This document describes the development of a neural network (NNET) to retrieve ice water path (IWP) from radar and satellite data. The NNET has a final configuration of 3 hidden layers with [16 14 12] neurons. It was trained on radar and geostationary satellite data and evaluated for its ability to generalize IWP retrievals to new areas. Statistical analyses and example retrievals show the NNET can estimate IWP with a median difference of -0.3g/m2 compared to targets, though differences range from -300 to +454g/m2 for 50% of cases.

1. NeuralNetwork from RADS to IWP NNET_LOGIWP/
• Final status : 3HL of [16 14 12] neurones
• Learning Data Base = RASTA radar 95GhZ IWC (here cumulated from Z=9km)
and MTSAT GEO 10.8, 12, 6.8 IR channels & 3.8 WV
• Statistical criteria on NNET performances
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Fig 1. Boxplots 0-1; 1-2; 2-4
and 4-40 kg/m2
Fig 2. Boxplots overall 0-40 kg/m2
median difference : Output - Target
IWP=-0.3g/m2 !!
50% of differences range in [-300;+454g/m2]
Fig 3. ECDF Output (black)
vs Target IWP (blue)

2. F01 - 20140116 HL=[16 14 12]
on RASTA scan Z>=9km, IWP<2 kg/m2
1D fitting Output (red) vs Target (blue)
Output filled : Y*0.9 to Y*1.1
0 MIS wr 2kg.m-2
0 FA
10/10
F01MT18 NNET 2D generalization HIWP
Areas with IWP>500g/m^2
MTSAT Radiance 1 map derived :
Areas with Rad1<1.25 (black) &Rad1<0.9(grey)
F09 – 20140128 HL=[16 14 12]
Peak-to-valley phase ok
F09MT05 2D generalization HIWP
Areas with IWP>500g/m^2
MTSAT Radiance 1 map derived :
Areas with Rad1<1.25 (black) &Rad1<0.9(grey)
1D fitting Output (red) vs Target (blue)
0 MIS
4 FA
08/10
1D fitting : dashed blue=Target, black=Output from NNet 2D generalization from MTSAT Rads images to IWP map!
IWP retrieved map MTSAT RAD1

3. F06 – 20140123 HL=[16 14 12]
on RASTA scan Z>=9km, IWP<2 kg/m2
F06MT27 NNET 2D generalization HIWP
Areas with IWP>500g/m^2
MTSAT Radiance 1 map derived :
Areas with Rad1<1.25 (black) &Rad1<0.9(grey)
1D fitting Output (red) vs Target (blue)
3 MIS
0 FA
07/10
F08 – 20140127 HL=[15 13 11] F08MT14 NNET 2D generalization HIWP
Areas with IWP>500g/m^2
MTSAT Radiance 1 map derived :
Areas with Rad1<1.25 (black) &Rad1<0.9(grey)
1D fitting Output (red) vs Target (blue)
4 MIS
0 FA
08/10

4. F11 – 20140130 HL=[15 13 11]
F11 MT35- 2D generalization HIWP
Areas with IWP>500g/m^2
MTSAT Radiance 1 map derived :
Areas with Rad1<1.25 (black) &Rad1<0.9(grey)
1D fitting Output (red) vs Target (blue)
0 MIS
0 FA range
09/10
F14 – 20140204 HL=[16 14 12] F14 MT18 - 2D generalization HIWP;
Areas with IWP>500g/m^2
MTSAT Radiance 1 map derived :
Areas with Rad1<1.25 (black) &Rad1<0.9(grey)
1D fitting Output (red) vs Target (blue)
1 MIS range
1 FA range
08/10

5. F16 - 20140207. Peak-to-valley in phase F16MT22 NNET 2D generalization HIWP
Areas with IWP>500g/m^2
MTSAT Radiance 1 map derived :
Areas with Rad1<1.25 (black) &Rad1<0.9(grey)
Absolute color scale : 0.5-12kg/m2
1D fitting Output (red) vs Target (blue)
4 MIS
0 FA
07/10
F19 - 20140209 F19MT29 2D generalization HIWP
Areas with IWP>500g/m^2
MTSAT Radiance 1 map derived :
Areas with Rad1<1.25 (black) &Rad1<0.9(grey)
1D fitting Output (red) vs Target (blue)
0 MIS
0 FA
09/10

6. Absolute color scale : 0.5-12kg/m2
F22 - 20140217 F22 MT33 - 2D generalization HIWP;
Areas with IWP>500g/m^2
MTSAT Radiance 1 map derived :
Areas with Rad1<1.25 (black) &Rad1<0.9(grey)
1D fitting Output (red) vs Target (blue)
2 MIS ranges
3 FA ranges
06/10
F23 – 20140116 F23 MT21 2D generalization HIWP
Areas with IWP>500g/m^2
MTSAT Radiance 1 map derived :
Areas with Rad1<1.25 (black) &Rad1<0.9(grey)
1D fitting Output (red) vs Target (blue)
1 MIS
1 FA
08/10