Adding Ristic convection scheme

[Nikolar97]

TYPE: New feature
KEYWORDS: convection, forecast, cloud, precipitation
SOURCE: Ivan Ristic (Weather2 - www.weather2.rs)
DESCRIPTION OF CHANGES:

To improve cloud and precipitation forecast we developed new convective scheme and we implemented it in WRF model. Convective clouds have always been a great challenge for meteorologists, among other things, due to the inability to describe processes of cloud formation, development and dissipation in a satisfactory manner. Applying parameterization in to the models has lead to simpler form of equations that could be used in practice, and thus different types of convective schemes in numerical weather prediction models appeared. Proposed convective scheme is based on basic elements that affect convection such as convective available potential energy (CAPE), vertical velocity at the base of the cloud, the amount of ice in the cloud and important assumptions. The scheme is conceived as a wet vertical turbulent diffusion and a logical continuation of dry vertical planetary boundary layer (PBL) turbulent diffusion. The scheme determines the vertical levels in the model where the convective cloud begins and ends. Integrated in the model this scheme showed good results in practice.

A complete description is now found in Ristic I., Kordic I., April 2022: Convective velocity scale and its application in convective parameterization
which can be found at ResearchGate:
https://www.researchgate.net/publication/359716993_Convective_velocity_scale_and_its_application_in_convective_parametrization

LIST OF MODIFIED FILES:
Registry/Registry.EM_COMMON
phys/Makefile
phys/module_cu_ristic.F
phys/module_cumulus_driver.F
phys/module_physics_addtendc.F
phys/module_physics_init.F

TESTS CONDUCTED:
Test 1 ( Naples, Italy 11th August, 2016)
Night summer convection developed in Tyrrhenian sea moved slowly toward east and arrived around 12 UTC to the city of Naples, (Figure 1). Convection and clouds over Naples can be seen both on the cloud maps from the model as well as from satellite images and they correspond well (Figure 2 and Figure 3).

Figure 1. (WRF Ristic micro+conv scheme, precipitation from 06-12 UTC, 11.8.2016.)

Figure 2. ( WRF Ristic micro+conv scheme clouds at 12 UTC, 11.8.2016.) Figure 3. (Satelite image 11.8.2016., sat24.com)

Test 2 ( Sicily, Italy 8th September, 2017)
Mix of stratiform and convective clouds formed over Mediterranean sea (between Sicily and Africa) and caused precipitation over Sicily that lasted for couple of hours.This situation was forecasted well with proposed scheme (Figure 4). The cloud cover from the model with proposed convective scheme (Figure 5) correspond well with the satellite image (Figure 6).

Figure 4. (WRF Ristic micro+conv scheme, precipitation from 12-18 UTC, 8.9.2017.)

Figure 5. (WRF Ristic micro+conv scheme clouds at 12 UTC, 8.9.2017.) Figure 6. (Satelite image 12 UTC , 8.9.2017., sat24.com)

[dudhia]

@weiwangncar check if this passed the tests. Note that this is a convection scheme, different from the microphysics that is already contributed.

[weiwangncar]

This PR passes the regression test:

Test Type              | Expected  | Received |  Failed
= = = = = = = = = = = = = = = = = = = = = = = =  = = = =
Number of Tests        : 23           24
Number of Builds       : 60           58
Number of Simulations  : 158           156        0
Number of Comparisons  : 95           92        0

Failed Simulations are: 
None
Which comparisons are not bit-for-bit: 
None