Subject: Re: Dust in Erin and Felix Date: Fri, 28 Sep 2001 07:10:03 -0400 From: "Joseph M. Prospero" To: Douglas Westphal References: 1 Thanks Doug. Joanne was really trying to get dust into that thing. Joe At 08:19 PM 27-09-01, you wrote: >Hello All, > >I put a series of daily composites of TOMS AI, NAAPS AOD, GOES-E Vis, and >SeaWiFS images in: > > >http://www.nrlmry.navy.mil/aerosol/Case_studies/20010909_erin/pride_composite_loop.html > >Use the '|<' and '>|' buttons to step one frame at a time. > >You can see Erin at about 18N, 52W on 9/4 (frame 0). There is very little >dust in it's vicinity. It then heads NW towards the U.S., and away from >Africa. It >does not appear to injest dust. > >Felix is in a similar location (20N, 48W; frame 7) on 9/11. It has quite >a bit of dust behind (east of) it. It then heads ENE, parallel to the >African Coast >and the pool of dust. It appears to injest Saharan dust as it heads ENE. >The high-res SeaWiFS images distributed by Norm Kuring a week ago clearly >showed this. > >There probably isn't much dust in Erin because of the initial state and >its subsequent track. > >Felix would be a much better target for studying the potential effects of >dust on cirrus. > >Hope this helps some! > >Doug > >"Joseph M. Prospero" wrote: > > > > I am pretty sure that it is not dust but rather pollution. The very > high concentrations and fine size would preclude that. (BTW in an early > email someone > > quoted 1800 per LITER and later the number 1800 per CC was mentioned. I > assume that the latter was correct.) I will present to you a number of lines of > > evidence, mostly stuff from Doug Westphal's NRL web site: > > www.nrlmry.navy.mil/aerosol > > > > First some satellite images, Seawifs: > > On 9 Sept > > > http://www.nrlmry.navy.mil/~westphal/satellite/seawifs/eus/200109/2001090912_eus.jpg > > On 10 Sept (poor coverage): > > > http://www.nrlmry.navy.mil/~westphal/satellite/seawifs/eus/200109/2001091012_eus.jpg > > On both the 9th and 10th you can see a lot of grungy gray aerosol north > of the circulation. There is some stuff along the coast as well. > > On 11 Sept > > > http://www.nrlmry.navy.mil/~westphal/satellite/seawifs/eus/200109/2001091112_eus.jpg > > Re the 11th I did not realize how close the storm was to the coast. It > certainly explains the sky/wind conditions over NY on that horrible day. > That is why > > they had such clean air that day, because Erin sucked out all the dirty > stuff. > > On 12 Sept: > > > http://www.nrlmry.navy.mil/~westphal/satellite/seawifs/eus/200109/2001091212_eus.jpg > > > > Now I show you aerosol distributions from Westphal's NAAPS aerosol > model for the seme sequence of days. These show sulfate (read, "pollution > in general"), > > smoke (biomass burning) and dust. > > > http://www.nrlmry.navy.mil/~westphal/globaer/ops_01/world/200109/2001090918_globaer_ops_world.gif > > > http://www.nrlmry.navy.mil/~westphal/globaer/ops_01/world/200109/2001091018_globaer_ops_world.gif > > > http://www.nrlmry.navy.mil/~westphal/globaer/ops_01/world/200109/2001091118_globaer_ops_world.gif > > > http://www.nrlmry.navy.mil/~westphal/globaer/ops_01/world/200109/2001091218_globaer_ops_world.gif > > > > It is clear that there was considerable sulfate aerosol and pollution > aerosol in general in the region of Eric. In fact, where you don't see > aerosol off the > > east coast it is probably because Erin sucked it up. > > > > Using another product of Doug's we can see the dust distribution and a > part of the sulfate over the Atlantic: > > > > 10 Sept > > > http://www.nrlmry.navy.mil/~westphal/globaer/ops_01/carib/200109/2001091018_globaer_ops_carib.gif > > 11 Sept > > > http://www.nrlmry.navy.mil/~westphal/globaer/ops_01/carib/200109/2001091118_globaer_ops_carib.gif > > > > There is no doubt that there was an incredible amount of dust going > into the eastern side of FELIX. Is it possible with TRIMM to look at > changes in the cloud > > droplet distribution across Felix to see if there is any difference > that could be linked to dust? > > > > The point to keep in mind that there is almost always a LOT of aerosol > over the North Atlantic. The interesting question is the role of these > different > > aerosol types in modifying cloud properties. The North Altantic is a > good place to study this because of the fact there are so many different > aerosol sources > > and the concentrations are so high. > > > > Re biomass burning. The biomass burning in northern savanah Africa is > in the winter. There is no signficant biomass burning in the summer that > would impact > > the North Atlantic. > > > > For those of you interested in aerosols, I have an ad hoc (1/2 times a > week, more during interesting times) aerosol report that I mail out. I scan the > > Seawifs, TOMS, AVHRR, etc imagery for interesting events, and interpret > them using Doug Westphal's web site and his NAAPS model. If you are > interested, sign > > up. > > =========================================================== > > To subscribe send a blank e-mail to: dustlist-subscribe@rsmas.miami.edu > > To unsubscribe, send a blank e-mail to: > dustlist-unsubscribe@rsmas.miami.edu > > =========================================================== > > > > Regards, Joe > > > > At 10:55 AM 9/27/2001 -0400, Joanne Simpson wrote: > > > > > Hi Folks interested in Erin/dust: Do you believe the part of this > message that I underlined? I thought it was clearly proved that African > dust was what we > > > were interested in. How can we tell the difference between Sahel > smoke and Sahara dust?? I thought Joe found years ago that we were > getting Saharan dust in > > > both Barbados and Florida on those little screens. I would like an > answer to this to send to Yoram as he is the Goddard person looking at > MODIS. I just > > > can't believe that aerosols, perhaps Ice Nuclei such as koalinate (?) > do not affect cirrus. Please give me the scocp, thanks, Joanne> > > > > > > Mime-Version: 1.0 > > > >Date: Wed, 26 Sep 2001 15:53:31 -0700 > > > >To: Joanne Simpson > > > >From: Yoram Kaufman > > > >Subject: Re: Detecting dust in outflow from Hurricane Erin on September > > > > 10, 2001 > > > >Cc: king@climate.gsfc.nasa.gov, Jose Vanderlei Martins:;, > > > > remer@climate.gsfc.nasa.gov > > > > > > > >Joanne, MODIS aerosol and cloud properties are not derived for the > > > >same pixels. I.e. aerosol is derived only for cloud free (and cirrus > > > >free) pixels. Cloud analysis assumes that aerosol has no impact. The > > > >later may be a problem if substantial amount of aerosol is present > > > >above clouds. > > > > > > > >High CN and CCN concentrations I would suspect are not due to dust > > > >but rather fine mode aerosol like smoke from the Sahel unless there > > > >is a clear evidence of dust. > > > > > > > >I am in France now but will be happy to discuss with you and Michael > > > >after return (after Oct 20). One way to detect dust above the clouds > > > >is to observe the cloud (+aerosol) reflectance for the 0.47-0.86 > > > >micron range. Dust will depress the blue part of the spectrum. > > > >Additionally it may possible to observe it using TOMS UV index if the > > > > > > >50 km foot print is not too large. > > > > > > > >>Hi Mike and Yoram: I have an exciting question for MODIS--can we > tell from > > > >>the Hurricane upper outflow whether there are dust particles mixed > with the > > > >>ice particles? If we could show this it would be very exciting and > worth > > > >>writing up. > > > >> I have a theory about the intrusion of African dust into > Hurricane > > > >>Erin in the Atlantic on September 9 and 10, 2001. CCN and CN counts > by one > > > >>of the NOAA aircraft shows that Erin had a very dirty eye due to > ingestion > > > >>of African dust. > > > >>I believe the only way it could get there is up in the clouds and > from the > > > >>inner clouds into the eye. The experts say it does not come in via the > > > >>lower boundary layer. Many people think rain would wash it out of the > > > >>clouds, but I think enough must stay aloft to get into the eye and > also out > > > >>in the cirrus outflow. Why is it so hard to get MODIS data on the > > > >>composition and sizes of cirrus particles? The position of the > Center of > > > >>Erin is about 35 N and 65 W at 11:13 GCT Sept 10. Can we discuss this?? > > > >>Thanks so much, Joanne > > > >> > > > >>********************************************************** > > > >>Joanne > Simpson Phone: > > > >>(301) 614-6360 NEW > > > >>Chief Scientist for Meteorology > > > >>Earth Sciences Directorate > > > >>Mail Code 912 > > > >>Building 33, Room C407 NEW FAX: (301) 614-5484 NEW > > > >>Goddard Space Flight Center/NASA > > > >>Greenbelt, MD 20771 > > > >> > > > >>E-Mail: simpson@agnes.gsfc.nasa.gov UNCHANGED > > > >> > > > >>** ******************************************************** > > > > > > > >With best regards > > > > > > > >Dr. Yoram J. Kaufman > > > >Senior Scientist, Climate and Radiation Branch > > > >_______________________________________________________ > > > >code 913 (build. 33 room A308) > > > >NASA/ Goddard SFC Fax: 301-614-6307 Tel: 301-614-6189 > > > >Greenbelt, MD 20771 Home Tel: 301-989-0773 > > > >_______________________________________________________ > > > >To learn about the Earth Observing System - "Terra" mission: > > > >http://terra.nasa.gov 2 million hits since Feb 2000 > > > >http://earthobservatory.nasa.gov 8 million hits since April 1999 > > > >http://visibleearth.nasa.gov 4 million hits since Aug 2000 > > > > > > > > > > ********************************************************** > > > Joanne > Simpson Phone: > (301) 614-6360 NEW > > > Chief Scientist for Meteorology > > > Earth Sciences Directorate > > > Mail Code 912 > > > Building 33, Room C407 NEW FAX: (301) 614-5484 NEW > > > Goddard Space Flight Center/NASA > > > Greenbelt, MD 20771 > > > > > > E-Mail: simpson@agnes.gsfc.nasa.gov UNCHANGED > > > > > > ** ******************************************************** > > >