1 The RadOn method and associated error analysis Delanoë J., Protat A., Bouniol D., Testud J. C entre d’étude des E nvironnements T errestre et P lanétaires CloudNET meeting : Paris Julien Delanoë 4/5 th April 2005

2 Outline Rad ar On ly Algorithm Error analysis Retrieval

3 Radar Only Algorithm RadOn Principle of the radar retrieval method

4 Principle of the Radar Algorithm (1) Z Doppler Velocity V d =V t +w  Density law and Area diameter relationships D m (V t ) N 0 * =f(D m,Z) IWC, , r e  V t retrieval

5 First step : Retrieval of V T from V D V d =w+V t Hypothesis (*) : for a long enough time span 2 methods: V t -Z : Statistical relationship between V d and Z Assuming (*), we obtain V t from Z (V t =aZ b ) New approach Running Window: Every 30s we compute the mean V d over ±10 minutes (like Matrosov) for each radar gate.

6 Running Window (20min) Advantages: Better resolution than Matrosov method More variability of V t than V t -Z But instability of RadOn when V t <5cm.s -1 V t from V t -Z relationship 04/14/03 Palaiseau Retrieval of terminal fall velocity with different methods

7 Principle of the Radar Algorithm (2) Z Doppler Velocity V d =V t +w  Density and Area diameter relationships D m (V t ) N 0 * =f(D m,Z) IWC, , r e  V t retrieval

8 Principle of the radar retrieval method (2) Second step : estimate of the particle density  (D) and area A(D) from V T -Z relationship V t -Z relationship obtained from radar is compared to microphysical V t -Z relationships with different density and area laws. Microphysical V t -Z relationships :  (D)=a  D b  and v(D)=f(m(D),A(D),a d,b d ) (Mitchell 1996) Where m(D)=(  /6) a  D 3+b , A=  D  and a d, b d are the continuous drag coefficients (Khvorostianov and Curry 2002). From coefficients of V t -Z radar relationship we estimate the best density diameter and area diameter relationships.

9 Example : 04/14/2003 Palaiseau black: V t -Z obtained by the radar red: The best density and Area relationships

10 Principle of the Radar Algorithm (3) Z Doppler Velocity V d =V t +w  Density and Area diameter relationships D m (V t ) N 0 * =f(D m,Z) IWC, , r e  V t retrieval Step unchanged (see Delft presentation)

11 Principle of the Radar Algorithm (4) Z Doppler Velocity V d =V t +w  Density law and Area diameter relationships D m (V t ) N 0 * =f(D m,Z) IWC, , r e  V t retrieval Step unchanged (see Delft presentation) Direct relationship:

12 Principle of the Radar Algorithm (5) Z Doppler Velocity V d =V t +w  Density and Area diameter relationships D m (V t ) N 0 * =f(D m,Z) IWC, , r e  V t retrieval

13 Clouds parameters Using D m N 0 * and Gamma shape => Clouds parameters

14 Evaluation of RadOn using the microphysical database

15 Evaluation of RadOn using the microphysical database Dataset: CLARE 98, CARL 99, EUCREX, ARM SGP, FASTEX, CEPEX, CRYSTALFACE We impose a density law and area diameter relationships for a radar at 35 and 95GHz: A(D)=  D  with several couples of coefficients  (D)=aD b with several couples of coefficients We compute V t, Z, IWC,  and re from the in- situ measurements, assuming A(D) and  (D) RadOn Algorithm IWC, , r e from RadOnIWC, , r e micro  Entries of the algorithm :Vt and Z e from in situ data

16 bias bias + std bias - std 4 « Density diameter relationships »: b=-1.4, -1.1, -0.8, « Area diameter relationships»

17 bias bias + std bias - std

18 bias bias + std bias - std

19 RadOn Retrieval: 14th April 2003: Palaiseau Deep ice cloud 15th April 2003: Palaiseau Cirrus case

20 Retrieval 14 th April 2003 IWC rere N0*N0*   (D)=0.022D -0.6 A(D)=  /4D 2

21 Retrieval 15 th April 2003 IWC rere N0*N0*   (D)=0.0005D -1.3 A(D)=  D 1.4

22 Future work Refine the error analysis Run Radon on all the CloudNET sites, for all frequencies Statistical study of density, IWC, , r e …. Comparison with Radar/Lidar and other Radar algorithm

23 IWC retrieval from different method 1.RadOn with running window 2.RadOn with Vt-Z 3.IWC-Z-T R.J Hogan 4.IWC-Z Protat et al.

24 With running windowV t -Z IWC-Z-T RJHIWC-Z Protat et al

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