Monthly Archives: June 2007

NOAA Cover Up Of US Historical Climate Network Surface Station Photographs

Since 2002 (see the AASC 2002 Annual Meeting minutes), we have been seeking to have photographs of the US Historical Climate Network (HCN) sites made available. The HCN sites are used as part of the diagnosis of the surface temperature anomalies on monthly and yearly time scales, as well as the United States contribution to the construction of the global average surface temperature trend used in climate assessments such as the 2007 WG IPCC Report (see Figure SPM.3a, for example).

NOAA, however, has consistently failed to provide these photographs. As result, several scientists have independently obtained photographs for specific locations (e.g.,

Davey, C.A., and R.A. Pielke Sr., 2005: Microclimate exposures of surface-based weather stations – implications for the assessment of long-term temperature trends. Bull. Amer. Meteor. Soc., Vol. 86, No. 4, 497–504


Mahmood, R. S. Foster and D. Logan, 2006: The GeoProfile metadata, exposure of instruments, and measurement bias in climatic record revisited. Int. J. Climatol., 26, 1091-1124),

and have identified significant siting problems with a number of locations. Since this HCN data is so central to the discussion of climate change, it is imperative that the actual locations where the data is being collected be adequately documented.

Recently, Anthony Watts has established a website [] to record these photographs. He has worked to assure that the photographs are obtained appropriately.

As a result of this effort, NOAA has removed location information from their website as to where they are located. This information has been available there for years. NOAA wrote in an e-mail defining their new policy which reads

“Your inquiry was forwarded to me by our webmaster. I’m glad you’ve found MMS to be a useful tool in your research. MMS is our primary source of station metadata for National Weather Service Cooperative Observer and several other networks, and we are actively working to provide increased detail for a larger number of stations.

It sounds as though you’ve used the system enough that once you’ve located a station using the search, you’re clicking on the station name hyperlink and opening a separate station details window. The managing party for a station has always been visible by clicking on the “Other Parties” tab. In the case of NWS Coop stations (the USHCN research network relies upon a subset of stations in the NWS Coop program), this is usually the NWS office that administers the site. This information was previously included at the bottom of the Identity tab’s “form view,” but was removed from that view early this week because in some cases it also revealed the name of the Cooperative observer.

Cooperative observers are volunteers who donate their time in the interests of the public good with a reasonable expectation that their personal information will remain private. It is the NCDC’s policy to protect observer details, based upon Freedom of Information Act (FOIA) Update, Vol. X, No. 2, 1989, which exempts the application of FOIA in certain cases and establishes privacy protection decisions in accordance with the Privacy Act of 1974 (2004 edition). This exemption applies when the personal privacy interest is greater than any qualifying public interest for disclosure.

If you have other questions regarding MMS, please feel free to contact me. I am often away from my desk, so my response may not be immediate.”

This is clearly a procedure to avoid making these photographs available. Indeed, in the papers that have been published with photographs of these HCN sites, care was taken to not publish the address or name of the observer.

This failure to permit interested parties to obtain the photographs is even more distrubing as the photographs for most of the sites apparently already exist! I have found out that

“over 4 years ago there was a big push in the Cooperative Observer program to make sure that all 7000+ sites across the country were photodocumented. All 120 Data Acquisition Programs were equipped with high quality digital cameras. Most took photos. However, at the higher levels where they were developing the upload and archive system for the photos the issue of observer privacy was raised and as best we can tell the result was that those photos were not archived and certainly are not available.”

This is a very disturbing development, as individuals in NOAA’s leadership have used their authority to prevent the scientific community and the public access to critical information that is being used as part of establishing climate and energy policy in the United States.

The solution to this issue is, of course, straightforward. Either make the photographs where datasets are being used in research (i.e. the HCN sites), available, or permit others to take them. Privacy rules, such as not publishing the names and addresses of the observers, should be made, however, the photographs themselves, viewing the site, and views in the four orthogonal directions must be public. Volunteers who are HCN Cooperative Observers need to either grant this permission or not volunteer.

The new NOAA policy is a deliberate attempt to avoid presenting this information for scrutiny.

Comments Off

Filed under Climate Change Metrics

Guest Weblog By Robert Maddox

Dr. Robert Maddox is internationally recognized as an expert on mesoscale cloud systems, who has worked at the National Severe Storms Lab in Norman Okalhoma, and is now at the University of Arizona in Tucson. His characterizations of mesoscale convective complexes (MCCs) was pioneering.

He has graciously agreed to write a guest weblog for Climate Science, as well as also post on his own website (madweather). Dr. Maddox’s weblog is important since it provides another example of the lack of consideration by NOAA on the need for proper siting of instrumentation that is required to monitor weather and climate.

The weblog follows.

Comments on the NWS Radiosonde Replacement System (RRS) Robert A. Maddox 21 June 2007

I have recently become very concerned about several aspects of the NWS sounding program, in particular the RRS – see: I have learned of this program because the upper-air sounding system at Tucson has recently been replaced, and also physically relocated. Until this happened, I was not really aware that such a program has been underway since summer 2005 (see Fig 1.) Given the important character and potential impacts of the RRS implementation on both climate and weather research and prediction, I would have assumed that the program would be highly visible and that widespread communication between the NWS and its private sector, academic, and research customers would have preceded implementation decisions. This appears to be a bad assumption. The last formal, NOAA-wide data users meeting was apparently held in the late 1990s. I discuss two aspects of the RRS program below.

Figure 1 – Map showing the NWS upper-air stations in the conterminous U.S. Purple underlining identifies the sites currently using the new RRS sondes. Green underlining indicates sites to be converted between now and September. The new sondes were first used at KLWX (8-1-05) and KSLC (9-20-05). The most recent conversions were at KMFL (5-7-07) and KTUS (6-4-07).

I. Relocation of the Tucson upper-air observing site (WMO 72274)

When the TUS NWS Office announced on their website that the upper-air site had been relocated to the roof of the NWS/USGS building on campus, I (a long-term user of upper-air data) was quite surprised and shocked. This change in the site location occurred after upper-air observations had been taken at the Tucson airport for 51 years. (The Tucson upper-air site was relocated from Davis Monthan AFB to the Tucson airport on March 1st of 1956.) The RRS relocation of the site on June 4, 2007, shifts the upper-air observing site from an open, surface location, reasonably representative of the desert, to the roof of a three-story building in an urban, artificial environment with tall buildings, trees, vegetation and irrigation (see Fig. 2). This relocation is not an NWS action that will preserve the long-term stability of the Tucson upper-air observations.

Figure 2 – Photo of the RRS white tracking dome on the roof of the NWS/USGS building. The view is to the west-southwest toward the city center from the roof of a five story U of A parking garage to the east of the NWS/USGS building.

Unfortunately, even though the NWS Office is on the University of Arizona campus, there were no discussions during the planning process for this possible move with the many weather and climate researchers on campus. The NWS apparently did not share any information publicly until the move was imminent. This is certainly a dismal example of communication and interactions amongst the management of the local NWS office and their academic neighbors, who are customers/users of the local and national NWS observational data. However, the relocation announcements “followed NWS procedures.” But, the NWS official procedures are so ineffective that none of the major organizations that process and archive upper-air data from the NWS (e.g., FSL, NCAR RAP, and Univ. of Wyoming) appear to have been aware that the move happened. Soundings processed with bad elevation, latitude, and longitude data have been going into the upper-air archives since the move. As of this morning (June 21, 2007 at 1200 UTC) FSL still is processing the TUS sounding using the old station history data for the airport location, which is of course no longer operational!

Several of us from the Department of Atmospheric Science visited the NWS Office last week to learn more about the relocation and the new RRS system (many of the soundings taken from the new site have seemed quite bizarre). A look at the new system installation left me flabbergasted. The new site does not meet WMO guidelines for an upper-air site (see pages B-1-3 at ). The roof launch site has significant nearby obstructions – larger buildings NW to E within 50 to 500 or 600 yards (i.e., the stadium to the east). A nine story building towers above the 3rd floor roof launch site only about 600 feet to the north (Fig. 3). Additionally, the white-painted, roof-top site, where the new, required surface observing instruments [information at (], have also been installed, is cluttered with everything from large heating and cooling systems venting air in close proximity to the surface sensors, to a variety of additional obstructions and antennas and a satellite dish (Fig. 4). Based on viewing the RRS installations on the roof of the NWS/USGS building, I feel that there is probably not as badly a selected upper-air site location in the rest of the nation. Note that the green tub or bowl in the Fig. 3 photograph is where the sounding balloon is inflated, out in the open and whatever weather might be occurring, as the person taking the sounding prepares for release. The wooden “gizmo” has been locally fabricated to allow the balloonist to move the balloon around on the roof, before final release, to try to account for wind direction and the location of higher buildings and obstructions. Tucson is apparently the only upper-air site in the country that does not have an enclosed structure for balloon inflation.

Figure 3 – Photo of two large U of A buildings located just to the north of the NWS/USGS building. See text for explanations of the green tub and wooden “gizmo” in the bucket.

Figure 4 – Photo of the new surface observing system installed on the roof of the NWS/USGS building looking east toward the U of A football stadium.

II. Instrument problems associated with the new Sippican sondes.

During our visit we also learned that the unusual soundings (e.g., Fig. 5 and Fig. 6) that began after the move were not only due to the unrepresentative local campus environment, nearby tall buildings, and the cluttered roof-top environment, but were also due to a hygrister problem on the new sondes (yes, the NWS did a concurrent change in both observing site location and sonde instruments at Tucson). I have also learned that the thermistor on the Sippican sondes frequently produces unreliable data.

It apparently is not coated with a hydrophobic agent, leaving it vulnerable to easy wetting and the subsequent effects of evaporation, freezing, and sublimation.

Figure 5 – Skew-T plot of TUS sounding for 1200 UTC June 16, 2007. Note that the very dry layer indicated by the purple arrow is due to hygrister problems of the Sippican sonde (sounding from UCAR RAP upper-air page).

Figure 6 – Skew-T plot of TUS sounding for 0000 UTC June 16, 2007. A very dry layer is present again above the surface. The temperature structure on the roof top, and just above, seems very strange (sounding from UCAR RAP upper-air page).

I am appalled that the installation process continues moving forward (refer back to Fig. 1), even though the data from the new sondes are not consistently reliable. Apparently the sensor inaccuracies are not systematic but are often related to the local conditions at the time of the flight (see Fig. 7 and all the sounding examples). Thus, it seems that significant, random noise is being introduced into the long-term, upper-air data archives. Examples of pathologically low dewpoint temperatures during the early minutes of flights are shown in the two TUS soundings above, and Fig. 8 and Fig. 9 show examples of soundings where the thermistor problems have created significant layers of meteorologically implausible data. The NWS has not informed users – be they private vendors, or university or government or private sector forecasters or researchers – of the Sippican sonde’s instrument problems, and the new instabilities in both the real-time, upper-air data and their archives. The sensor problems and unrepresentative soundings going into the archives are not issues that the NWS should deal with essentially internally and seemingly in quasi-secrecy.

Figure 7 – Time series of integrated precipitable water (IPW) from GPS data (blue) for TUS from June 16 through June 21, 2007. The RRS sonde flights’ IPW (red diamonds) for the same period are shown. For this period the RRS sonde data are consistently dry relative to the GPS IPW (both morning and evening flights) except that the morning flight on the 20th was strangely too moist (arrow indicates that diamond, which is almost off the figure – figure from NOAA FSL).

Figure 8 – An RRS sounding from Tallahassee, FL taken at 0000 UTC on July 7, 2006. There are many physically unrealistic layers present from the surface to 400 mb (sounding from the University of Wyoming upper-air web site).

Figure 9 – An RRS sounding from Chanhassen, MN taken at 1200 UTC on June 18, 2007. The data appear physically unrealistic from 700 to 500 mb (sounding from the University of Wyoming upper-air web site).

Comments Off

Filed under Guest Weblogs

New Study On The Prediction Skill Of The Multi-Decadal Global Climate Models

On May 31, 2007 there was an article in Nature by Harvey Leifert that was titled “Warmer world gets wetter – Satellite observations suggest climate models are wrong on rainfall”.

Excerpts from the article read

“Global warming will increase worldwide precipitation by three times the amount predicted by current climate models, according to a study based on two decades’ worth of satellite observations.

The discrepancy between the models and the data might mean that the models are wrong. Or it might be that two decades is not long enough to test their predictions….”

This study conflicts with the claims such as that of

Richard Seager, Mingfang Ting, Isaac Held, Yochanan Kushnir, Jian Lu, Gabriel Vecchi, Huei-Ping Huang, Nili Harnik, Ants Leetmaa, Ngar-Cheung Lau, Cuihua Li, Jennifer Velez, and Naomi Naik: Model Projections of an Imminent Transition to a More Arid Climate in Southwestern North America Published online 9 April 2007 [DOI: 10.1126/science.1139601] (in Science Express Reports)

as discussed on Climate Science (see and see).

The new study

Frank J. Wentz, Lucrezia Ricciardulli, Kyle Hilburn, and Carl Mears: How Much More Rain Will Global Warming Bring? Published online 31 May 2007 [DOI: 10.1126/science.1140746] (in Science Express Reports)

clearly shows that we have a poorer understanding of the climate system than has been communicated by assessments such as the 2007 IPCC Report.

The abstract of their paper reads

“Climate models and satellite observations both indicate the total amount of water in the atmosphere will increase substantially due to global warming at a rate of 7% K-1. However, the climate models predict global precipitation will increase at a much slower rate of 1-3% K-1. A recent analysis of satellite observations does not support this prediction of a muted response of precipitation to global warming. Rather, the observations suggest that precipitation and total atmospheric water have increased at about the same rate over the last two decades.”

Of course, this study conflicts with the findings of

Smith, T. M., X. Yin, and A. Gruber (2006), Variations in annual global precipitation (1979–2004), based on the Global Precipitation Climatology Project 2.5° analysis, Geophys. Res. Lett., 33, L06705, doi:10.1029/2005GL025393,

where they write for the period 1979–2004 that precipitation tends

“have spatial variations with both positive and negative values, with a global-average near zero.â€?

Indeed, the diversity of observational results exemplifies our large remaining uncertainty of both the models and observations.

Comments Off

Filed under Climate Models

New Scitizen Weblog On The Importance of Heterogeneous Human Climate Forcings Has Been Published

A new weblog has been published on Scitizen as part of my monthly column on that website. The title is

The Importance of Heterogeneous Human Climate Forcings on Skillful Prediction of Regional Climate

The abstract reads.

“The role of heterogeneous human climate forcings as they affect skillful prediction of regional climate variability and change was inadequately reported on in the 2007 IPCC WG1 Report. This column briefly discuses why these forcings are so important in altering tropospheric weather patterns.”

Comments Off

Filed under Climate Change Forcings & Feedbacks, Climate Science Reporting

Simulated And Observed Variability In Ocean Temperature And Heat Content by AchutaRao Et Al

There is a new paper on comparing ocean heat content changes with model simulations of this change, as well as an effective analysis of the role of the observation system on diagnosing this climate metric (thanks to Willie Soon and Inkstain for alerting me to the article). The paper is

AchutaRao, K. M., M. Ishii, B. D. Santer, P. J. Gleckler, K. E. Taylor, T. P. Barnett, D. W. Pierce, R. J. Stouffer, and T. M. L. Wigley, 2007: Simulated and observed variability temperature and heat content. 10768–10773 PNAS June 26, 2007 vol. 104 no. 26.

The abstract reads,

“Observations show both a pronounced increase in ocean heat content (OHC) over the second half of the 20th century and substantial OHC variability on interannual-to-decadal time scales. Although climate models are able to simulate overall changes in OHC, they are generally thought to underestimate the amplitude of OHC variability. Using simulations of 20th century climate performed with 13 numerical models, we demonstrate that the apparent discrepancy between modeled and observed variability is largely explained by accounting for changes in observational coverage and instrumentation and by including the effects of volcanic eruptions. Our work does not support the recent claim that the 0- to 700-m layer of the global ocean experienced a substantial OHC decrease over the 2003 to 2005 time period. We show that the 2003–2005 cooling is largely an artifact of a systematic change in the observing system, with the deployment of Argo floats reducing a warm bias in the original observing system.”

The paper emphasizes that ocean heat content is the appropriate climate diagnostic to monitor global warming or cooling; e.g. see their statement at the beginning of their paper,

“Observations suggest that the world’s oceans were responsible for most of the heat content increase in the earth’s climate system between 1955 and 1998″,

and they extend their analysis through 2006 in the new paper. This need to focus on ocean heat content changes has been a major recommendation of Climate Science (e.g. see # 4).

Their paper also identified a problem with the diagnosis of ocean cooling which was independently found by Lyman et al (see).

However, there are issues in this paper that the authors are silent about.

They are:

1. In Figure 5 in their paper, there appears to be a lack of significant continued warming in recent years. Since the ocean heat content changes can be used to diagnose the radiative imbalance of the climate system (see and see), this indicates at most only a small radiative warming recently. This lack of warming is at variance to their claim that the model results and the observations are consistent. The paper spent time (appropriately) questioning the Lyman et al 2006 study, but did not pursue the significance of this mismatch between the observations and the predicted more-or-less monotonic warming by the models.

2. The authors’ confidence in the models provides a hypothesis that can be tested over the next few years to confirm or refute the predictive skill of their models. The challenge is for them to show they can skillfully predict the recent (last few years) lack of global -average ocean warming, as well as its change over the next few years. As posted on Climate Science in the weblog

A Litmus Test For Global Warming – A Much Overdue Requirement,

this real time comparison between models and observations is an essential test that is required to accept their model predictions as skillful.

In the Climate Science weblog, I posed the following question,

“What is the magnitude of ocean heat storage changes each year?”

and added

“For global warming to occur, the heat, as measured in Joules, needs to increase each year.

The heat accumulation for the period from 2002 to the present and into the future needs to be a high priority. For example to sustain a global warming rate of 1 Watt per meter squared since 2002 for the following ten years requires the accumulation of 1.6 *10**23 Joules within the climate system.”

3. The authors should have presented both their model results and observations in units of Watts per meter squared (as recommended in Pielke 2003). The model forcings should have been separated into terms of radiative forcing and radiative feedback.

The reason to separate is so they can compare with the 2007 IPCC Statement for Policymakers which gives a mean value of 1.78 Watts per meter squared (see Figure SPM.2) for the “Global average radiative forcing (RF) estimates and ranges in 2005″. The radiative forcing diagnosed from the observed ocean heat content changes includes both the radiative forcing and the radiative feedbacks (e.g. the water vapor feedback).

Unfortunately, the AchutaRao et al paper is silent on this issue. See also

The Net Climate Feedbacks Must Be A Negative Effect On The Global Average Radiative Imbalance If The IPCC Conclusion Of Net Anthropogenic Radiative Forcings Is Correct.

Thus while this peer reviewed paper is a constructive contribution to the debate, it did not address other key questions for which it has the results to accomplish. Climate Science recommends that the authors take this next step in their assessment.

Comments Off

Filed under Climate Change Forcings & Feedbacks, Climate Change Metrics

A New Excellent Paper- A Review Of Vegetation–Atmosphere Interactions And Their Influences On Mesoscale Phenomena

There is an excellent review paper that provides further documentation of the first-order role of land surface processes within the climate system. The paper is

McPherson,Renee A., 2007: A review of vegetation–atmosphere interactions and their influences on mesoscale phenomena.Progress in Physical Geography 31(3) DOI: 10.1177/0309133307079055

The abstract reads,

“Vegetation strongly influences exchanges of energy and moisture between land and
atmosphere through (1) the vegetation’s response to incoming radiation and its emission of longwave radiation (2) the vegetation’s physical presence, and (3) the plant’s transpiration. These processes affect the diurnal temperature range, processes in the atmospheric boundary layer, cloud cover, rainfall, differential heating, and atmospheric circulations. This paper overviews how vegetation interacts with surface energy and moisture budgets and reviews both observational and modelling studies that examine how vegetation affects weather and climate on the mesoscale (ie, phenomena 10s to 100s of kilometres in horizontal size).”

Among the conclusions, Dr. McPherson writes,

“The transformation of regional vegetation coverage to different land uses, especially the substitution of native forest with cropland, can result in local or regional climate changes as significant as those ascribed to the enhancement of atmospheric greenhouse gases by humans. Hence, it is important that scientists help policymakers put into perspective the consequences of various sources of weather modification.”

This important role of vegetation as a component of the climate system was recognized, for example, by the 2005 National Research Council Report titled Radiative Forcing of Climate Change: Expanding the Concept and Addressing Uncertainties , but was not appropriately reported on in the 2007 IPCC WG1 Report (i.e. see Chapter 8 and Chapter 9). Dr. McPherson has provided a very effective peer reviewed publication that documents an important climate change issue that the IPCC inadequately communicated to policymakers to policymakers.

Comments Off

Filed under Climate Change Forcings & Feedbacks

Additional Evidence On The Bias In The IPCC WG1 Report On The Assessment Of Near-Surface Air Temperature Trends

As a further example of the selective use of papers by the IPCC WG1 Report, I summarize here the sequence of papers and comments on the role of land-use change on near-surface air temperature trends.

The original paper

Kalnay E., and M. Cai, 2003: Impact of urbanization and land-use change on climate. Nature, 423, 528-531

resulted in vigorous comments on their conclusions including two Comments published in response in Nature;

Trenberth, K.E., 2004: Rural land-use change and climate. Nature, 427, 213, doi:10.1038/427213a. doi:10.1175/JCLI3612.1.

Vose, R.S., T.R. Karl, D.R. Easterling, C.N. Williams, and M.J. Menne, 2004: Impact of land-use change on climate. Nature, 427, 213-21

The originnal Kalnay and Cai paper and the two Comment were reported on in Chapter 7 of the 2007 IPCC WG1 Report.

However, Cai and Kalnay responded to the Trenberth and Vose et al Comments in the same Nature issue, but their Reply WAS NOT Cited in the 2007 IPCC WG1 Report! This Reply is

Cai, Ming and Eugenia Kalnay: 2004 Climate (communication arising): Impact of land-use change on climate Nature 427, 214 (15 January 2004) | doi:10.1038/427214a

This is certainly not an example of presenting the diversity of published perspectives on this issue.

Moreover, there have been follow up peer reviewed papers on this issue which appeared in time for the 2007 IPCC Report. They were, however, ignored. These papers include:

Kalnay, E., M. Cai, H. Li, and J. Tobin, 2006: Estimation of the impact of land-surface forcings on temperature trends in eastern United States J. Geophys. Res., Vol. 111, No. D6, D06106.

Objective views on this sequence of events must conclude the Report is biased.

Comments Off

Filed under Climate Change Metrics

Error In The Economist On Their Coverage Of Climate Issues

The Economist is an excellent publication. However, as I have communicated before on Climate Science, it is occasionally inaccurate in its coverage. This occurs very clearly in the June 23rd-27th issue in an otherwise very good article.

The article is “Arnie’s uphill climb” and the error is in their insert “Where smog comes from”. The data that they present is “California’s greenhouse-gas emissions by end-use sector, 2004%”.

However, it is incorrect to refer to “greenhouse-gas” as “smog”! As defined by the American Meteorological Society’s Glossary of Meteorology, the definition is

“smog—As originally coined in 1905 by Des Voeux: a natural fog contaminated by industrial pollutants, a mixture of smoke and fog. Today, it is the common term applied to problematical, largely urban, air pollution, with or without the natural fog; however, some visible manifestation is almost always implied. Smogs are constituted in great variety, but a major dichotomy exists between the photochemical smogs of nitrogen oxides and hydrocarbons emitted mainly by automobile engines and, on the other hand, the sulfur-laden, sometimes deadly, smogs produced by the large-scale combustion of fuel oil and coal. Both types contain carbon monoxide, carbon dioxide, and a variety of particulates. See Los Angeles (photochemical) smog, London (sulfurous) smog.”

It is unclear if the author of this figure unintentionally used the wrong word, or if it was used to draw a greater attention to the figure. It either case, it is an error.

Comments Off

Filed under Climate Science Misconceptions, Climate Science Reporting

More On The Suppresion Of Climate Change Views

There is an Online NewsHour interview entitled

“Oregon Global Warming Skeptic Finds Controversy”

with the header

“Oregon state climatologist George Taylor does not believe that global warming is due to human activity. Now, Oregon Gov. Ted Kulongoski wants him to stop using the state climatologist title. NewsHour correspondent Lee Hochberg reports from Oregon and Washington on the controversy.”

It is worth listening to (or reading the transcript) as it shows how politicians are seeking to usurp the ability of scientists to present the diversity of views on climate (thanks to Jim Angel to alerting us to it). George Young is certainly well qualified as a climatologist (he was President of the American Association of State Climatologists for two years and has been the state of Oregon NOAA recognized State Climatologist for years.

Whether one agrees or not with Mr. Taylor (or the other climatologists whose voices are being stifled), this is an inappropriate politicalization of climate science to promote a particular view.

Comments Off

Filed under Climate Science Reporting

Important New Paper On The Urban Effect On Temperature And Other Climate Metrics

There is an important new paper that has appeared which adds significantly to the understanding of the role of urban areas within the climate system.. The paper is

Jin Menglin, J. Marshall Shepherd and Christa Peters-Lidard, 2007: Development of a parameterization for simulating the urban temperature hazard using satellite observations in climate model, Nat Hazards DOI 10.1007/s11069-007-9117-2 [subscription required].

The abstract reads,

“Abstract Urban surface temperature is hazardously higher than surrounding regions (so-called urban heat island effect UHI). Accurately simulating urbanization-induced temperature hazard is critical for realistically representing urban regions in the land surface- atmosphere climate system. However, inclusion of urban landscapes in regional or global climate models has been overlooked due to the coarse spatial resolution of these models as well as the lack of observations for urban physical properties. Recently, National Aeronautics and Space Administration (NASA) Earth Observing System (EOS) Moderate Resolution Imaging Spectroradiometer (MODIS) observations illustrate important urban physical properties, including skin temperature, surface albedo, surface emissivity, and leaf area index, It is possible to identify the unique urban features globally and thus simulate global urban processes. An urban scheme is designed to represent the urban-modified physical parameters (albedo, emissivity, land cover, roughness length, thermal and hydraulic properties) and to include new, unique physical processes that exist in urban regions. The urban scheme is coupled with National Center for Atmospheric Research (NCAR) Community Land Model Version 2 (CLM2) and single column coupled NCAR Community Atmosphere Model CAM2/CLM2 to assess the mechanisms responsible for UHI. There are two-steps in our model development. First, satellite observations of albedo, emissivity, LAI, and in situ observed thermal properties are updated in CLM2 to represent the first-order urban effects. Second, new terms representing the urban anthropogenic heat flux, storage heat flux, and roughness length are calculated in the model. Model simulations suggest that human activity-induced surface temperature hazard results in overlying atmosphere instability and convective rainfall, which may enhance the possibility of urban flood hazard.”

Excerpts read,

“More importantly, although a single urban region may not result in a large impact on global climate, the collective impact of all urban regions on the global climate system is as yet unknown and unstudied. Jin et al. (2005a) show that zonal mean UHI has 1–3 degree warming over the Northern Hemisphere latitudes, implying that the collective UHI may be a significant contributing factor in the overall global warming signal.”


“The current urban scheme does not include potentially important urban land-atmosphere feedbacks, in particular, urban aerosols’ impacts on surface insolation and aerosol-cloud rainfall interactions over urban regions. Therefore, the presented urban impacts are limited to those resulting from changes in the urban surface only. Future model development on coupled urban land-atmosphere interactions is essential for fully understanding the extent of urban impacts.”

The role of urban areas within the climate system is yet another human climate effect whose role was minimized in the 2007 IPCC WG1 Report.

Comments Off

Filed under Climate Change Metrics