Premium
Global observations of aerosol‐cloud‐precipitation‐climate interactions
Author(s) -
Rosenfeld Daniel,
Andreae Meinrat O.,
Asmi Ari,
Chin Mian,
Leeuw Gerrit,
Donovan David P.,
Kahn Ralph,
Kinne Stefan,
Kivekäs Niku,
Kulmala Markku,
Lau William,
Schmidt K. Sebastian,
Suni Tanja,
Wagner Thomas,
Wild Martin,
Quaas Johannes
Publication year - 2014
Publication title -
reviews of geophysics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 8.087
H-Index - 156
eISSN - 1944-9208
pISSN - 8755-1209
DOI - 10.1002/2013rg000441
Subject(s) - environmental science , aerosol , cloud condensation nuclei , atmospheric sciences , earth's energy budget , climate model , cloud physics , precipitation , lidar , satellite , meteorology , remote sensing , cloud computing , climate change , radiation , geology , physics , computer science , operating system , oceanography , quantum mechanics , astronomy
Cloud drop condensation nuclei (CCN) and ice nuclei (IN) particles determine to a large extent cloud microstructure and, consequently, cloud albedo and the dynamic response of clouds to aerosol‐induced changes to precipitation. This can modify the reflected solar radiation and the thermal radiation emitted to space. Measurements of tropospheric CCN and IN over large areas have not been possible and can be only roughly approximated from satellite‐sensor‐based estimates of optical properties of aerosols. Our lack of ability to measure both CCN and cloud updrafts precludes disentangling the effects of meteorology from those of aerosols and represents the largest component in our uncertainty in anthropogenic climate forcing. Ways to improve the retrieval accuracy include multiangle and multipolarimetric passive measurements of the optical signal and multispectral lidar polarimetric measurements. Indirect methods include proxies of trace gases, as retrieved by hyperspectral sensors. Perhaps the most promising emerging direction is retrieving the CCN properties by simultaneously retrieving convective cloud drop number concentrations and updraft speeds, which amounts to using clouds as natural CCN chambers. These satellite observations have to be constrained by in situ observations of aerosol‐cloud‐precipitation‐climate (ACPC) interactions, which in turn constrain a hierarchy of model simulations of ACPC. Since the essence of a general circulation model is an accurate quantification of the energy and mass fluxes in all forms between the surface, atmosphere and outer space, a route to progress is proposed here in the form of a series of box flux closure experiments in the various climate regimes. A roadmap is provided for quantifying the ACPC interactions and thereby reducing the uncertainty in anthropogenic climate forcing.