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Prior datasets are essential in cloud microphysics, serving as independent datasets that establish relationships between measured and retrieved cloud properties, such as liquid water content (LWC) and ice water content (IWC). These datasets help ascertain the parameters necessary for computations involving particle size distributions (PSD) and directly influence the uncertainty in retrieved cloud properties. This document also discusses methods for parameterization, the development of in-situ measurement techniques, and the need for sharing and evaluating prior datasets to enhance our understanding of cloud properties and their uncertainties.
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Prior Information Datasets Jennifer Comstock JulienDelanoë
What are prior datasets? • Prior datasets are any independent datasets used to develop relationships between measured quantities and retrieved quantities LWC=aZb • The slope ‘a’ and exponent ‘b’ are determined using prior measurements or simulations • Prior datasets directly influence the uncertainty in retrieved cloud properties
Example of normalized PSD Delanoë and Hogan (2008) Delanoë et al. (2013)
How do we define M(D) and A(D)? • M(D) is required to compute IWC and reflectivity from PSD • A(D) is required to compute extinction and terminal fall velocity from PSD M(D)=aDb A(D)=cDd What sort of parameterisation can we use? Can we link a and b and c and d to reduce the degree of freedom? Heymsfield, a and b can be parameterised using T°C
Relationshipsbetweenice PSD moments Delanoë et al. (2013)
How canweget good CWC measurementsfrom in-situ? • New probes? • IKP? • Colorado Laser Hygrometer (CLH) – L. Avallone • Cloud Spectrometer & Impactor (CSI) – DropletMeasurements • CWC using radar and PSD measurementsduring DYNAMO campaign (Fontaine et al.)
Other Datasets • Common input datasets (temporal and spatial resolutions) • Well characterized evaluation datasets (i.e. surface and TOA flux measurements) • Other assumptions • Extinction-to-backscatter ratio • Single-scattering properties • …. Assumptions for scattering properties for aggregates (T-Matrix) Hogan et al. 2012
Needs • Understanding and quantifying uncertainty in prior datasets • Developing common methods for formulating prior datasets • Prior datasets as a function of altitude, temperature, extinction, reflectivity? • Accurate measurements of bulk LWC and IWC • Repository for sharing prior datasets • Others?
Discussion Topics • What quantities are well constrained? • What measurements are highly uncertain? • What measurement gaps exist for developing prior datasets?
