MWR and MWR3C data during MAGIC

M. P. Cadeddu Argonne National Laboratory

First MAGIC Science Workshop, May 5-7, 2014, Brookhaven National Laboratory, Upton, NY, 11973

OVERVIEW

• Overview of MWR and MWR3C instruments

• Data availability

• Instrument calibration

• Retrievals

• Summary

MWR and MWR3C

MWRMWR3C MWR3C rain sensor

MWR

2- frequencies: 23.8 and 31.4 GHzNo azimuth scanningTime resolution ~ 1/20 s in LOS mode and ~1/50s in tip modeCalibration performed using ‘tip curves’Measurements: Sky brightness temperaturesPhysical quantities: Retrieved precipitable water vapor and liquid water path

MWR3C

3- frequencies: 23.834, 30, 89 GHzTime resolution ~ 1/20 s - Azimuth scanning possibleCalibration performed using ‘tip curves’Measurements: Sky brightness temperaturesPhysical quantities: Retrieved precipitable water vapor and liquid water path. Increased sensitivity to small amounts of liquid water.Embedded accelerometer for accurate pointing readings

DATA AVAILABILTIY

MWR

MWR3C: No data until 2012/11/15

CALIBRATION

The MWR and MWR3C use the cloudless sky as a reference to calibrate the noise diode.

Calibration is achieved by plotting airmass vs. opacity and extrapolating the line to airmass zero. Bilateral scan to collect points at different airmasses.

The radiometer needs to be leveled and the pointing accuracy needs to be know within fractions of degrees.

MWR CALIBRATION (continued…)

Mounting the radiometer on a ship causes multiple negative effects due to:

1) Ship listing 2) Ship movement (pitch, roll)

Listing cannot be easily corrected but its effect can be minimized by frequently checking the alignment of the radiometer. Its effect is a deterioration in the calibration.

Expecte

d pointing during ca

libration sc

an

Actual pointing during calibration scan

• Pitch and roll can be corrected if navigation data are available.

• New calibration software was developed to post-processed the data when the navigation data were available.

• Because the MWR needs to scan to low angles we couldn’t use the small angle approximation (θ=p2+r2).

CALIBRATION (continued…)

p

y

r

V

X

Y

Z

Vo

0

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v=YPRv0 Y=0

MWR CALIBRATION (continued…)

Equivalent zenith brightness temperature difference between two sides of the scan

RETRIEVALS

ARM provides statistical and physical retrievals of LWP and PWV

Statistical retrievals available in real-time.• MWR linear regression • MWR3C neural network

Physical retrievals MWRRET (not yet available for MAGIC)

PWV RETRIEVALS

MWR STAT

MWR3C NN-Archive

MWR3C NN-reproc

LWP RETRIEVALS-ALL

MWR STAT

MWR3C NN-Archive

MWR3C NN-reproc

LWP RETRIEVALS CLEAR SKY

MWR STAT

MWR3C NN-Archive

MWR3C NN-reproc

RAIN MITIGATION

RAIN MITIGATION (continued)

SUMMARY

MWR and MWR3C data available through most of the deployment

Calibration was corrected for the MWR the MWR3C has embedded accelerometer

MWR statistical retrievals (mwrlos) have high uncertainty (flagged yellow)

MWR3C NN neural network retrievals will be reprocessed with new NN coefficients

Physical retrievals MWRRET are not yet available for MAGIC (may be available upon request from PI)

Care should be used when data are used during rain

For questions or any concern with the data email me mcadeddu@anl.gov

For details on ARM microwave radiometer:

M.P. Cadeddu, J.C. Liljegren, D.D. Turner: The Atmospheric Radiation Measurement (ARM) program network of microwave radiometers: instrumentation, data, and retrievals, Atmos, Meas. Tech., 6, 2359-2372, 2013.

THANK YOU