Newsgroups: lter.ced Path: LTERnet!news From: "Bruce P. Hayden" Subject: CED 1.5 Message-ID: <1992Jun29.152630.4784@lternet.washington.edu> Sender: news@lternet.washington.edu Organization: Long Term Ecological Research Date: Mon, 29 Jun 1992 15:16:12 GMT ***************************************************************** ***************************************************************** *** *** *** *********** *********** ********** *** *** * * * * *** *** * * * * *** *** * * * * *** *** * ********* * * *** *** * * * * *** *** * * * * *** *** * * * * *** *** * * * * *** *** *********** *********** ********** *** *** *** ***************************************************************** ***************************************************************** Vol.1 No.5 :::::: file name:CED1.5 :::::: July 1, 1992 ***************************************************************** ***************************************************************** CED is the Climate/Ecosystem Dynamics bulletin board of the LTER network. In CED you will find exchanges of ideas, information, data, bibliographies, literature discussions and a place to get to experts within the LTER community. We are interested in both climate controls on ecosystems and ecosystem controls on climate. As this is an inter-disciplinary activity, we hope to provide things that you might not come across in your work at your LTER site. CED is a product of the LTER climate committee and contributions to CED for general e-mail release may be sent to either David Greenland of Andrews LTER [Greenlan@oregon.uoregon.edu] or to Bruce Hayden of the Virginia Coast Reserve LTER [bph@envsci.evsc.virginia.edu]. We expect that the scope of CED will evolve and reflect the interests of the contributors and users of this service. CED will be issued as the preparation work gets done (monthly?). Back-releases of CED may be requested from Hayden by the file name given in the masthead. Feedback on CED from LTER scientists is welcome (non-$$$$ contributions also welcome.) For example, please forward citations of climate & ecosystem publications on your site. We will keep a LTER wide bibliography on Climate/Ecosystem Dynamics that we pass on via E-mail. ***************************************************************** ***************************************************************** *** *** *** *** *** OZONE *** *** *** *** *** ***************************************************************** ***************************************************************** Ozone Update -- 1992 Quadrennial Ozone Symposium on Ozone was held at the University of Virginia from June 4 through June 13, 1992. It was both tropospheric and stratospheric. No wonder it took 10 days! Well, we last reported to CED readers on Ozone capers following the Trout Lake Coordinating Committee meeting. Since then Canadian School Children have gone back to school, blind sheep have been cleared of having cataracts, evidence of an antarctic ozone hole in the 1950s has been revealed and charges of environmental terrorism have been levied at those who ask "Are halogens from volcanoes players in the ozone depletion story?" It has been busy since we last met like this. Canadian School Children -- Following NASA's February report of a imminent North American Ozone hole, Canada's Environment Minister pulled Canadian children out of school for fear of ultra-violet light exposure and cancer. No, it is not NASA who was accused of environmental terrorism. Within 4 days cooler heads had the kids back at their books. It took NASA longer than almost a month to "tone down" its warning. Blind Sheep -- Puntas Areans, at the tip of South America, made headlines this past year with reports of blinded sheep. Cataracts, UV-B, the Ozone Hole, and CFCs were the cast of characters in this story. No, the reporters of this story were not the environmental terrorists mentions above. The story was repeated in the media and among gossips at universities. A physics major and science editor at a major TV station in San Francisco (KGO-TV) must have said 'Hey, I am not going along with this pack of sheep.' He sent a reporter down to check out the blind sheep story. This non-Bo Peep reporter confirmed lost sheep who couldn't find their way due to blindness. It is not clear who but someone said "Lets check out the origin of the blindness." So eyeballs from a slaughter house were returned to California and tested at the vet school at UC-DAVIS. No cataracts. It was an epidemic of pink eye! Conjunctivitis of the ovine type. The cataract-UVB-ozone:hole-CFC, conclusion jumpers have not been heard from yet. 1950s Ozone Hole -- G. M. B. Dobson, inventor or the machine that measures ozone and gives out its readings as Dobson units, did some of his work over Halley Bay, Antarctica in 1956 and 1957. Pre-CFC days. He recorded only 150 Dobson units! In the 1960s and 1970s readings around 300 Dobson units were the values of the day. In 1958 (IGY year) French scientists reported only 120 Dobson units. Was there an Ozone Hole back then? Hard to say but not out of the question with these readings. If not CFCs then what? CED readers might remember that volcanoes also put out halogens and there are active volcanoes on the south polar continent!. I spoke of Mr. Erebus in an earlier CED. Environmental Terrorists -- Paul Crutzen, director of the Division of Atmospheric Chemistry of the Max Planck Institute of Chemistry in Mainz, Germany, at the Charlottesville Ozone Quadrennial's VIDEO TOWN MEETING (it is like Pepsi -- "Got to have one!") branded people who bring up the issue of volcanic halogens as ozone depleters as "environmental terrorists"! I never should have mentions Mount Erebus to you. You might in turn go out and say something and have your career ruined. It is hard to know where science and political science begin and end these days. It looks like we are all going to have to become "environmentally correct." It reminds you of Alice in Wonderland. White is black and black is white. Perhaps a little George Orwell thrown in for effect. ***************************************************************** ***************************************************************** *** *** *** *** *** BIOGENIC ICE NUCLEI UP DATE *** *** *** *** *** ***************************************************************** ***************************************************************** How many biogenic ice nuclei make it from litter to the atmosphere? Schnell (1974), Bul. of Am. Metero. Soc. 55(6)670 reports fluxes from 10 to 1000 ice nuclei per square cm per day. When snow covers the ground, very few ice nuclei are loaded into the atmosphere. As the snow melts more and more ice nuclei are detected in the air. Ice nuclei in the air above a grass surface on a calm day was 1 nucleus per liter of air and would cause freezing at temperatures as warm as -6.5 C. Following mechanical disturbance of the grass surface 10 times as many ice nuclei were recorded in the air over the surface. Following a three day rain with the grass surface wet there were three orders of magnitude fewer ice nuclei in the air above the canopy than on dry days. Schnell also indicated that the nuclei may be volatile or liquid in nature. Just what are ice nuclei made of? Chemical tests of ice nuclei derived from leaf material indicate that they are insoluble in water, stable in all common organic solvents and that nucleating activity is lost upon heating above 60 C. They are about 0.1 micrometers in size (so they would scatter in the blue wave lengths). Terpines have been shown to be ice nuclei. Schnell reports that ice nuclei abundance in rain water matches biogenic availability in litter from the same geographic region. He thinks that this correlation indicates that a large proportion of the earth's atmospheric ice nuclei are biogenic. Schnell has also found ocean derived ice nuclei that are active at temperatures as high as -5 C. He notes that seawater rich in phytoplankton produce a large amount of ice nuclei (10s to 100s of millions of ice nuclei per gram of phytoplankton). Oceanic areas of low photoplankton productivity have low ice nuclei production. Do the clouds with ice crystals over the oceans pop up where ocean productivity is high? Sort of interesting! The penultimate papers in the Schnell-Vali team up were: Biogenic Ice Nuclei: Part I. Terrestrial and Marine Sources. J. Atm. Sci. 33:1554-1564. Biogenic Ice Nuclei: Part II. Bacterial Sources. J. Atm. Sci. 33:1565-1570. Those in the know who are interested in ECOSYSTEM CONTROLS ON THE WEATHER AND CLIMATE need these papers in their collection. To quote Schnell and Vali: "The changes in atmospheric ice nuclei concentrations can be related to large scale meteorological effects, thereby suggesting a cause and effect relationship controlled by meteorological characteristics / life history / source region of a particular air mass." ***************************************************************** ***************************************************************** *** *** *** *** *** ECOSYSTEMS AND SNOWFLAKES *** *** *** *** *** ***************************************************************** ***************************************************************** What determines what kind of snowflakes are formed in the atmosphere and then fall out to delight of off-from-school kids? First of all, air temperature is important. Second of all, the degree of vapor supersaturation relative to liquid water and to ice. A third variable is the geometrical (crystalline) properties of the ice nuclei (and you thought the ice nuclei story was over). Organic ice nuclei reduce the temperature at which freezing happens in the air! Different organics produce freezing at different temperatures and so different organics might well result in different shape snowflakes (plates, rods, hexagons, needles etc.) Kaolin, the clay mineral, is often listed as at the center of many snowflakes. It turns out that pure kaolin ice nucleates around -20 C. You just don't get nice star-like snowflakes at that temperature, just little gritty stuff. If it has organic films it may well cause nucleation at temperatures as warm as -3 C. Kaolin from most soils that gets lofted into the air is "contaminated" with organic compounds. At -12 C kaolin exposed to leaf derived organics is 4 orders of magnitude better at nucleation than pure kaolin. You get wonderful stellar snowflakes at this temperature. Well, we are in virgin territory here. The biogeography of biogenic ice nuclei is little worked on and snowflake morphology relative to what kind of organics is not yet systematically worked on. But, it is a nice story. The variety of forms of snowflakes falling from the sky might be determined in part by the ecosystem below! CED seeks to prod you to think new things. [Trivia: a mist of propane will cause ice crystals to form in the air at about -2 C. However, I do not recommend propane pollution but rather remind you that organic fluxes from the biosphere are related to atmospheric processes.] As a parting shot we might ask: What snow would be like in a world without life? If we take the position that the organics are not present then ice nucleation would occur on its own or on sea salts at -38 C or colder. Well, what kind of atmospheric ice is formed at such temperatures? Ohtake (J. Atm Sci. 27:509-511 1970) describes them as 20-faceted bi-pyramids on short prisms with two (0001) hexagonal faces, two sets of six (1011) trapezoidal faces and six 1010 prism faces and 14-faceted bi-pyramids on short prisms with two (0001) hexagonal faces and two sets of six (1011) trapezoidal faces. It is hard to believe that you could make very good snowmen out of that kind of stuff. Most of the exciting snowflakes are produced at temperatures warmer than -15 C. Hail??? In one study in Colorado, it was found that ice nuclei concentration in the air was as high as 100 per liter at the time of hail. Pre-storm background ice nuclei was only 1 per liter. The study indicated that mixing by down drafts and up drafts in the thunderstorm were needed to get the ice nuclei up into the atmosphere. Those strong winds that come before the storm may play a key role in getting biogenic ice nuclei into the storm. At this point it is worth remembering that the production of ice nuclei that do their work at various temperatures varies from biome to biome and so too must cloud physics and the weather that follows. See CED 1.4. ***************************************************************** ***************************************************************** *** *** *** *** *** GLOBAL TEMPERATURE *** *** IPCC Finds Warming in Data Manipulation *** *** *** ***************************************************************** ***************************************************************** One of the center pieces of the first IPCC [Intergovernmental Panel on Climate Change] report was the famous Jones and Wigley global temperature curves. From the beginning to the end of the records, temperatures increased 0.45 C (1880-1990). This spring the new, updated IPCC report was released and the Jones and Wigley temperature curve was there again. But it wasn't the same Jones and Wigley curve. The numbers were different. It had been made more "accurate" the report reports! The beginning of the record is now colder than it was in the first IPCC report and the end of the record is warmer than it was in the first IPCC report! An extra 0.15 C of warming was found in data manipulation. That is a 33% increase in the rate of warming. The graph starts out lower and ends up higher than before. The new graph has already shown up on the morning TV news shows and they report a 1 F temperature rise of the new more "accurate" IPCC report. To warming advocates it must seem like magic or manna from heaven. To warming skeptics it is a head-shaker. The manipulator of the data was given in the new IPCC report as one Mr. Chris Fallon, who in a meeting I was at, said and I quote, "The data don't matter." Saying the data don't matter to a bunch of card carrying climatologists is like questioning parentage. Scientists at the National Climate Data Center -- a place were the data does matter -- are trying to figure out just how Mr. Fallon got it to be colder early on and warmer later on. If it is ever figured out I will post the news in a later issue of CED. Mr. Fallon does agree that the data do show that almost all the warming in the record is nocturnal warming and that daytime temperatures have changed very little since record keeping began. But then, the data don't matter. Oh, how we love and trust our model output statistics. Now there is something you can put your trust in! ***************************************************************** ***************************************************************** *** *** *** *** *** HOW BIG MICROCLIMATE? -- An Ohio Story *** *** *** *** *** ***************************************************************** ***************************************************************** Most of our CED ecosystem controls on climate items have focused on regional and macroclimate impacts. In my view the best big microclimate change due to vegetation paper is by Edgar N. Transeau (1943) in The Transactions of the American Geophysical Union pages 154-166. Transeau was interested in the richness of floras in deep valleys and made the case for atmospheric controls on biodiversity. As we will see vegetation control of the atmosphere is also real. Transeau instrumented a small valley in the Hocking Hills about 50 miles SE of Columbus, Ohio. The site is a cove called Neotoma. Not many valleys are named after a simple rat. In addition to the native flora of southern Ohio there are species of a more southern climate, of glacial climates and or prairie climates. Neotoma is a refugia of several past climate episodes. Minimum Temperatures Within the one half mile long cove the lowest temperature recorded in a frost pocket was -25 F for the winter of 1942-1943. In the same year in a leaf-litter near the covehead, the lowest temperature recorded was above freezing (32.5 F). Within the cove soils with a good litte,r didn't freeze that year. The minimum temperature range that year with in this little cove was 57.5 F! That is a big microclimate difference. If this were the norm, then winter hardiness zones within this valley range from Zone 3 to Zone 10! In the leaf litter that year, the length of the growing season was 365 days. In the summer minimum temperatures in the 30s were recorded in the frost pocket and minimum temperatures were highest in the covehead forests where minimum temperatures were in the 60s. Absolute Monthly Minimum Temperatures (F) at Neotoma Habitats JAN SEPT Frost pocket -25.0 29.0 Lower NE slope -19.5 38.0 Upper NE slope -15.5 42.5 Ridge top -19.0 44.5 Covehead -16.0 40.0 Crevice +10.0 54.0 Leaf-litter (cove) +32.5 52.0 In winter the absolute range of minimum temperatures within Neotoma is 57.5 F and in summer 23.0 F. The very large wintertime range accounts for the Neotoma status as a refugia for southern species. Maximum Temperatures The highest temperature in 1941 occurred at cliff top (117 F). On the same day temperatures at the head of the cove reached only 76. The maximum temperatures for the year in the three mature forest units in the cove (red maple, chestnut oak and hemlock) occurred in April before leaf-out. Ample water supply and evapotranspiration precludes sensible heating of the air to expected summer highs. Absolute Monthly Maximum Temperatures (F) at Neotoma Habitats and at the Lancaster Weather Service Office 15 miles from Neotoma. J F M A M J J A S O N D Lancaster 56 60 62 88 92 95 102 85 92 71 73 66 Cliff top 68 71 85 102 109 110 113 117 115 107 84 73 Cove 49 43 49 80 68 74 76 76 77 73 57 55 Red Maple 56 54 61 89 86 87 87 88 83 81 69 62 Chest. Oak 55 61 64 90 89 87 90 93 86 86 76 67 Hemlock 59 54 58 83 87 85 89 90 82 85 71 65 Within Neotoma, at the cove and in the three forest stands, the highest temperature recorded was only 93 F which is 24 F cooler that at ridge top. For the most part mid-summer temperatures are in the 70s and 80s in the cove and adjacent forest stands. To have such low absolute maxima, most of the excess daily radiation must be given off as latent heat rather than sensible heat. Here in Charlottesville, Virginia with a fully charged soil moisture, say after a good soaking rain, temperatures do not get over 90 F. Why are coves warm places at night and in winter and cool places in the day and in summer and not cold spots or frost pockets due to simple cold air drainage? First coves are usually moist places with ample water supply even in drought years. With ample moisture for evapotranspiration hot days are uncommon. With active vegetation moisture and hydrocarbons added to the air and trapped in the cove airshed, minimum temperatures do not fall as much. High minimum temperatures increases the length of the growing season and a long growing season keeps the cove climate moderate. A synergism between vegetation and climate within a captive airshed. There is as much as 100 days difference in the length of the growing season within Neotoma (See discussion of the montane oasis in an earlier CED.) Length of the 1941 Frost Free period in Neotoma and at Lancaster Last Frost First Frost Frost Free Days Frost pocket May 25 Sep 26 124 Lower NE slope May 14 Oct 11 150 Upper NE slope Apr 22 Oct 29 190 Cove Apr 3 Nov 11 209 Crevice Apr 3 Nov 25 235 LANCASTER May 5 Sep 26 144 In a more recent paper on cove climates, Gaddy, Suckling and Meentemeyer (1984) in Arch. Met. Geoph. Biocl. Ser. B 34:155-162 an Appalachian Cove in South Carolina was found to be much warmer at cove head than down valley and that the blooming dates at covehead were as much as three weeks earlier than down valley. While coves are low places that might be thought to be filled with denser, cold air catchments, it is clear that processes which retard night time cooling must dominate the collection of all those molecules of air with low molecular velocities (the cold ones). The longer growing seasons and advancing of phenological stages weighs in for reduced radiative cooling at night. Transeau found that the cove had the highest vapor pressure of all his study sites. Using an atmometer he found it had the lowest evaporation at 15 to 18 inches above the surface. Wind speeds are low, radiation least, and vapor pressure deficit the smallest. High specific humidities and thus high dew point temperatures keep minimum temperatures warm. In effect there is a cove greenhouse of atmospheric water vapor. The cove keeps itself warm at night and evaporation keeps it cool by day. In the cove, Transeau recorded 1.8 times the canopy evaporation as outside the cove. ***************************************************************** ***************************************************************** *** *** *** *** *** CLIMATE AND WEATHER ON AN EARTH *** *** WITHOUT EVAPOTRANSPIRATION? *** *** *** ***************************************************************** ***************************************************************** With the development of atmospheric General Circulation Models (GCMs) we can ask such questions. [Shukla and Mintz. 1982. Science 215:1498-1501.] Shukla and Mintz contrasted a world where water on land was not limiting,a world where as much evapotranspiration as possible takes place, with a world in which the green evaporators were gone. In the world without stomates it was 15 to 25 C warmer for land areas north of 20 S. There was 125 Watts per meter squared less evaporative cooling. No bio-air conditioning! Since air got less water vapor, the calculated cloudiness was less and more sunlight got to the ground, 172 to 258 Watts per meter squared, and thus even greater sensible heating of the air by the ground (148 Watts per meter squared more than in our stomate rich world). Sort of like a shopping center parking lot. Without transpiration, thermal low pressure cells developed over the continents (average continental surface pressures fell by 5 to 15 mb -- that is a lot!] The excess upward motions over the continents in these thermal lows are compensated for by sinking air over the oceans building the strength of the subtropical anticyclones, especially the North Pacific where pressures 10 mb higher than we expeience (Lots of fair days in Hawaii!). With such mean pressure field changes, the circulation of the atmosphere would be different including greater equatorial pacific trade winds (speedy transit for Christopher Columbus to the new world), greater maritime flow into Alaska a bonanza for Bonanaza Creek) and very strong equatorward flow along the western littorals of the Americas (more smog holding capacity for you guys in LA!). There would also be a significant northward displacement of the jet stream northward. Rainfall: Europe and Asia had almost no rainfall in the transpiration free world. It rained like it does in our world only in places like India and Southeast Asia (near tropical waters). Over North America only 1 mm per day of model rain fell to the earth in the transpiration free world (that is about 14 inches per year and who needs trees anyway). That North America gets even that much is because of our proximity to the sea on three sides. Poor dry central Asia! In our world central Asia relies on recycled water from transpiration from the vegetation elsewhere in central Asia. The Himalayas to the south are a dam to the moist tropical air from the Indian Ocean. Well, all these changes are of little worry in that the real world, non-GCM model experiment can't be done. But this computer assisted thought experiment puts into view the role of life on earth. The physical world of weather and climate is not so immune to the will of the biosphere. Now for the Shukla and Mintz concluding paragraph: "Finally, on the question of whether the earth's vegetation cover and its modification by man have a significant influence on climate, and whether deforestation and afforestation, soil destruction and soil reclamation, or crop irrigation appreciably affect rainfall; the answer given by this study is that they do, if they are of large magnitude and large horizontal extent." Shukla and Mintz's stomate-free world is like ours would be if life had never left the sea! It is clear that at the planetary evapotranspiration controls atmospheric circulation, weather and climate to a very substantial degree. In your future schematics, point your climate-vegetation arrow both ways with large magnitude. ***************************************************************** ***************************************************************** *** *** *** *** *** DEWPOINT TEMPERATURES! 29 CENTS! *** *** *** *** *** ***************************************************************** ***************************************************************** I Know temperature. I know relative humidity. Radio Shack sells a cheap device that reads out both. LTER sites have expensive devices to do the same. How do I get dew point temperatures so that I can calculate vapor pressures and vapor pressure deficits? I can provide you a xerox of a table of dew point temperatures given temperature and relative humidity, if you send me a self-addressed, 29 Cent envelope. The table was published in Psychrometric Notes and Tables by Elmer Torok who happens to have been the Superintendent of Power for North American Rayon Corporation (1935)! If you have a Department of Textile Technology at your University, don't we all, you may well have Torok's little gem in your library. ----------------+--------------------------------+------------------------- Bruce P. Hayden | Dept. Environmental Sciences | bph@virginia.EDU (804) 924-0545 | Clark Hall, Univ. of Virginia | bph@virginia.BITNET (804) 924-7761 | Charlottesville, VA 22903 | (804) 982-2137(fax) ----------------+--------------------------------+-------------------------