An Analytical Formula for Potential Water Vapor in an Atmosphere of Constant Lapse Rate

Varmaghani, Ali

doi:10.3319/tao.2011.06.28.01(a)

Cited by 5 publications

(4 citation statements)

References 16 publications

(18 reference statements)

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“…The current total GDD achieved by August 4 could be achieved by July 25 if every hourly observation was raised by 1.53 °C, or if both minimum and maximum daily temperatures were increased by 1.50 °C. Roughly, this is the equivalent of changing elevation by 153 to 416 m based on an environmental lapse rate of 3.6 to 9.8 °C/1000 m ( Sheridan et al 2010 ; Varmghani 2012 ). Alternatively, one could drive about 217 km closer to the equator, assuming a change of 6.9 °C/1000 km ( Colwell et al 2008 ; Jump et al 2009 ).…”

Section: Resultsmentioning

confidence: 99%

Macrolepidoptera biodiversity in Wooster, Ohio from 2001 through 2009

Downer¹,

Ebert²

2014

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A Skinner mercury vapor light trap was operated from 2001 through 2009 in a residential backyard to document biodiversity within the moth families Thyatiridae, Drepanidae, Geometridae, Mimallonidae, Apatelodidae, Lasiocampidae, Saturniidae, Sphingidae, Erebidae (including Lymantriinae and Arctiinae), Euteliidae, Nolidae, and Noctuidae. When making comparisons to older literature, we recalculated our results to conform to the older classification of the Noctuoidea. Moths were released after identification. There were 501 species documented in 77581 captures from 1290 sampling dates. There was a perceived risk that released moths would fly back into the trap the following evening. This should result in an abnormal number of rare moths that are caught multiple times. The number of species caught twice versus the number caught once was no different than a similar ratio for surveys that used more traditional sampling methods. Therefore this concern does not seem to be valid for these data. These data are provided in a supplementary file available for download.There were three previous surveys conducted in nearby natural areas. They documented fewer species than were documented here. To understand this better, we examined several specialized groups of moths that tend to use host plants not typically found in an urban residential yard. More species in Schinia Hübner, Catocala Schrank, Acronicta Ochsenheimer, and Herminiinae Leech were found in this survey than the other local surveys. Only in the Papaipema Smith did we recover fewer species, though it was still above 70% of what was expected. This diversity could be a result of sampling effort, but it shows that this urban location has a very diverse moth fauna. We suggest that this diversity is partly due to the planting of native plant species in the area about the light trap. Therefore we would concur with others that urban landscapes can be planned to increase biodiversity relevant to more natural ecosystems.In this study we looked at the ratio of the number of species of Geometridae divided by the number of species of Noctuidae as one approach to evaluating the level of disturbance in the moth assemblage. Although the yearly average was nearly constant, the seasonal ratio ranged from 0.09 to 0.91 depending on the sampling date. We also calculated alpha diversity and found that seasonal change in alpha diversity greatly exceeded yearly differences. This strong seasonal component means that a comparison between two studies requires a correction for seasonality and similar sampling intervals. In this study, a shift of two weeks would be sufficient to result in a significant difference in alpha diversity. This is the equivalent of increasing temperature by 1.53 °C. Seasonal shifts limit the usefulness of this methodology for environmental assessment because the within season change exceeds the between season change. This problem is compounded when sampling designs interact with this seasonality.In describing our data, we made use of a growing degree day (GDD) model. Th...

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Section: Resultsmentioning

confidence: 99%

Macrolepidoptera biodiversity in Wooster, Ohio from 2001 through 2009

Downer¹,

Ebert²

2014

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“…VPD is defined as the difference between the saturation vapor pressure and the actual vapor pressure and is calculated using the following formulas [ Allen et al ., ; Han et al ., ; Varmaghani , ].

normalV normalP normalD = e^{*} ((), T_{a}) - e_{a}

e^{*} ((), T_{a}) = 0.6108 \exp ([], 17.27 \cdot T_{a} true/ ((), 237.3 + T_{a}))

where e *( T a ) is the saturation vapor pressure (kPa), e a is the actual vapor pressure (kPa), and T a is the air temperature (Celsius).…”

Section: Methodsmentioning

confidence: 96%

“…VPD is defined as the difference between the saturation vapor pressure and the actual vapor pressure and is calculated using the following formulas [Allen et al, 1998;Han et al, 2005;Varmaghani, 2012].…”

Section: Methodsmentioning

confidence: 99%

An improved satellite‐based approach for estimating vapor pressure deficit from MODIS data

Zhang

Niu

et al. 2014

JGR Atmospheres

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Vapor pressure deficit (VPD) is an important variable widely used in ecosystem and climate models. In this paper, an improved satellite-based approach to estimating VPD was presented that uses several remote sensing products coupled with field measured data. The proposed method exploits an optimized algorithm to derive near-surface actual vapor pressure (e a ) from Moderate Resolution Imaging Spectroradiometer (MODIS) data and upgrades Smith's (1966) methodology for estimating e a . The proposed new algorithm for calculating e a was evaluated against in situ measurements at 119 validation sites in China for 2 months in 2013. The mean absolute error (MAE) and root-mean-square error (RMSE) were less than 0.25 kPa and 0.33 kPa, respectively. The near-surface air temperature (T a ), which is an important input data for calculating VPD, was estimated from satellite-retrieved land surface temperature, and had an RMSE of less than 2.5 K. The estimated VPD values were validated with ground observation data from the Heihe River Basin for 5 months in 2012 and for all of China for August 2013. A coefficient of determination (R 2 ) of 0.912, MAE of 0.27 kPa, and RMSE value of 0.32 kPa were achieved for the 2012 test data, and corresponding values of 0.88, 0.278 kPa, and 0.367 kPa for the 2013 test data. These results are promising, especially considering the comparatively high spatial resolution (1 km) of the VPD map estimated from the satellite data. Potential applications include global evapotranspiration estimation, fire warning, and vegetation analysis.

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“…A.3), we can finally compute the PWV defined in Eq. (4) as a function of temperature, pressure, and relative humidity: (A.7) The literature reports further approximations or simplifications to reduce the number of variables, for example by assuming an atmosphere of constant lapse rate, which occurs only in moisture-free atmospheres (Varmaghani 2012),.…”

mentioning

confidence: 99%

Monitoring precipitable water vapour in near real-time to correct near-infrared observations using satellite remote sensing

Meier

Morris²,

Demory³

2021

A&A

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Context. In the search for small exoplanets orbiting cool stars whose spectral energy distributions peak in the near infrared, the strong absorption of radiation in this region due to water vapour in the atmosphere is a particularly adverse effect for ground-based observations of cool stars. Aims. To achieve the photometric precision required to detect exoplanets in the near infrared, it is necessary to mitigate the effect of variable precipitable water vapour (PWV) on radial-velocity and photometric measurements. The aim is to enable global PWV correction by monitoring the amount of precipitable water vapour at zenith and along the line of sight of any visible target. Methods. We developed an open-source Python package that uses imagery data obtained with the Geostationary Operational Environmental Satellites (GOES), which provide temperature and relative humidity at different pressure levels to compute the near real-time PWV above any ground-based observatory that is covered by GOES every 5 minutes or 10 minutes, depending on the location. Results. We computed PWV values on selected days above Cerro Paranal (Chile) and San Pedro Mártir (Mexico) to benchmark the procedure. We also simulated different pointing at test targets as observed from the sites to compute the PWV along the line of sight. To asses the accuracy of our method, we compared our results with the on-site radiometer measurements obtained from Cerro Paranal. Conclusions. Our results show that our publicly available code proves to be a good supporting tool for measuring the local PWV for any ground-based facility within the GOES coverage, which will help to reduce correlated noise contributions in near-infrared ground-based observations that do not benefit from on-site PWV measurements.

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An Analytical Formula for Potential Water Vapor in an Atmosphere of Constant Lapse Rate

Cited by 5 publications

References 16 publications

Macrolepidoptera biodiversity in Wooster, Ohio from 2001 through 2009

Macrolepidoptera biodiversity in Wooster, Ohio from 2001 through 2009

An improved satellite‐based approach for estimating vapor pressure deficit from MODIS data

Monitoring precipitable water vapour in near real-time to correct near-infrared observations using satellite remote sensing

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