The Adequacy of Urban Weather Observations: A View Based on Oklahoma Mesonet Experiences Ken Crawford, Program Director Integrated Surface Observing Systems NWS Office of Science and Technology Presented at the “Challenges in Urban Meteorology: A Forum for Users and Providers” September 21, 2004

Answers to the Following Questions Are Based Upon: 15 years in planning, operating and maintaining the Oklahoma Mesonet 15 years in planning, operating and maintaining the Oklahoma Mesonet 25 MS theses and Ph. D. dissertations built around data from the Oklahoma Mesonet and produced by my graduate students 25 MS theses and Ph. D. dissertations built around data from the Oklahoma Mesonet and produced by my graduate students 11 years in operating a K-12 outreach program and 8 years in operating an award-winning public safety program — both built around the OK Mesonet 11 years in operating a K-12 outreach program and 8 years in operating an award-winning public safety program — both built around the OK Mesonet 15 years as an operational forecaster for the NWS 15 years as an operational forecaster for the NWS 2-3 years spent in planning COOP modernization and the building of a National Mesonet 2-3 years spent in planning COOP modernization and the building of a National Mesonet

Questions and Answers QUESTION: What are the requirements for timeliness, accuracy, and precision for urban applications of meteorological information? Do current observing systems meet these requirements? Timeliness: 5 minute observations prior to 2010; 1 minute or less for observations from 2010 and beyond Timeliness: 5 minute observations prior to 2010; 1 minute or less for observations from 2010 and beyond Accuracy/Precision: Accuracy/Precision: 1.Temperature — 0.3 ºC & 0.01 ºC 2.Wind Speed — 2% of reading & 0.03 m/sec 3.Wind Direction — 3 º & 0.05º 4.Humidity — 3% & 0.03% NO!! NO!!

Questions and Answers QUESTION: Where current observing systems do not meet urban requirements, which unmet needs have the highest priority? 1. Stations must be properly sited — even urban sites 2. High resolution data are needed — spatial and temporal 3. Numerous variables must be measured — Need more than just temperature, wind and humidity (e.g., must measure components of the surface energy budget; radiometric temperature; air quality observations) 4. Data Quality-Assurance is critical 5. Data must be available in the public domain within 1-2 minutes of its collection

Questions and Answers QUESTION: What are the major challenges in collecting, processing, assimilating, and communicating urban weather observations to meet urban users’ requirements? Collecting: Are we using highly reliable systems that work under the most adverse of conditions (e.g., RF radio links to LETS agencies)? Collecting: Are we using highly reliable systems that work under the most adverse of conditions (e.g., RF radio links to LETS agencies)? Processing: Are we using high-end PCs with multiple units handling distributed tasks? Processing: Are we using high-end PCs with multiple units handling distributed tasks? Assimilating: Have we remembered the ultimate user? Assimilating: Have we remembered the ultimate user? Communicating: Have we remembered the ultimate user? Communicating: Have we remembered the ultimate user?

Questions and Answers QUESTION: Are the education, training and outreach challenges related to weather observations being addressed? No, not really. This process is incredibly uneven across the United States. Two primary weaknesses exist: 1.Data and information are not communicated in a form/format that users need/want. (e.g., all images should be under the control of local users/first responders) 2.Formal training programs are practically non-existent Shameless Commercial: There are some model programs in existence — OK-FIRST is one and it was honored by Harvard University as “one of the five-most innovative programs in American Government” in 2001

We Must Use What We Have More Efficiently For Example…

Mesonet Site Locations “Wheat” Sites “West” Sites “East” Sites The wheat-belt, after harvest, functions like an urban heat island during the afternoon.

SOM Seminar – Matt Haugland Across Oklahoma’s Winter Wheat Belt The Diurnal Cycle of Land-Atmosphere Interactions Reverse Inland “Sea breeze” Circulation COOL WARM HHL HLL Divergence The city-center (i.e., the wheat belt) becomes warm during the afternoon and induces low-level convergence.

SOM Seminar – Matt Haugland Across Oklahoma’s Winter Wheat Belt The Diurnal Cycle of Land-Atmosphere Interactions After Harvest, June (WWB – AC) Diurnal Temperature & Pressure Anomalies The result is an afternoon warm anomaly over the wheat belt and a co-located low pressure anomaly.

Temperature (comparison between Micronet and nearby Mesonet sites) MATT HAUGLAND Pasture-Level Influences Note the cold anomaly mid-way between two Mesonet sites spaced 20 miles apart!

Several trees to the southeast of a site result in low measured values of radiation during the first several hours of the day. Blue line: an unobstructed station The Impact of the Near-Sensor Environment on the Resulting Observations

A large transmission pole to the southeast of a site causes an obstruction to the pyranometer for about an hour each morning. The Impact of the Near-Sensor Environment on the Resulting Observations

Despite a negative wind speed anomaly from the NNW, Bixby has a positive temperature anomaly (4-6 F) with NNW winds. Possible cause: the Tulsa metro area is NNW of Bixby. But the wind obstructions appear to cause large negative temperature anomaly when wind does not come from Tulsa. Notice a warm spike with west winds - another town is upstream!

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