{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

FindellEltahir-03-US

FindellEltahir-03-US - 570 JOURNAL OF HYDROMETEOROLOGY...

Info icon This preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
570 V OLUME 4 J O U R N A L O F H Y D R O M E T E O R O L O G Y q 2003 American Meteorological Society Atmospheric Controls on Soil Moisture–Boundary Layer Interactions. Part II: Feedbacks within the Continental United States K IRSTEN L. F INDELL Geophysical Fluid Dynamics Laboratory, Princeton University, Princeton, New Jersey E LFATIH A. B. E LTAHIR Parsons Laboratory, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts (Manuscript received 6 March 2002, in final form 26 November 2002) ABSTRACT The CTP-HI low framework for describing atmospheric controls on soil moisture–boundary layer interactions is described in a companion paper, Part I. In this paper, the framework is applied to the continental United States to investigate how differing atmospheric regimes influence local feedbacks between the land surface and the atmosphere. The framework was developed with a one-dimensional boundary layer model and is based on two measures of atmospheric thermodynamic properties: the convective triggering potential (CTP), a measure of the temperature lapse rate between approximately 1 and 3 km above the ground surface, and a low-level humidity index, HI low . These two measures are used to distinguish between three types of early-morning atmospheric conditions: those favoring moist convection over dry soils, those favoring moist convection over wet soils, and those that will allow or prevent deep convective activity, independent of the surface flux partitioning. Analyses of multiyear CTP-HI low scatterplots from radiosonde stations across the contiguous 48 United States reveal that during the summer months (June, July, and August) positive feedbacks between soil moisture and moist convection are likely in much of the eastern half of the country. Over the western half of the country, atmospheric conditions and the likelihood of moist convection are largely determined by oceanic influences, and land surface conditions in the summer are unlikely to impact convective triggering. The only area showing a potential negative feedback is in the dryline and monsoon region of the arid Southwest. This potential arises because of the topography of this and surrounding regions. A relatively narrow band of stations lies in between the eastern and western portions of the country, in some years behaving like the stations to the west and in other years behaving like the stations to the east. 1. Introduction a. Motivation Feedbacks from the earth’s surface to the atmosphere are an instrumental part of global climatic processes. Extensive research on the El Nin ˜o–Southern Oscillation phenomenon connects anomalous sea surface temper- atures (SSTs) in the eastern Pacific Ocean with dramatic shifts in weather patterns over much of the globe. Like SSTs, vegetation cover and soil moisture content control the partitioning of energy fluxes at the earth’s surface, and, like SSTs, land surface conditions in some regions yield more significant feedback influences than others.
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern