Prior Information Datasets

1. Prior Information Datasets Jennifer Comstock JulienDelanoë

2. 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

3. Example of normalized PSD Delanoë and Hogan (2008) Delanoë et al. (2013)

4. 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

5. Relationshipsbetweenice PSD moments Delanoë et al. (2013)

6. 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.)

9. 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

10. 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?

11. Discussion Topics • What quantities are well constrained? • What measurements are highly uncertain? • What measurement gaps exist for developing prior datasets?

12. Extra Slides

14. IWC Comparisons