JEROME PATOUX
DEPARTMENT OF ATMOSPHERIC SCIENCES
UNIVERSITY OF WASHINGTON, SEATTLE

BOUNDARY LAYER MODELING

Our research group continues and extends the long legacy of boundary layer modeling at the University of Washington, from Robert Fleagle and Joost Businger to Robert A. Brown, Kristina Katsaros, W. Timothy Liu, Gad Levy, Ralph C. Foster, Suzanne Dickinson, Lixin Zeng, Bart Brashers, and myself. The current version of our UWPBL model draws from modified Ekman dynamics in the midlatitudes and mixed layer modeling in the tropics. It consists of a suite of codes and subroutines to:
1 - Calculate the surface stress and surface wind from a value of the geostrophic wind at the top of the boundary layer (aka, the "direct model").
2 - Calculate the geostrophic wind from a value of the surface wind (AKA, the "inverse model").
3. Calculate the surface pressure pattern corresponding to a swath of satellite surface wind vectors or to a grid of NWP model analysis of surface wind vectors (aka, the "pressure retrieval model").

OCEAN VECTOR WINDS

The University of Washington Planetary Boundary Layer (UWPBL) model has been used extensively to produce geostrophic and gradient wind fields, as well as surface pressure fields from scatterometer surface wind measurements. These fields can be used to calculate a new set of surface wind vectors and improve the original satellite wind fields by reducing directional errors due antenna geometry and rain.

As part of the International Ocean Vector Wind Science Team, we propose methodologies for calibrating, validating, and improving ocean vector wind data sets from an atmospheric perspective, while also using ocean vector winds in various applications.

SYNOPTIC MIDLATITUDE AND TROPICAL METEOROLOGY

The combination of global, high-resolution satellite wind measurements, planetary boundary layer modeling, and wind partitioning offers a new insight into the kinematics and dynamics of various phenomena, such as [of particular interest in our past, current, and future research] fronts and frontal waves (developing on the trailing cold front of mature systems), extreme weather events (e.g., "bombs"), the baroclinic signature of SST fronts on the surface wind field and midlatitude cyclones, tropical cyclogenesis, inertial instabilites at the equator, and wind bursts and convection associated with the MJO.

In these images, the structure of primary and secondary midlatitude cyclones is revealed in the surface pressure and wind divergence, including T-bone structures.

There is evidence that western boundary currents, in particular the Gulf Stream in the North Atlantic Ocean and to some extent the Kuroshio in the North Pacific Ocean, influence the mean position of the storm tracks. They imply a particular spatial distribution of sea-surface temperature, the presence of a sea-surface temperature front, and a transport of heat from the tropics into the midlatitudes that affect stratification and baroclinicity in the boundary layer, and therefore influence the development of midlatitude disturbances. However, these surface processes compete with the upper-levels in driving cyclogenesis and cyclone intensification. We are therefore developing strategies to analyze and separate the effects of surface and upper-level processes, with particular attention to latent heat fluxes at the air-sea interface, horizontal transport of moisture, and pre-conditioning of the boundary layer, and advection of absolute vorticity at upper-levels. Such strategies include cyclone tracking and upper-level trough tracking, conditional statistical analysis, numerical modeling, and backward trajectory analysis.

In the tropics, , and in particular in the Indian Ocean/Western Pacific Ocean, two phenomena are of interest: (1) inertial instabilities and the corresponding displacement of the ITCZ and convection, with implications for our understanding of the Indian monsoon and tropical cyclone development; and (2) westerly wind bursts associated with the Madden-Julian Oscillation (MJO), in which individual convective (convergent) elements can be observed to travel westward while the envelope containing those convective elements progresses eastward on time scales of 50 to 60 days. We approach both problems with a combination of satellite wind, SST, rain and liquid water content data analysis, a wind partitioning technique separating irrotational and non-divergent components, and boundary layer modeling.

NEAR-REAL-TIME APPLICATIONS

Sea-level pressure retrieval and its by-products can be beneficial to weather forecasters, as we have shown at the Ocean Prediction Center, where forecasters were using QuikSCAT-derived products to guide the issuance of wind advisories and warnings. We are currently transitioning to other capabilities using ASCAT and hopefully Oceansat-2 in the near future.

Satellite-derived surface products were also made available to weather forecasters during the T-PARC and ITOP field campaigns to help with the identification of weather systems of interest and the deployment of planes, ships, and other measuring resources.

We are currently developing new products for the validation and interpretation of SAR-derived winds in hurricanes.

PUBLICATIONS

• Patoux, J., and R.C. Foster, 2012: Cross-validation of scatterometer measurements via sea-level pressure retrieval, IEEE TGARS, 50(7 PART1):2507-2517.
• Patoux, J., R.C. Foster and R.A. Brown, 2010: A method for including mesoscale and synoptic-scale information in scatterometer wind retrievals, Journal of Geophysical Research, 115, D11105, doi:10.1029/2009JD013193.
• Levy, G and J. Patoux, 2009: Indian Ocean near-equatorial symmetric stability from satellite observations: An elusive connection to atmospheric convection, Int. J. of Rem. Sensing, in press.
• Booth, J., L. Thompson, J. Patoux, K. Kelly and Suzanne Dickinson, 2009: The signature of the midlatitude tropospheric storm tracks in the surface winds, Journal of Climate, 23, 1160-1174.
• Carrère, L., F. Mertz, J. Dorandeu, Y. Quilfen and J. Patoux, 2009: Observing and studying extreme low pressure events with altimetry, in Sensors, Special Issue "Ocean Remote Sensing", 9(3), 1306-1329, doi:10.3390/s90301306.
• Patoux, J., X. Yuan and C. Li, 2009: Satellite-based midlatitude cyclone statistics over the Southern Ocean. Part I: Scatterometer-derived pressure fields and storm tracking, Journal of Geophysical Research, D04105, doi:10.1029/2008JD010873.
• Yuan X., J. Patoux and C. Li, 2009: Satellite-based midlatitude cyclone statistics over the Southern Ocean. Part II: Tracks and surface fluxes, Journal of Geophysical Research, D04106, doi:10.1029/2008JD010874.
• Patoux, J., R.C. Foster and R.A. Brown, 2008: Evaluation of scatterometer-derived oceanic surface pressure fields, Journal of Applied Meteorology, 47, 835-852.
• Von Ahn, J. M., J. M. Sienkiewicz, and J. Patoux, 2006: A comparison of sea level pressure analyses derived from QuikSCAT winds to manual surface analyses produced in the NOAA Ocean Prediction Center, in Weather and Forecasting Proceedings.
• Patoux, J., G.J. Hakim and R.A. Brown, 2005: Diagnosis of frontal instabilities over the Southern Ocean, Monthly Weather Review, 133, 863-875.
• Patoux, J., 2004: UWPBL 4.0, the University of Washington Planetary Boundary Layer (UWPBL) model, University of Washington, 77 pp.
• Patoux, J., R.C. Foster and R.A. Brown, 2003: Global pressure fields from scatterometer winds, Journal of Applied Meteorology, 42, 813-826.
• Patoux, J. and R.A. Brown, 2002: A gradient wind correction for surface pressure fields retrieved from scatterometer winds. Journal of Applied Meteorology, 41, 133-143.
• Patoux, J. and R.A. Brown, 2001: Spectral analysis of QuikSCAT surface winds and two-dimensional turbulence. Journal of Geophysical Research, 106, D20, 23,995-24,005.
• Patoux, J. and R.A. Brown, 2001: A scheme for improving scatterometer surface wind fields. Journal of Geophysical Research, 106, D20, 23,985-23,994.