Moisture Transport and Other Hydrometeorological Features Associated with the Severe 2000/01 Drought over the Western and Central Canadian Prairies

Liu, Jinliang; Stewart, Ronald E.; Szeto, Kit K.

doi:10.1175/1520-0442(2004)017<0305:mtaohf>2.0.co;2

Cited by 62 publications

(39 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These modes consist of regimes, described by Stocker et al (2001, p. 435) as local maxima in the probability density function of atmospheric fields, and abrupt shifts in those regimes, such as the Pacific decadal oscillation (PDO) or El Niño-Southern Oscillation (ENSO). Such modes may directly affect regional temperatures through advection, adiabatic expansion, and compression (Wallace et al 1996), and affect regional hydrology through alteration of atmospheric moisture transport (Liu et al 2004;Dominguez and Kumar 2005), stormtrack trajectories (Rogers 1997;Favre and Gershunov 2006;Wang et al 2006), and evaporation (Hember et al 2005).…”

Section: Introductionmentioning

confidence: 99%

Effects of Serial Dependence and Large-Scale Tropospheric Circulation on Midlatitude North American Terrestrial Carbon Dioxide Exchange

Hember

Lafleur

2008

Journal of Climate

View full text Add to dashboard Cite

Linear regression was used to relate modes of tropospheric circulation variability to estimates of gross ecosystem production (GEP) and ecosystem respiration (ER) measured at 14 midlatitude North American eddy covariance (EC) towers. The North Atlantic Oscillation (NAO) exhibited a north-south gradient in its effect on fluxes, with negative influence on fluxes at central and northeastern stations and positive influence on fluxes at southeastern stations. During spring, average values of GEP and ER within the northern "cold" sector decreased by 22 and 12 g C m Ϫ2 (18% and 11%), respectively, in response to a unit increase (ϩ1 standard deviation) in the expansion coefficient of the NAO mode. Despite a northward advancement of the "warm" sector during summer, GEP and ER remained negatively correlated with the NAO at northern stations, decreasing on average by 48 and 30 g C m Ϫ2 (8% and 6%), respectively. During spring, the North Pacific Oscillation (NPO) reduced GEP and ER at central and northeastern stations on average by 20 and 7 g C m Ϫ2 (16% and 6%) and increased GEP and ER at southern and west coast stations on average by 53 and 49 g C m Ϫ2 (12% and 17%) in response to a unit increase in the NPO. This pattern persisted into summer, only shifted northward, with flux decreases of 19 and 24 g C m Ϫ2 (3% and 5%) at northern stations and increases of 72 and 82 g C m Ϫ2 (9% and 16%) at central stations. The direction of the flux response in each case was supported by synoptic conditions inferred from composite maps of North American circulation and gridded surface air temperature anomalies. The magnitude and timing of the relationships differed between stations and was attributed to differences in geographic location and plant functional type. Difficulty in the interpretation of significant correlations was attributed to the short sample length of typical EC records and unmodeled variability, including, for example, modulation by the NAO during high NPO. Despite these limitations, long-term monitoring EC stations show promise in characterizing the regional and ecosystem-specific carbon cycle response to low-frequency modes of tropospheric circulation variability and may play a critical role in validating ecosystem model responses to such phenomena.

show abstract

Section: Introductionmentioning

confidence: 99%

Effects of Serial Dependence and Large-Scale Tropospheric Circulation on Midlatitude North American Terrestrial Carbon Dioxide Exchange

Hember

Lafleur

2008

Journal of Climate

View full text Add to dashboard Cite

show abstract

“…Although droughts are common on the prairies little is known about what initiates, maintains and terminates these extreme events (Liu et al 2004). Accurate high resolution soil water monitoring would provide significant insight on drought development, progression and termination.…”

mentioning

confidence: 99%

Improvements to the accuracy of modelled soil water content from the Second Generation Prairie Agrometeorological Model

Gervais¹,

Bullock²,

Mkhabela

et al. 2010

Can. J. Soil. Sci.

View full text Add to dashboard Cite

Gervais, M., Bullock, P., Mkhabela, M., Finlay, G. and Raddatz, R. 2010. Improvements to the accuracy of modelled soil water content from the Second Generation Prairie Agrometeorological Model. Can. J. Soil Sci. 90: 527Á542. The direct measurement of soil water on a regional scale is often not practical due to large instrumental and labour requirements. Alternatively, soil water estimates can be derived using models. The Second Generation Prairie Agrometeorological Model (PAMII) models soil water, crop development and evapotranspiration (ET) in order to derive an estimate of crop water use. The objective of this study was to validate, and if necessary modify, the soil water component of PAMII using weather and soil water data collected from several spring wheat trials in Saskatchewan and Manitoba during the 2003 though 2006 growing seasons. Comparison of modelled and measured soil water values yielded a RMSE of 62 mm. For most site-years, PAMII overestimated soil water during the second half of the growing season, which was caused by an increase in modelled canopy resistance (r c ) before the crop experienced water stress. The r c function was thus modified so that r c would not increase until the soil water content was B0.5 of plant available water. Overall this modification reduced the RMSE from 62 to 56 mm. In addition, modelled soil water was underestimated during periods that experienced consecutive days of precipitation. This was because the model stopped infiltration when the top-zone reached saturation. When modified to allow infiltration to continue independent of the top-zone's water content, the RMSE was further reduced to 53 mm. Overall, both modifications reduced the RMSE of modelled soil water by 9 mm, and this reduction was highly significant (PB0.01).Key words: Prairie Agrometeorological Model (PAMII), soil water modelling, evapotranspiration, Canadian prairies Gervais, M., Bullock, P., Mkhabela, M., Finlay, G. et Raddatz, R. 2010. Ame´lioration de la pre´cision de la teneur en eau du sol e´tablie graˆce au mode`le agrome´te´orologique des Prairies de 2 e generation. Can. J. Soil Sci. 90: 527Á542. Mesurer directement la teneur en eau du sol a`l'e´chelle re´gionale est rarement pratique en raison de l'importance du mate´riel et du travail que cela requiert. Paralle`lement, on peut de´river une estimation de ce parame`tre graˆce a`divers mode`les. Le Prairie Agrometeorological Model de 2 e ge´ne´ration (PAMII) mode´lise la teneur en eau du sol, la croissance des cultures et l'e´vapotranspiration (ET) pour estimer la quantite´d'eau utilise´e par les plantes. La pre´sente e´tude devait valider et au besoin modifier la composante du PAMII relative a`la teneur en eau du sol a`partir des donne´es me´te´orologiques et des releve´s de la teneur en eau recueillis a`l'occasion de plusieurs essais de culture du ble´de printemps effectue´s en Saskatchewan et au Manitoba, durant la pe´riode ve´ge´tative, entre 2003 et 2006. En comparant la teneur en eau du sol mode´lise´e a`celle e´tablie par mesure directe, o...

show abstract

“…Our findings of drier values throughout the atmospheric profile may also be linked to amplification of the westerly flow, due to deepening of the Aleutian Low or cyclone intensification on the East coast of the United States; intensification of the western US ridge steers Pacific low pressure systems northward through Canada, which would effectively block Pacific moisture advection into the western states (Namias, 1983). A study of the 2000/2001 severe drought over western and central Canada also noted pronounced reductions in precipitable water over the region (Liu et al, 2004). Persistence of dry conditions only at lower levels in the profile may indicate changes in synoptic conditions that impede the flow of moisture into the region, such as enhanced westerly or southwesterly wind flow cutting off the flow of Gulf of Mexico moisture into the region (Bryson and Baerreis, 1968;Saleeby and Cotton, 2004;Booth et al, 2006) that feeds convective storm precipitation.…”

Section: Resultsmentioning

confidence: 99%

Vertical moisture profile characteristics of severe surface drought and surface wetness in the western United States: 1973–2002

Garrity

Cerveny

Wentz

2009

Intl Journal of Climatology

View full text Add to dashboard Cite

Drought can be viewed as a three-dimensional phenomenon rather than simply a surface feature. We characterize drought across the western United States from 1973 to 2002 in a three-dimensional context by examining its vertical moisture extent using NCEP/NCAR Reanalysis data derived from rawinsonde moisture profiles. We then apply a discriminant analysis to establish the degree of difference between the vertical moisture profiles of extreme drought and extreme wetness conditions. The mean vertical moisture profiles of dry cases are measurably drier than those of wet regions, particularly at the lower levels of the profile. The discriminant analysis of the 9254 cases indicates that moisture in the lowest (850 hPa) level of the profile is most important in identifying dry versus wet regions, and, consequently, implies a strong influence of convective precipitation in defining surface drought and wet conditions in the study region.

show abstract

Moisture Transport and Other Hydrometeorological Features Associated with the Severe 2000/01 Drought over the Western and Central Canadian Prairies

Cited by 62 publications

References 16 publications

Effects of Serial Dependence and Large-Scale Tropospheric Circulation on Midlatitude North American Terrestrial Carbon Dioxide Exchange

Effects of Serial Dependence and Large-Scale Tropospheric Circulation on Midlatitude North American Terrestrial Carbon Dioxide Exchange

Improvements to the accuracy of modelled soil water content from the Second Generation Prairie Agrometeorological Model

Vertical moisture profile characteristics of severe surface drought and surface wetness in the western United States: 1973–2002

Contact Info

Product

Resources

About