Polarization Weather Radar Development from 1970–1995: Personal Reflections
Round 1
Reviewer 1 Report
This manuscript reviews the onset and evolution of ``dual'' polarization radar techniques in the ground based precipitation radar community. The authors have literally written not just this manuscript, but many seminal manuscripts that are decribed here. Some examples follow. First, V.N. Bringi's manuscripts with Thomas Seliga in 1976 and 1978 conceptually ground-breaking manuscripts that allowed for rapid polarization-diverse pulsing schemes for precipitation radars. Since microwave precipitation radars have significantly shorter echo decorrelation times, the techiniques reviewed in this work will likely be viewed favorable for a long time to come. The authors rightfully interpret their methods in the context of applications with longer echo decorrelation times such as Synthetic Aperture Radars. Second, Zrnic's manuscript with Sachidananda in 1986 made a quantitative breakthrough in applying ``Reed's theorem'' in fundamental signal processing to quantitatively benchmark dual-polarization estimators for precipitation radars. This manuscript provided a seminal analysis of the variance of specific differential phase. Among the many memorable ``unique signatures'' in that paper was an equation with so many cross-covariance terms that it took and entire column to fit in ! In the context of such mind-boggling complexity, the authors simplified perspective in this work provides an excellent companion read that sets the stage for the gruelling rigour championed by the authors in the past.
Specific comments follow :
1. Two tech notes written by Rummler in 1968 laid the foundation for Dusan Zrnic's breakthough in 1986. Although this is outside the dates in this manuscript and outside the scope of polarimetry, the authors may consider acknowledging this work.
2. Good to see Roger Chau and Martin being acknowledged in the context of their institutions. The authors do an admirable job in acknowleging developments in contiguous communities such as air-borne radars and fully polarimetric radars. In the spirit of this, I suggest that the authors acknowledge developments in the cloud radar community (such as those championed by Anthony Illingworth). Much like the previous comment, this may be a little after the final date mentioned in the manuscript.
Comments for author File: 
Comments.pdf
Author Response
The authors appreciate the very positive response from the reviewer on our manuscript.
specific comments:
1. We have added 4 references now, two from Rummler, one from Berger and Groginsky and Zrnic (1977) in lines 603-604 of the revised version ie [109-112].
"In both [107, 108] the authors drew on important works concerning pulse pair estimators of Doppler velocities [109-112] to obtain the statistics of the polarimetric variables (ZDR, Φdp)."
2. Early on in Section 2 we describe Matrosov's work using a 35 GHz cloud radar for detection of ice crystal types using elliptical depol ratio. We are not aware of any seminal work in use of dual-polarization radar in cloud physics prior to 1995.
Reviewer 2 Report
This paper is an historical and highly technical tutorial account of the development of polarization diversity weather radar technology and applications for research and operations. It will be a useful and comprehensive reference for specialists in the field of polarimetric radar meteorology and for graduate students or others conducting research in the field. It will also be useful for specialists, students, and others involved the the broader areas of weather radar research and applications. Although this paper represents the "Personal Reflections" of the authors, they are highly qualified to comment on the field and have accurately reflected contributions from other experts and labortories. The lists of references is exceptional.
In my opinion the title should be changed to reflect better the content of the paper.
I suggest: "Polarization Weather Radar Development from 1970-1995: Personal Reflections"
Or simply: "Polarization Weather Radar Development from 1970-1995"
The latter title would remove the connotation that the paper's content might be excessively personally biased, which it is not.
Finally I suggest an independent editorial review for language usage. And change the word 'lead" to "led" when using it as the past tense of "lead" wherever it is found in the manuscript. Grammatical usage is quite good and appropriate throughout and requires no revision.
Bob Serafin
Author Response
The authors thank NCAR Director-Emeritus Bob Serafin for his very positive review of our manuscript.
We have changed the title somewhat following his first suggestion:
"Polarization Weather Radar Development from 1970-1995: Personal Reflections"
We have corrected "lead" to "led" as appropriate.
Since the reviewer comments in his concluding sentence that the grammatical usage is quite good throughout and requires no revision, we see no need for an independent review of language usage.
Reviewer 3 Report
Review Comments on atmosphere-630515
Title: Role of electromagnetics in polarization radar development from 1970-1995: Personal reflections
Comments: Polarimetry, especially dual-polarization technique, is the most important and revolutionary step in weather radar applications. This paper presents a very nice summary of the key institutions and personnel responsible for the development of weather radar polarimetry.
This paper is very helpful for the new generation weather radar engineers, hydrologists, and meteorologists to understand the original contribution in this field and possibly move forward with new technologies. I strongly recommend acceptance of this manuscript.
Following are a few very minor comments that require further clarifications in the revision.
-> Please expand the acronyms such as AMS, DSD, RHI, etc. at their first appearances.
-> Line 521: …and testing advanced technology for weather applications.
I would recommend using “advanced radar technology” since NOAA has many other critical missions which are not facilitated at NSSL.
-> I understand this paper is mainly summarizing the development of weather radar polarimetry, which is currently operational. I still think adding a brief discussion of future directions/challenges (or shortcomings of current implementation of dual-polarization technique) will be helpful. Also, I would suggest the authors consider expanding the summary to 50 years (i.e., 1970-2020). The authors are more than qualified to do this! It is sad that many general readers or even meteorologists/hydrologists do not even know where the dual-polarization technique was original from.
Author Response
We are pleased by the very positive comments made by the reviewer on our manuscript.
Response to minor comments:
We have expanded the acronyms at their first appearance. We have re-phrased the NSSL mission as:
"The NSSL is the research arm of the US National Weather Service (NWS) with the mission of advancing the understanding of weather processes, research to improve forecasting and warning techniques, and development of operational applications. NSSL is NOAA's primary radar laboratory for advancing radar technology, the prime example being NSSL’s role leading up to the deployment of the WSR-88D Doppler systems (NEXRAD) by the NWS."
3.
In our conclusions we have discussed the role of dual-pol radar in numerical models that predict physical properties in bulk manner or in terms of superparticles. We also comment on the new push for Lagrangian modeling. In terms of future directions phased array technology has not, in our opinion, met the quality of dual-pol data needed for National Weather Service products. Since our review stops in the mid-1990s we did not add anymore on future challenges. The main shortcoming of the "hybrid" mode is cross-coupling error which has been known for a long time. This error (for an ideal antenna system) manifests itself mainly in regions of ice crystals which have a mean orientation angle which is nearly constant along the propagation path (say > 10 deg) and the differential propagation phase is also large. For a non-ideal antenna it depends on the cross-polar lobes ie whether the peak xpol occurs at boresight or if it occurs off boresight as 4 symmetric lobes (for prime-focus fed parabolic reflector antennas) with a deep minimum at boresight. These issues came up much later than mid-1990s so we did not include it.
Regarding extending the review to 2020: it is beyond the scope of this review paper.
