Diabatic effects of clouds and precipitation over the Atlantic Ocean

Recent decades have seen unprecedented changes in sea ice thickness and extent, in ocean and atmosphere temperatures and circulation, and in greenhouse atmospheric constituents across the North Atlantic Climate System. Not only such changes directly affect the UK climate, weather and air quality but also, via tele-connections, they drive changes further afield with major economic impacts on agriculture, fisheries, water, energy, transport and health worldwide.
Accurate predictions of climate and numerical weather models are still jeopardized by large uncertainties related to the inadequate way clouds and their radiative properties are represented and to accurate knowledge of precipitation intensity and accumulation (IPCC 2013, see online at www.ipcc.ch).
One key to unravelling the complexity of cloud and precipitation feedbacks lies in clarifying the association between atmospheric circulation regimes, cloudiness and precipitation. Diabatic processes, and especially latent heat release due to the condensation of water vapour, can have a profound impact upon the development of extratropical cyclones by directly affecting storm dynamics and shaping the extratropical circulation, e.g. through the generation of vorticity, which are believed to contribute to a longer life span for precipitation systems and to heavy rainfall. Recent satellite measurements have the potential to improve our understanding of diabatic effects of clouds and precipitation. Specifically the Global Precipitation Measurement (GPM), launched by NASA and JAXA in February 2014 (http://gpm.nasa.gov) offer the unprecedented opportunity with its constellation of satellites to provide the next generation of space-borne precipitation measurements with better sampling (3-hourly over a specific location), higher accuracy (with a Ku-Ka band radar), finer spatial resolution (up to 0.1o x 0.1o), and greater coverage (from the tropics to high latitudes) than ever before (Fig. 1). By exploiting satellite retrieval schemes that depend on some type of cloud-resolving model latent heat products have been routinely produced by the GPM Science Team since the beginning of the mission [1]. Similarly, since its launch in 2006, CloudSat (http://cloudsat.atmos.colostate.edu/) has added a ‘‘new dimension’’ to cloud and precipitation retrievals from space-based platforms providing for the first time a tool to assess vertical distributions of the properties of most types of clouds around the planet using reflectivity measurements from the 94 GHz Cloud Profiling Radar (CPR). Vertically resolved radiative flux and heating rate data set which are consistent with observed reflectivities from the CloudSat’s CPR are available as Level 2 FLXHR product