Therefore, we recommend that AR(1) + WN model is employed before tropospheric trends are to be determined with the greatest reliability.