Does anyone know how frequently sand storms and dust storms that arise from middle east or north africa travel to Pakistan and North India? I was wondering, in view of the already worsening air pollution levels in North India, events such as dust and sand storms reaching the subcontinent may exacerbate the situation. How rare or common are such sand and dust storms being carried from their place of origin (usually middle east and north africa) and intermix with fog or haze intensified by smoke or other atmospheric pollutants in another far off location? Has there been any similar, possible mixing of phenomena (dust storm and smog) reported/documented/studied anywhere around the globe at any time, preferably that was also caught by polar or geostationary satellites?
I was looking at a true-color or natural color satellite image acquired on 29th Oct. 2017 by the Visible Infrared Imaging Radiometer Suite (VIIRS) on board the joint NASA/NOAA Suomi-National Polar orbiting Partnership (S-NPP) satellite around early afternoon. I've attached a screenshot of the image as well as provided the full link to access the satellite imagery. These satellite images have been stitched together to create a global mosaic. Unlike MODIS, VIIRS do not show any data gaps (except sun glints!). I found this satellite image particularly compelling because it clearly shows the sand storm picking up over northern Saudi Arabia and moving around Iraq, Iran, Caspian Sea towards Afghanistan with the movement of wind. I also think the Earth's rotation from west to east has a role to play in the movement and direction of the wind laden with sand and dust. But it seems difficult to understand their dynamics. The smog over North India and parts of Pakistan can be differentiated from the sand storm over middle east in this satellite image. In North India this is the time of the year when there are intentional crop fires due to the traditional slash-and-burn agriculture practice.
https://worldview.earthdata.nasa.gov/?p=geographic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor,MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor(hidden),Reference_Labels,Reference_Features,Coastlines&t=2017-10-29&z=3&v=35.36312211019146,20.982499883984907,83.45687211019145,44.32624988398491&ab=off&as=2017-10-01&ae=2017-10-31&av=3&al=true
The problem of interaction of the long range transport of fine dust particles with the locally generated photochemical smog is both common and challenging. We are still missing, however, many important details to correctly represent the heterogenous phase chemistry associated with such "hybrid photochemical smog episodes". I hope that with some additional measurements and advancements in theoretical chemistry, the more realistic simulations will be possible within the next decade.
As far as the frequency of events of the long range transport of fine dust particles to India and Pakistan is concerned the most common knowledge indicates two periods, April-June and September-November. Considering the fact that last year 122 dust storm were reported in Iraq alone, we can consider these event to be very common.
The case shown on the satellite image included in the question is ideal to test the currently available models of the photochemical smog with the particulate matter component. I recall seeing very similar satellite imagery for the smog events in China in the early 2000s albeit without the comprehensive study of the aerosol dynamics.
I have used satellite images such as the one you showed to look at dust storm event in Northern Africa, Middle East, and Western China over the last 15 years or so. Satellite images capture very nicely the huge events but it can be difficult to detect the smaller lower concentration events. The number of dust events have increased but I am not sure how the amount of time that dust is in the air versus air pollution in general in northern India compare to each other. For sure, when dust is added to current air pollution it will be impacted.
Below are two links to slides I put on my research gate profile during the last couple of years showing satellite images of huge dust events in the area that I thought you might find interesting to look at.
https://www.researchgate.net/publication/281443694_Slides_---_Remote_Sensing_to_Detect_Dust_Storms_---_Northern_Arabia_Example
https://www.researchgate.net/publication/275273496_Slides_---_Remote_Sensing_to_Detect_Dust_Storms_---_Arabian_Peninsula_Example
Pat
Thanks Behrouz, Janusz and Pat for your useful comments and for sharing these interesting articles & slides. I will take a look.
Meanwhile, an air quality monitoring agency has confirmed the contribution of the Oct-Nov. dust storm event in worsening the north India pollution levels. The situation is still quite grim. Although remote sensing is a priceless tool in such cases, it goes without saying ground based sensors are indispensable to complete the picture.
http://www.thehindubusinessline.com/news/national/dust-storm-in-west-asia-precipitated-delhi-smog-crisis-safar/article9963498.ece
Varies spatially and temporarily, the Ahwaz and kuwait 🇰🇼 may be the highest occurrence rates of SDS in the Middle East (average annual 21 in Kuwait)
more in Al-Dousari et al. 2017.
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Article Types, Indications and Impact Evaluation of Sand and Dust St...
Article Dust fallout characteristics within global dust storm major ...
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