Cloud Properties and Associated Radiative Heating Rates in the Tropical Western Pacific
Radiative heating of the atmosphere affects cloud evolution and atmospheric dynamics. The most direct means available for determining radiative heating profiles is to measure profiles of thermodynamic and cloud properties (temperature, humidity, liquid and ice water content) and use these profiles to calculate radiative fluxes. Obtaining accurate, high resolution profiles of these properties requires active remote sensing instruments. Instruments capable of making these measurements and the techniques for interpreting these measurements for meteorological applications have only recently become available. The Atmospheric Radiation Measurement (ARM) program operates instruments including millimeter wavelength radars and microwave radiometers to measure cloud property distributions at sites around the world including three in the tropical western Pacific region. We have analyzed several months of ARM observations from Manus and Nauru to calculate time series of vertical cloud property profiles and associated radiative fluxes and heating rates. To test the validity of these radiative profiles, we have conducted closure tests that compare calculated radiative fluxes at the surface and top of atmosphere to measurements from the ARM sites and from geostationary satellite. The cloud and radiation profiles exhibit distinct vertical structure with strong boundary layer and cirrus features at both sites. Manus, which was much more convectively active than Nauru during the study period, also exhibits a mid-level cloud feature near the melting level. The two sites exhibit very different diurnal cycles. This data set will be an important tool for describing radiative processes in the tropics and assessing the simulation of these processes in dynamical models.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 901170
- Report Number(s):
- PNNL-SA-50277; KP1205010; TRN: US200713%%77
- Journal Information:
- Journal of Geophysical Research. D. (Atmospheres), 112:D05201, Vol. 112
- Country of Publication:
- United States
- Language:
- English
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