NASA’s Clouds and the Earth’s Radiant Energy System (CERES) project integrates CERES, Moderate Resolution Imaging Spectroradiometer (MODIS), and geostationary satellite observations to provide top-of-atmosphere (TOA) irradiances derived from broadband radiance observations by CERES instruments. It also uses snow cover and sea ice extent retrieved from microwave instruments as well as thermodynamic variables from reanalysis. In addition, these variables are used for surface and atmospheric irradiance computations. The CERES project provides TOA, surface, and atmospheric irradiances in various spatial and temporal resolutions. These data sets are for climate research and evaluation of climate models. Long-term observations are required to understand how the Earth system responds to radiative forcing. A simple model is used to estimate the time to detect trends in TOA reflected shortwave and emitted longwave irradiances.
The cloud top height of marine boundary layer clouds (MBLCs) in the mid-latitudes has received less attention than that of subtropical MBLCs and is investigated here using cloud mask data, which were based on observations from the cloud-aerosol lidar and infrared pathfinder satellite observation (CALIPSO) satellite. This study provides a comprehensive overview of the observational characteristics of variations in cloud top height of MBLCs and fog frequency over the mid-latitudes. Seasonal variations in the cloud top height of mid-latitude MBLCs as well as the differences in these seasonal variations between the Northern and Southern hemispheres were determined. For example, over the North Pacific, the cloud top height is high in winter (up to 1800 m) but low in summer (down to 800 m), whereas in the Southern Hemisphere, the seasonal variation is not well defined, with heights ranging from 1300 to 1500 m. While clear seasonal variations in the frequency of fog occurrence are found over the North Pacific and the northwest Atlantic, the fog frequency over the Southern Ocean is almost constant irrespective of the season. High correlations were found between the MBLC top height and stability indexes and between the fog frequency and some surface parameters such as temperature difference between the surface air and the sea surface. The latitudinal variations in the cloud top height of MBLCs in summer and winter over the Southern Ocean were compared with those over the North Pacific. The difference in cloud top heights between nighttime and daytime is also presented.
The combined influences of the westerly phase of the quasi-biennial oscillation (QBO-W) and solar maximum (Smax) conditions on the Northern Hemisphere extratropical winter circulation are investigated using reanalysis data and Center for Climate System Research/National Institute for Environmental Studies chemistry climate model (CCM) simulations. The composite analysis for the reanalysis data indicates strengthened polar vortex in December followed by weakened polar vortex in February-March for QBO-W during Smax (QBO-W/Smax) conditions. This relationship need not be specific to QBO-W/Smax conditions but may just require strengthened vortex in December, which is more likely under QBO-W/Smax. Both the reanalysis data and CCM simulations suggest that dynamical processes of planetary wave propagation and meridional circulation related to QBO-W around polar vortex in December are similar in character to those related to Smax; furthermore, both processes may work in concert to maintain stronger vortex during QBO-W/Smax. In the reanalysis data, the strengthened polar vortex in December is associated with the development of north-south dipole tropospheric anomaly in the Atlantic sector similar to the North Atlantic oscillation (NAO) during December-January. The structure of the north-south dipole anomaly has zonal wavenumber 1 (WN1) component, where the longitude of anomalous ridge overlaps with that of climatological ridge in the North Atlantic in January. This implies amplification of the WN1 wave and results in the enhancement of the upward WN1 propagation from troposphere into stratosphere in January, leading to the weakened polar vortex in February-March. Although WN2 waves do not play a direct role in forcing the stratospheric vortex evolution, their tropospheric response to QBO-W/Smax conditions appears to be related to the maintenance of the NAO-like anomaly in the high-latitude troposphere in January. These results may provide a possible explanation for the mechanisms underlying the seasonal evolution of wintertime polar vortex anomalies during QBO-W/Smax conditions and the role of troposphere in this evolution.