Liquid Water Path (LWP): UWisc climatology
"This work describes a new climatology of cloud liquid water path (LWP), termed the University of Wisconsin (UWisc) climatology, derived from 18 yr of satellite-based passive microwave observations over the global oceans. The climatology is based on a modern retrieval methodology applied consistently to the Special Sensor Microwave Imager (SSM/I), the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI), and the Advanced Microwave Scanning Radiometer (AMSR) for Earth Observing System (EOS) (AMSR-E) microwave sensors on eight different satellite platforms, beginning in 1988 and continuing through 2005. It goes beyond previously published climatologies by explicitly solving for the diurnal cycle of cloud liquid water by providing statistical error estimates, and includes a detailed discussion of possible systematic errors." (O'Dell et al, 2008)
Key Strengths
Explicitly solves for the diurnal cycle of cloud liquid water
Solutions work well with boundary layer clouds.
Includes Error estimates.
Key Limitations
Solutions do not work as well for deep convection.
Method is sensitivity to cloud+rain liquid water
Expert Developer Guidance
From the README: The diurnal cycle is assumed to a be function of month and location on the global
only. For example, we assume that, for a given location, the diurnal cycle
is the same in every January, but the diurnal cycle for January may be
different from that of February for the same location. For each 1x1 degree
grid box, the diurnal cycle has been fit to the following form:
LWP(t) = M + A1 cos(t-T1) + A2 cos 2(t-T2)
leading to a total of five fit parameters in all. For some pixels with not very
much data, the cos 2(t-T2) term was left out, so a single sinuosoid was used in
the fit. For pixels and months in complete darkness, it is assumed that there
is no diurnal cycle, so only the "M" parameter was determined. (O,Dell, U. Wisc)
Key Figures
Total cloud liquid water path (July 1998) and estimated 1-sigma error. (Climate Data Guide; D. Shea)
Top: LWP at ~186E longitude. Bottom: LWP from 120E-360E at 5.5N latitude. (Climate Data Guide; D. Shea)
Other Information
1x1
- O’Dell, Christopher W., Frank J. Wentz, Ralf Bennartz, 2008: Cloud Liquid Water Path from Satellite-Based Passive Microwave Observations: A New Climatology over the Global Oceans. J. Climate, 21, 1721–1739
- Wentz, F. J., 1997: A well-calibrated ocean algorithm for special sensor microwave imager. J. Geophys. Res., 102, 8703–8718