Global positioning system radio occultation (GPS RO) refractivity data obtained from the first Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) for the years 2007 to 2012 were used to estimate an overall climatology for the height of the marine boundary layer (MBL) over the central North Pacific Ocean including the Hawaiian Island region (10°N-45°N; 125°W-175°W). The trade wind days are identified based on the six-year National Centers for Environmental Prediction (NCEP) global analysis for the same period. About 87% of the RO soundings in summer (June-July-August, JJA) and 47% in winter (December-January-February, DJF) are under trade wind conditions. The MBL height climatology under trade wind conditions is derived and compared to the overall climatology. In general, MBL heights are lowest adjacent to the southern coast of California and gradually increase to the south and west. During the summer (JJA) when the northeasterly trade winds are the dominant surface flow, the median MBL height decreases from 2.0 km over Kauai to 1.9 km over the Big Island with an approximate 2 km maximum that progresses from southwest to northeast throughout the year. If the surface flow is restricted to trade winds only, the maximum MBL heights are located over the same areas, but they increase to a median height of 1.8 km during DJF and 2.1 km during JJA. For the first time, the GPS RO technique allows the depiction of the spatial variations of the MBL height climatology over the central North Pacific.

A network of 40 real-time, automated atmospheric monitoring stations was deployed in Oklahoma City and officially commissioned on 8 November 2008: the Oklahoma City Micronet (OKCNET). The Oklahoma City Micronet includes 36 stations mounted on traffic signals which utilize the Vaisala WXT510 sensor. As part of the design of the WXT510, an impact sensor is utilized for the collection of rainfall observations. Prior to deployment in Oklahoma City, an array of 33 WXT510 sensors were deployed at the OKCNET intercomparison facility and compared with traditional instruments used to measure rainfall including tipping bucket rain gauges and a Geonor weighing gauge. The results of the comparison revealed that a consistent, linear bias was present between the WXT510 sensors and the traditional gauges whereby, on average, the traditional gauges measured approximately 26% less precipitation than the WXT510 sensors. In addition, the variation in recorded rainfall between WXT510 sensors was consistent with that recorded by the tipping bucket gauges. As such, a correction was developed using the WXT510 and tipping bucket data. This correction was applied to the WXT510 rainfall observations and cross-verified using the Geonor gauge data. The overall result of the study yielded a bulk correction that can be applied to rainfall observations recorded by the WXT510 to greatly improve the accumulated rainfall values. This correction is designed to improve the overall accuracy of the observations without specifically calibrating each individual WXT510 sensor and is valid regardless of rainfall intensity, length of the precipitation event, seasonal characteristics of the rainfall, or rainfall type (i.e., stratiform, convective, etc.).

Abstract. In this study, high-resolution radiosondes from the MAGIC field campaign and ERA5 global reanalysis data are used to assess the elevated ducting layer characteristics along the transect over the northeastern Pacific Ocean from Los Angeles, California to Honolulu, Hawaii. The height of the planetary boundary layer (PBLH) increases as the strength of the refractivity gradient and resultant ducting decrease from east to west across the analysis transect. The thickness of the ducting layer remains remarkably consistent (~110 m) in the radiosonde data. On the other hand, the ERA5 generally resolves the ducting features well but underestimates the ducting height and strength especially over the trade cumulus region near Hawaii. A simple two-step end-to-end simulation is used to evaluate the impact of the elevated ducting layer on RO refractivity retrievals. A simple two-step end-to-end simulation is used to evaluate the impact of the elevated ducting layer on RO refractivity retrievals. A systematic negative refractivity bias (N-bias) below the ducting layer is observed throughout the transect, peaking approximately 70 meters below the PBL height (−5.42 %), and gradually decreasing towards the surface (−0.5 %). Further, the underestimation of the N-bias in the ERA5 data increases in magnitude westward and while the correlation of the N-bias with the minimum gradient and sharpness are all strong; there is no evidence of zonal dependence.