Investigating the influences of dust storms on precipitation in Iran using WRF-CHEM model

Mastooreh Ameri1, Khosro Ashrafi1, Sarmad Ghader2, Mohammad Amin Mirrezaei1

1 School of Environment, College of Engineering, University of Tehran, Tehran, Iran 2 Space Physics Department, Institute of Geophysics, University of Tehran, Tehran, Iran

UNC Institute for the Environment, Chapel Hill, NC OCTOBER 2020 Is there any relationship between dust storm events and precipitation spatial-temporal changes in Iran?

1 Climatology of Iran 35.5% Hyper-arid 29.2% Arid 20.1% Semi-arid 5% Mediterranean 10% Wet

Arid and Semi-arid climate

Low Average Annual Precipitation Significant variation of precipitation (Spatially and Temporally) High Evapotranspiration Rate Multi-year Drought

2 Iran ‣ Total Precipitation: 222 mm (6% reduction in comparison to long-term) Hydrological ‣ Average temperature growth (in comparison to long-term) ‣ Slight to Extreme Drought year 2017 ‣ Dust Storm event: 18 provinces ‣ Extreme Drought: Bushehr, Khuzestan and Sistan and Baluchestan

National Drought Warning and Monitoring Center (NDWMC) annual report (2017) 3 Clouds and Precipitation

‣ Aerosol Scattering and absorbing solar radiation Atmospheric and Surface energy budget Earth’s Hydrological Cycle Precipitation Changes

‣ Cloud Microphysics

CCN activation In-Cloud Changes in cloud albedo Activation and cloud life time And Droplet Formation

Aerosol Particles 4 Study Area Parent Domain: • Parts of Sahara Desert • Saudi Arabia • Iraq • Turkey • Mediterranean Sea • Parts of Turkmenistan • Afghanistan • Pakistan • Iran

Grid Points: 87 Horizontal 45 Km 78 Horizontal 45 Km

Nest Domain: • Iran 127 Horizontal 15 Km Grid Points: 112 Horizontal 15 Km 5 Terrestrial GFS Data Data Chemical Emission Background Data Data metgrid WPS Emission

METEOROLOGY PREP CHEM Anthropogenic DATA and Biogenic Gridded Emissions Emission

WRF-CHEM 3.6.1

Post-Processing and Visualization (NCL, GrADS) 6 Data Sets

 Air Quality Monitoring stations

The Iranian Department of Environment Maximum PM10 and PM2.5 concentrations of 30 provinces of Tehran Air Quality Control Company Iran

 Synoptic data: Average report of every 3 hour Capital cities Iranian Meteorological Organization

 Satellite data

NASA - Earth Observing System Data and Information System

7 Dust Storm Events

Dust Score • Aqua/ AIRS 11 – 14 MARCH 2017 3 DUST STORM EVENTS 12 – 15 Dust Surface Mass Concentration • MERRA-2 APRIL 2017 2 – 5 Precipitation Estimate • Aqua/ AIRS MAY 2017 8 Modeling Options

MODEL CONFIGURATION PHYSICAL SCHEMES MICROPHYSICS* Aerosol-aware Thompson Scheme CUMULUS PARAMETERIZATION* Grell – Freitas Ensemble Scheme SURFACE LAYER Revised MM5 Scheme LAND SURFACE Unified Noah Land Surface Model PLANETARY BOUNDARY LAYER Yonsei University Scheme (YSU) SHORTWAVE RADIATION Goddard LONGWAVE RADIATION Rapid Radiative Transfer Model (RRTM) EMISSION SCHEMES ANTHROPOGENIC/BIOGENIC RETRO and EDGAR EMISSION DUST EMISSION GOCART 9 Soil and Atmospheric moisture content Particle Emission PM particles amount in the atmosphere

Wind Speed and Energy Lifting and moving particles into the atmosphere Dust particles amount and components

10 Temperature ( ºC)

11 Pressure (mbar)

12 Vertical Pressure Gradient Average Elevation in each grid cell in the atmosphere Dominant land use

13 Wind Speed and Direction

14 Precipitation (mm)

15 16 PM10 and PM2.5

17 Maximum Concentrations Khuzestan (Ahvaz) PM10 Concentration 1000 1. South-West (Khuzestan) PM10 500 Dust Storm #1 (ΜG/M3) rd 3 Day 0 13 March 2017

TIME ()

2. South-East (Sistan and Baluchestan) Sistan and Baluchestan (Zabol) PM10 , PM2.5 Concentrations Dust Storm #2 1000 2nd and 4th Day PM10 , PM2.5 500 13, 15 April (ΜG/M3) 0

3. South (Bushehr) TIME (hour) Dust Storm #3 Bushehr (Genaveh) PM , PM Concentrations 4th Day 10 2.5 5 May 2017 2500 2000 1500 PM10 , PM2.5 (ΜG/M3) 1000 500 0

TIME (hour) 18 • Precipitation amounts (chem) < Precipitation amounts (without chem)

Dust Storms influenced precipitation

• Reductions in precipitation amount (chem) occurs later than reductions in precipitation amount (without chem)

Day 3 and 4 Dust Storms reduced precipitation amounts

• Southern, South-eastern and South-western parts of Iran Severe Dust Storm

Simulated Precipitation amounts < Observed Precipitation amounts Precipitation amounts (chem) < Precipitation amounts (without chem)

• Stations with higher elevation Simulated Precipitation amounts < Observed Precipitation amounts

Topography and Elevation have important effects on simulation estimations 19 • Precipitation trends of stations during dust storm period mostly is

Increasing Decreasing

• The mean cumulative precipitation for the dust episodes during

March Aerosol - Cloud feedbacks 12.45 mm to 12.84 mm April 31 mm to 30.86 mm May 8.79 mm to 7.78 mm

• The largest anomaly in total cumulative precipitation values 0.8 mm Last Day of May Episode

20