scholarly journals Incorporation of inline warm-rain diagnostics into the COSP2 satellite simulator for process-oriented model evaluation

2019 ◽  
Author(s):  
Takuro Michibata ◽  
Kentaroh Suzuki ◽  
Tomoo Ogura ◽  
Xianwen Jing
Keyword(s):  
Regional Analysis ◽  
Model Performance ◽  
Multiple Model ◽  
Climatic Impact ◽  
Process Diagnostics ◽  
Post Process ◽  
Warm Rain ◽  
Process Oriented ◽  
Warm Rain Process ◽  
Microphysical Processes

Abstract. Cloud Feedback Model Intercomparison Project Observational Simulator Package (COSP) has been widely used to diagnose model performance and physical processes via an apple-to-apple comparison to satellite measurements. Although the COSP provides useful information about clouds and their climatic impact, outputs that have a subcolumn dimension require large amounts of data. This can cause a bottleneck when conducting sets of sensitivity experiments or multiple model intercomparisons. Here, we incorporate two diagnostics for warm-rain microphysical processes into COSP2, the latest version of the simulator. The approach used here employs existing diagnostic methodologies that probe how the warm-rain processes occur using statistics constructed from simulators of multiple satellite instruments along with their subcolumn information. The new diagnostics are designed to produce statistics online during the COSP execution, eliminating the need to output subcolumn variables. Users can also readily conduct regional analysis tailored to their particular research interest (e.g., land–ocean differences), using an auxiliary post-process package after the COSP calculation. This inline tool also generates global maps of the occurrence frequency of warm-rain regimes (i.e., non-precipitating, drizzling, and precipitating) classified according to CloudSat radar reflectivity, putting the warm-rain process diagnostics into the context of geographical distributions of precipitation. The inline diagnostics are applied to the MIROC6 GCM to demonstrate how known biases common among multiple GCMs relative to satellite observations are revealed. The inline multisensor diagnostics are intended to serve as a tool that facilitates process-oriented model evaluations in a manner that reduces the burden on modelers for their diagnostics effort.

scholarly journals Incorporation of inline warm rain diagnostics into the COSP2 satellite simulator for process-oriented model evaluation

2019 ◽  
Vol 12 (10) ◽  
pp. 4297-4307 ◽  
Author(s):  
Takuro Michibata ◽  
Kentaroh Suzuki ◽  
Tomoo Ogura ◽  
Xianwen Jing
Keyword(s):  
Optical Depth ◽  
General Circulation ◽  
Regional Analysis ◽  
Circulation Model ◽  
Radar Reflectivity ◽  
Multiple Model ◽  
Climatic Impact ◽  
Warm Rain ◽  
Process Oriented ◽  
Warm Rain Process

Abstract. The Cloud Feedback Model Intercomparison Project Observational Simulator Package (COSP) is used to diagnose model performance and physical processes via an apple-to-apple comparison to satellite measurements. Although the COSP provides useful information about clouds and their climatic impact, outputs that have a subcolumn dimension require large amounts of data. This can cause a bottleneck when conducting sets of sensitivity experiments or multiple model intercomparisons. Here, we incorporate two diagnostics for warm rain microphysical processes into the latest version of the simulator (COSP2). The first one is the occurrence frequency of warm rain regimes (i.e., non-precipitating, drizzling, and precipitating) classified according to CloudSat radar reflectivity, putting the warm rain process diagnostics into the context of the geographical distributions of precipitation. The second diagnostic is the probability density function of radar reflectivity profiles normalized by the in-cloud optical depth, the so-called contoured frequency by optical depth diagram (CFODD), which illustrates how the warm rain processes occur in the vertical dimension using statistics constructed from CloudSat and MODIS simulators. The new diagnostics are designed to produce statistics online along with subcolumn information during the COSP execution, eliminating the need to output subcolumn variables. Users can also readily conduct regional analysis tailored to their particular research interest (e.g., land–ocean differences) using an auxiliary post-process package after the COSP calculation. The inline diagnostics are applied to the MIROC6 general circulation model (GCM) to demonstrate how known biases common among multiple GCMs relative to satellite observations are revealed. The inline multi-sensor diagnostics are intended to serve as a tool that facilitates process-oriented model evaluations in a manner that reduces the burden on modelers for their diagnostics effort.

scholarly journals On Different Microphysical Pathways to Convective Rainfall

2018 ◽  
Vol 57 (10) ◽  
pp. 2399-2417 ◽  
Author(s):  
Sonia Lasher-Trapp ◽  
Shailendra Kumar ◽  
Daniel H. Moser ◽  
Alan M. Blyth ◽  
Jeffrey R. French ◽  
...  
Keyword(s):  
Wind Shear ◽  
Vertical Wind Shear ◽  
Cloud Droplet ◽  
Vertical Wind ◽  
Convective Precipitation ◽  
Convective Rainfall ◽  
Warm Rain ◽  
Warm Rain Process ◽  
Microphysical Processes ◽  
Ice Production

ABSTRACTThe Convective Precipitation Experiment (COPE) documented the dynamical and microphysical evolution of convection in southwestern England for testing and improving quantitative precipitation forecasting. A strong warm rain process was hypothesized to produce graupel quickly, initiating ice production by rime splintering earlier to increase graupel production and, ultimately, produce heavy rainfall. Here, convection observed on two subsequent days (2 and 3 August 2013) is used to test this hypothesis and illustrate how environmental factors may alter the microphysical progression. The vertical wind shear and cloud droplet number concentrations on 2 August were 2 times those observed on 3 August. Convection on both days produced comparable maximum radar-estimated rain rates, but in situ microphysical measurements indicated much less ice in the clouds on 2 August, despite having maximum cloud tops that were nearly 2 km higher than on 3 August. Idealized 3D numerical simulations of the convection in their respective environments suggest that the relative importance of particular microphysical processes differed. Higher (lower) cloud droplet number concentrations slow (accelerate) the warm rain process as expected, which in turn slows (accelerates) graupel formation. Rime splintering can explain the abundance of ice observed on 3 August, but it was hampered by strong vertical wind shear on 2 August. In the model, the additional ice produced by rime splintering was ineffective in enhancing surface rainfall; strong updrafts on both days lofted supercooled raindrops well above the 0°C level where they froze to become graupel. The results illustrate the complexity of dynamical–microphysical interactions in producing convective rainfall and highlight unresolved issues in understanding and modeling the competing microphysical processes.

An Investigation of Hydrometeor Latent Cooling upon Convective Cold Pool Formation, Sustainment, and Properties

2019 ◽  
Vol 147 (9) ◽  
pp. 3205-3222 ◽  
Author(s):  
Holly M. Mallinson ◽  
Sonia G. Lasher-Trapp
Keyword(s):  
Cold Pool ◽  
Convective Activity ◽  
Dominant Term ◽  
Convective Clouds ◽  
Cold Pools ◽  
Warm Rain ◽  
Warm Rain Process ◽  
Microphysical Processes ◽  
Pool Formation ◽  
Melting Level

Abstract Downdrafts extending from convective clouds can produce cold pools that propagate outward, sometimes initiating new convection along their leading edges. Models operating at scales requiring convective parameterizations usually lack representation of this detail, and thus fail to predict this convective regeneration and longer episodes of convective activity. Developing such parameterizations requires an improved understanding of the physical drivers of cold pools, and detailed studies of the roles of all the contributing microphysical processes have been lacking. This study utilizes a set of 12 simulations conducted within a single convective environment, but with variability in the microphysical fields produced by varying parameters influencing warm-rain or ice processes. Time-integrated microphysical budgets quantify the contribution of each hydrometeor type to the total latent cooling occurring in the downdrafts that form and sustain the cold pool. The timing of the onset of the cold pool is earlier in cases with a stronger warm rain process, but both graupel and rain were equally as likely to be the dominant hydrometeor in the downdraft first forming the cold pool. Graupel sublimation is the dominant term in sustaining the cold pool in all simulations, but the evaporation of rain has the strongest correlation to the cold pool expansion rate, depth, and intensity. Reconciling the current results with past studies elucidates the importance of considering: graupel sublimation, the latent cooling only in downdrafts contributing to the cold pool, and latent cooling in those downdrafts at altitudes that may be significantly higher than the melting level.

scholarly journals Machine Learning the Warm Rain Process

2020 ◽  
Author(s):  
Andrew Gettelman ◽  
David John Gagne ◽  
Chih-Chieh Chen ◽  
Matthew Christensen ◽  
Zachary Lebo ◽  
...  
Keyword(s):  
Machine Learning ◽  
Warm Rain ◽  
Warm Rain Process

scholarly journals Benchmarking and Process Diagnostics of Land Models

2018 ◽  
Vol 19 (11) ◽  
pp. 1835-1852 ◽  
Author(s):  
Grey S. Nearing ◽  
Benjamin L. Ruddell ◽  
Martyn P. Clark ◽  
Bart Nijssen ◽  
Christa Peters-Lidard
Keyword(s):  
Land Surface ◽  
Model Performance ◽  
Land Surface Model ◽  
Surface Model ◽  
Process Diagnostics ◽  
Surface Energy Fluxes ◽  
Structural Error ◽  
Intercomparison Project ◽  
Parameter Values ◽  
Process Level

Abstract We propose a conceptual and theoretical foundation for information-based model benchmarking and process diagnostics that provides diagnostic insight into model performance and model realism. We benchmark against a bounded estimate of the information contained in model inputs to obtain a bounded estimate of information lost due to model error, and we perform process-level diagnostics by taking differences between modeled versus observed transfer entropy networks. We use this methodology to reanalyze the recent Protocol for the Analysis of Land Surface Models (PALS) Land Surface Model Benchmarking Evaluation Project (PLUMBER) land model intercomparison project that includes the following models: CABLE, CH-TESSEL, COLA-SSiB, ISBA-SURFEX, JULES, Mosaic, Noah, and ORCHIDEE. We report that these models (i) use only roughly half of the information available from meteorological inputs about observed surface energy fluxes, (ii) do not use all information from meteorological inputs about long-term Budyko-type water balances, (iii) do not capture spatial heterogeneities in surface processes, and (iv) all suffer from similar patterns of process-level structural error. Because the PLUMBER intercomparison project did not report model parameter values, it is impossible to know whether process-level error patterns are due to model structural error or parameter error, although our proposed information-theoretic methodology could distinguish between these two issues if parameter values were reported. We conclude that there is room for significant improvement to the current generation of land models and their parameters. We also suggest two simple guidelines to make future community-wide model evaluation and intercomparison experiments more informative.

scholarly journals Evaluation of soil moisture in CMIP5 simulations over contiguous United States using in situ and satellite observations

2016 ◽  
Author(s):  
Shanshui Yuan ◽  
Steven M. Quiring
Keyword(s):  
United States ◽  
Soil Moisture ◽  
Soil Column ◽  
Regional Analysis ◽  
Soil Layer ◽  
Model Performance ◽  
Coupled Model ◽  
Cmip5 Models ◽  
Near Surface

Abstract. This study provides a comprehensive evaluation of soil moisture simulations in the Coupled Model Intercomparison Project Phase 5 (CMIP5) extended historical experiment (2003 to 2012). Soil moisture from in situ and satellite sources are used to evaluate CMIP5 simulations in the contiguous United States (CONUS). Both near-surface (0–10 cm) and soil column (0–100 cm) simulations from more than 14 CMIP5 models are evaluated during the warm season (April–September). Multi-model ensemble means and the performance of individual models are assessed at a monthly time scale. Our results indicate that CMIP5 models can reproduce the seasonal variability in soil moisture over CONUS. However, the models tend to overestimate the magnitude of both near-surface and soil-column soil moisture in the western U.S. and underestimate it in the eastern U.S. There are large variations in model performance, especially in the near-surface. There are significant regional and inter-model variations in performance. Results of a regional analysis show that in deeper soil layer, the CMIP5 soil moisture simulations tend to be most skillful in the southern U.S. Based on both the satellite-derived and in situ soil moisture, CESM1, CCSM4 and GFDL-ESM2M perform best in the 0–10 cm soil layer and CESM1, CCSM4, GFDL-ESM2M and HadGEM2-ES perform best in the 0–100 cm soil layer.

scholarly journals Generalized nonlinear height–diameter models for a <i>Cryptomeria fortunei</i> plantation in the Pingba region of Guizhou Province, China

Web Ecology ◽  
2018 ◽  
Vol 18 (1) ◽  
pp. 29-35 ◽  
Author(s):  
Zongzheng Chai ◽  
Wei Tan ◽  
Yuanyuan Li ◽  
Lan Yan ◽  
Hongbo Yuan ◽  
...  
Keyword(s):  
Model Performance ◽  
Forest Growth ◽  
Performance Criteria ◽  
Forest Monitoring ◽  
Growth And Yield ◽  
Guizhou Province ◽  
Biomass Estimation ◽  
Multiple Model ◽  
Nonlinear Growth ◽  
The Relationship

Abstract. The relationship between height and diameter (H-D) is an important component in forest growth and yield models, and a better understanding of the relationship will improve forest monitoring, management, and biomass estimation. Sixteen nonlinear growth functions were fitted to H-D data for 1261 trees from a Cryptomeria fortunei plantation in the Pingba region of Guizhou Province, China. Of the 1261 trees, 80 % were randomly selected for model calibration, while the remaining trees were reserved for model validation. All models were evaluated and compared by means of multiple-model performance criteria. Although all 16 models showed a good fit to the dataset and each of them accounted for more than 75 % of the total variation in height, a large difference in asymptotic estimates was observed. The Chapman–Richards, Weibull, and Näslund models were recommended for C. fortunei plantations, due to their satisfactory height prediction and biological interpretability.

Insights into the Evolving Microphysical and Kinematic Structure of Northeastern U.S. Winter Storms from Dual-Polarization Doppler Radar

2017 ◽  
Vol 145 (3) ◽  
pp. 1033-1061 ◽  
Author(s):  
Matthew R. Kumjian ◽  
Kelly A. Lombardo
Keyword(s):  
Doppler Radar ◽  
Elevation Angle ◽  
Model Performance ◽  
Radar Data ◽  
Added Value ◽  
Dual Polarization ◽  
Differential Phase Shift ◽  
Winter Storms ◽  
Microphysical Processes ◽  
Ice Production

The recent Weather Surveillance Radar-1988 Doppler (WSR-88D) network upgrade to dual-polarization capabilities allows for bulk characterization of microphysical processes in northeastern U.S. winter storms for the first time. In this study, the quasi-vertical profile (QVP) technique (wherein data from a given elevation angle scan are azimuthally averaged and the range coordinate is converted to height) is extended and applied to polarimetric WSR-88D observations of six Northeast winter storms to survey their evolving, bulk vertical microphysical and kinematic structures. These analyses are supplemented using hourly analyses from the Rapid Refresh (RAP) model. Regions of ascent inferred from QVPs were consistently associated with notable polarimetric signatures, implying planar crystal growth when near −15°C, and riming and secondary ice production at higher temperatures. The heaviest snowfall occurred most often when ascent and enhanced propagation differential phase shift ([Formula: see text]) occurred near −15°C. When available, limited surface observations confirmed heavy snowfall rates and revealed large snow-to-liquid ratios at these times. Other cases revealed sudden, large melting-layer excursions associated with precipitation-type transitions near the surface. RAP analyses failed to capture such complex evolution, demonstrating the added value of dual-polarization radar observations in these scenarios and the potential use of radar data for assessing model performance in real time. These insights are a preliminary step toward better understanding the complex processes in northeastern U.S. winter storms.

Microphysical Processes in Cirrus and Their Impact on Radiation: A Mesoscale Modeling Perspective

Cirrus ◽  
2002 ◽  
Author(s):  
Vitaly I. Khvorostyanov ◽  
Kenneth Sassen
Keyword(s):  
Optical Properties ◽  
General Circulation ◽  
Climate Models ◽  
Cooling Effect ◽  
Climatic Impact ◽  
Positive Feedbacks ◽  
Cloud Forcing ◽  
Two Factors ◽  
Upper Level ◽  
Microphysical Processes

The impact of cloudiness on the global radiative budget and its climatic consequences have been widely discussed during the last three decades. It was gradually recognized that the climatic effect of cloudiness depends on its height: low- and middle-level cloudiness have a total cooling effect on the Earth climatic system, while the upper-level clouds, cirrus, may have mostly a warming effect (IPCC 1995). The net effect of cirrus (i.e., warming or cooling), is much less clear because neither their microphysical and optical properties, nor the processes that govern their formation, are well understood and parameterized in climate models. These uncertainties have stimulated several major field projects performed within the International Satellite Cloud Climatology Project (ISCCP; Rossow and Schiffer 1991) with subsequent data analysis reports [e.g., FIRE IFO-I (1990), FIRE IFO-II (1995), and EUCREX (Raschke et al. 1996)]. The relevant theoretical works, and even the simplest climate models, indicate that the climatic impact of cirrus depends on their microstructure: clouds composed of small crystals with effective radii less than about 16 μm have a total cooling effect, but clouds of larger crystals have a warming effect (Stephens et al. 1990). It was shown that the total cloud forcing at the top of the atmosphere (TOA) is positive from a few to a few tens of watts per square meter for the large crystals and decreases with decreasing crystal radius (Fu and Liou 1993). Most of the previous theoretical studies of cirrus radiative properties, after choosing some model of microphysics and some values for the mass extinction and absorption coefficients, then prescribed them to the whole cloud, neglecting any vertical variations. Simulations with general circulation models (GCMs) showed that cirrus clouds with their optical properties parameterized in such a way (i.e., constant with height) have a total warming effect and positive feedbacks with respect to greenhouse gas-induced global warming (e.g., Ramanathan et al. 1983; Wetherald and Manabe 1988). Today, the estimation of the warming/cooling effect of cirrus has become even more complicated due to two factors. First, for many years the usual in situ probes allowed the measurement of ice crystals with radii only larger than 25-50 μm, so the smallest and most optically and radiatively active crystals were unresolved.

Further Results on Moist Nearly Neutral Flow over a Ridge

2006 ◽  
Vol 63 (11) ◽  
pp. 2881-2897 ◽  
Author(s):  
M. M. Miglietta ◽  
R. Rotunno
Keyword(s):  
Coriolis Force ◽  
Numerical Solutions ◽  
Wrf Model ◽  
Rainfall Rate ◽  
Experimental Conditions ◽  
Available Water Content ◽  
Warm Rain ◽  
Temperature Regimes ◽  
Neutral Flow ◽  
Microphysical Processes

Abstract In a recent study, the authors performed numerical simulations of moist nearly neutral flows over a ridge using the Weather Research and Forecasting (WRF) Model in a regime where the Coriolis force can be neglected and with the simple Kessler (warm rain) microphysical scheme. In the present work, further numerical solutions using more general and realistic experimental conditions are discussed. The upstream-propagating disturbance, which was found in the author’s previous study to desaturate the initially saturated sounding for intermediate mountain heights, is present for all the simulations with taller mountains considered in the present work. The inclusion of the Coriolis force however suppresses the upwind propagation of the dry region and weakens the downstream development of convective cells. The sensitivity to different microphysical schemes has also been investigated. The simple Kessler scheme was compared with a more complete scheme, by Lin et al., which includes ice species. Some differences between the warm-rain-only and ice-microphysics simulations emerge mainly as a consequence of the different distributions of initial cloud water needed to produce a steady-state environmental flow. The effects of the different microphysical schemes on the rainfall rate have also been analyzed, with significant differences between them emerging in the case of narrower mountains. Finally, the sensitivity of the rainfall to the surface temperature has been studied, showing that for higher surface temperatures, the rainfall rate can be smaller although the available water content is larger, as a consequence of the differing microphysical processes activated in the different temperature regimes.

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