# Presentation: 462366

## Water Vapor Profiling from the CoSSIR Radiometric MeasurementsJames Wang/Instrumentation Sciences Branch, Hydrospheric & Biospheric Sciences Laboratory

**Historical Nature of Project: **Retrievals of water vapor profiles from the previous millimeter-wave radiometric
- measurements (with either aircraft or satellite sensors) near the 183.3 GHz water vapor line were limited to an altitude
- range of 0-11 km.
**Objective: **The GSFC’s airborne _Co_mpact _S_canning _S_ubmillimeter-wave _I_maging _R_adiometer (CoSSIR) provides
- additional measurements with 4 channels near the strong water vapor line of 380 GHz, which potentially extends water
- vapor profiling capability up to an altitude of about 15 km.
**Results:  **The figure (next slide) demonstrates CoSSIR’s water vapor profiling capability.  The data were acquired from
- the transit flight on board the ER-2 aircraft from Houston, Texas to Costa Rica on January 14, 2006. Measurements from
- 8 channels at 193.31, 183.33, 183.36.6, 3800.8, 3801.8, 3803.3, 3806.2, and 640 GHz, and at 3 observational
- angles, were used to retrieve water vapor mixing ratios at 1, 3, 5, 7, 9, 11, 13, and 15 km altitudes, as well as total
- precipitable water (TPW).
- The figure displays the variations of these mixing ratios and TPW with latitude.  The mixing ratios measured by the MMS
- (Meteorological Measurement System, owned by NASA/Ames) in proximity to the aircraft (between 17-19 km) and the
- TPW values derived (by Remote Sensing System, Santa Rosa, California) from the near-concurrent TRMM passes
- along the flight path were included for comparison. The CoSSIR retrieved mixing ratios at 3 different observational angles
- are generally in agreement, which implies consistency in radiometric measurements.
- There is an excellent agreement between the TPW values retrieved by the CoSSIR and those derived from TRMM.
- There appears to be a slight correlation between the MMS measured mixing ratios at 17-19 km and
- those retrieved by the CoSSIR in the 9-15 km altitude range.

**Impact Statement:** **Water vapor in the upper troposphere has significant impact on global radiative fields, stratospheric chemistry, and the effect on global climate change.  The new measurements  will enhance studies of such impact.**

## Retrievals of Water Vapor Profiles With CoSSIR Radiometric Measurements

## Objective:  The objective of this work is to measure surface temperature, Ts, of the entire Greenland Ice Sheet (GIS), and individually in its six major drainage basins, and also to analyze extent and duration of seasonal melt. 

**D. K. Hall*, R. S. Williams, Jr.** and  N. E. DiGirolamo+**
***Cryospheric Sciences Branch, NASA/GSFC, **U.S. Geological Survey, +SSAI**
**Historical Nature of Project:**  Previous work has used AVHRR (Advanced Very High Resolution Radiometer) data to study trends of Ts in the Arctic and specifically in Greenland at 6.25-km resolution (see Comiso, 2006), revealing a warming trend from 1981 to the present. In this work, we use higher-resolution MODIS (Moderate Resolution Imaging Spectroradiometer ) land-surface temperature (LST) data products (Wan et al., 2002) at 1-km resolution over the GIS from 2000 - 2006.
**Objective:**  The objective of this work is to measure surface temperature, Ts, of the entire Greenland Ice Sheet (GIS), and individually in its six major drainage basins, and also to analyze extent and duration of seasonal melt.

**Results (Past):  **In previous work, we used the 8-day LST MODIS product at 5-km resolution to measure ice-sheet Ts under clear-sky conditions (Hall et al., 2006). The mean Ts of the GIS is shown in Table 1 as calculated from that product during the most-active part of the melt season, ~May 1 through August 12 of each year (days 121-225).  The mean Ts is highest in 2002 and 2005, in agreement with previous work by other researchers indicating that those were large melt years.
**Results (Present):**  Our new results are derived from 1-km resolution, daily seasonal melt maps for the years 2000 - 2006 (Fig. 1). The year 2006 shows the least amount of melt in terms of melt-season length, followed by 2000. The years 2004 and 2006 show a large areal extent of melt (purple in Fig. 1) in the southern part of the GIS, however that melt lasted only a few days. The yellow, orange and red colors represent more-sustained melting (see Fig. 1 key), and are seen mostly in the years 2002 - 2005, especially in Greenland around the margin of the ice sheet. Also of note is the relatively-large area of sustained melt lasting 46-90 days in the northwestern part of the GIS in 2005, a “warm” year.

**Table 1**: Mean and SD clear-sky Ts (C) of the Greenland Ice Sheet from Hall et al. (2006).

## The lowest interannual variability in mean Ts is in the SE basin of the 6 major basins of the ice sheet, and the highest is in the most-northerly basin. There is no definite pattern of increasing Ts over the study period, though 2000 and 2001 were the years with the lowest mean Ts of the 7 years. In each basin the mean Ts decreased in the 2006 melt season, relative to 2005. 

- Comiso, J.C. (2006) Arctic warming signals from satellite observations, *Weather*, 61(3):70-76.
- Hall, D.K., R.S. Williams, Jr., K.A. Casey, N.E. DiGirolamo and Z. Wan (2006) Satellite-derived, melt-season surface temperature of the Greenland Ice Sheet (2000-2005) and its relationship to mass balance, *GRL, *L11501, doi:10:1029/2006GL026444.
- Wan, Z., Y. Zhang, Q. Zhang, and Z.-L. Li (2002) Validation of the land-surface temperature products retrieved from Terra Moderate Resolution Imaging Spectroradiometer data,  *RSE*, 83:163-180.
- Zwally, H.J., M.B. Giovinetto, J. Li, H.G. Cornejo, M.A. Beckley, A.C. Brenner, J.L. Saba and D. Yi, (2005) Mass changes of the Greenland and Antarctic ice sheets and shelves and contributions to sea-level rise: 1992 – 2002, *Journal of Glaciology,* 51(175):509-527.** **

**Figure 1. **Colors represent melt occurring on 3 or more consecutive days from 2000 to 2006, cloud-cover permitting. (For example, if days 1 and 2 were clear, day 3 was cloudy, and day 4 was clear, this is considered 3 consecutive days.) A land mask is shown in green. The six major drainage basins reported in Zwally et al. (2005) are shown as black lines on each map.

- The lowest interannual variability in mean Ts is in the SE basin of the 6 major basins of the ice sheet, and the highest is in the most-northerly basin. There is no definite pattern of increasing Ts over the study period, though 2000 and 2001 were the years with the lowest mean Ts of the 7 years. In each basin the mean Ts decreased in the 2006 melt season, relative to 2005.
**Future Direction:** Further analysis is ongoing to analyze in detail Ts , timing and duration of melt in each of the 6 basins.

**Impact Statement:**** ****The surface temperature of the Greenland Ice Sheet is one of several indicators of the state of the ice sheet.  Combined with other parameters, surface temperature provides information about the ice-sheet mass balance and thus its potential for contributing to sea-level rise.**

## Ocean-Atmosphere Sensor Integration System (OASIS) Fleet Grows

- John Moisan/Ocean Sciences Branch, Hydrospheric & Biospheric Sciences Laboratory
**Project Introduction:** The OASIS vessel is a surface autonomous platform developed at NASA/GSFC. The vehicles are solar powered, communicate through the Iridium satellite network, utilize a state-of-the-art autopilot software package capable of actively avoiding ships at sea, can accommodate 500 pounds of sensor payload, and are designed for open ocean deployment and survival of hurricane conditions.
**Objective:**  To make measurements on ocean-atmosphere processes that typically are collected in conjunction with a large ship based research activity.
**Project Development: **OASIS I was completed last spring and OASIS II was just recently completed early this fall.   Field testing of the platforms is presently ongoing. Funds are in place to complete fabrication of 6 additional platforms by summer 2007 (OASIS III-VIII).
- The U.S. Coast Guard HQ has recently completed a review of the platform and has passed on its   recommendations for safe autonomous operations of the platforms.
- We have been funded recently under a NASA ROSES call to develop a Telesupervised Adaptive Sensor  Fleet capability with NASA/GSFC Software engineers and Carnegie Mellon University under an ESTO project.
**Future Direction:**  The project has been included also as a potential platform to support the U.S. Surface Ocean Lower Atmosphere Study (SOLAS). A suite of air-sea sensors for heat and gas are being installed into the forward section to support these investigations. Work is underway to field test the capability of a small fleet to dynamically map out small ocean features such as a phytoplankton bloom.
- Additional applications for OASIS are being developed for Cal/Val activities and Hurricane studies.

## Impact Statement: OASIS is capable of making long term in situ observations of fields and processes necessary to support the 

**Impact Statement: ****OASIS**** ****is capable of making long term in situ observations of fields and processes necessary to support the **
**development of next generation satellites and satellite-based algorithms for a wide array of processes not directly observable from **
**space-based platforms**** **