Newsgroups: lter.ced Path: LTERnet!news From: "Bruce P. Hayden" Subject: CED 1.7 Sept Message-ID: <1992Aug28.193817.14709@lternet.washington.edu> Sender: news@lternet.washington.edu Organization: Long Term Ecological Research Date: Fri, 28 Aug 1992 19:27:52 GMT ***************************************************************** ***************************************************************** *** *** *** *********** *********** ********** *** *** * * * * *** *** * * * * *** *** * * * * *** *** * ********* * * *** *** * * * * *** *** * * * * *** *** * * * * *** *** * * * * *** *** *********** *********** ********** *** *** *** ***************************************************************** ***************************************************************** Vol.1 No.7 :::::: file name:CED1.7 :::::: September 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 Daniel Pommert [daniel@lternet.washington.edu] by the file name given in the masthead. Daniel can also add people to the CED mailing list. 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. ***************************************************************** ***************************************************************** *** *** *** *** *** From the Alaska CC Trip *** *** *** *** *** ***************************************************************** ***************************************************************** Many of the items for this issue of CED were collected during the Alaska Coordinating Committee trip to Fairbanks and points north. Otherwise -- there wouldn't be a CED issue this month. At Keith Van Cleve's sit-down dinner for 70 or so a conversation about relative humidity broke out. No hush came over the crowd. Complements on Alaska's weather were bandied about however. "How comfortable it is here." "What is the relative humidity in summer." "Oh. Between 50% and 100%." While such conversation might be viewed as buttering up the host, the notion that 50 to 100% relative humidity is nice might be debated. For example: a Washington, D.C. August day might clock in at 50% relative humidity (Alaska nice) with an afternoon temperature of 90 F. That would put the dewpoint temperature at about 69 F (you wont need covers at night with that dewpoint) and the amount of water in the air at 31 grams per kilogram of air. Meanwhile, in Alaska, it is 70 F and 50% relative humidity and the dewpoint is only 50 F and the amount of water in the air is 15.2 grams per kilogram of air. Both lovely places had the same relative humidity but one had twice as much water in the air! By morning, in Alaska, the temperature would be about 50 F and sleeping in the all-together shouldn't done with out blankets for fear of hypothermia. One thing you don't find in Alaska is nights when it is to humid (absolute humidity) to sleep! When you have to speak about relative humidity in polite society, and when I am around, say the words 'relative humidity' with a hushed voice. There might be a fly on the wall! That is old reports lingo for eavesdropping. Being evaporators ourselves, things get life threateningly tight when the dewpoint temperature of the air is the same as our skin temperature (33 C or 91.4 F). You might find such condition on the shores of the Persian Gulf. Don't go there unless your are sent. At night, the temperatures might fall to 91.4 but no lower. Just think, hyperthermia while you try to sleep! You can't cool by sweating; so, all you can do is take off all your clothes, hope there are no clouds in the sky (common), take a spread eagle position on the ground and try radiating and much body light to the cold sky (255 K, -18 C or -0.4 F ) as you can. Better, head inland where the air is drier or find an air conditioned place somewhere. The rule of thumb is: the higher the dewpoint temperature the more difficult it is to stay cool and the more work our body has to do to keep homeostatic thermal equilibrium. ***************************************************************** ***************************************************************** *** *** *** *** *** Below-ground Temperatures *** *** Arctic to Tropics *** *** *** ***************************************************************** ***************************************************************** Gus Savage (Arctic Tundra LTER) reminded LTER field trippers of the benchmark Lachenbruch and Marshall paper in Science (1986) on soil temperatures, permafrost and global warming. [Changing climate: Geothermal Evidence from Permafrost in the Alaskan Arctic, Science 234:689-696.] When I got back from foraging at Prudhoe Bay with the CC committee another underground temperature and climate change paper was on my desk was [Cermak, Bodri, and Safanda, 1992. Underground Temperature Fields and Changing Climate: Evidence from Cuba, Global and Planetary Change Section 97:325-337]. You are probably wondering how a global change journal could be 97 issues (years) old! Well, it is our old friend Paleogeography, Paleoclimatology, Paleoecology in modern sartorial meaningfulness. In these papers, global warming and surface disturbance of the surface vegetation cover are proposed as the cause of soil warming. In the case of Cuba, a 2 to 3 C surface warming is indicated by the profile of temperatures with depth. The warming is attributed to forest clearing and the switch to agricultural ecosystems some 100 to 200 years ago! In the case of the Alaskan Arctic, a 2 to 4 C surface warming is indicated by the profile of temperatures with depth. For 14 bore holes in the tundra, here are the dates (in years) for the onset of warming based on a best fit linear model: 1910, 1956, 1937, 1891, 1928, 1940, 1944, 1940, 1943, 1952, 1950, 1916, 1906, 1923, 1895. Most of these dates are before the global peak in warmth in 1940 and the date by which most of the global warming to date has taken place, i.e. 1940 [see Idso & Balling (1991) Theor. Appl. Climatol. 44:37-41]. Lachenbruch and Marshall note that the warming got started latest at the more inland sites north of the Brooks Range. Evidence of the earliest warming are from the Prudhoe Bay area: 1885, 1873, 1876, 1927, 1873, 1878, 1835, 1855, and 1868. Lachenbruch found warming from the most recent decade or two restricted to the Prudhoe Bay area where there was surface disturbance do to oil drilling beginning 5 to 7 years before 1984. The Alaskan Arctic data is consistent with the Idso and Balling report that almost all of the warming in the global temperature recorded occurred before 1940. In the tropics, carbon extraction for human use is blamed for the warming in the record. In the Arctic, carbon extraction for human use can be blamed for the very recent local warming evident in the soil temperature profile record in the oil fields area. One of the most interesting things about these papers, especially the one on Cuba, is that changing the surface vegetation covering of the landscape leaves a record behind in soil temperatures. These warmings confound the signature of atmospheric warming that might be present. Analysis of such records is not cheap as boreholes about 400 m deep are required. At 50 cm soil temperatures are a good estimate (with an added constant depending on the vegtation cover) of contemporary mean annual temperatures. In the tropics, the difference in temperatures between a rainforest and bare soil is about 6 K. Pastures and grasslands are 2.5 K higher than under bare soil. You change the vegetation -- you change soil temperatures at depths. Is there a record of forest fire clearings of old in borehole temperature logs? Perhaps an LTER scientist in the know knows of a paper on the subject. It would be interesing to see how long soil warming lasts following a forest fire. ***************************************************************** ***************************************************************** *** *** *** *** *** Broca's Brain on the North Slope *** *** *** *** *** ***************************************************************** ***************************************************************** Dateline CC Meeting Field Trips: Cephlomorphometrics as an indicator of mental prowess has slipped out of fashion (see Gould's The Mismeasures of Man). But contemporary fashion, the baseball cap with the little 7-button plastic fastener on the back, permits observations of cranial perimeters in an unobtrusive manner. Such a survey was taken of members of the LTER coordinating committee and fellow travelers at the LTER CC Big-Alaska Shootout! Here is how it works (the methods section of this little report). You count the number of buttons on the hat fastener that show. The possibilities are 0,1,2,3,4,5, and 6. Twenty cap wearers were approached from behind by this reporter (N=20) and tabulated on the spot! The mean was 2.4 beads showing plus or minus 1.273 (kurtosis -.582; skewness .151). Better run to the closet and check your hat to see where you fit. The histogram below gives the frequency distribution. Not bad for N=20. Y=frequency of buttons showing | 6 | ******** | ******** | ******** 5 | ******** ******** | ******** ******** | ******** ******** 4 | ******** ******** ******** | ******** ******** ******** | ******** ******** ******** 3 | ******** ******** ******** ******** | ******** ******** ******** ******** | ******** ******** ******** ******** 2 | ******** ******** ******** ******** | ******** ******** ******** ******** | ******** ******** ******** ******** 1 | ******** ******** ******** ******** ******** ******** | ******** ******** ******** ******** ******** ******** | ******** ******** ******** ******** ******** ******** +----|--------|--------|--------|--------|--------|--------|--------| 0 0 1 2 3 4 5 6 CAP BUTTONS SHOWING The NSF leadership on the field trip was approached from behind and tabulated as well. Results: smaller heads than the total population (mean = 2.0) and a variable lot (SD = 1.581). They have a large coefficient of variation compared to the total population 79.057 vs 53.050. But have zero skewness. Surprise! The NSF leadership group had the only 0 button subject (pinhead?) and the only 5 button subject (fathead?) Organizers of the CC meeting and field trips were also isolated and tabulated. 1.333 +/- .577 with a coefficient of variation of 43.301 (on the pinheadish side). It is noteworthy that the graduate student minions at Toolik lake scored a robust 3.667 +/- .577 with a 15.746 coefficient of variation. A number of the field trip participants were sans billed baseball cap. Observations indicate considerable cranial girth and a dullness of eyes thus indicating that a hats-that-don't-have-buttons hypothesis that would merit study. Statistics on gender or subfield of ecology were not taken (not PC), nor on family-way status. Because individual egos are involved, the data base for this study will not be put in network archives. You will have to live with the "meta data" in this report. As to the significance of the findings your really should read Gould's The Mismeasures of Man. ***************************************************************** ***************************************************************** *** *** *** *** *** Coldfoot Black Spruce *** *** *** *** *** ***************************************************************** ***************************************************************** Dateline: Coldfoot, Alaska from the Bus. Boy, the black spruce here on the southern slopes of the Brooks Range have a wimpy root base! Upturned tress, and there weren't all that many, weigh for a lack of wind storms. Could this be? Atlas check. Fairbanks: mean annual wind speed 5 mph with an average monthly range from 3 to 7 mph. That is less than half of the average in the lower 48. Along the arctic coast of Alaska the average is 13 mph. So why are the winds so modest and black spruce so ill equipped for winds. The driving acceleration for wind speed is the pressure gradient, but the realized wind depends on latitude and that term we can't touch or feel, the almost unreal coriolis force. The wonderful Smithsonian Meteorlogical Tables (Table 39) gives wind speeds for a range of naturally occurring pressure gradients, and for a spectrum of latitudes. At Luquillo, hurricane strength winds (72 knots) are produced by a pressure gradient of .03 mb per mile. This same storm moved to Coldfoot would have winds of only 28 knots. Look at it this way. Luquillo trade winds, say 10 knots, are sustained by a .004 mb per mile horizontal pressure gradient. That same forcing pressure gradient at Coldfoot, Alaska would produce only a wimpy 4 knot wind. The winds up on the Arctic coast, which average 13 mph, are high because steep pressure gradients occur there associated with coastal storms especially when there is open water around. Unlike our more temperate latitudes, Arctic coastal storms move from east to west. These arctic storms are monsters to the eye (many isobars tightly "coiled") with hurricane level pressure gradients but lesser winds. The Smithsonian Meteorological Tables don't even give pressure gradients that could make a 72 knot wind way up there. It is to the good fortune of Coldfoot black spruce that these coastal storms don't move into the interior of Alaska with their mighty pressure gradients else the Coldfoot black spruce would need to be renamed Picea mariana horizontalis! How about some fancy index of required root holding power per degree of latitude poleward of the equator. If I were a government agency I would need to give this index an acronym like: RRHPPDLPE. Not as catchy as acid rain or global warming! Well, what does knock over the poorly anchored black spruce? The two best candidates are summer convective thunderstorms and winds associated with fire storms. I await word from our Alaska friends on the truth about knocking over black spruce. ***************************************************************** ***************************************************************** *** *** *** *** *** Toolik Lake Dew *** *** *** *** *** ***************************************************************** ***************************************************************** The coordinating committee field trip to Toolik Lake was blessed with clear skies, sunshine, moonlight and loons on the lake and in the tents. While the darkness was short and the time for radiative cooling restricted to a few hours, temperatures still fell enough to cause a light dew on the ground. Relative humidity reached 100%. Dew was evidence of those surfaces that cooled to the dew point temperature. At sunrise, on an early walk prompted by to cold diuresis, I surveyed the Toolik compound for surfaces that had dew. My observations are: Rocks and pebbles of all types -- undewed. Grass flower heads -- dewed. Styrofoam cups -- undewed. 55 gallon drum painted black -- undewed. Wood from resource pile (there is no trash at Toolik) -- undewed. Construction Aluminium -- heavily dewed. Construction Iron -- undewed. Painted Aluminium -- undewed. Aluminium foil -- heavily dewed. Horizontal leaves -- dewed. Vertical leaves -- undewed. Explaining the observations. The heat balance of each object determined which got cold enough to reach the dewpoint. Heat losses: radiation to the sky and space and conduction to the molecules of the air. Heat gains: radiation from the sky. The last item needed to understand the heat balance is the heat storage of the objects. We will assume that during the high sun of the previous day all these objects had the same temperature. The sky temperature (radiative) was probably around 255 K or -18 C. The dewpoint temperature at the surface was between 5 and 10 C. Radiative losses to the sky exceeded the radiative gains from the sky so temperatures fell on the night in question. Some surfaces got cold enough for a covering of dew and some did not Rocks and Pebbles: high heat capacity and large storage; high heat conductivity (heat moves within the mass rapidly; emissivity around .95; not enough stored heat loss for temperature fall to the dewpoint. Grasses and leaves: Adequate heat conductivity; emissivity = .95; low heat capacity and low mass/surface area ratio means there is not much heat to get rid of and temperatures fell rapidly. The vertical leaves did not "see as much of the sky as the horizontal leaves and did not cool to the dewpoint. Non-Aluminium metal: high heat capacity, high conductivity, high emissivity (.95). Stored heat adequate to keep minimum temperatures above the dewpoint. Aluminium (non-painted): low emissivity (.05), i.e. it gives of IR radiation to the sky by does not absorb IR from the sky. It cools down rapidly at night and lots of dew forms. Paint the surface (paint emissivity = .95) and it is like any other metal and dew would not have formed. I looked for polished silver (it also has an emissivity of .05) but could find none even on the resource pile. Had I found any it would have had a nice covering of dew. Mobile homes in environs of cold, dry, clear air cool down so rapidly at night that they tend to creek and groan as the skin temperatures fall. Like a spook house! Wood: no dew because it is a poor conductor of heat. The heat it gets from the sun in the daytime has a hard time making it to the surface where it can be radiated away. On this night it was dewed. There would be real evolutionary advantage for a plant in water starved places to have a surface with a low emissivity. Then they would be better dew collectors. It would help plants like lichens. To my knowledge there is not literature which gives the emissivity of a wide range of plants. If any of the readers know of any, I would sure like to hear about it. In the next item we will talk about some plants that are expert at harvesting water from the air by facilitating frost formation! ***************************************************************** ***************************************************************** *** *** *** *** *** Ice and Lichens *** *** *** *** *** ***************************************************************** ***************************************************************** One of the responses on the recent CED discussions of the role of biogenic ice nuclei was from Thomas Kieft (Jornada LTER). Tom has four wonderful papers dealing with ice nucleation activity in lichens. [Ice Nucleation Activity in Lichens, 1988, Applied and Environ. Microbio. 54(7):1678-1681. Measurement of Ice Nucleation in Lichens Using Thermal Analysis. 1992. Cryobiology 29:400-406. Molecular Sizes of Lichen Ice Nucleation Sites ... 1992. Cryobiology 29:407-413. Characterization of Biological Ice Nuclei from a Lichen. 1990. J. of Bacteriology 172(6):3519-3523.] Kieft's work shows that the surface of arid land lichens have proteinaceous "spots" that cause ice to collect at temperatures of -4 C where other parts of the liken surface do not cause ice to form. He showed that the ice nuclei on the surface were not of bacterial origin. Most of lichens tested could cause ice formation at temperatures warmer than -8 C and as warm as -1.9 C. He found that there was negligible ice activity warmer than -8 C for rocks, plants and soil. He hypothesizes that lichens are dependent on atmospheric moisture and derive benefit from increased moisture deposition as a result of ice nucleation. Remember past CEDs where we discussed the advantage ice crystals have over liquid water in accumulating water vapor from the air. Ice crystals grow very rapidly compared to liquid water and so a water needing plant that could get ice crystals to form on its surface and then melts at with sunrise and absorb it there after would have an advantage. Now if lichen had a low emissivity they would be in the catbird seat. They could cool rapidly get into the ice nuclei temperature range and begin to pull water out of the air!. Unfortunately we have no data on the surface emissivity of lichens. It seems reasonable however that the surface proteins of lichens are there because of the selection advantage of lichen genotypes ***************************************************************** ***************************************************************** *** *** *** *** *** Update on Ozone War *** *** *** *** *** ***************************************************************** ***************************************************************** As a long-term observer of the ozone war, Kenneth M. Towe's letter to Science magazine (7 August 1992) was xeroxed and filed right away. Towe's letter takes issue with the famous Stolarski paper [Science 17 April 1992, p. 342] "Measured trends in stratospheric ozone". The Stolarski article indicates that there has been a decline in actual total column ozone levels. Towe notes and shows that the measured data show no decline in total column ozone at all! You have to remove a bunch of stuff from the record (seasonal, solar and quasibiennial oscillation components plus data from atmospheric nuclear tests 'where appropriate' what ever that means. When Stolarski did this out came the trend he reported. Towe notes that it is possible the CFCs have reduced ozone in recent years but other offsetting factors have made up the loss and so there has been no change in total column ozone since 1956! Stolarski agrees with Towe that the solar ultraviolet flux at the surface will respond to the actual ozone in the air and not to the trend term he extracted from the data. In spite of all this, UVB at the surface seems to have been reduced in recent years. In the words of Pooh: "Oh, bother!" It is a good thing, after all, that those Canadian school kids were permitted to go back to school after the NASA scare of last February. And the pink eye in sheep, well review the last several issues of CED on that one. Cheers for this month. ----------------+--------------------------------+------------------------- 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) ----------------+--------------------------------+-------------------------