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Morrison-Gettelman Reflectivity Calculation #473

Open tsupinie opened 4 years ago

tsupinie commented 4 years ago

I modified the Morrison-Gettelman microphysics code to output reflectivity using the existing calculation, and the output field doesn't look realistic. It has large areas of 75+ dBZ and peaks well over 100 dBZ. Outside of the 70+ dBZ areas, there are also no areas of 30 dBZ+. Here's an example image:

mg_refl

So I've been digging into the scheme and the reflectivity calculation associated with it, and I've noticed a few oddities.

  1. It appears that the absurd reflectivity values come from the qi reflectivity, the calculation for which is here: https://github.com/NCAR/ccpp-physics/blob/01c2257ab1538b3e9a51fed5a5b10f4dda5bfddf/physics/micro_mg3_0.F90#L4396 In particular, it's divided by the precip fraction which in the default configuration is either 1 or 10^-6. So in areas where precip fraction is 10^-6, that's a free 60 dBZ, which seems a little weird for cloud ice.

  2. It doesn't appear that rain is used in the reflectivity calculation. There is a block that calculates the contribution from rain via rain rate here: https://github.com/NCAR/ccpp-physics/blob/01c2257ab1538b3e9a51fed5a5b10f4dda5bfddf/physics/micro_mg3_0.F90#L4413-L4423 However, the rainrt variable is never set to anything other than 0, so the else branch is always taken here.

The source for the reflectivity calculations in the code is just given as a person, with no other documentation, so I'm not sure how to proceed from here.

(I realize there's probably a reason that reflectivity isn't output in the repository code, and that reason may be that that's a known issue.)

climbfuji commented 4 years ago

@SMoorthi-emc @junwang-noaa @AnningCheng-NOAA for your information

SMoorthi-emc commented 4 years ago

Dom, This is clearly a bug. I have never looked at reflectivity in this scheme, thus never caught this. We will have to look in the original version of MG3 to see if this bug was there or if we introduced it. Maybe Anning knows. Moorthi

SMoorthi-emc commented 4 years ago

Well, I looked at the original code we received. The bug is already there.

SMoorthi-emc commented 4 years ago

The above comments are about rainrt.

climbfuji commented 4 years ago

The above comments are about rainrt.

Thanks, Moorthi, for looking into this. Something to clean up in the future!

AnningCheng-NOAA commented 4 years ago

I agree with moorthi. The bug was there when MG3 had been delivered and we have not got time to work on the reflectivity.

On Fri, Jul 10, 2020 at 8:45 PM SMoorthi-emc notifications@github.com wrote:

The above comments are about rainrt.

— You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub https://github.com/NCAR/ccpp-physics/issues/473#issuecomment-656952354, or unsubscribe https://github.com/notifications/unsubscribe-auth/ALQPMIIYMIVWBL4SMEXY2YDR26Y3PANCNFSM4OW5HWEA .

climbfuji commented 3 years ago

@AnningCheng-NOAA @SMoorthi-emc we are doing some housekeeping, have you had a chance to look at this issue?

AnningCheng-NOAA commented 3 years ago

Yes, I do..

On Fri, May 14, 2021 at 5:32 PM Dom Heinzeller @.***> wrote:

@AnningCheng-NOAA https://github.com/AnningCheng-NOAA @SMoorthi-emc https://github.com/SMoorthi-emc we are doing some housekeeping, have you had a chance to look at this issue?

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dustinswales commented 2 years ago

@AnningCheng-NOAA @SMoorthi-emc Any updates on this issue? (I know MG is not used in any of the currently supported physics suites, so I'm not sure if this is even an issue anymore?)

SMoorthi-emc commented 2 years ago

Dustin, I haven't seen any updates; I don't know much about reflectivity calculations. I don't know if Anning has added anything. Nevertheless, reflectivity is just a diagnostic quantity - it does not interact with the forecast. I assume someone could add this code. Moorthi

On Fri, Aug 19, 2022 at 5:01 PM dustinswales @.***> wrote:

@AnningCheng-NOAA https://github.com/AnningCheng-NOAA @SMoorthi-emc https://github.com/SMoorthi-emc Any updates on this issue? (I know MG is not used in any of the currently supported physics suites, so I'm not sure if this is even an issue anymore?)

— Reply to this email directly, view it on GitHub https://github.com/NCAR/ccpp-physics/issues/473#issuecomment-1221089116, or unsubscribe https://github.com/notifications/unsubscribe-auth/ALLVRYTS2FBUJN7PNYDKTJTVZ7YYVANCNFSM4OW5HWEA . You are receiving this because you were mentioned.Message ID: @.***>

-- Dr. Shrinivas Moorthi Research Meteorologist Modeling and Data Assimilation Branch Environmental Modeling Center / National Centers for Environmental Prediction 5830 University Research Court - (W/NP23), College Park MD 20740 USA Tel: (301)683-3718

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AnningCheng-NOAA commented 2 years ago

Jili had added radar reflectivity for MG3 in RRFS, but nobody has had time to work on it in UFS. I have no idea when I will get time to work on this.

On Fri, Aug 19, 2022 at 7:31 PM SMoorthi-emc @.***> wrote:

Dustin, I haven't seen any updates; I don't know much about reflectivity calculations. I don't know if Anning has added anything. Nevertheless, reflectivity is just a diagnostic quantity - it does not interact with the forecast. I assume someone could add this code. Moorthi

On Fri, Aug 19, 2022 at 5:01 PM dustinswales @.***> wrote:

@AnningCheng-NOAA https://github.com/AnningCheng-NOAA @SMoorthi-emc https://github.com/SMoorthi-emc Any updates on this issue? (I know MG is not used in any of the currently supported physics suites, so I'm not sure if this is even an issue anymore?)

— Reply to this email directly, view it on GitHub <https://github.com/NCAR/ccpp-physics/issues/473#issuecomment-1221089116 , or unsubscribe < https://github.com/notifications/unsubscribe-auth/ALLVRYTS2FBUJN7PNYDKTJTVZ7YYVANCNFSM4OW5HWEA

. You are receiving this because you were mentioned.Message ID: @.***>

-- Dr. Shrinivas Moorthi Research Meteorologist Modeling and Data Assimilation Branch Environmental Modeling Center / National Centers for Environmental Prediction 5830 University Research Court - (W/NP23), College Park MD 20740 USA Tel: (301)683-3718

e-mail: @.*** Phone: (301) 683-3718 Fax: (301) 683-3718

— Reply to this email directly, view it on GitHub https://github.com/NCAR/ccpp-physics/issues/473#issuecomment-1221168696, or unsubscribe https://github.com/notifications/unsubscribe-auth/ALQPMIM3DN2V2CYJACHRFXTV2AKMFANCNFSM4OW5HWEA . You are receiving this because you were mentioned.Message ID: @.***>