Characteristics of the surface layer above a row crop in the presence of local advection
Fuente:
Redalyc
Gespeichert in:
| 1. Verfasser: | |
|---|---|
| Format: | Artículo científico |
| Sprache: | en |
| Veröffentlicht: |
Universidad Nacional Autónoma de México
2006
|
| Schlagworte: | |
| Online-Zugang: | |
| Tags: |
Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
|
| _version_ | 1876442868227244032 |
|---|---|
| author | P. I. Figuerola |
| author_facet | P. I. Figuerola |
| contents | Characteristics of the surface layer above a row crop in the presence of local advection P. I. Figuerola P. R. Berliner Biología row crop Advection convection In some arid land, the irrigated fields are not contiguous and are surrounded by large patches of bare land.During the summer time and rainless season, the solar radiation flux is high and the surface temperatureduring daylight in the dry bare areas, is much higher than that of the air. The sensible heat generated overthese areas may be advected to the irrigated fields. The crops are usually planted in rows and the irrigationsystems used (trickle) do not wet the whole surface, the dry bare soil between the rows may develop high soilsurface temperatures and lead to convective activity inside the canopy above the bare soil. Advection fromthe surrounding fields and convective activity inside the canopy affect the layer above the crop. We studiedthe surface layer above an irrigated tomato field planted in Israel´s Negev desert. The crop was planted inrows, trickle irrigated and the distance between the outer edges of two adjacent rows was 0.36 m at the timeof measurement. The gradients in temperature and water vapor pressure were obtained at various heightsabove the canopy using a Bowen ratio machine. The residual in the energy balance equation was used as acriterion to determine the equilibrium layer. During the morning, unstable conditions prevail, and the equilibriumlayer was between Z/h ~ 1.9 and 2.4. In some particular circumstances, in the late morning, the bare soilbetween the rows reached extremely high temperatures and during conditions with low wind speeds freeconvection was identified. During these hours the residuals of the energy budget to the heights Z/h = 1.5and 2.4 were significantly different from zero and an extremely large variability was evident for the Z/h = 3.2layer. Local advection took place during the afternoon resulting in an increase in the stability of the uppermostmeasured layer and propagated slowly downwards. The equilibrium layer was between Z/h ~ 1.5 to 2.4. Theresiduals were significantly different from zero for the uppermost layers Z/h = 2.7 and 3.2 during theseperiods. Our findings suggest that the depth and location of the internal equilibrium layer above trickleirrigated row crop fields surrounded by dry bare areas, vary in response to wind speed and the temperatureof the soil in between the rows of the crop. For some time intervals, the computation of fluxes using theconventional flux-gradient approach measurements was not possible. 2006 artículo científico 0187-6236 https://www.redalyc.org/articulo.oa?id=56519202 en http://www.redalyc.org/revista.oa?id=565 Atmósfera application/pdf Universidad Nacional Autónoma de México Atmósfera (México) Num.2 Vol.19 |
| format | Artículo científico |
| id | redalyc_56519202 |
| institution | Redalyc |
| language | en |
| publishDate | 2006 |
| publisher | Universidad Nacional Autónoma de México |
| spellingShingle | Characteristics of the surface layer above a row crop in the presence of local advection P. I. Figuerola Biología row crop Advection convection Characteristics of the surface layer above a row crop in the presence of local advection P. I. Figuerola P. R. Berliner Biología row crop Advection convection In some arid land, the irrigated fields are not contiguous and are surrounded by large patches of bare land.During the summer time and rainless season, the solar radiation flux is high and the surface temperatureduring daylight in the dry bare areas, is much higher than that of the air. The sensible heat generated overthese areas may be advected to the irrigated fields. The crops are usually planted in rows and the irrigationsystems used (trickle) do not wet the whole surface, the dry bare soil between the rows may develop high soilsurface temperatures and lead to convective activity inside the canopy above the bare soil. Advection fromthe surrounding fields and convective activity inside the canopy affect the layer above the crop. We studiedthe surface layer above an irrigated tomato field planted in Israel´s Negev desert. The crop was planted inrows, trickle irrigated and the distance between the outer edges of two adjacent rows was 0.36 m at the timeof measurement. The gradients in temperature and water vapor pressure were obtained at various heightsabove the canopy using a Bowen ratio machine. The residual in the energy balance equation was used as acriterion to determine the equilibrium layer. During the morning, unstable conditions prevail, and the equilibriumlayer was between Z/h ~ 1.9 and 2.4. In some particular circumstances, in the late morning, the bare soilbetween the rows reached extremely high temperatures and during conditions with low wind speeds freeconvection was identified. During these hours the residuals of the energy budget to the heights Z/h = 1.5and 2.4 were significantly different from zero and an extremely large variability was evident for the Z/h = 3.2layer. Local advection took place during the afternoon resulting in an increase in the stability of the uppermostmeasured layer and propagated slowly downwards. The equilibrium layer was between Z/h ~ 1.5 to 2.4. Theresiduals were significantly different from zero for the uppermost layers Z/h = 2.7 and 3.2 during theseperiods. Our findings suggest that the depth and location of the internal equilibrium layer above trickleirrigated row crop fields surrounded by dry bare areas, vary in response to wind speed and the temperatureof the soil in between the rows of the crop. For some time intervals, the computation of fluxes using theconventional flux-gradient approach measurements was not possible. 2006 artículo científico 0187-6236 https://www.redalyc.org/articulo.oa?id=56519202 en http://www.redalyc.org/revista.oa?id=565 Atmósfera application/pdf Universidad Nacional Autónoma de México Atmósfera (México) Num.2 Vol.19 |
| title | Characteristics of the surface layer above a row crop in the presence of local advection |
| topic | Biología row crop Advection convection |
| url | https://www.redalyc.org/articulo.oa?id=56519202 |