This study examines the simultaneous water-atmosphere exchange of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) on the continental shelf of the Gulf of Cadiz, as well as the effect it has in terms of the radiative balance in the atmosphere, between 2014 and 2016. The experimental database consists of new measurements of the spatial and seasonal distribution of CO2 partial pressure (pCO2) and N2O concentration in 2016. pCO2 shows a wide range of variation influenced mainly by seasonal thermal variations (8.0 μatm 0C-1), as well as with the relative intensity of biological activity. There is experimental evidence of a progressive increase of pCO2 over the last 2 decades, with an estimated gradient of 4.2 ± 0.7 μatm y-1. During 2016, the Gulf of Cadiz acted as a slight source of CO2 to the atmosphere, with a mean flux of 0.4 ± 2.2 mmol m-2 d-1. The analysis of concentration variations in the water column shows that nitrification is the main N2O production process in the study area, although in the more coastal zone there are signs of inputs related to continental and sediment contributions, most probably induced by denitrification processes. In 2016, the Gulf of Cadiz acted as a weak sink of atmospheric N2O, with a mean flux of -0.1 ± 0.9 μmol m-2 d-1. From previous studies, performed with a similar methodology, an interannual database (2014-2016) of water-atmosphere fluxes of CO2, CH4 and N2O, normalized to the mean wind speed in the area, has been generated. Considering their respective Global Warming Potential (GWP) a joint greenhouse gasses (GHG) flux, expressed in CO2 equivalents of 0.6 ± 2.0 mmol m-2 d-1, has been estimated, which extended to the area of study indicates an approximate emission of 67.9 Gg CO2 y-1. However, although there is a high uncertainty associated with the spatial, temporal and interannual variations of CO2, CH4 and N2O fluxes in the Gulf of Cadiz, the exchange of greenhouse gasses could be influencing a radiative forcing increase in the atmosphere. When considering the available information on local and global estimates, the uncertainty about the effect of the joint exchange of GHGs to the atmosphere from the coastal seas increases significantly.

Observations have revealed that the rapidly warming Arctic is also moistening in certain regions and seasons. As water vapour is the strongest greenhouse gas, it contributes to the enhanced warming of the Arctic via the water vapour feedback. Water vapour estimates are uncertain in the Arctic due to the low amount of ground stations and challenges in satellite remote sensing. Thus, it is not surprising to see uncertainties in water vapour trends across reanalyses, which use these observations. In contrast to lower latitudes, Arctic humidity profiles feature inversions where the specific humidity increases with height. The representation of humidity inversions in current models and satellite products and the radiative effect of humidity inversions is poorly studied. Furthermore, the ability of ground-based microwave radiometers (MWRs) to capture humidity inversions has yet to be analyzed. The year-long Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition in the Arctic Ocean provides excellent reference water vapour observations to evaluate the water vapour products of models and satellites. Radiosonde observations are complemented by two MWRs with complementary water vapour sensitivity. The first part of this thesis includes two studies to quantify the benefit of the synergy of the two MWRs for water vapour products compared to the use of single MWRs. In the first study, the measurements of each MWR were quality controlled and atmospheric

Atmospheric longwave (thermal) and shortwave (solar) radiation sets the Earth's energy balance, playing a crucial role in weather and climate. While the fundamental physics of radiation are well-known, radiative flux can vary by orders of magnitude across space, time, and frequency, making the total flow of energy through the atmosphere difficult to compute and understand. This doctoral thesis focuses on simplifying the spectral dimension via developing algorithms for more efficient, accurate, and transparent calculation of radiation for Earth system modeling as well as theoretical work with t

between day and night, and keeps it warm through heat retention via the greenhouse effect. The atmosphere redistributes heat and moisture among different The atmosphere of Earth consists of a layer of mixed gas (commonly referred to as air) that is retained by gravity, surrounding the Earth's surface. It contains variable quantities of suspended aerosols and particulates that create weather features such as clouds and hazes. The atmosphere serves as a protective buffer between the Earth's surface and outer space. It shields the surface from most me The atmosphere of Earth consists of a layer of mixed gas (commonly referred to as air) that is retained by gravity, surrounding the Earth's surface. It contains variable… Atmospheric circulation is the large-scale movement of air through the troposphere, and the means (with ocean circulation) by which heat is distributed around Earth. The large-scale structure of the atmospheric circulation varies from year to year, but the basic structure remains fairly constant because it is determined by Earth's rotation rate and the difference in solar radiation between the equator and poles. The axial tilt of the planet means the location of maximum heat is continually changing, resulting in seasonal variations. The uneven distribution of land and water further breaks up the flow of air. The flow of air around the planet is divided into three main convection cells by latitude. Around the equator, the Hadley cell is driven by the rising flow of air along the equator. In the upper atmosphere, this air flows toward the poles. At mid latitudes, this circulation is reversed, with ground air flowing toward the poles with the Ferrel cell. Finally, in the high latitudes is the Polar cell, where air again rises and flows toward the poles. The interface between these cells is responsible for jet streams. These are narrow, fast moving bands that flow from west to east and typically form at an elevation of around 9,100 m (30,000 ft). Jet streams can shift around depending on conditions. They are strongest in winter, when the boundaries between hot and cold air are the most pronounced. In the middle latitudes, it is instabilities in the jet streams that are responsible for moving weather systems. As with the oceans, the Earth's atmosphere is subject to waves and tidal forces. These are triggered by non-uniform heating by the Sun, and by the daily solar cycle, respectively. Wave-like behavior can occur on a variety of scales, from smaller gravity waves that transfer momentum into the higher atmospheric layers, to much larger planetary waves, or Rossby waves. Atmospheric tides are periodic oscillations of the troposphere and stratosphere that transport energy to the upper atmosphere.

Satellite measurements are used to quantify the atmospheric greenhouse effect, defined here as the infrared radiation energy trapped by atmospheric gases and clouds. The greenhouse effect is found to increase significantly with sea surface temperature. The rate of increase gives compelling evidence for the positive feedback between surface temperature, water vapor and the greenhouse effect; the magnitude of the feedback is consistent with that predicted by climate models. This study demonstrates an effective method for directly monitoring, from space, future changes in the greenhouse effect.