Search Results

You are looking at 1 - 10 of 12 items for :

  • Water vapor x
  • Assimilation of Satellite Cloud and Precipitation Observations x
  • All content x
Clear All
K. Franklin Evans

defined at the boundaries of the radiative transfer layers. Thus the water path of each layer is derived from the average mixing ratio at the layer boundaries and the pressure change across the layer. Height is input, but is only used to select which hydrometeors are active according to a specified height range for each hydrometeor species. A subroutine interface is provided for the calculation of the channel-averaged molecular absorption profile from temperature, pressure, water vapor, and ozone

Full access
Fuzhong Weng

been pursued by some major centers. At the European Centre for Medium-Range Weather Forecasts (ECMWF), Moreau et al. (2004) developed a one-dimensional variational (1DVAR) system to assimilate the radiances at the microwave window channel frequencies that are more sensitive to cloud liquid water, water vapor, sea surface wind, and temperature. The 1DVAR retrievals of the vertically integrated cloud liquid water and water vapor are then assimilated into a four-dimensional variation (4DVAR) system

Full access
Qing Yue, K. N. Liou, S. C. Ou, B. H. Kahn, P. Yang, and G. G. Mace

. Since tropical cirrus clouds locate in the upper troposphere above which temperature is cold and the water vapor amount is low, the contribution of emissions from water vapor above cirrus is small compared to the transmission through the cloud and the emission from the cloud itself, and can be neglected. Thus, I 0 is simply referred to as the clear radiance in this study. Here B ν ( T c ) is the cloud Planck radiance at a wavenumber ν , and the cloud temperature is denoted by T c . The cloud

Full access
Graeme L. Stephens and Christian D. Kummerow

about 10%–20%. b. Cloud liquid water path The differential emission of microwave radiation by clouds and water vapor at selected microwave frequencies provides the basis for estimating the vertically integrated cloud water content (LWP). This approach has mainly been applied over the global oceans (e.g., Greenwald et al. 1993 ; Alishouse et al. 1990 ; Curry et al. 1990 ) although methods have been developed to use these microwave emission measurements in conjunction with infrared emission

Full access
Fuzhong Weng, Tong Zhu, and Banghua Yan

a physical initialization method, and found that SSM/I rain-rate products developed by the National Oceanic and Atmospheric Administration (NOAA) produced the best prediction results. Zou and Xiao (2000) assimilated the Geostationary Operational Environmental Satellite (GOES)-8/9 upper-tropospheric water vapor–tracking wind vectors into the fifth-generation Pennsylvania State University–National Center for Atmospheric Research Mesoscale Model (MM5) through the four-dimensional variational

Full access
Ruiyue Chen, Fu-Lung Chang, Zhanqing Li, Ralph Ferraro, and Fuzhong Weng

are not applicable over land because of the strong and highly variable microwave emission of the land surface. The emission from ocean surfaces is less variable, so cloud LWP can be estimated from satellite-observed microwave radiances. However, LWP retrieval accuracy is affected by the sea surface temperature, surface wind speed, atmospheric precipitable water vapor, and radiometric calibration while uncertainties in the absorption coefficients used in the microwave radiative transfer model also

Full access
Chinnawat Surussavadee and David H. Staelin

window channels over ocean also yield water path information, but multiple channels are required to help distinguish the effects of water vapor and ocean roughness from absorption by water droplets. The instrument of primary interest in this paper, AMSU, scans cross track with only a single angle-dependent polarization. The altitude distributions of hydrometeors can be inferred, for example, using the opaque oxygen band channels near 54, 118, and 425 GHz. Only frequencies penetrating down to cell

Full access
Peter M. Norris and Arlindo M. da Silva

, discussed above is for the nonconvective fraction of the grid cell assuming saturation in the convective fraction. The in-cloud condensate water content, ρ c , is also diagnostic: an exponential decay with height above surface with a scale height dependent on the local column integrated water vapor amount—total precipitable water (TPW)—in kg m −2 . Namely, The standard CCM3 uses globally uniform values ρ cs = 0.21 g m −3 and h c 0 = 700 m. The in-cloud condensate water path, Γ c ≡ ∫ ρ c dz

Full access
Philippe Lopez

a scheme with two prognostic variables (cloud liquid water plus vapor on the one hand, and total ice on the other hand) in the Met Office’s Unified Model. Lopez (2002) proposed a parameterization of large-scale moist processes with one prognostic variable for cloud condensate (liquid plus ice) and another for precipitation (rain plus snow) that can be used in NWPMs and data assimilation. In contrast to the previous statistical schemes in which the assumed total water distribution was

Full access
Arthur Y. Hou and Sara Q. Zhang

assimilation of rain-affected microwave radiances at ECMWF, channels that are more sensitive to scattering by model-generated solid precipitation are not used ( Moreau et al. 2004 ). Precipitation assimilation using the model as a strong constraint can also produce moisture fields in conflict with other types of observation such as total column water vapor ( Lopez et al. 2006 ). Yet, the ability to use precipitation information to improve analysis products is important since the representation of the

Full access