EPIC Radar and Sounding Sampling Strategy

 

Radar

The C-band radar on-board the R.V. Ronald H. Brown was operated 24 hours/day during the EPIC ITCZ leg from 22:00 UTC on the 9th of September until 00:20 UTC on 2 October, 2001. The scanning strategy utilized a continuous 10 minute cycle with the following sequence:

1. 360° Rain scan

2. 360° Volume scan (FAR, EVAD, or NEAR)

3. RHI 's (optional)

 

Details on each radar scan are provided in the tables below.

 

Scan: Rain

 Angles (°)  0.5, 1.3, 2.1
 Resolution (°)  1.0
 Pulse Width (usec)  2.0
 Antenna Speed (°/sec)  18
 Sampled Variables  T, Z, V, W
 Number of Samples  55
 Number of Bins  1200
 Gate spaceing (m)  250
 Max Range (km)  300
 PRF (/s)  500
 Unambiguous Velocity (m/s)  6.7
 Major Mode  PPP
 Variable Thresholds  T: LOG, Z: LOG&CSR, V:SQI&CSR, W: SIG&SQI&LOG
 LOG (dB)  0.8
 SIG (dB)  10
 CSR (dB)  18
 SQI  0.4
 Speckle  Z on, V on

Scan: FAR

 Angles (°)  0.5, 1.3, 2.1, 2.9, 3.6, 4.5, 5.4, 6.4, 7.4, 8.5, 9.8, 11.2, 12.8, 14.8, 16.8, 19.2, 22.2, 26.0, 30.0, 35.0
 Resolution (°)  1.0
 Pulse Width (usec)  1.2
 Antenna Speed (°/sec)  18
 Sampled Variables  T, Z, V, W
 Number of Samples  55
 Number of Bins  600
 Gate spaceing (m)  250
 Max Range (km)  150
 PRF (/s)  910
 Unambiguous Velocity (m/s)  12.2
 Major Mode  RPHASE
 Variable Thresholds  T: LOG, Z: LOG&CSR, V:SQI&CSR, W: SIG&SQI&LOG
 LOG (dB)  0.8
 SIG (dB)  10
 CSR (dB)  18
 SQI  0.4
 Speckle  Z off, V off

Scan: EVAD

 Angles (°)  0.8, 1.5, 3.2, 5.5, 7.9, 10.3, 12.7, 15.1, 17.6, 20.0, 22.6, 25.1, 27.8, 30.5, 33.2, 36.1, 39.1, 42.2, 45.4, 48.9, 53.4
 Resolution (°)  1.0
 Pulse Width (usec)  1.2
 Antenna Speed (°/sec)  18
 Sampled Variables  T, Z, V, W
 Number of Samples  55
 Number of Bins  600
 Gate spaceing (m)  250
 Max Range (km)  150
 PRF (/s)  910
 Unambiguous Velocity (m/s)  12.2
 Major Mode  RPHASE
 Variable Thresholds  T: LOG, Z: LOG&CSR, V:SQI&CSR, W: SIG&SQI&LOG
 LOG (dB)  0.8
 SIG (dB)  10
 CSR (dB)  18
 SQI  0.4
 Speckle  Z off, V off

Scan: NEAR

 Angles (°)  0.5, 1.3, 2.1, 3.0, 4.2, 5.7, 7.4, 9.0, 11.0, 15.0, 18.0, 22.0, 26.0, 30.0, 34.0, 39.0, 44.0, 50.0, 55.0, 60.0
 Resolution (°)  1.0
 Pulse Width (usec)  1.2
 Antenna Speed (°/sec)  18
 Sampled Variables  T, Z, V, W
 Number of Samples  55
 Number of Bins  600
 Gate spaceing (m)  250
 Max Range (km)  150
 PRF (/s)  910
 Unambiguous Velocity (m/s)  12.2
 Major Mode  RPHASE
 Variable Thresholds  T: LOG, Z: LOG&CSR, V:SQI&CSR, W: SIG&SQI&LOG
 LOG (dB)  0.8
 SIG (dB)  10
 CSR (dB)  18
 SQI  0.4
 Speckle  Z off, V off


Upper Air Sounding

Vaisala soundings were launched 6 times/day from the fantail of the ship. The nominal launch times (i.e., approximate times when the sounding reached the tropopause) were:

 Time (UTC)  Time (L)
 00:00  18:00
 04:00  22:00
 08:00  02:00
 12:00  06:00
 16:00  10:00
 20:00  14:00

Note -the actual release time was approximately 1.25 hours prior to the nominal launch time. For example, the 00:00 UTC (18:00 L) sounding was actually released at about 22:45 UTC (16:45 L).

 

 

 

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