5. Section E: Climatology
Konstantin Vinnikov & Russell R. Dickerson
This section of the report describes an activity by the State Climatologist Office for Maryland. It
includes a routine climate service for citizens and climate research which results should be
important for citizens and for Government of Maryland. Particularly, our research is related to
analysis of observed climate and air quality change in the Maryland and its vicinity.
Abstract
Observed 1989-2007 change in seasonal/diurnal variations of Ozone concentration at five
East Coast CASTNET stations have been assessed statistically and it has been shown that
significant improving of air quality at these stations is resulted from SIP Call, not from
simultaneous climate change.
Maryland State Climatologist Office continued to archive observations of MD COOP
meteorological stations and study available very long climatic records for MD and vicinity,
longer than 95 years. During year 2009, Office prepared and provided specific
meteorological information in response to ~160 data request from MD citizens, businesses
and organizations.
Office initiated study climatology of anthropogenic emissions of air pollutants at MD and
vicinity, climatology of air quality, and regional-scale interaction between air quality and
climate. Temporal evolution of seasonal, diurnal and weekly cycles in anthropogenic
emissions and air pollutants is preliminary evaluated.
Study of observed climate change in Maryland and vicinity revealed that contemporary
global warming 1895-2008 has been accompanied by a decrease in summer -and increase in
autumn precipitation in MD, VA, and other Mid-East Coast states. These changes in
precipitation result in the observed summer decrease and autumn increase of river runoff.
Century-scale decreasing trends in variance of Tmax are found in observations at of 8 of 9
chosen meteorological stations at Maryland.
Observed century-scale climate change in Maryland is consistent with global warming
scenario: slow warming with increasing total precipitation but decreasing seasonality.
Quantitatively, MD-century-scale climate warming trend is approximately equal to global
one and looks as relatively weak signal at the background of natural climate variability. But
even very weak trend is getting significant for long time interval. Currently, the most
important environmental factor of global warming scenario at Maryland is sea level rise.
1
Task 1:
The State Climatologist will quantify the changes in seasonal and diurnal cycles of ozone
observed at MD sites where the ozone and temperature records are suitable. Temporal linear
trends and step changes associated with the NOx SIP Call will be evaluated. A full analysis of
the chemical climatological will be a multiyear endeavor.
1989-2007 hourly observation of Ozone and Surface Air Temperature at five East Coast CASTNET
sites has been analyzed. The Figures 5.1 and 5.2 displays the main result of trend analysis in
atmospheric ozone. Statistical technique is described in (Vinnikov et al, 2002). Scientific details are
discussed in (Bloomer, 2009; Bloomer et al., 2009; Bloomer et al., 2010).
The most important scientific conclusions are:

During the past two decades, ozone concentrations have been, in general, decreasing as seen in
both the linear trend analysis and when comparing averages before and after a large reduction in
power plant NOx emissions during the existing regulatory ozone season. Results are consistent
across the entire rural eastern US.

The greatest downward trends in pollution ozone occur at the locations and times of greatest
smog – in the summer months, during the afternoon, at the most polluted sites. This presents
strong evidence that the implementation of power plant NOx emission controls have decreased
regional, rural, surface ozone amounts when and where improvements are most needed.
Improvements as great as 10 ppb were observed follow the SIP call.

The winter months and early spring show increasing ozone amounts. This may result from
decreased NO titration or other effects and warrants further investigation.

Maxima in the early spring at the highest latitude stations with significant elevation above sea
level indicate stratospheric intrusions and widely-spread, long-lived pollutants acting as
reservoir species for ozone formation are a relatively strong source of ozone to these stations.
The absence of a daily temporal trend and the absence of significant differences before and after
the US stationary source emission reductions support this conclusion for the spring months.

There is evidence that daytime values are remaining high later into the year than they were
before 2002. This may be the result of local climate change and the possibility that the ozone
season is getting longer and is worthy of further research.

Summer temperatures are warming during the times of ozone decreases in our analysis. But, it
is well known that ozone generally increases with warming air temperatures. This is additional
proof that emission reductions, and not changes in weather or climate, are responsible for the
observed, decreasing, ozone trends.
See full scientific description of this work in: Bryan J. Bloomer, Konstantin Y. Vinnikov and
Russell R. Dickerson, 2009: “Changes in Seasonal and Diurnal Cycles of Ozone and
Temperature in the Eastern U.S.”, Atmospheric Environment:
http://www.atmos.umd.edu/~kostya/Sclim/Reports/BloomerVinnikovDickerson_OzoneTempCycles.doc .
2
Figure 5.1. Diel and seasonal distribution of 1989-2007 means, standard deviations and linear
trends of ozone concentrations observed at five rural eastern US monitoring stations of the
CASTNET network contour plotted across local standard time and month. Decreases and negative
values are shaded. Note that the most polluted sites (Beltsville and Penn State) show the greatest
decreases in ozone and that the decreases occur at the times of greatest concentration. More rural
and high elevation sites show a stronger spring maxima. Sites at high altitude show the weakest diel
cycles.
3
Figure 5.2. Diel and Seasonal distribution of observed ozone concentrations at five rural monitoring
stations across the eastern U.S. of the CASTNET network for the period 1989-1998, before a 43%
average NOx reduction at power plants, and for the period 2003-2007, afterwards. Decreases and
negative values are shaded.
4
Task2:
Support the activities preformed by the Office of the State Climatologist of Maryland, such as
the collection and archiving of meteorological data from surface stations, radar, research
aircraft, etc.
The State of Maryland Climatologist Office is Maryland’s hub for all climate-related information.
We provide climate data to Maryland state businesses, agencies, students, researchers, and citizens
of Maryland. We maintain links with many cooperative meteorological stations in the state, the
National Climatic Data Center (NCDC), National Weather Service Forecast Offices, National
Atmospheric and Oceanic Administration (NOAA), and many other private sources of climate and
weather information.
Summary of Activities in 2009
The State of Maryland Climatologist Office received approximately 160 data requests in 2009. The
majority of data requests are sent via e-mail to climate@atmos.umd.edu. We also receive several
requests via telephone and mail. The State Climatologist Office is responsible for answering these
requests in a timely manner. The type of data request that we most often receive are archived
temperature and precipitation data. Most of this data is obtained from NCDC and is then forwarded
on in a useful form to the user. We also have data requests from several law firms asking for
weather information that occurred on a specific day. Students and research scientists also request
data on a regular basis. Their requests can vary from climatological information to hydrological
information to investigating the upcoming seasonal weather outlook. Some governmental agencies
that contact us for climate data include the Frontier Group for Environment Maryland, GeoTechnology Associates, Inc., Baltimore County Department of Public Works, United States Naval
Academy, etc. Overall, most data requests are processed using NCDC data, with National Weather
Service (Sterling, VA office) data as the runner-up. All of the data we send out is official data,
unless otherwise stated.
The State of Maryland Climatologist Office is also active with Maryland COOP stations. We
receive and archive monthly e-mails and letters from approximately 30 observing stations in
Maryland, in which they send a summary of the daily weather for each month. These sites are
located across the State of Maryland and are managed by private citizens.
The Assistant to State Climatologists Lisa Wojdan has redesigned the official web site of the Office.
Current version is in the http://www.atmos.umd.edu/~climate . It is still in process of developing.
We begin to collect the longest, more than 95 years, daily climatic records for MD and vicinity that
can be used for analysis of trends in climate variability and heat wave statistics. Figure 5.3 provides
schematic map of such stations with such a long records which data is available now. We continue
work on quality control and homogenization of these time series. They will be made available
through our web site.
5
Figure 5.3. Maryland and vicinity: Map of stations with available climatic records longer than 95
years. NCDC/NOAA stations ID numbers are used here instead of stations’ names.
Task 3:
The State Climatologist will prepare surface data and aircraft meteorological profiles
(temperature, humidity, and winds) for comparison with WRF or MM5 modeling output.
[DALE, Elena, Jeff!]
6
Task 4:
The State Climatologist will prepare a list and description of activities, studies and analyses
related to air quality (e.g., ozone and fine particles) that could be completed and would be of
benefit to MDE.
We here list three main research directions related to air quality and climate:
1. Climatology of Anthropogenic Emissions of Air Pollutants at MD and Vicinity. This work will
consist of climatic analysis of atmospheric pollution by power plants, industrial activities,
transportation, agriculture, residential heating, etc for Maryland and its vicinity. The pollutants
that affect air quality and global or regional climate will be studied first. They include NOx,
SO2, Carbon Dioxide, and direct heat production. Temporal evolution of seasonal, diurnal and
weekly cycles in anthropogenic emission of air pollutants will be studied.
2. Climatology of Air Quality at MD and Vicinity. This work will consist of climatic analysis of
multi-year hourly records of the Ozone, Sulfur Dioxide, Carbon Monoxide, PM2.5 etc at air
quality monitoring stations. The main attention will be paid to temporal evolution of seasonal,
diurnal and weekly cycles in the air quality parameters.
3. Regional Scale Interaction between Air Quality and Climate. Regional changes in weather and
climate conditions may affect air quality and changes in air quality or other regional
environmental factors can be attributed to changes in regional weather and climate regime. We
expect that decreasing in anthropogenic emissions of NOx and SO2 should make a quality of
atmospheric air less sensitive to weather/climate fluctuations. We will use available observed
data to empirically evaluate interaction between air quality and climate.
The first direction in Task 4: The State Climatologist Office for MD has initiated systematic
analysis of observational records related of air quality for MD and its vicinity. This analysis is
based on a statistical study of observed time series of air quality and meteorological variables. Most
of these variables have well pronounced seasonal and diurnal variations in their statistics. This
defines a direction of our work - to study the evolution in diurnal and seasonal cycles of the
variables. The necessity to properly resolve diurnal cycles requires hourly observations. Multi-year
records are needed for trend analysis.
We analyzed emission of atmospheric pollutants by power plants in Maryland and neighboring
states. Figures 5.4 and 5.6 display time series of hourly emissions of SO2, NOx, CO2, Heat, and
Electricity by all power plants at MD and OH for 1997-2009. EPA Prepackaged Power Plant
Emissions data sets have been used from EPA web site:
http://camddataandmaps.epa.gov/gdm/index.cfm?fuseaction=emissions.wizard
Figures 5.5 and 5.7 display evolution of diurnal and seasonal cycles in the variables averaged for
each three-year time intervals: 1997-1999, 2000-2002, 2003-2005, and 2006-2009. Analogous
estimates for other U.S. East Coast states can be found in our quarterly report
7
http://www.atmos.umd.edu/~kostya/Sclim/Reports/State_Climatologist_Report_October_2009.ppt .
We will mention here only few main of the preliminary conclusions. We found that current regional
direct heat release by the power plants at few of the U.S. East Coast states exceeds current
anthropogenic greenhouse global warming forcing (~1 W/m2). This means that regional heat
pollution of the environment can be responsible for part of observed regional climatic trends. In the
future, anthropogenic heat emission is going to be another major factor of global climate change,
even more significant compared to emission of Carbon Dioxide. Direct heat emission should be
well monitored and analyzed as an important factor of environmental change.
Preliminary Conclusions:

Diurnal/Seasonal patterns of MD Power Plants SO2 and CO2 emissions as well as heat
generated have not changed significantly during past decade.

OH Power Plants SO2 emissions are decreasing in time with increasing of electricity
production.

MD Power Plants NOx emissions have been decreasing during past decade. Maximum of
Diurnal/Seasonal pattern of these emissions has moved from early afternoons in 1007-1999 to
winter season in 2006-2009.

OH, WV and PA do not show decreasing of NOX emissions outside the ozone season.

Heat emissions by Power Plants at East Coast States can affect regional climate.
This analysis should be continued. Currently available EPA data on plant emissions is not well
documented and contains many errors that should be revealed and corrected in process of
communication with the archive holder. Other than power plants sources of emissions should be
taken into account.
8
Figure 5.4. MD: Time series of total hourly emissions
9
Figure 5.5. MD: Temporal evolution of diurnal/seasonal cycles in total plants emissions
10
Figure 5.6. OH: Time series of total hourly emissions
11
Figure 5.7. OH: Temporal evolution of diurnal/seasonal cycles in total plants emissions
12
The second direction in Task 4: In the study of climatology of air quality at Maryland and vicinity
we concentrated on two pollutants: ozone and sulfur dioxide. The result for ozone are discussed
above, in the Task 1 report section. They are limited by studying of climatology of Ozone observed
at five East Coast CASTNET stations. Climatology of SO2 has been studied based on multi-year
hourly observation at 7 stations which geographical location is shown in Figure 5.8. Estimates of
seasonal and diurnal variations of SO2 concentrations at these stations are shown in Figure 5.9. The
next scientific conclusions follow from these estimates:
•
Seasonal cycle of SO2 with late winter (reduced loss rates due to H2O2 and OH) maxima
always exists in surface data at MD and its vicinity.
•
Diurnal cycle of SO2 depends on diurnal cycle of local pollutants and on the diurnal
evolution of boundary layer.
•
High elevated monitoring stations at National Parks do not display noticeable diurnal
cycle in SO2.
•
Unexpected well pronounced diurnal cycle in observation of Piney Run, MD station
reveals complex small scale circulation but that come remins a mystery!
These estimates will be used for model validation. The work is in progress
Figure 5.8. Location of air quality monitoring stations with hourly Sulfur Dioxide observation in
MD and vicinity
13
Figure 5.9. Seasonal and Diurnal variations of multi-year mean SO2 concentration observed at 7
stations in Maryland and vicinity.
14
Research in the third direction of Task 4 is in the very beginning and conclusive results were not
yet obtained in 2009.
Task 5:
With UMD matching funds, the State Climatologist will examine additional sites to determine
the observed climate change for Maryland and the surrounding area. This study will include
analysis of the urban heat island effects as well as the impact of climate change on air quality.
Climatological data will be compiled and provided to outside investigators.
Work on this task has been run in three directions:

Assess observed and model simulated century scale climatic trends in temperature and
precipitation at Maryland and vicinity.

Examine observed century scale climatic trends in averages and variability of maximum and
minimum surface air temperatures at MD.

Urban Heat Island and Impact of climate change on air quality.
The first direction in Task 5:
The contemporary global warming signal is relatively small compared to local climate variability at
each location. Maryland has very good history of meteorological observations, nevertheless, the last
comprehensive analysis of climate at Maryland initiated and funded by Maryland’s Government has
been accomplished just a hundred years ago. The reports have been published in three volumes in
1899, 1907 and 1910. We do not know, yet, how the climate of Maryland has been changing during
the past century and if the observed changes correspond to climate model simulations of global
warming scenarios. So we collected available climatic and hydrological records for the past century
and addressed to them the next few questions:
1. What are observed century-scale climatic trends and their seasonality in Maryland averages
of temperature, precipitation, and runoff?
2. Was the observed climate change favorable or unfavorable for well being of MD citizens?
3. What are observed climatic trends in other East Coast states?
4. Does the observed climate change in MD and vicinity agree with global warming model
simulations?
Preliminary conclusions:
• Maryland and other Mid-East Coast states enjoy beautiful climate with seasonal Max of
precipitation in the summer and Min in the autumn.
•
Global warming 1895-2008 has been accompanied by a decrease in summer -and increase in
autumn precipitation in MD, VA, and other Mid-East Coast states.
•
These observed changes in precipitation are real and result in the observed summer decrease and
autumn increase of river runoff.
•
GFDL/NOAA Climate Model global warming scenario simulations give us some hope that the
observed century scale summer precipitation trend in MD & VA is going to change from a
decreasing trend to an increasing trend.
15
•
A more spatially and temporally detailed (but not more reliable) forecasts of future Maryland
climate could be obtained from regional (high resolution) models forced by global climate
models simulations. See, for example, North American Regional Climate Change Assessment
Program (NARCCAP) web site (http://www.narccap.ucar.edu/).
Observed century-scale climate change in Maryland is consistent with global warming scenario:
slow warming with increasing total precipitation but decreasing seasonality. Quantitatively, MDcentury-scale climate warming trend is approximately equal to global one and looks as relatively
weak signal at the background of natural climate variability. But even very weak trend is getting
significant for long time interval. Currently, the most important environmental factor of global
warming scenario at Maryland is sea level rise.
The next Figures 5.10-13 display results of the observed temperature, precipitation and river
runoff data analysis. Figure 5.14 reproduces climate model simulated time series of summer
precipitation at MD and VA for more than 2 hundred years. These are results of three GFDL/NOAA
CM2.1 climate model simulations (runs) with IPCC SRES A1B scenario forcing. The work should
be continued.
Figure 5.10. East Coast States: Observed seasonal variation of mean surface air temperature (a) and
trend (b)
(b)
(a)
16
Figure 5.11. East Coast States: Observed seasonal variation of mean precipitation (a) and trend.
(a)
(b)
17
Figure 5.12. East Coast Rivers: Observed seasonal variations of mean runoff (a) and trend (b).
(a)
(b)
18
Figure 5.13. The most important observed century scale climatic trends at Maryland (a) and
Virginia (b).
(a)
(b)
19
Figure 5.14. GFDL/NOAA CM2.1 model simulated time series of MD and VA summer
precipitation for the past and current centuries. These three model runs reproduce observed long
term decreasing in summer precipitation. This trend is changing for increasing of summer
precipitation in simulations for 21st century.
20
The second direction in Task 5. Study of century-scale changes in MD’s climate and its variability.
We analyzed trends in daily max and min air temperatures and their variability at few MD stations
with more than 95 year observations. We are looking for, so named, asymmetry in trends of Tmax
and Tmin. TREND(Tmin)>Trend(Tmax) in records from 1950 has been found in many earlier analyses
all over the world (Easterling et al., 1997). This asymmetry has often been considered as a signature
of global warming because the greenhouse effect of CO2 is better pronounced at the time of Tmin,
early in the morning, when atmosphere is more transparent compared to the afternoon time of T max.
More recently, Vose et al (2005) reported that trends in Tmax and Tmin are more or less equal from
1979. We estimated such trends in century long records. Figure 5.15 and 5.16 display observed
data and trend estimates for 3 stations at MD.
Preliminary conclusions are:
•
A century-scale warming trends can be clearly seen in observations of Tmax/Tmin at 5 of 9
chosen meteorological stations at Maryland.
•
An expected asymmetry with Trend(Tmin)>Trend(Tmax) is found in observations of 3 of 9
chosen stations. Five other stations display an opposite Trend(Tmin)<Trend(Tmax).
•
Century-scale decreasing trends in variance of Tmax are found in observations at of 8 of 9
chosen meteorological stations.
This work is in progress. Next steps will include analysis of all stations, better trend model, statistics
of heat waves occurrence and trends in heat waves occurrence and length.
Figure 5.15. Daily observations of Max and Min temperature at three stations at Maryland.
21
Figure 5.16. Seasonal variations of multi-year averages (solid lines) and trends (dashed lines) of
Tmax and Tmin – left panels. Seasonal variations of variance (solid lines) and trend in variance
(dashed lines) of Tmax and Tmin – right panels.
The third direction in Task 5:
Urban heat island and its impact on air quality. It has been recognized that properly homogenized
long-term climatic records for the Continental US do not show significant urbanization warming
effect (Peterson, 2003). Nevertheless, in specific for different cities meteorological situations
mesoscale heat islands can amplify effect of heat waves on air quality. The question is, do the
observed climatic records display an increase trend in occurrence of extremely high air
temperatures? The estimates presented in Figure 5.17d,e,f for observations in Beltsville, MD show
that there were no such changes in 2003-07 compared to 1989-98. This is one of relatively small
MD cities. But, an occurrence of high Ozone concentration events at this station has been
decreasing during the same time (Figure 5.17d,e,f). Another statistic from the same data is number
of events with daily one hour ozone concentration exceeded specified level and number of such
events with different length. Table 5.1 shows such statistics for Ozone concentration above 75 ppb.
22
Figure 5.17. Beltsville, MD. 1989-98 to 2003-07 change in occurrences (in %) of hourly Ozone
concentrations above 85, 75, & 65 ppb events (a,b,c), and hourly surface air temperature above 32, 30, &
27oC events (d,e,f).
(a)
(b)
(c)
(d)
(e)
(f)
23
Table 5.1. BELTSVILLE, MD. Ozone season: May to September
Number of events with daily one hour max OZONE is equal or above 75 ppb
Days Days
Year
with
with
observ. event
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
153
146
145
149
153
153
151
92
118
143
153
153
152
153
143
151
123
151
150
64
63
78
50
81
63
58
33
45
61
61
37
52
57
24
32
33
49
51
1
24
23
21
22
27
26
21
12
15
19
23
19
20
23
14
22
16
19
20
Number of the events with the length ≥ N Days
N
2 3 4 5 6 7 8 9 10 11 12 13 14
14
17
17
11
17
14
11
10
11
13
13
10
10
11
9
8
11
11
14
9
10
15
8
12
9
9
5
9
8
10
4
7
7
1
1
4
7
8
8
7
10
4
6
5
6
3
4
6
8
2
6
6
0
1
2
5
7
4
3
7
2
4
4
4
3
2
5
4
1
5
5
0
0
0
3
2
3
2
4
2
4
2
2
0
2
4
3
1
2
3
0
0
0
2
0
2
1
2
1
4
2
1
0
1
4
0
0
1
2
0
0
0
1
0
0
0
1
0
2
1
1
0
1
2
0
0
1
0
0
0
0
1
0
0
0
1
0
2
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Table 5.2. BELTSVILLE, MD. Ozone season: May to September
Number of events with daily one hour mean temperature is equal or above 30ºC
Days
Days
Year with
with
observ. event
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
153
146
145
149
153
153
151
92
118
143
153
153
152
153
143
151
123
151
150
24
19
51
19
45
31
40
9
33
45
47
22
21
55
23
27
29
45
45
1
10
10
14
9
11
16
13
5
12
20
13
10
8
15
12
16
13
13
15
Number of the events with the length ≥ N Days
N
2 3 4 5 6 7 8 9 10 11 12 13 14
6
5
13
5
8
8
8
2
7
10
9
8
6
12
7
8
9
8
14
4
2
10
2
7
4
4
1
5
6
7
3
3
6
3
2
5
6
9
2
2
5
1
3
3
2
1
2
4
5
1
2
5
1
1
2
4
4
1
0
2
1
2
0
2
0
2
3
4
0
1
5
0
0
0
3
3
1
0
2
1
2
0
2
0
2
2
2
0
1
4
0
0
0
3
0
0
0
2
0
2
0
2
0
2
0
2
0
0
2
0
0
0
2
0
0
0
2
0
2
0
1
0
1
0
2
0
0
2
0
0
0
1
0
0
0
1
0
2
0
1
0
0
0
1
0
0
2
0
0
0
1
0
0
0
0
0
2
0
1
0
0
0
1
0
0
1
0
0
0
1
0
0
0
0
0
2
0
1
0
0
0
1
0
0
1
0
0
0
1
0
0
0
0
0
1
0
1
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
1
0
1
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
24
Table 5.2 displays analogous statistic for heat waves with maximum daily temperature equal or
larger than 30ºC. We can see that for period from 1989 to 2007 there is no noticeable change in
occurrence of heat waves at Beltsville, MD. But we still see significant decrease in multi-day ozone
events. It looks as if climate warming is not leading factor in air quality. We continue such analysis
with other climatic records. Work is in progress.
Task 6:
UMD will submit to MDE a quarterly update of tasks 1-5.
Quarterly progress reports to MDE have been presented at quarterly meetings. The PowerPoint files
of these presentations are available from the web site:
http://www.atmos.umd.edu/~kostya/Sclim/Reports/
References:
Bryan J. Bloomer, 2008: Air Pollution Response to Emissions Changes at Power Plants in the
Eastern United States. Ph. D. in Meteorology, Dissertation.
Bryan J. Bloomer, Konstantin Y. Vinnikov and Russell R. Dickerson, 2009: “Changes in Seasonal
and Diurnal Cycles of Ozone and Temperature in the Eastern U.S.”, Atmospheric Environment,
Submitted.
http://www.atmos.umd.edu/~kostya/Sclim/Reports/BloomerVinnikovDickerson_OzoneTempCycles.doc
Bloomer, B. J., J. W. Stehr, C. A. Piety, R. J. Salawitch, and R. R. Dickerson (2009), Observed
relationships of ozone air pollution with temperature and emissions, Geophys. Res. Lett., 36,
L09803, doi: 10.1029/2009GL037308.
Peterson, T.C., 2003: Assessment of Urban Versus Rural In Situ Surface Temperatures in the
Contiguous United States: No Difference Found. J. Climate, 16, 2941-2959.
Vinnikov, K. Y., A. Robock, and A. Basist, Diurnal and seasonal cycles of trends of surface air
temperature, J. Geophys. Res., 107(D22), 4641, doi:10.1029/2001JD002007, 2002.
Vose, R. S., D. R. Easterling, and B. Gleason (2005), Maximum and minimum temperature trends
for the globe: An update through 2004, Geophys. Res. Lett., 32, L23822,
doi:10.1029/2005GL024379.
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