PISTON Modeling and Observation SynergyYMC 4th workshop, Feb 2019 PISTON Modeling and Observation...

YMC 4th workshop, Feb 2019

PISTON Modeling and Observation Synergy

Sue Chen1, Carolyn Reynolds1, Maria Flatau1, Matthew Janiga1

Tommy Jensen2, Adam Rydbeck2

Adam H. Sobel3

Sue van den Heever4

Derek Posselt5

Ray Pallav6

1Naval Research Laboratory, Monterey2Naval Research Laboratory, Stennis3Columbia University4Colorado State University5Jet Propulsion Laboratory6Florida Institute of Technology


Diurnal Cycle

Seasonal Cycle

UpscaleOrganization

Storm ClusterMultiple Storm Clusters

Individual Storms

ConvectiveCoupled Mesoscale

Convective Systems

1-10 kmHours

Individual clouds

10-1000 kmDays-Weeks

El Nino

1000’s kmWeeks-Month

BSISOEquatorial WavesMJO

> 10,000 kmMultiple seasons/years

Weather Seasonal to Subseasonal Climate

Annual Cycle

Sea

UpscaleOrganization

Ocean

Buoyancy/wind driven Costal currentsBasin-scale circulations – Pacific and Indian Ocean exchange

Terrain

Urban/Land and hydrology

Shallow marginal sea

Deep basinOcean subsurface

Thermocline

Shear, tidal, buoyancy, and internal wave mixing

Ocean sea temperature profile

Ocean mixed layer (< 100 m)

Costal upwelling/downwelling

Fresh water lens/Barrier Layer

Diurnal warm layer

Ocean surface layer (1 m)

Multiscale Interaction Processes

Terrain

Surface fluxes

River discharge to ocean


• COAMPS high resolution sensitivity experiments • Coastal air-sea-land interaction• Ocean response to typhoon• Diurnal cycle

• Navy global ESPC • Diurnal cycle• BSISO prediction

Naval Research Laboratory Research Group


6.1 PISTONKey Scientific Accomplishments

Philippines has the highest number of rivers in the MC region (Julie Pullen, Olivia Cabrera)

Run 1.) Climatology: Monthly mean discharge for 39 rivers in the Philippines from Perry et al., 1996; Barron & Smedstad, 2002

Run 2.) Realistic: Adds 1 standard deviation to climatological discharge, with seasonal cycle representative of the climate zones where each river is situated. Also adds Abra River (40 rivers total).

Abra RiverIncreased by one STD

Agno Abra

1.67 km


COAMPS atmosphere: 1.67 km COAMPS ocean (NCOM): 2 kmAug 21, 2017 Realistic

Observation

Climate river database

OBS

COAMPS

COAMPS


Compared to the cntl experiment, the increased river discharge in expAinduced:• An earlier convective initiation (3-4h)

over ocean• A delay of convective initiation (1-2h)

over land• A reduction of the precipitation

maximum over land• A shift of both the ocean and land

rain diurnal cycle

Grid 3 Domain Mean Ocean and Land Hourly Precipitation (mm)

Mean 2016-2017 August observed diurnal precipitation observation

Land precipitation (16-17N, 120-121E)


NESM captures NW-SE “tilt”, but amplitude is too strong. ECMWF anomalies are weak. Positive signal in CFSv2 most likely related to bias in time-mean state.

The Boreal Summer Intraseasonal Oscillation (BSISO) anomalies in OLR (shaded, W m-2) and 850-hPa u (contours, ci = 1 m s-1, negative values dashed) for 3-week forecasts initialized when observed BSISO was active over western Indian Ocean.

NRL Global ESPC SUBX Experiments (JJA 1999-2015)


NESM OLR cold bias over eastern MC north of Australia (convection too deep and/or too active) and warm bias

over eastern Indian Ocean.

ECMWF has smaller OLR biases and comparable wind biases as NESM.

CFSV2 has pronounced warm bias in ORL (weak convection) over south eastern Asia and MC.

The 0-40 day forecast bias in OLR (shaded, W m-2) and 850-hPa u (contours, ci = 1 m s-1, negative values dashed).

NRL Global ESPC SUBX Experiments (JJA 1999-2015)


IO: 21 days

WP= 12 days

BSISO1: 17 days

Better 2012-2014 forecast skill for the Indian Ocean region than for the Western Pacific

NRL ESPC forecast skill for the OLR/wind based BSISO modes

NRL ESPC

The green lines show the anomaly correlation for the 1st PC, the red for the 2nd PC and the black lines indicate the bivariate correlation.


Sobel (Columbia University) Research Group

• Air-sea interaction influence on BSISO propagation

• Rain and wind speed relationship over island

• BSISO moisture budget• Ocean mixed layer response during

BSISO

YMC 4th workshop, Feb 2019Atmosphere-Ocean-Land coupled modeling(Sobel Research Group)

Coupled simulations WRF V3.8.1 (Wang et al. 2015, Zhang et al. 2017, Chen et al. 2017)

• dx = 9 km, 45 levels• ICs and BCs: ECMWF-Interim• physical schemes (ACM2, NoaH,

WDM6)• No convective parameterization

o HYCOM (Hybrid Coordinate Ocean Model) V2.2

• dx = 0.08°• 30 vertical layers

o Coupling: (Chen et al. 2016, Curcic et al, 2016)

o Integration: from July 10 to end of August

Uncoupled simulationso WRF V3.8.1 o 6-hourly SST from ECMWF-Interim o time independent SST (accidently)

ETOPO1

HYCOMWRF


U850: Coupled vs. Uncoupled simulations(Sobel Research Group)

• Strong westerly south of the BSISO convection, weak easterly north of convection

ERA-I

CoupledUnCoupled


Rain: Coupled vs. Uncoupled simulations(Sobel Research Group)

• BSISO is faster and noisier in the uncoupled simulation• BSISO in the coupled simulation has similar speed with TRMM

mm/dDays from July 10 2016

CoupledUnCoupled


Wind speeds at 850 hPa and rain at Borneo and Luzon (Sobel Research Group)

o Rain in Borneo has local maximum at lower wind speed, local minimum for wind speed 3-4 m/s , and increase further

o consistent with idealized experiments in Wang and Sobel 2017. This nonlinear relation should be of fundamental importance to the understanding of rain over islands

o No local maximum rain at small wind speed in Luzon at low wind speed: away from equator by one Rossby radius of deformation; land/sea breeze weaker at subtropical latitudes.

TRMM: Borneo 3 °S - 5 °N TRMM: Luzon 15 °N - 19 °N


Sue Van Den Heever (CSU) Research Group

• CRM simulations across the scales• Several goals:

– Upscale and downscale development of convective contributions to the BSISO - Ben Toms

– Global teleconnections of the MJO – Ben Toms– Cold pool processes and convective initiation –

Aryeh Drager– Island flow regimes – Stacey Kawecki


Cloud-resolving simulation of a BSISO event(Van Den Heever Research Group)

Simulation Domain increase

decrease

neutral

LegendLatter Phasescell expansecell depthcell numbercell longevity

Early Phasescell expansecell depthcell numbercell longevity

Intermediate Phasescell expansecell depthcell numbercell longevity

northeastward propagation

active lobe

Mesoscale/IntraseasonalRelationship

We discovered a relationship between the evolution of mesoscale convection and intraseasonal anomalies of the BSISO using a cloud-

resolving model

The Relationship Between the Boreal Summertime Madden-Julian Oscillation and Tropical Deep Convective Morphology, to be submitted to Journal of the Atmospheric Sciences

YMC 4th workshop, Feb 2019Global teleconnections of the MJO

Example global perspective of MJO teleconnections (300-mb

geopotential)

Globally integrated subseasonal variability

associated w/ MJO

We quantified the global prevalence of MJO teleconnections and found that they strongly depend on the phase of the QBO (a tropical stratospheric

oscillation).

The Global Signature of the Madden-Julian Oscillation and its Modulation by the Quasi-Biennial Oscillation, to be submitted to Journal of Geophysical Research: Atmospheres


Cold Pool Responses to Changes in Soil Moisture(Van Den Heever Research Group)

Colors: at z ~ 20 mWhite isosurface: cloud water + cloud ice, 0.1 g/kgBlue isosurface: rain water, 0.1 g/kg

Note: only 1/9 of the domain is shown

The RAMS simulations:• 14 hours starting at 7 LT (analysis period: 12 – 17

LT)• 150 km × 150 km × 21 km domain• Δx = Δy = 125 m, Δz stretched from 40 m to 250 m• modified Luzon initial sounding with no winds• RAMS 2-moment bin-emulating bulk microphysics• coupled to LEAF-3 land surface model• initialized with 75% and 25% of soil saturation

[WET-SOIL (animation below) and DRY-SOIL]

Summary of results:• Cold pools tracked and composited using a modified

version of Drager and van den Heever (2017, JAMES) algorithm.

• DRY-SOIL cold pools have ~twice the area and are ~twice as strong as WET-SOIL cold pools during the early stages of their lifecycles but dissipate more rapidly.

• WET-SOIL cold pools exhibit water vapor rings; DRY-SOIL cold pools do not.

Aryeh J. Drager, Leah D. Grant, and Susan C. van den Heever, to be submitted to JAMES


How do diurnally-driven circulations govern convective organization, accumulated precipitation patterns, and aerosol transport in the Maritime Continent?

Idealized Set Up

Strong Meridional Winds

(STRONG-EXP)Weak Meridional

Winds(WEAK-EXP)

24 Simulations

Case Study Set Up• Orography substantially alters the flow

• STRONG-EXP the orography induces a reverse flow, lee-vortex formation and a wake

• WEAK-EXP the orography induces upslope flow around the entire island

Surface Streamlines

Tracer Redistribution

• Flat: Tracers lofted in correlation with moisture flux convergence and cloud formation associated with the sea breeze.

• 1 km orography: tracers are lifted from the surface and lofted in the wake, but 80% of original tracer remains in lowest level in the wake

Cross Section Tracers for Zero_Wind 5-km resolution [#/kg dry air]

• After 24 hours of simulation (first panel), tracers released from Baguio are being advected westward at about 4 km

• Tracers are advected into the valley region south of Baguio over night and stay through the afternoon, maybe a result from weak horizontal winds in the valley

• By the evening, tracers have advected out of the valley south of Baguio.

The roles of island size and orography in the diurnal cycle of tropical convection and aerosol transport – Stacey Kawecki and Susan van den Heever, in prep to be submitted to Atmospheric Chemistry and Physics.

YMC 4th workshop, Feb 2019Derek Posselt (JPL) Research Group

Understanding Convection-Environment InteractionKey questions:• Magnitude of the response of convection to changes in

environment?• Which environmental factors have the largest influence?• Does sensitivity depend on convective morphology?Methodology: use simulations of convection as a laboratory• Monte Carlo sensitivity analysis: randomly perturb all

parameters simultaneously• Systematic parameter perturbation: compute Jacobian

for many different combinations of environmental factors and examine the response


Ensemble of High Resolution SimulationsPosselt Research Group

• RAMS model run at 250 meter grid spacing for 3 cases with variable CAPE and shear.

• Perturbations to environment consistent with tropical variability used to generate an ensemble

• Finding: convection is highly sensitive to changes in its environment

• Storer et al. (2019; QJRMS) – to be submitted

High CAPE and ShearMean Precipitation Rate

Max Vertical Velocity

1.0 4.0

50 60 45

Low CAPE and ShearModerate CAPE and Shear

High CAPE and Shear Low CAPE and ShearModerate CAPE and

Shear

2.5


Ensemble of Coarse Resolution SimulationsPosselt et al. (2019, JAS) – in revision

• Examine the high-sensitivity case (Feb 23,1999)

• Produce a large ensemble of 10,000 cloud resolving model simulations at 2 km grid spacing

• Systematically perturb environment and model physical parameterizations to attribute sensitivity

• Microphysical processes and perturbations to environment both have a large effect on convective vertical motion and heating.

• Lower to middle free troposphere temperature and relative humidity (T3,T4 and RH2) are the primary controls on outcomes of convection

10,000 Monte Carlo Simulations

Systematic Sensitivity Analysis


Terrain and Urban ModelingRay Pallav (FIT)

• MJO and topography interaction• MJO and BSISO in complex terrain • Role of urban on diurnal cycle


24

Role of topography on the MJO/ISO in the Maritime Continent (Ray Pallav )

• Vertically integrated moisture budget shows decrease in precip when topography is removed.

• VADV increases over areas A and C, but decreases over area B.

• HADV increases over area B.

• Processes may be different in different parts of the Maritime Continent.

Tan, Ray, Barrett, Tewari and Moncrieff (2018): Role of topography on the MJO in the Maritime Continent: a numerical case study, Climate Dynamics, https://doi.org/10.1007/s00382-018-4275-3.


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Sensitivity of simulated MJO/ISO precipitation due to topography (Ray Pallav)

GTOPO30 (Control) ASTER Diurnal Cycle

- Diurnal cycle is enhanced when high resolution topography data is used.- Similar results over the Philippines (Luzon)

• Topographic influence in previous studies may have been underestimated• No impct on the MJO propagation

30 sec (1km) terrain ASTER: 1 sec (30m) terrain Feb 2010, MJO passage

YMC 4th workshop, Feb 2019Role of urban areas (Manila) on the diurnal cycle

T2 (℃）

Qsh (w m2）Qlh (w m2）

• Urban surfaces are too dry in models -- small (large) latent (sensible) heat flux -- stronger

Single layer canopy model

15 sec (~500m)

YMC 4th workshop, Feb 2019Summary

The PISTON Modeling PI team was able to use prior synoptic observations to investigate:• Diurnal cycle• Air-sea-land interaction during BSISO• Ocean response to BSISO• Relation of MJO and tropical deep convection• Global teleconnections of MJO • Atmosphere cold pool interaction with soil moisture • Aerosol transport and its interaction with diurnal cycle• Convection-environment interaction• MJO & BSISO interaction with terrain• Diurnal cycle in urban area

YMC 4th workshop, Feb 2019Future Work

• Use observations from the 2018 PISTON field campaign to study multiscale interaction

• Monsoon and typhoon interaction• Air-sea interaction

• Typhoon• Diurnal warm layer• Barrier layer• Active and inactive phases• Diurnal cycle• Convection initiation• Cloud processes• Aerosol and cloud interaction

PISTON Modeling and Observation SynergyYMC 4th workshop, Feb 2019 PISTON Modeling and Observation...

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